Oil Cooler Question—Functionality

[Fresh1179]

I am trying to convince myself that I messed something up. I replaced my entire cooling system last week and was doing some wiring for my SPAL fan today, which I could not get to function. I believe a helpful member of the community may have pointed me in the right direction to get the fan functioning correctly.

After running the car stationary, and getting the car up to temp, the fan did not cut on so I shut everything down. I was looking around and noticed that the oil cooler was ice cold. The lines to the cooler were cold as well indicating to me that no oil was being diverted to the cooler.

Is this normal? I can’t imagine it is. Could this be caused by something stupid on my part like installing the thermostat upside down. The air conditioner blows tepid air, and I can’t figure out if this is a result of the non functioning fan or some other fault. Any ideas?


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[Lukem3]

The oil cooler is bypassed from the oil filter housing when oil is cold. Once it gets up to a certain temp the oil flows through the cooler. Takes longer to heat up then coolant does

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[Fresh1179]

Yea I guess I was just worried about the recent install. The oil temps had reached around 200, I figured the oil would be diverted at that point.


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[Lukem3]

They should divert at that point. The oil thermostat might be bad or installed incorrectly, or the lines or cooler could be plugged up. Check pids for oil temp and coolant temp. If the sensor isn't reading correctly for either it won't divert the oil to the cooler.

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[Fresh1179]

Hmm. Thermostat hasn’t been acting up but that doesn’t mean anything...the oil cooler has less that 500 miles on it. The lines were functioning perfectly prior to the cooling system overhaul. It’s bothering me haha.

Edit: I will check in INPA to make sure they are reading correctly.

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[Lukem3]

There's an oil thermostat in the oil filter housing, that could be stuck closed. I'll look more into service data when I get home

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[Fresh1179]

I am thinking of the possible causes of not redirecting the fuel to the cooler lines. I have the Bentley manual but I broke my foot so I’m sitting in the damn urgent care.

1) the mechanical thermostat located in the oil filter housing.

2) plug in the lines (has to be impossible, but impossible things happen with this car. However, I did replace the oil cooler 500 miles ago and the lines were fine then.)

3) the oil cooler and with blockage (I can’t imagine that this would be the source given the age of the oil coper?)

4) issue with the temp sensor in lower radiator hose? (Struggling to understand how this could be linked, but am ordering a replacement today)

5) Did I pull an idiot move and install the coolant thermometer upside down. I don’t think I could be that dumb but...maybe.


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[WOLFN8TR]

Did you properly bleed the system? Aluminum radiator’s are a bit more different to bleed than the stock radiator.

I don’t think the Tstat fits properly upside down IIRC. This is the correct position.

[Fresh1179]

Yea I bled the system and have it elevated right now to let the air rise. My main concern is that at no point did any of the oil divert into the oil cooler which has me real worried. I’ll check on air in the system, I just can figure out why that would effect the oil cooler function?


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[Lukem3]

Haven't been able to find much in service data. Did find on an aftermarket website claiming that the stock divertion is still limited when the oil thermostat is wide open. This is what I would do.
Recheck your oil level and coolant level.
Start the car, crack the bleeder screw on the coolant hose. Just to eliminate this and to ensure all your air is out, put heat on max. Once bubbles stop coming out of the bleeder screw and only fluid, close the screw. Shut the car off, let it cool and add more coolant if you lose a lot.
Hook up scanner and find a temp gun. Check temperature readings on your scanner of the coolant and the oil. Make sure both are around atmospheric temperature when fully cold and they climb properly to eliminate a sensor issue. Let the car idle and heat up to operating temp on the coolant. Drive it watching your oil Temps very carefully on the scanner and your tach. If it starts to climb too high pull over and shut the car off. If it stays at correct temp driving around for 15mins, hop out and check both hoses with the temp gun. If there is any noticicable difference in the two hoses I would mostly likely be able to say everything is okay. If the oil temp gets too high or both hoses are the exact same temperature then we can go from there. You can also try to check the oil pressure to make sure the pump is functioning but these engines don't have a port and require drilling and taping ports into your filter housing or buying an aftermarket filter housing.

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[Lukem3]

Bmw states not to idle the car for long periods at a time. Can't find the source but iirc it's because the pump being mechanical, doesn't put out adequate engine oil pressure until off idle. It's a guess but a possibility that just idling the car with the thick oil we use makes it very hard to circulate to the cooler. That's why I would try what I posted above to get a better understanding of what's going on.

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[Fresh1179]

Bmw states not to idle the car for long periods at a time. Can't find the source but iirc it's because the pump being mechanical, doesn't put out adequate engine oil pressure until off idle. It's a guess but a possibility that just idling the car with the thick oil we use makes it very hard to circulate to the cooler. That's why I would try what I posted above to get a better understanding of what's going on.

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I really appreciate the advice. I will follow all the steps and check back in. Hopefully it will all be good news!


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[Lukem3]

Any update? Curious for my own knowledge

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