Overheat immediately after start up

[JustAWhisper]

I didn't think it was a system bleed issue, as the water pump was changed (replaced with OE) several months ago when it was colder, but I also haven't been driving the car much so I went ahead and bled the system this morning. Coolant level was fine and I didn't really see any bubbles come out, but I ran errands afterward and had no issues. Ambient temps were not as a high as yesterday (~100 vs 107), so it's hard to be sure if the problem is really fixed, but it looks somewhat promising. I'll check later to see if the coolant level went down at all and see if the issues comes back when it gets really hot again.

[sapote]

When in doubt, grab the radiator lower hose which tells you if system was properly bled and good coolant flowing through radiator. Doing this costs only 2 cents.

[bigjae46]

Make sure you turn on the heater to open the water valve.

There is a valve on the driver’s side which controls flow through the heater core. When you drain the coolant system, you’ll drain some out of the heater core loop which creates an air pocket.


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[TexaZ3]

Try Evans waterless coolant.

[Obioban]

Try Evans waterless coolant.

I run that in the suburban, as it's lower effort and no pressure (so no stress on everything else), but it's worse at cooling than traditional coolant-- so a terrible idea for an overheating car.

[TexaZ3]

I run that in the suburban, as it's lower effort and no pressure (so no stress on everything else), but it's worse at cooling than traditional coolant-- so a terrible idea for an overheating car.

Not unless the overheating is a result of water vapors and air trapped in the system. But I agree, it is worse at cooling than regular coolant - though not by much.

[JustAWhisper]

It's not an air bubble. After re-bleeding the system, the water level did not go down at all. I haven't seen the overheating resurface but that's because it hasn't been as hot.

My working theory is that the clutch fan is just starting to fail, but I'm going to have a friend read my codes first.

[sapote]

My working theory is that the clutch fan is just starting to fail, but I'm going to have a friend read my codes first.

Did you try to find out how hot is the rad lower hose?

[JustAWhisper]

So, after reading codes the car is throwing an "Engine Temperature Implausible," which I guess means that the DME is seeing conflicting information, which points to a sensor issue. The lower radiator hose sensor was replaced a couple years ago, which makes the main engine temp sensor under the intake manifold the more likely culprit, but it's a massive pain to get to.

Is there anything else that could generate this code that I should check first before pulling the intake manifold off?

[Lukem3]

So, after reading codes the car is throwing an "Engine Temperature Implausible," which I guess means that the DME is seeing conflicting information, which points to a sensor issue. The lower radiator hose sensor was replaced a couple years ago, which makes the main engine temp sensor under the intake manifold the more likely culprit, but it's a massive pain to get to.

Is there anything else that could generate this code that I should check first before pulling the intake manifold off?

https://www.m5board.com/threads/whic...ty-etc.191708/

Either top sensor or thermostat from the looks of it

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[sapote]

which makes the main engine temp sensor under the intake manifold the more likely culprit, but it's a massive pain to get to.

It should be on the big aluminum pipe and toward the front near the water pump. I thought it is easier to get to as compared to non-M engine.

[JustAWhisper]

https://www.m5board.com/threads/whic...ty-etc.191708/

Either top sensor or thermostat from the looks of it

Yeah, that's what I thought. At least it's only two things to chase. I know I can replace the thermostat easily as I've done it before, at least.

It should be on the big aluminum pipe and toward the front near the water pump. I thought it is easier to get to as compared to non-M engine.

Yeah, I see that on a diagram. Did you remove the entire intake manifold or just the airbox and elbow? If I can get to it without removing the manifold, that would make it much easier.

[Lukem3]

If you don't want to take rhe intake out you should be okay just taking the oil filter housing off. Dont quote me, but looks like there should be roon. You'll need a new gasket obviously

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[heinzboehmer]

The intake manifold is easier to remove than the oil filter housing, imo.

Actually, if I needed to remove the oil filter housing for whatever reason, I would definitely take the manifold off to get some extra space. Once you get the hang of how the clamps work, it takes like five minutes to remove.

[sapote]

The intake manifold is easier to remove than the oil filter housing, imo.

Actually, if I needed to remove the oil filter housing for whatever reason, I would definitely take the manifold off to get some extra space. Once you get the hang of how the clamps work, it takes like five minutes to remove.

+1. One of the good thing on the M3 is ease of Intake removal; I took me about the whole day to do the same thing on non-M car.