Overheating

[v6power]

Hi all,
A couple of weekends ago whilst sitting in traffic on an averagely warm day, I watched the temperature gauge creep up & up. It got to @ the 3/4 mark and I took the decision to turn around and get some air flowing!! I have only had the car (320/6) for a few weeks so was unsure what was normal. What would your suggestions be? Are there any tests that I can do to check the thermostat or sender is working OK?

Ta Ade

[Jeroen]

If this only happens when waiting in trafficit is most likely the fan clutch gave up on you and is not providing enough air flow anymore. If you experience temp problems during fast driving as well it's more likely to be a coolant flow problem (thermostat not opening fully, clogged radiator, old water pump).

[Reck]

I've had continuous overheating problems with my E21 so I'm pretty well versed in this now.

Flush and refill cooling system. If radiator is really clogged up you can take it out, turn it upside down and run a hose through it. Bleed by jacking up front slightly, running with rad cap off and the heating on full while squeezing all the cooling pipes. There are different kinds of fans - mine is just bolted to the front of the water pump, so make sure the belt is tight. Some people have replaced theirs with electric fans which shift more air.

To test the thermostat, remove it and heat in a pan of water with a thermometer to make sure it opens at the right temperature (85 I think? depends on the country..)

Once you've eliminated clogs and the thermostat, you might want to look at bleeding again (some of those airlocks can be a bitch to get out). Failing that, have a look at the water pump. I ended up replacing mine, but there wasn't much wrong with the original tbh as the impeller was metal, not plastic like you get on newer cars.

After having gone through all this, I've a feeling that the short period of overheating I experienced when my radiator burst has damaged the head gasket in some way and is leaking compression into the coolant, as I can never seem to get all the air out (more just becomes present after extended periods of bleeding). Still, it never goes above 3/4 so I'm not going to fix until I can afford a recon engine.

The difference between halfway and 3/4 is only 5 degrees or so I think, so not a massive problem, but I think it still points to some underlying issue that is worth sorting.

[Jeroen]

Thanks for adding that!

A few remarks:
-old water pumps loose their capacity as the impeller gets corroded
-difference between halfway and three quarters is ab 8-9 degrees, still ok but if the temp rises any further the overheating might kill the head gasket
-erratic temp readings on the instrument cluster can indicate a corroded connection on temp sender (on thermostat housing) or at he back of the cluster, temp senders do fail every now and then as well, in my case it showed a high temp on the gauge when the actual temp was just perfect

[v6power]

And that's why we join online forums!!

Thank you to both of you, I will let you know how I get on

Ta Ade