Temp-related question

[sixspeedslug]

Car temp. readout goes down when cruising and especially a downhill. It goes back up over a few minutes when throttle becomes more necessary. Never overheats. Just dips when there isn't much load on the engine. I believe it's the water pump or oil/coolant temp. sensor. There is a bit of water pump noise anyways. So I bought both and will be replacing both regardless. Just curious if anyone has any other ideas?

[SoCalZman]

Before my E46, I had a E34 with a similar problem. They found the water pump blades were completely gone. Dodged a bullet.

[sixspeedslug]

Before my E46, I had a E34 with a similar problem. They found the water pump blades were completely gone. Dodged a bullet.

F. I have to drive a bunch today before I have time to do the job tonight. Time to pray to the car-gods for their mercy. Thanks for the story buddy.

[SoCalZman]

Let us know how it looks.

[kayger12]

How about at highway speed? Sounds like maybe thermostat to me.

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[johnrando]

Hmmm. My temp readout varies too. Never figured it was a problem.

[danewilson77]

How about at highway speed? Sounds like maybe thermostat to me.

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+1


Hmmm. My temp readout varies too. Never figured it was a problem.

No way.

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[sixspeedslug]

If cruising at 2-2500rpm it will dip a couple mm..

[3ZHP]

Is the engine taking longer to worm up to the normal mid point operating temp


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[johnrando]

Yes, not the gauge, but if I go to the actual computer temp numbers.

[kayger12]

Yes, not the gauge, but if I go to the actual computer temp numbers.

OP-- are we talking the temp gauge or the hidden menu temp function?

[3ZHP]

I was referring to the idiot gage, if the stat is stuck open it will take longer to get to the mid point


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[Newjack]

How about at highway speed? Sounds like maybe thermostat to me.

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+1

Sounds like your thermostat is sticking open. It will take a while to get warm and then at highway speeds your tempt needle will drop to about 11 o'clock on the gauge.

[LivesNearCostco]

I had a thermostat stuck open. The dash gauge didn't dip but when I used the secret OBC temp display, I could see the coolant temp went as low as 70C when coasting downhill in cool weather. After replacing thermostat, I think the temp usually stayed above 80C even when coasting downhill.

[alexandre]

Running temp is from 90 to just under 100, on my car at least.


iP4S + TT2

[sixspeedslug]

OP-- are we talking the temp gauge or the hidden menu temp function?
When driving, the temp. gauge.

[kayger12]

Thermostat methinks.

[sixspeedslug]

Word big bird

[BimmerWill]

+2 for thermostat... Had same problem myself. New t-stat problem resolved

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