Engine rattle sound

[Redcup]

You only need to leave 1 in on the top and 1 on the bottom on each side,so take the extra 2 out that you left in at the bottom. There's a bleed plug on the engine,takes an 8mm allen to remove if i remember right,park the truck facing uphill or with the front tires on ramps,and slowly back the bleed plug out while it's running,you don't want to pull it right out,just back it out enough a little anti-freeze will bleed past it,and that'll burp the system if it's still got air in it,also run the heater at full temp while you're doing it.
What thermostat are you running,as you can get away with a 192 on a stock truck,with-out tuning,you can even drop down to a 180 with out tuning ,but i'd change the 180 back to a 192 or the factory 203 for the winter if you live where it gets cold

I got the 192* colorstat that ken226 recommended. I'll pull the two slats from the bottom so it will be one on top and bottom. And since it's actually nice out on a day I have off I'll crack the drain plug too. It's on the block right? I don't have the bleed plug on the water pump as a coolant line runs there.

 

[Ken226]

I got the 192* colorstat that ken226 recommended. I'll pull the two slats from the bottom so it will be one on top and bottom. And since it's actually nice out on a day I have off I'll crack the drain plug too. It's on the block right? I don't have the bleed plug on the water pump as a coolant line runs there.

You can bleed it through the temp sensor hole. Pull the sensor, fill till you see coolant come out, then put the sensor back.

 

[Wild one]

I got the 192* colorstat that ken226 recommended. I'll pull the two slats from the bottom so it will be one on top and bottom. And since it's actually nice out on a day I have off I'll crack the drain plug too. It's on the block right? I don't have the bleed plug on the water pump as a coolant line runs there.

Post a picture of the front of your engine,you should have an Allen pipe plug fairly close to the thermostat housing. If you're standing at the front of the truck looking at the engine,it'll be to the right of the thermostat housing
Did you check the thermostat before you installed it , by chucking it in a pot of water on the stove,and using something like a meat thermometer to monitor the water temp of where the thermostat opens.
Just cause it's a new thermostat , doesn't mean it's any good.
Kens idea will also work,just be careful you don't break the wires attached to the sensor, or twist it off in the block.

 

[Redcup]

Post a picture of the front of your engine,you should have an Allen pipe plug fairly close to the thermostat housing. If you're standing at the front of the truck looking at the engine,it'll be to the right of the thermostat housing
Did you check the thermostat before you installed it , by chucking it in a pot of water on the stove,and using something like a meat thermometer to monitor the water temp of where the thermostat opens.
Just cause it's a new thermostat , doesn't mean it's any good.
Kens idea will also work,just be careful you don't break the wires attached to the sensor, or twist it off in the block.

This is what I have. There is a small coolant line that comes out of it. When I bought it it had a nipple where the plug usually is. Found a picture of the pump if that helps. Not 100% exact but shows the connection sticking out.

 

[Wild one]

This is what I have. There is a small coolant line that comes out of it. When I bought it it had a nipple where the plug usually is. Found a picture of the pump if that helps. Not 100% exact but shows the connection sticking out.

On your truck,follow Kens tip of loosening off the temp sensor,but be careful,they are prone to breaking if you go all Bohunk on them

 

[Redcup]

On your truck,follow Kens tip of loosening off the temp sensor,but be careful,they are prone to breaking if you go all Bohunk on them

I'll make sure I am careful when loosening the sensor. Don't need a new problem. I'll report back the outcome.

 

[Ken226]

I'll make sure I am careful when loosening the sensor. Don't need a new problem. I'll report back the outcome.

Even after bleeding the system through the sensor hole,

Also go through the trusty ole 'cap on, pump the upper hose/cap off, top off the radiator' trick a few times. With the engine idling. Until the radiator stays full. I always keep doing it until the coolant is hot enough that I know the thermostat has opened and it's circulating.

It takes me about 2 or three iterations before the radiator stays full.


One time doing that, I was on about the 3rd iteration, when pretty much exactly at 200*F, I put the radiator cap on, and the very first squeeze on the radiator hose I heard a gurgling from back of the engine, then the upper hose just fully collapsed! Like, flat as a pancake!

When I took the radiator cap off, it took another half gallon to fill back up.

