Need some help diagnosing a cooling problem

[WMick]

Hi Folks - I'm at a bit of a loss on this one... Hoping you might have some insight to share.
2004 Ram1500, 5.7L 4x4.

Here's the story and symptoms -
Temperature gauge reads good while driving. Slowly wavers a bit around the midpoint on the gauge. But when idling, it creeps up towards the red line. !!!
Less than adequate heat coming from the interior vents.
Getting a cylinder 5 misfire code periodically...
Losing a bit of coolant very very slowly, but can't find a physical leak.
I felt as though I might have a small head or gasket leak, so I treated it with this stuff https://rislone.com/ca/wp-content/uploads/2018/09/31136-PDS.pdf
Also changed thermostat... with 203 deg.
Top Rad Hose from stat is quite hot. Lower Rad hose is quite cold. Rad itself seems quite cold. Fairly certain it's not getting warm enough to engage the fan-clutch.
Parked Truck on incline and went through several cycles of heat-cool-squeeze hoses-start-stop-rev up, etc.. to burp.
Rad is not plugged... I can easily move coolant back and forth through it, when squeezing top hose.
There is no bubbling in reservoir..
No Steam from tailpipe.

Nothing has changed. All symptoms are the same as above.
I read somewhere that there is an air vent port plug somewhere....(removable with allen wrench) but I'll be darned if I can find it... Any help pointing me to it would be great...

I could be wrong, but it seems like I have poor circulation. (if any?)

Pump Problem?? I've changed a few water pumps in other vehicles over the years... typically because they started leaking through the seal.... Not the case this time... Is there a chance that a coolant pump would just stop pumping?? Impeller spun off shaft? I think it's likely the 2004 original pump. Doesn't look like an easy job to replace. I'd like to exhaust other options or prove it somehow before I go tearing into the pump.

Any and all advice will be greatly appreciated....
Thanks Folks,

Wayne

 

[Karlsweg]

Bad clutch fan. With engine running CAREFULLY touch a rolled up newspaper on the mechanical fan and see if it stops. You can google it to see what I’m talking about.

 

[WMick]

Thanks Karlsweg, for the response.
I presume you are suggesting that the fan is not engaging properly.... leading to the overheating.
I want to run something past you... and get your thoughts.. Maybe I have it all wrong???
As I understand it, the clutch fan should engage when the warm air running across it reaches about 170 degrees.
If this is the case, I don't believe mine would even try to engage right now,,,...as the radiator is not getting anywhere close to 170 degrees.... The Radiator is barely warm to the touch when the engine is showing a gauge temperature of normal/high. If it were a bad fan causing my issues, I would expect to have hot water leaving the rad. My outgoing water is quite cool. Seems to me that the heat is not even getting into/through the rad...
Help me understand...
Thanks

 

[Bloody_Knuckles]

It sounds like the water pump isn't pumping.

 

[turkeybird56]

Clogged radiator, not allowing coolant to circulate back to the engine. If thermostat good and pumping to radiator, and bottom (return) hose cold, coolant not going back to the motor. So either one heck of an air blockage and/or bad radiator (All IMHO).....

FROM DIYA SITE:

Why is lower radiator hose cold when motor is at operating temperature?

I replaced thermostat, since the car had a DCT for thermostat. After replacing, the bottom radiator hose is cold. i took the thermostat back out and checked it in a boiling water pot, and it wouldn't open. got a replacement from the store and it opened good in the boiling water. reinstalled and the car still has cold lower radiator hose. car has good heat so i think maybe water pump is bad or radiator is blocked? anyone seen this problem before?


Posted by jtom617 on Jan 16, 2016

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1 Answer

L Pfaff

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• Ford Master
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Ensure thermostat is installed right side up or it wont allow proper flow. If thermostat is correct other problems could be Air in cooling system, low coolant level, plugged rad internal, water pump failure,coolant flow valve stuck,internal engine combustion leak to cooling system.

 

[RonJon '06]

I'm also thinking it's a bad water pump. Not too difficult of a job on the 5.7L.

 

[WMick]

I'm also thinking it's a bad water pump. Not too difficult of a job on the 5.7L.

I'm definitely leaning in the pump direction as well.... What really has had me stumped is the fact that the truck is really not "overheating" while driving. If I had no pump at all, I'm thinking it would boil over in fairly short order?
Rad seems OK... Two thermostats with same results..., Not enough heat in Rad to engage the fan clutch.
The more I think about it... I am guessing that the pump is moving some fluid, but not quite enough at Idle RPM... (damaged, clogged or loose impeller??) Out on the road with some air cooling assist and with impeller RPM up, it is moving just enough coolant to keep things in check. (We are at freezing temperatures here right now and I'm not trying to tow anything heavy.)

I'm betting on it... I picked up a pump last night... Just contemplating if I have enough time to complete the job in an evening.. I will need to fabricate a spanner wrench to help remove the fan... That will be the easy part. Aside from that, it looks pretty straight forward... Seized and broken bolts are my nemesis...
I will update...
Thanks for now.

