Car overheats on the highway

[Julien]

I've never had this problem before with my e30s... they all usually overheat at idle (fan issues). When i have the a/c on in my 318i at 60-70mph it starts overheating to 3/4 of the gauge. I have 2 electric fans (a/c fan and a m44 e36 fan) running on high the whole time, new water pump, (used) e36 radiator, all shrouds, and thermostat... all bled properly. Anyone have any ideas? car runs perfectly around town and at idle.


Thanks
Julien
92 318ic

[Mike325]

Could be a collapsing hose. Check out the hoses while someone revs the engine. Must only happen at 3k and up rpm and you are only there for a few seconds while you are around town.

[87-325ic]

is it fine driving it around town?

clogged radiator?
misrouted hose? (it happens)
backwards t-stat?

[Julien]

i'm either thinking clogged radiator or a collapsing hose (but does that really affect cooling that much?)


julien

[jlevie]

The fans aren't a factor at highway speed. And having them on may actually reduce airflow through the radiator. My first suspicion would be a bad thermostat (yes I saw that it was new, but even new parts can fail). I'd pull the stat and test it to see if it is opening. After that, a clogged up cooling system, collapsed hose or a head gasket leak are possibilities.

[Mike325]

A t-stat can be checked by feeling the upper hose to see if it is hot. That will tell you it is opening or not.

[Julien]

the upper radiator hose is hot and under pressure when the car is hot.. and the heat works great, so i guess that rules ou a few things.


Thanks for the help,
Julien

[jlevie]

the upper radiator hose is hot and under pressure when the car is hot.. and the heat works great, so i guess that rules ou a few things.

That only means that some fluid is flowing through the thermostat. It doesn't tell you whether the stat is fully opening at the correct temperature. You find that out by testing the thermostat.

[Mike325]

Yes, it needs to be fully tested in some hot water. Let us know what you find after this.

[bimmer freaks]

overheating

I had a similar problem, and believe it or not it was the fan shroud. It was loose and I secured it down with the necessary clips and the problem was gone instantly....check it. I was running about at the 3/4 mark and now it doesn't go past 1/2 way...A/C or no A/C.

[mattdk318i]

I had a similar problem, and believe it or not it was the fan shroud. It was loose and I secured it down with the necessary clips and the problem was gone instantly....check it. I was running about at the 3/4 mark and now it doesn't go past 1/2 way...A/C or no A/C.

True, The shroud in my Cabbie was loose and when i secured it the temp went down as well.