 

[Redcup]

Even after bleeding the system through the sensor hole,

Also go through the trusty ole 'cap on, pump the upper hose/cap off, top off the radiator' trick a few times. With the engine idling. Until the radiator stays full. I always keep doing it until the coolant is hot enough that I know the thermostat has opened and it's circulating.

It takes me about 2 or three iterations before the radiator stays full.


One time doing that, I was on about the 3rd iteration, when pretty much exactly at 200*F, I put the radiator cap on, and the very first squeeze on the radiator hose I heard a gurgling from back of the engine, then the upper hose just fully collapsed! Like, flat as a pancake!

When I took the radiator cap off, it took another half gallon to fill back up.

So do you pump the upper hose when it is cold then add fluid? I let the truck warm up and when the t-stat opened up around 193 the squeezed the upper hose. There were a couple big bubbles but it only took maybe a cup of fluid. Cracking the sensor gave me fluid immediately. Nervous about messing with it while it is running as that big ol fan is right there spinning. Not in the mood to recreate maximum overdrive.

After doing the above a couple times I took it on some errands. Still swings between 208 and 220. So far I have bled the system, since replacing the stat, maybe 8 times. This time I parked on a hill and hopped the curb so the radiator cap was the highest point. Oh I use on of those giant funnels that attach to the radiator where the cap goes. I fill it to about a liter. The picture is from a few weeks ago but this is what I use.



Another question. Are my temps normal with a 193* t-stat? Maybe I am chasing nothing.

 

[Wild one]

So do you pump the upper hose when it is cold then add fluid? I let the truck warm up and when the t-stat opened up around 193 the squeezed the upper hose. There were a couple big bubbles but it only took maybe a cup of fluid. Cracking the sensor gave me fluid immediately. Nervous about messing with it while it is running as that big ol fan is right there spinning. Not in the mood to recreate maximum overdrive.

After doing the above a couple times I took it on some errands. Still swings between 208 and 220. So far I have bled the system, since replacing the stat, maybe 8 times. This time I parked on a hill and hopped the curb so the radiator cap was the highest point. Oh I use on of those giant funnels that attach to the radiator where the cap goes. I fill it to about a liter. The picture is from a few weeks ago but this is what I use.



Another question. Are my temps normal with a 193* t-stat? Maybe I am chasing nothing.

Not for a 192 t-stat.Pull the thermostat and check it. These days the chance of a t-stat being good or lasting for more then a couple months depends alot on how lucky you are.It's very common to have to install 3 or 4 thermostats before you finally get a good one.

 

[Ken226]

So do you pump the upper hose when it is cold then add fluid? I let the truck warm up and when the t-stat opened up around 193 the squeezed the upper hose. There were a couple big bubbles but it only took maybe a cup of fluid. Cracking the sensor gave me fluid immediately. Nervous about messing with it while it is running as that big ol fan is right there spinning. Not in the mood to recreate maximum overdrive.

After doing the above a couple times I took it on some errands. Still swings between 208 and 220. So far I have bled the system, since replacing the stat, maybe 8 times. This time I parked on a hill and hopped the curb so the radiator cap was the highest point. Oh I use on of those giant funnels that attach to the radiator where the cap goes. I fill it to about a liter. The picture is from a few weeks ago but this is what I use.



Another question. Are my temps normal with a 193* t-stat? Maybe I am chasing nothing.

My truck runs at 192*, pretty much all the time. When towing a trailer up a hill, it'll get up to 200ish, but drops back quickly when over the top.

It sounds like you've pretty effectively got all the air out of the system. At this point, I very much doubt that this is the issue.

Have you tried flushing your system with CLR or similar?

 

[Redcup]

Not for a 192 t-stat.Pull the thermostat and check it. These days the chance of a t-stat being good or lasting for more then a couple months depends alot on how lucky you are.It's very common to have to install 3 or 4 thermostats before you finally get a good one.

Would really hate to test the t-stat again and have to do the bleeding all over again. Should have just put the old stat back in as it was working fine.

My truck runs at 192*, pretty much all the time. When towing a trailer up a hill, it'll get up to 200ish, but drops back quickly when over the top.

It sounds like you've pretty effectively got all the air out of the system. At this point, I very much doubt that this is the issue.