 

[Dodge 1500 4X4]

The Lower radiator hose should be warmer it is supplied by the output of the water pump, the upper hose should allot cooler if the radiator is doing its job and the thermostat being open supplies cooler antifreeze to the engine block, is that the original radiator you cannot see the clogged cooling fins, because of all of the dissimilar metals in the cooling system, how is the antifreeze, it should be a 75% AF and 25% water the water in the antifreeze is what dissipates the heat, I don't think your water pump is bad when they are bad AF will be leaking out of the weep hole. get a infrared temp gun it will tell you the temps, also have you pressurized the cooling system and see if it holds pressure I believe 21 psi is the setting
Good Luck hope this helps

 

[crash68]

The Lower radiator hose should be warmer it is supplied by the output of the water pump, the upper hose should allot cooler if the radiator is doing its job and the thermostat being open supplies cooler antifreeze to the engine block, is that the original radiator you cannot see the clogged cooling fins, because of all of the dissimilar metals in the cooling system, how is the antifreeze, it should be a 75% AF and 25% water the water in the antifreeze is what dissipates the heat, I don't think your water pump is bad when they are bad AF will be leaking out of the weep hole.

You have the flow backwards, the upper hose of the radiator will be the hotter of the two. The lower hose feeds the coolant back to the engine/water pump. If the pump sucked the coolant from the top, then if you lost just a little bit of coolant the pump would air lock. A water pump can be bad without leaking.
Coolant is usually mixed at 50/50 unless you need an extended cold weather freeze protect below about -30°F. The higher anti-freeze percentage lowers the heat transfer ability.

 

[WMick]

Update ---- FAIL !!!
Pulled the pump last night... and there seemed to be nothing wrong with it... Thinking (maybe??) slipping on shaft when it get hot? But I doubt it...
Got poking around a bit more.... With Both rad hoses off the pump, I tried blowing through the rad with my mouth... LOTs of restriction... I will know better to try this first next time.

Looking back at my symptoms and initial assumptions.... Squeezing the top hose and having coolant shoot up out of the filler neck at the other end is apparently NOT a good test for rad flow... In hindsight, I was probably squishing the fluid back through the block to the other end of the rad.

By this point, I already had destroyed the box that the pump came in. Decided to go ahead and install the new one anyway... Old spare on the shelf.....
Now I'm Rad shopping.
I like fixing my own stuff because its a learning experience.... Just sucks when I'm "learning" with $200 parts....

PS - Helpful hint for someone attempting a pump replacement for the first time... Trace the new pump out on a piece of cardboard and poke holes in the bolt locations... Insert the bolts in the cardboard map, one by one, as you take them out.. (to get them back in the right spot later)... and DON'T use the brand new pump box for cardboard... (in case you decide to return it.

 

[LoneWolf3574]

This might be a dumb question at this point, but did you ever take a temperature gun and check the temperatures across the radiator? My daughter's car was having temperature issues and I was about to replace the pump when my dad (old school mechanic, ASE master, and a boss with fixing cars) suggested I check the temperature of on each side of the radiator, top to bottom to see if some of the tubes were plugged. Sure enough, I found the lower 1/3 of the radiator ~30F cooler than the rest of it, new radiator, problem resolved.

 

[pacofortacos]

No sense in keeping the old water pump, the seals usually aren't any good after they dry out on a used pump - at least in my experience. And it is way to much work to put a pump in and have it leak right away.

 

[WMick]

This might be a dumb question at this point, but did you ever take a temperature gun and check the temperatures across the radiator? My daughter's car was having temperature issues and I was about to replace the pump when my dad (old school mechanic, ASE master, and a boss with fixing cars) suggested I check the temperature of on each side of the radiator, top to bottom to see if some of the tubes were plugged. Sure enough, I found the lower 1/3 of the radiator ~30F cooler than the rest of it, new radiator, problem resolved.

Nope - Never thought of that... But I will next time.... Good idea
Thanks

 

[WMick]

Update...
Amazing the difference a good Rad makes.... Changed it last night... and now I cant even force the thing to overheat with cardboard covering the rad.

Interesting Chat with the Rad Repair guy... (where I bought the new rad)....
He showed me spots on my old rad where it looks like calcium bleeding around the ends of some tubes... He said that is a likely precursor to some leaks, even if it weren't plugged...
Also showed me a heater core that they cut in half.... Completely plugged "Solid" with this Calcium type stuff.
He said once a tube is actually plugged with no flow, it is very difficult to flush or get things moving again. Heater Cores cost a lot more to replace at the shop than rads.. ($1500)
I asked what a person can do to prevent this type of thing.... (apparently some sort of reaction between the antifreeze and the aluminum engine parts)
He said you cant "stop" it... but you can minimize it by......
1. Do a full flush and replace every 2-3 years.
2. Use proper antifreeze and distilled water when adding.
3. Run your heater often... Even in the summer time.. To keep things circulating through it and not stagnating in one spot for too long...

I think I'm good to go, on this one.. Thanks for all the help...
Wayne