E30 Zone

Hi all, happy xmas and all that! Sorry for the length of the post, but if I say all I know now it should be a help!

I was driving back up to Kent from spending xmas with my folks down south yesterday, and the car suddenly started overheating. It's a 1990 320i.

It's been fine until then, staying nicely at half way, then suddenly as I set off, the temp started creeping up and up to the red. I pulled over, released the cap (slowly) and waited for the car to cool. Set off again, then the same 5-10 mins down the road. Did this a few times then limped to a garage and had to get the car towed home, not happy!

Strangely, there was still hot air coming out of the heaters. When stationery it took a while to heat up but when trying to drive, it went up pretty quick.

I don't think there's any air stuck in the system, I've squezzed all the hoses with the expansion cap off as this normally works for me, but no sign of any airlocks, and it was very sudden. The recovery bloke thought waterpump, but if the heaters are still working, is this right? I replaced my waterpump and visous when I did the belts about 6 months ago so both should be ok. Although I have a feeling my GSF viscous is a bit iffy, it seems to come on when you start the car, give it a couple of revs and it stops, then it just doesn't come on again. I don't think it's just the viscous because when my old one didn't work i could just run the heaters on max and keep the engine at a reasonable temp.

So, the question is, what the #*/# do i do now, all thoughts and comments more than welcome!!

cheers,
si

have you had to top up water more often recently.

Check dipstick and oil filler cap to ensure the oil is black and not going creamy coloured (ie oil mixing with water.

have you bled water system with heaters in hot position , from bleed valve on radiator.

(just given my 325 in to nelly to replace engine as head/head gasket is gone)
try doing search in tech for overheating.

hi bally, thanks for the reply.

I have had to top up water occassionally, but not often, and it's not changed in all the time i've had the car.

No signs of oil and water mixing and no mayo anywhere.

I'm searching for bits and pieces in other threads and gathering info at the moment, not getting very far though!

I haven't bled the system with heaters on hot etc, i'm considering flushing it all out and starting again and seeing how it behaves then, but it's been a while since i last did it, so could do with some easy guidance? Bleeding the air out can be a pain in the .... sometimes I find! What's the best way?

Ta,
si

bump bump!

anyone with any suggestions or ideas? How can I test my waterpump to see if it's working, and is there a way i can test my thermostat too? I'd say these are two good starting points, what do you think?

bump again, I need some help please zoners?!!!

Hi mate,

I don't know if I'm being thick or not but it sounds like the problem is definately in the viscous area. The viscous should spin the whole time - it should NEVER stop if the engine is switched on. This is because the viscous is attached to the water pump which is driven by the belt that goes round the crank pulley. If the engine's switched on then the crank pulley should be turning constantly, hence the viscous will always be spinning. So, if the revs go up then the crank should spin faster so in turn the viscous will spin faster.

First thing I'd check is: ensure belt not too loose (i.e: slipping) or too tight (i.e: stopping the pump from spinning). Then see if there's movement in the viscous by gently wobbling the fan - if there is movement then it's tired (note: good way to temporarily fix a tired viscous is to just tack weld it to the nut).

Sounds like the only reason it's overheating is because the fan isn't spinning to cool the water in the radiator so the temp will obviously just keep rising. The fact you have hot air coming out the heater usually means there is no air in the system & the thermostat is working fine.

If you were DRIVING at any appreciable speed, it's nothing to do with the viscous fan coupling. The mechanical fan is just there for traffic and traffic jams.
Water pump failure isn't impossible, but it's unusual for the rotor to fail on E30s. Could be more common with poor quality aftermarket pumps, I suppose.
You say your fan actually stops turning? Certainly shouldn't do that! Does the water pump pulley stop turning?
Fan belt must be very slack if it does, and the pump bearings seizing!
Pump could only be running intermittently, which would probably keep some output from the heater, but might still overheat the engine, but I can't imagine the fan belt taking this for long.
If none of the above is relevant, then check: 1) the small hose from the top of the radiator to the coolant tank is clear. 2) The rubber hoses are nice and hard when the cooling system is up to temperature. 3) The thermostat.

Hi all, thanks for comments.

rrchevy, the viscous may be part of the problem, but I don't think it's all of it. The fan spins normally but doesn't click in and go "whoosh" when the engine gets up to and over half way on the temp gauge. I had this problem before I changed it and could keep it cool in traffic with the heaters on full blast. There's something more to it this time!

brian, I'm glad to hear from you! As I say, the viscous isn't the major issue, I think that's secondary. My water pump came from GSF about 6 months ago so should be fine. Would heat come through the heaters if it didn't work? The fan doesn't stop turning at all, just to clarify. All the pulleys are turning fine, the belt tension is about right. Any way to check if the pump could be running intermittently?

The small hose from rad to exp tank (is this a return hose?) is clear, I've blown through it. The rubber hoses don't get hard at temp, I can squeeze them easily. Do Halfrauds do a thermostat I could rely on? Is this likely? The top hose seems to get nice and warm.

Thanks, and let me know what you think?

si

If the hoses don't get hard, then the system isn't pressurising, so is probably just boiling!
Check out the cap on the coolant bottle.
There was a safety recall on these caps in 1992, but lots of E30s escaped it.
The problem with the cap is not relevant to your problem, but if you give your VIN to your BMW dealer, they will be able to tell whether yours has been replaced, and if not, should give you a free shiny new one.

hi brian, thanks for your reply.

To be honest, the hoses have never really got hard, but I think the system is pressurising because the bleed valve works as it should and the coolant will flow out of the expansion tank with the lid off when it warms up, showing there is pressure i think?

The cap has always been fine in the past, and I think it is one of the newer ones with the yellow inside and the correct number printed on it.

I'll give the whole system a flush tomorrow, and recheck that all the pipes and rad are clear. Although I am puzzled because top hoses get warm and the bottom rad hose stays cool, so it seems all is as it should be.

AAAAAAAAHHHHHHHH!?!?!?!?!!!

Also, check the coolant level sensor is screwed up tight in the expansion tank & is sealing ok. It most probably isn't this but best just to check. I had a problem in the past where the sensor would go to a certain tautness then slip on the thread as the thread was knackered on the expansion tank (used some ptf tape until I got hold of a new one). Hence, I was losing pressure there but there does seem to be more to your problem than this though.

Might also be an idea to get a block test done at a a reputable garage just for peace of mind - shouldn't cost more than a tenner.

rrchevy, thanks for your suggestion.

I have noticed there may be a problem with the expansion tank and the cap sealing properly, as it seems to take quite a lot of effort to get the cap on now, and I did hear some noise as if air was escaping.

As a result, first thing I'm going to do is pick up a new tank and cap from a scrappy, then I'll replace all the hoses if that doesn't solve it. There's still no sign of mayo in the oil or the water so fingers crossed it's nothing major. Would a bad seal on the expansion tank cause this kind of overheating?

ta,

si

If the system doesn't pressurise, it will blow the coolant out with any kind of hard driving.

Adding to Brian's previous comment over time the expansion cap can cease to work, go to BMW and get a replacement they arn't expensive, however I think there was also a product recal on some M20 expansion caps when you visit your BMW dealer ask if they have any record of the part being replaced under recall on your car and if it was subject to the recall, if so you might even score the cap for free.

that'll teach me to skim over the thread and not read it properly.

thanks guys, should be collecting the cap tomorrow and I'm picking up another tank too in case the thread's knackered for some reason. I don't think this will solve the problem but it'll be a good starting point so I can flush the system through and check there aren't any blockages.

What next if that doesn't work? Should the thermostat be the next thing to replace??