Have you tried flushing your system with CLR or similar?

I don't have the ability to flush my system. I live at an apartment and there are no spigots for me to hook up to. And the only reason I keep going the rebleed route is that after about a half hour of sitting the upper hose is soft and feels empty. It's rock hard when running though. Also for the first 15-20 minutes the truck runs 188-199. My drive to work is about 40 minutes. Half 55mph then through two stop lights the last half is 65. The first 20ish minutes, even driving back being 70mph for the first stretch, the temps are 188-199. The last 10 minutes the temps slowly climb to the 208-220 range. The first part I can see when the stat opens as it will hit 199~ and then drop down to 189-190 and slowly climb back up. Even when I was bleeding I could never get above 194. It would switch between 194 and 195 a bunch then drop to 189 then just sit at 192. And that's with increasing the idle to 1200-1500. It's almost like the stat just stops working after 20 minutes. The motorad did the same thing but when bleeding I could get it up to 200. it was all over the place. With the one I have no it is 99.9% of the time the same. I thought maybe it was the temps but it does the same thing if it is 60 or 105. And it will never go above 225. a couple weeks ago it would hit 230 but never above.


Oh and the advice to run some injector cleaner got rid of the random misfires. If I monitor for it I get 1 in 3 or 4 random cylinders when starting the first time but never afterwards. So maybe just a fluke. Does Jscan have the ability to monitor and record? Like have it running and go for an hour drive and then review the temps and whatever afterwards.

 

[Wild one]

Would really hate to test the t-stat again and have to do the bleeding all over again. Should have just put the old stat back in as it was working fine.



I don't have the ability to flush my system. I live at an apartment and there are no spigots for me to hook up to. And the only reason I keep going the rebleed route is that after about a half hour of sitting the upper hose is soft and feels empty. It's rock hard when running though. Also for the first 15-20 minutes the truck runs 188-199. My drive to work is about 40 minutes. Half 55mph then through two stop lights the last half is 65. The first 20ish minutes, even driving back being 70mph for the first stretch, the temps are 188-199. The last 10 minutes the temps slowly climb to the 208-220 range. The first part I can see when the stat opens as it will hit 199~ and then drop down to 189-190 and slowly climb back up. Even when I was bleeding I could never get above 194. It would switch between 194 and 195 a bunch then drop to 189 then just sit at 192. And that's with increasing the idle to 1200-1500. It's almost like the stat just stops working after 20 minutes. The motorad did the same thing but when bleeding I could get it up to 200. it was all over the place. With the one I have no it is 99.9% of the time the same. I thought maybe it was the temps but it does the same thing if it is 60 or 105. And it will never go above 225. a couple weeks ago it would hit 230 but never above.


Oh and the advice to run some injector cleaner got rid of the random misfires. If I monitor for it I get 1 in 3 or 4 random cylinders when starting the first time but never afterwards. So maybe just a fluke. Does Jscan have the ability to monitor and record? Like have it running and go for an hour drive and then review the temps and whatever afterwards.

To me it sounds like you might have a dud thermostat,the worst of it,is it's a very common problem.
You can easily do a home cleaning on your injectors.
There's a video in the first post,that's basically a carbon copy of the way i clean them.

Injector cleaning

Supposed to go cold and snow for the next 10 days,so i figured it was a good time to pull the injectors and give them a cleaning.Got them soaking in injector cleaner,where i'll probably leave them for a couple days before using some carb and choke cleaner to wash them out using my old homemade...

www.ramforum.com

When it's time to do the plugs a little maintence on the coils never hurts.

Coil cleaning pics

Yea i know my picture taking abilities suck,lol Hopefully you guys can tell how i go about cleaning up the coils from the pic's. The first pic,is just a pic of everything disassembled.If your truck has the resistors under the spring in the coil towers,you'll want to remove them and clean them...

www.ramforum.com

 

[Ken226]

I don't have the ability to flush my system. I live at an apartment and there are no spigots for me to hook up to.

Hopefully that isn't what it needs then. Perhaps you have a friend or relative?

And the only reason I keep going the rebleed route is that after about a half hour of sitting the upper hose is soft and feels empty.

