Gremlin in the radiator?!?!?

[CalDad14]

So I feel like I'm hearing a constant humming(whirring, pump motor running, poss. fan spinning, but not rad. fan) from the front of the radiator on the driver side.....

It's not the radiator fan, it's not the A.C., not the defroster.

In regards to the "1st start of the day";
I know what it sounds like when it's really cold or really hot. It's not that.

2017 Ram 1500, 5.7, 6-speed, 392gears. 4×4, approx. 37500kms.

I have been noticing my coolant temp fluctuating from 92°C(197°F), jumps to 101°C(213°C) then is suddenly/very quickly back to 92°C(197°F). It will do that not only driving, but at idle.

When this happens, the oil temp can(not every time), also fluctuate w/the coolant temp. 93°C(199°F) - 99°C(210°F) - 93°C(199°F).

After five days of this, I started to get a "low oil pressure" message flash(4 a split sec.) on the 1st start up of the day and only the 1st start of the day. Message immediately goes away, oil pressure gauge is right where it usually is upon fire up. Running RP 5-20, oil looks good, level is nearly perfect. Upper part of the cross hatch area on the dip stick. I got the message 5 consecutive days in a row. Didn't get it this morning.

No check engine light. It's kind of frustrating, cause the truck is running really good. But I still feel like somthing just isn't right.

Any ideas are welcomed. Thanks guys.

 

[mikeru]

I have no idea about the noise. It's difficult to troublshoot anything remotely, especially sounds. Especially when you don't even include a sound clip or video.

It's normal for oil temp to track with coolant temp. The temps you posted don't seem unusual. What are your concerns with that?

Your oil pressure sending unit might be going out. Installing a temporary oil pressure gauge would be conclusive on whether your oil pressure really is dropping low enough to trigger a CEL. You could also just inspect the sending unit. Oil on the connector side usually indicates that it's bad or on its way out.

 

[Burla]

So my guess what you are trying to ask is can a failing water pump be the cause of a low oil pressure reading, because in your estimation there is no way it can be true. I don't the answer, maybe.

Go get rmi 25 and run it through your cooling system and check the overflow tank, if there is slime or gel this WILL remove it and deposit it in over flow. Also, run your heater and make sure this is getting through heater core. Replace thermostat, the whining can be the water pump, maybe this will free it up, and I say maybe. This is the cheap way forward and in theory might help if your theory is true that something in the cooling system is choking the engine creating an oil pressure issue, which is a little thin if I am being honest. There is no downside to adding rmi 25 and replacing t stat, these likely should be done anyhow.

 

[CalDad14]

I did make a video, but you can't hear the noise in said video! So I didn't post it.

In regards to coolant & oil temps. Yes, I am accustomed to seeing them change/track in unison. Just not so dramatically, that is my concern.

 

[StateOfMind]

I am following this thread, as I love a mystery. My big question is how do you only rack up 3300 miles a year?!?
Hope this gets sorted for you

 

[mikeru]

I did make a video, but you can't hear the noise in said video! So I didn't post it.

In regards to coolant & oil temps. Yes, I am accustomed to seeing them change/track in unison. Just not so dramatically, that is my concern.

If you can't hear it in the video, are you sure it's really making noise?

Just kidding (mostly lol). I can't say how much the temps should fluctuate, but there will always be some of that going on. I'd be more concerned if the temps were getting over the 220°F and up range, especially if it's not being used in extreme conditions such as towing heavy up a grade. The temperatures you posted are well within safe limits.

 

[CalDad14]

It's been awhile!...... Here's a quick video of what happens upon the first start up of the day. Watch for the "low oil pressure" message that pops up for just a split second. Also, I've noticed that, when cold, on start up, my Coolant & Oil temp gauges start at 40°C every single time. I find that, curious. Another thing, I don't get a trans temp reading until after the engine starts. I can't recall if that's always how it's been?

Can someone confirm that's how it's supposed to be, is that how your guys' 4th gens temp readings work, pre-ignition as well? Thanks.

https://photos.app.goo.gl/ZQrcxQjVE6uvsymm7

 

[indept]

Found it

 

[Atcer2018]

It's been awhile!...... Here's a quick video of what happens upon the first start up of the day. Watch for the "low oil pressure" message that pops up for just a split second. Also, I've noticed that, when cold, on start up, my Coolant & Oil temp gauges start at 40°C every single time. I find that, curious. Another thing, I don't get a trans temp reading until after the engine starts. I can't recall if that's always how it's been?

Can someone confirm that's how it's supposed to be, is that how your guys' 4th gens temp readings work, pre-ignition as well? Thanks.

https://photos.app.goo.gl/ZQrcxQjVE6uvsymm7

On my 2018 the coolant and oil temps always start out at 72F regardless of outside or actual fluid temps. I do get a transmission temp before startup but it’s always at 40F if I recall correctly. I have the larger evic dash display so that may be the reason I get a pre ignition transmission temp reading.

Your truck sounds like the fan is running on startup. Open the hood and physically look to see if it’s spinning as that drone sounds like the fan. I have an electric fan and it doesn’t spin on cold start. A mechanical fan may have a bad fan clutch but I have no experience so I’m no help with that.

