Coolant system antics

[Oldmactech]

03’ e53 3.0 had head gasket 13k miles ago. Recently getting low coolant warning, comes back 2-300 miles later (doesn’t get lots of mileage .) Top off, move on. Dash temp sensor rock solid straight up.

Wife said a tiny bit of white smoke on cold start. Little stumble on cold start also, goes away on second start.

Noticed upper and lower rad hoses were tight when warm, this morning the rad hoses were slightly less tight but good bit of pressure when I loosened the overflow cap.

Pretty hot where I am, mid 90’s during the day.

Anything I should worry about?


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[80stech]

You probably have a bit of head gasket/cracked head problem.

[Effduration]

Are you sure both your fans are working? Aux fan (comes on with AC) and clutch fan (newspaper test)?

If you are losing coolant, you have a leak and have to find it.


To RULE OUT a head gasket problem, run the car to temp one day, and let it sit overnight with cooling system closed. The next morning, before startup, pull plugs and swab each cylinder looking for coolant. I found coolant in cylinder 6 in this manner.

These cars usually take head gaskets pretty well.. but why did you need a head gasket 13k miles ago?

Btw - 2 months ago, you mentioned a stumble on cold start-up…BUT no coolant loss…did you ever figure it out or is it the same issue?

[Oldmactech]

Originally Posted by Effduration

Are you sure both your fans are working? Aux fan (comes on with AC) and clutch fan (newspaper test)?

If you are losing coolant, you have a leak and have to find it.


To RULE OUT a head gasket problem, run the car to temp one day, and let it sit overnight with cooling system closed. The next morning, before startup, pull plugs and swab each cylinder looking for coolant. I found coolant in cylinder 6 in this manner.

These cars usually take head gaskets pretty well.. but why did you need a head gasket 13k miles ago?

Btw - 2 months ago, you mentioned a stumble on cold start-up…BUT no coolant loss…did you ever figure it out or is it the same issue?

I bought it several years ago with a leaking overflow tank. Thought I could replace the tank and go forward. Tank lasted about 2 hours. Block test revealed head gasket failure. Did the gasket in the driveway, worked fine 13k plus miles. Concerned it has failed again.

Started getting cylinder 5 /6 misfire codes CEL and fuel codes. Replaced coils and both upstream O2’s (bank 1 had a heater not working), and the CEL has stayed off for 40-50 miles.

I will check the viscous fan and the AC fan as suggested.

Thanks all.


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[Oldmactech]

I’m going under it tomorrow to look for leaks, is it odd that the coolant hoses are tight after sitting overnight?


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[80stech]

Have a look at the spark plugs. They will likely tell the story or at least give a clue.

[Oldmactech]

Brief followup, looks like the electric fan is not functioning- comes on with AC right?
And the cold start valve connecting hose was a bit cockeyed- maybe enough to create a stumble?


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[stiubhartach]

The pressure tanks only last a couple of years. It might be going again. Put dye in it and look for the leak with a black light

[Effduration]

Originally Posted by Oldmactech

I’m going under it tomorrow to look for leaks, is it odd that the coolant hoses are tight after sitting overnight?

If hoses are still tight (hard with pressure) after sitting overnight, that is a sign that exhaust gasses are entering the cooling system...

Originally Posted by Oldmactech

Brief follow-up, looks like the electric fan is not functioning- comes on with AC right? And the cold start valve connecting hose was a bit cockeyed- maybe enough to create a stumble?

Yes Aux fan should come on with AC..It may also come one when you unplug the coolant temp sensor in lower radiator hose. It also flickers on at every start-up .

In my case both aux fan and clutch fan had failed, I didn't notice it (no error codes) and the car overheated in traffic while a family member was driving it.

[Oldmactech]

Update: seems aux fan has failed. Put 12v to it, nothing. Ordered a fan. Need to test the switch also.

For the first time the fail fail popped up on my creator 310 Scanner but don’t see a module to test anything.


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