Coolant is going somewhere. If it goes from full to, not full, then I doubt it's because there is air in the system. Eventually the air would either find it's way out or stay put. A closed system can't keep taking on new coolant, forever. Perhaps test the cooling system for exhaust gasses to make sure there's no head gasket issue. The test kit is fairly cheap at a parts store.

It's rock hard when running though. Also for the first 15-20 minutes the truck runs 188-199

That indicates that the thermostat is fine. It opens when it should and the cooling system keeps up fine, under low load. That's how mine works,all the time.

Yours seems to be getting into trouble when it's been working hard for awhile.

The first part I can see when the stat opens as it will hit 199~ and then drop down to 189-190 and slowly climb back up. Even when I was bleeding I could never get above 194. It would switch between 194 and 195 a bunch then drop to 189 then just sit at 192.

This is the typical asymptotic sinusoidal waveform of a mechanical thermostat chasing a set temp value. It's another indication that the thermostat is working fine. That's exactly what mine does, or any proportional integral derivative style temperature controller.

The motorad did the same thing but when bleeding I could get it up to 200. it was all over the place. With the one I have no it is 99.9% of the time the same. I thought maybe it was the temps but it does the same thing if it is 60 or 105. And it will never go above 225.

That's about when the electric fan kicks on and adds alot of capacity to the cooling system.

These cooling systems are pretty simple and you've already picked the low hanging fruit. There are only a few things left that haven't been definitively verified. Fans or sediment clogged passages.


So thus far, you cooling system works fine when under low load. Under load, it can't quite keep up and heat builds up. But when the electric helper fan kicks on, the extra air flow keeps brings the temps back down to the fans turn-on threshold.

How confident are you that your clutch fan is good? If it were me, I'd be flushing the system with some CLR or RMI25.


I seem to remember @Burla posting a thread about RMI25 coolant system cleaner awhile back. He just leaves it in for awhile, then does a drain and refill later? Perhaps he could chime in, as this might be an option for you.

 

[Redcup]

To me it sounds like you might have a dud thermostat,the worst of it,is it's a very common problem.
You can easily do a home cleaning on your injectors.
There's a video in the first post,that's basically a carbon copy of the way i clean them.

Injector cleaning

Supposed to go cold and snow for the next 10 days,so i figured it was a good time to pull the injectors and give them a cleaning.Got them soaking in injector cleaner,where i'll probably leave them for a couple days before using some carb and choke cleaner to wash them out using my old homemade...

www.ramforum.com

When it's time to do the plugs a little maintence on the coils never hurts.

Coil cleaning pics

Yea i know my picture taking abilities suck,lol Hopefully you guys can tell how i go about cleaning up the coils from the pic's. The first pic,is just a pic of everything disassembled.If your truck has the resistors under the spring in the coil towers,you'll want to remove them and clean them...

www.ramforum.com

Thanks for the tips. I plan on doing a tuneup before winter this year as it's been on my list since I bought the truck. But the truck always has other plans!

Hopefully that isn't what it needs then. Perhaps you have a friend or relative?




Coolant is going somewhere. If it goes from full to, not full, then I doubt it's because there is air in the system. Eventually the air would either find it's way out or stay put. A closed system can't keep taking on new coolant, forever. Perhaps test the cooling system for exhaust gasses to make sure there's no head gasket issue. The test kit is fairly cheap at a parts store.





That indicates that the thermostat is fine. It opens when it should and the cooling system keeps up fine, under low load.




This is the typical asymptotic sinusoidal waveform of a mechanical thermostat chasing a set temp value. It's another indication that the thermostat is working fine. That's exactly what mine does.




That's about when the electric fan kicks on and adds alot of capacity to the cooling system.

These cooling systems are pretty simple and you've already picked the low hanging fruit. There are only a few things left that haven't been definitively verified. Fans or sediment clogged passages.


So thus far, you cooling system works fine when under low load. Under load, it can't quite keep up and heat builds up. But when the electric helper fan kicks on, the extra air flow keeps brings the temps back down to the fans turn-on threshold.

How confident are you that your clutch fan is good? If it were me, I'd be flushing the system with some CLR or RMI25.


I seem to remember @Burla posting a thread about RMI25 coolant system cleaner awhile back. He just leaves it in for awhile, then does a drain and refill later? Perhaps he could chime in, as this might be an option for you.