The fluctuations in temp in your first post are normal. The oil temp will always lag slightly behind the coolant as oil is slower to heat up or cool down than antifreeze and water. It absorbs and dissipates heat slower. It’s not unusual to come to a stop and your coolant temps rise by 10 degrees and as soon as you start to move forward air crosses the radiator and cools the liquid inside down as it flows through the system. None of your coolant or oil readings are outside of the normal temperature range.

Have you had work done on the cooling system? There may be air trapped inside the closed system creating air pockets. The air pockets can cause sudden movements in the temp readings. Have you tried bleeding the thermostat or using a burp funnel on the radiator cap opening.

At this point I’d be more concerned about the low oil pressure warning.

 

[CalDad14]

Well I finally had a tech agree with me that the fluctuations I'm seeing aren't normal. Recommended we replace the thermastat. Which we did. This was the outcome. Sorry, video not great.

I'm starting to think it's the oil cooler, oil pressure sensor, oil temp sensor?...........
Since this issue has started(end of March), I can hear a fan that is constantly running in the front of the rad. Just a quiet fan constantly running, and has been for months now, along w/the random "low oil pressure" messages upon the 1st start up of the day. It's not the loud fan that comes on when the truck is really hot.

If anyone can give their knowledge on how the radiator could affect the oil pressure, oil pressure sensor and oil temp or vise-versa? The outside temperature doesn't matter in regards to the fan I hear, or the coolant temp yo-yo'ing. Thanks guys.

New video by T T

photos.app.goo.gl

 

[Atcer2018]

I watched your video and I'm not seeing any temps out of the ordinary. I’m down in the states so my metric conversions aren’t great but your truck seemed to be running about 96c or 204F. The stock thermostat is 204 iirc. Under acceleration it rose to about 100C or 212F which is normal. After you stopped accelerating temp returned to 96C with a 204f thermostat which would be normal.

Oil temps are always going to be slower to respond than the coolant temp. Once warmed up the oil temp will run as much as 10 degrees higher than coolant.

Your oil pressure was in the 380-400Kpa range or 54-59psi which would be about right under load.

In your first video the fan noise could be heard and I have no idea what that is about. Maybe a 5.7 owner can shed more light on the fan issue as I believe the newer 5.7 trucks have both an electric fan and a mechanical fan.

As far as your temps and oil pressure on the video it appears pretty normal. It’s also normal for oil pressure and temp along with coolant temp to fluctuate depending on speed and load. For example, It’s 91f or about 32c here today and my truck was cruising along with the AC on at 85kmh reading the standard temp of 204f to match the thermostat. I encountered a long hill with a steep grade and the temp climbed to 220f while accelerating to about 100kmh. Going back down the hill on the other side the temp fell to 206f in less than a minute.

 

[BadHemi2014]

Frankly everything looks and sounds perfectly normal to me. In fact that's one of the quietest hemis I've heard.
Mind often gives that split second low oil pressure warning. I always assumed it was basically a glitch, a lag in signal where the oil pressure is low for an instant before the engine starts. The coolant and oil temp fluctuations seem fine.
Mine is a 2014 with about 139K miles, 33K of those I've put on myself over the past 5 years.
I think you're probably fine, honestly.

 

[CalDad14]

Gremlin is alive and well.

The "low oil pressure" message that, up until this point, I only ever saw on the first start up of the day. Didn't see for about a month. Well, it popped back up, again, just for a split second. But this time well after the truck was warmed up. Oil & filter are brand new.

It's not the rad. It's clear, not gummed up in any way. I feel the fluctuating coolant temps is a by-product of whatever is not operating properly in the oil cooling system.

I feel the "low oil pressure" message and the electric fan I can hear running all the time and never turns off unless you turn the engine off and let it cool down, are directly related. That fan kicks on once the coolant temp hit's 57°C(135°F), or the oil temp goes above 40°C(104°F). I don't know which, but one of those is activating that fan! I've been taking notes!

A couple weeks ago we did a trip to the lake, super hot outside. The oil temp hit 104°C(219°C), wasn't even going that fast. 125km/h(77mph) to pass. The faster I drove the hotter the oil temps would get. Yes, I know it sounds like that's how it should work! But I've run the truck at 80mph, middle of summer plenty of times, and the oil temp has never gone above 96°C(204°F). Also, I felt like if I didn't slow down, the oil temp would've kept climbing. Kind of feel like that's what I might have to do just to get a check engine light to trip???

The outside ambient temp nor the speed I'm travelling at isn't affecting the coolant temp fluctuations. Whether it's 5°C(41°F) or 35°C(95°F) outside, whether I'm travelling at 30km/h(18mph) or 110km/h(68mph) the coolant temp fluctuations are the same. But the outside ambient temp and speed have a great affect on the oil temps.

I feel the oil cooler is possibly someway involved in this. If someone could give me some insight on how the oil cooler operates in regards to the electric fan I hear running basically all the time. Does the oil cooler work in tandem with the radiator? Is the oil cooler it's own entity all together? How does the oil pressure sensor work? Is the oil pressure sensor and temp sensor combined as one unit? Are they separate? How does one work with other, and do they have anything to do w/the electric fan that is located in front of radiator fan?

Thanks to everyone. Take care.