Overheated & Confused

[cruisin5]

I have a '91 535i w/162k miles. It's had a few replacements in the past few months: radiator, water pump, thermostat. The cooling system's also been bled repeatedly and I have no leaks. Nonetheless, I keep overheating but in unsual ways. For example, after not driving it for a couple of days I'll be on the road for 10 minutes when the "check engine" light comes on and the temp gauge is in the red. I'll pull over immediately, wait 20 minutes or so, turn the car back on, and incredibly, the temp gauge will drop to normal and I'll continue on my merry way.

2nd example: recently I drove 70 miles on the highway to visit family. I parked the car for about 15 minutes (I was meeting up with someone) then turned it on again to drive another mile or so (local streets). Within a few minutes my temp gauge was in the red.

Finally, I did the same trip in reverse. The car was fine for about 70 miles (highway), about a few blocks from my house I heated up again.

My mechanic pressure checked the system and it seems to be fine. At this point he thinks it might be a head gasket or even worse, a cracked cylinder. Are these really the only options left for this problem? And if so, does that mean I may need to replace the engine??

I've had the car for about 7 months, so I don't know what kind of treatment (or mistreatment) it's had in the past. Any suggestions? I really enjoy the car and would hate to give it up.

Thanks!!

[Jay 535i]

FWIW, in my time on this board I've seen this issue pop up a lot, and I've had it myself. While the causes vary, they're usually not too costly to fix. The challenge is in finding the problem.

Sorry I can't be more helpful, but you'll get some great expert advice here. But if it makes you feel better, it's a common problem with a usually simple solution -- although it will take time and effort to identify the source of the problem.

[begeta50]

Did you change the clutch fan? I was having a lot problems with my, and I replace the clutch fan, and it is fix.

[Paul in NZ]

is it actually overheating and not just the gauge?????

[cruisin5]

FWIW, in my time on this board I've seen this issue pop up a lot, and I've had it myself. While the causes vary, they're usually not too costly to fix. The challenge is in finding the problem.

Sorry I can't be more helpful, but you'll get some great expert advice here. But if it makes you feel better, it's a common problem with a usually simple solution -- although it will take time and effort to identify the source of the problem.

Thanks Jay, I appreciate that. I'm sure I'll get some useful advice.

Best!

[cruisin5]

Did you change the clutch fan? I was having a lot problems with my, and I replace the clutch fan, and it is fix.

Yes, the clutch fan was changed.

[cruisin5]

is it actually overheating and not just the gauge?????

When I raise the hood, I can feel the very intense heat which I know is not normal.

[Paul in NZ]

have you made sure the overflow tube from rad to expansion tank is clear

[cruisin5]

have you made sure the overflow tube from rad to expansion tank is clear

No, I haven't checked that personally. But, my mechanic had it for a few days, that's something he should have checked, right? If it is blocked, would it cause it to overheat intermittently?

[Kalevera]

So how much RTV was used when installing that new water pump and thermostat? Was a gasket even used on the water pump flange?

I love unearthing this bubba stuff.


best, whit

[bill g]

Symptoms sure sound like faulty fan or fan clutch - at speed on highway there is good airflow through radiator, fan is not needed. Then in local streets and stop/start driving the fan needs to work.
Other things to consider -
If any hoses are old they could be collapsing.
Obstructions in front of radiator.
Ignition timing way off (eg. due to faulty ECU - never heard of this actually happening). You would probably also notice reduced performance.

Bill G Melbourne Aust

[cruisin5]

So how much RTV was used when installing that new water pump and thermostat? Was a gasket even used on the water pump flange?

I love unearthing this bubba stuff.


best, whit

RTV & gasket? I didn't do it myself so I don't know. I can ask. But without the gasket wouldn't I see some sort of leak?

[cruisin5]

I'll take a look at those options, particularly the fan clutch.

Thanks, Bill.

[Bimmer93]

Inspect the air conditioners condenser to make sure it's not clogged because it's an older car and with time bugs and road grim fills in those gaps if you know what I mean. With higher speeds its enough to rush air though, Think of it as clogged arteries.