I asked around and I was able to find a place. It doesn't have a spigot but I can just buy 50 gallons of distilled water and do it that way. Do I need to remove the block plugs? Really worried about damaging the plugs and have a new nightmare. Or would it be worth the $300 and have a shop do it for me?

As for the clutch fan. I was going to replace it when I did the waterpump as it doesn't look the best. The pot metal has corrosion and the metal has some rust. But the $400 price tag stopped me. Is the e-fan mod a better choice/cheaper?

The upper hose thing is odd. I am going to rent the tester and hope it doesn't turn yellow. To me it's like it is losing pressure after a bit of sitting. When the hose was soft and felt empty I bled the system and it took maybe 8oz of coolant. But even before putting the funnel on, the coolant level was just below the hole for the reservoir.

 

[Ken226]

Thanks for the tips. I plan on doing a tuneup before winter this year as it's been on my list since I bought the truck. But the truck always has other plans!


Or would it be worth the $300 and have a shop do it for me?

Only you can answer that. Everyone's financial situation is different. 300$ is a fortune to one man, and the price of lunch for another.

As for the clutch fan. I was going to replace it when I did the waterpump as it doesn't look the best.

There are a few videos on YouTube that'll give you an idea of how to test it. Tried the old newspaper/magazine test?

The pot metal has corrosion and the metal has some rust. But the $400 price tag stopped me.

Test it using a few different methods. That'll help with the risk/reward calculus on spending $235

55056840AC - Genuine Mopar Fan Clutch

MoparPartsGiant.com offers the great deal for genuine Mopar parts, 55056840AC. Fan Clutch for $332.20. All parts are backed by the Mopar's warranty.

www.moparpartsgiant.com

Is the e-fan mod a better choice/cheaper?

I wouldn't bother with that unless you intend to buy a tuner so you can change the temp thresholds. Otherwise, your new e_fan won't come on until the temp hits about 230* anyway.

The upper hose thing is odd. I am going to rent the tester and hope it doesn't turn yellow.

Fingers crossed.

 

[Redcup]

Only you can answer that. Everyone's financial situation is different. 300$ is a fortune to one man, and the price of lunch for another.




There are a few videos on YouTube that'll give you an idea of how to test it. Tried the old newspaper/magazine test?




Test it using a few different methods. That'll help with the risk/reward calculus on spending $235

55056840AC - Genuine Mopar Fan Clutch

MoparPartsGiant.com offers the great deal for genuine Mopar parts, 55056840AC. Fan Clutch for $332.20. All parts are backed by the Mopar's warranty.

www.moparpartsgiant.com

I wouldn't bother with that unless you intend to buy a tuner so you can change the temp thresholds. Otherwise, your new e_fan won't come on until the temp hits about 230* anyway.




Fingers crossed.

Used that tester you mentioned and tested several times. Each time was after a nice drive. Tested using the reservoir as I didn't want to pop the radiator cap and have a mess. Each test came back negative.

Next question; is the brown crap on the coolant dipstick normal? The brown stuff was darker but I cleaned it off when I changed the water pump. From max line to the tip it looked like what the tip does. Is it just from sitting in the reserve for 7 years?

Checked the fan clutch. Crawled under the truck and moved the fan back and forth but it had no play and made no noise. Gave it a good spin and it rotated maybe once. Noticed a bit of resistance when spinning. Then did the newspaper method. Which I though meant going in the newspaper and looking for a new truck Sorry about the fan the ac was on.

After starting the truck up from sitting for maybe an hour. Dash showed 178 when did this. And yes I was able to spin it in reverse.

20250726 135928

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

www.youtube.com

After doing the leak test. So maybe running 10 minutes:

20250726 140048

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

www.youtube.com

If I could I would take everyone out for a beer or pizza that has been helping me. I really appreciate it. I would be lost otherwise or shotgunning parts till it gets better.

 

[Ken226]

Used that tester you mentioned and tested several times. Each time was after a nice drive. Tested using the reservoir as I didn't want to pop the radiator cap and have a mess. Each test came back negative.

Next question; is the brown crap on the coolant dipstick normal? The brown stuff was darker but I cleaned it off when I changed the water pump. From max line to the tip it looked like what the tip does. Is it just from sitting in the reserve for 7 years?

Checked the fan clutch. Crawled under the truck and moved the fan back and forth but it had no play and made no noise. Gave it a good spin and it rotated maybe once. Noticed a bit of resistance when spinning. Then did the newspaper method. Which I though meant going in the newspaper and looking for a new truck Sorry about the fan the ac was on.

After starting the truck up from sitting for maybe an hour. Dash showed 178 when did this. And yes I was able to spin it in reverse.

20250726 135928

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

www.youtube.com

After doing the leak test. So maybe running 10 minutes:

20250726 140048

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

www.youtube.com

If I could I would take everyone out for a beer or pizza that has been helping me. I really appreciate it. I would be lost otherwise or shotgunning parts till it gets better.

My dipstick is clean, except for the Kool aid purple of the coolant.




Also, I put a sharpie mark on a fan blade and gave it a spin. I got half a rotation.

My 2013 has 91,000 miles on it.

 

[Ken226]

Used that tester you mentioned and tested several times. Each time was after a nice drive. Tested using the reservoir as I didn't want to pop the radiator cap and have a mess. Each test came back negative.

Next question; is the brown crap on the coolant dipstick normal? The brown stuff was darker but I cleaned it off when I changed the water pump. From max line to the tip it looked like what the tip does. Is it just from sitting in the reserve for 7 years?

Checked the fan clutch. Crawled under the truck and moved the fan back and forth but it had no play and made no noise. Gave it a good spin and it rotated maybe once. Noticed a bit of resistance when spinning. Then did the newspaper method. Which I though meant going in the newspaper and looking for a new truck Sorry about the fan the ac was on.

After starting the truck up from sitting for maybe an hour. Dash showed 178 when did this. And yes I was able to spin it in reverse.

20250726 135928

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

www.youtube.com

After doing the leak test. So maybe running 10 minutes:

20250726 140048

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

www.youtube.com

If I could I would take everyone out for a beer or pizza that has been helping me. I really appreciate it. I would be lost otherwise or shotgunning parts till it gets better.

I tried the same test. Looks like the results were different. This is about 10 seconds after I started the engine, so completely cold and when the clutch fan should be at it's loosest. The viscous fluid in the clutch is supposed to provide more resistance and less slip, as the engine bay gets hotter:

2013 Ram Clutch Fan Magazine Test

Nope, I cant stop it.

rumble.com

 

[Yardbird]

The reservoir isn't going to give you an accurate test of your last drive.

You need hot water that just came from circulating around in the engine.

 

[Redcup]

My dipstick is clean, except for the Kool aid purple of the coolant.

View attachment 570373


Also, I put a sharpie mark on a fan blade and gave it a spin. I got half a rotation.

My 2013 has 91,000 miles on it.

The coolant came out clear when I drained it to do the water pump. I still have a couple gallons of it in a jug as I don't know where to get rid of it legally... I did look at the previous service records and it had a coolant flush done 12/23 had maybe 90k on the dial. That's also when the previous owner found out the right cv needed to be replaced and he dumped the truck. Maybe the dealer mixed the wrong coolant or what I don't want is that it had oil in it. I'm due for an oil change and plan on sending a sample off to blackstone. I'll also make sure it comes up through the dipstick instead of midstream.

I tried the same test. Looks like the results were different. This is about 10 seconds after I started the engine, so completely cold and when the clutch fan should be at it's loosest. The viscous fluid in the clutch is supposed to provide more resistance and less slip, as the engine bay gets hotter:

2013 Ram Clutch Fan Magazine Test

Nope, I cant stop it.

rumble.com

Just went out and tested the fan again. It's been sitting maybe 4 1/2 hours so stuff was warm not cold. I got the same results you did. I'll test it tomorrow morning before I go anywhere and see if the results are the same. This dang truck I swear is possessed. So is a flush and clutch in my future? Also is it safe to drive till I can afford this stuff? Like a month of to work and back?

The reservoir isn't going to give you an accurate test of your last drive.

You need hot water that just came from circulating around in the engine.

What would be the best way to do it? Take the radiator cap off, withdraw some fluid so the tester doesn't suck it up and, test from there while the truck is running? I know the stat has to open up or I'm testing the radiator. Would the coolant boil over?