E30 overheating

I would definetly be looking at the water pump, they have crppy plastic impellors which break, the heat at the top of the radiator could be conducted through the top hose from the cylinder head, the water pump is easy to replace, and isnt very expensive, make sure you replace the sealing ring too, but be aware that you will need to drain the cooling system and flush it out.

Cheema,

The radiator's working fine, hot water enters the radiator at the top, through gravity and pressure it is passed down through the radiator, as it runs down it is cooled in the core, so you should have hot at the top and cool at the bottom.

Are you getting flow through to the heater? Does it stay hot when the engine is warm? Other option could be the radiator cap, maybe not allowing the system to vent? You say the hose is hot, does it reach red on the guage?

Themostat changed?

Rob

Edited by Madrab

Also check that the fan is OK. With the engine idling, see if you can stop it with a rolled up newspaper.

Far in excess of 80% of a cars cooling process comes from the draft caused by forward motion.  The fan assists this process when idling in traffic.

Hoses do get too hot to touch in a perfect system.  So don't use that as a guide.

It could be the guage or the sender unit.  If it is *actually* overheating, and you have changed all the possibles...it could be a problem.  Are you running Super U/l fuel?  That can add a few degrees.

Other than that, I can only hope it's a blockage or an air-bubble.  Blockages will be in the most inaccessible areas, like the radiator or the heater matrix...where the pipes get down to small diameters.  Flushing with  a hose-pipe will not show the problem, as the water will simply pass through the clear bits.

Hi all thanks for the responses.

I have done the newspaper test, but I'n not sure on how many sheets of paper to use and how tightley to roll it up.
last time I rolled up about 3/4 of The Sun newspaper and I was able to stop the fan when the engine was quite. The fan did not tear the newspaper in the process. I bought a new fan clutch about 4 months ago from GSF. I did the paper test then and was still able to stop the fan, but then winter set in and abviously the car was not warming up as much in stationary traffic.

It does defintely overheat, I can safely dismiss the temperature guage being faulty.

It sounds more like a gunged radiator because the bottom half of the rad is very cold, I would have expected it to be luke warm at least, even with the cooling effect of the fan. Gunge normally ends up sitting in the bottom of the Rad

Hi Alan

Thanks for those pointer, I'll run the car with the fan removed and see if the whole of the Rad warms up.
Its actually an E30 Touring 1993 (one of the last ones from the factory). It has a black plastic bleed screw on top of the rad, I refilled and bled the system from both bleed screws witout any joy.

I have heard some bad things about GSF parts (where I bought my clutch fan from) what do people think about the following findings.

According to the packagaing on the box the the viscous is only supposed to be stored in one direction. When the engine is cold (1st thing in the morning), if I try to give the fan a stong push with one finger it spins at most half a revolution, if do the same spin test with the engine fully warm the fans spins 4 or 5 times. I thought it was supposed to be the other way round, ie harder to spin when hot.

Could it be a crappy aftermarket fan from GSF ??

Many thanks Dal

Hi,

Very roughly, this is how it works.

The extra resistance felt when cold is for two reasons. The viscosity of the oil changes as it heats up and the oil is driven from one chamber to another as ithe unit spins. The valve between these two chambers is controled by the bi-metal strip on the front of the unit. When the bi-metal strip is activated by the temp at the rad centre, it opens the valve and allows the oil the enter the first chamber again, therefore raising the resistance so the fan is driven quicker.

It is unlikely that you have a faulty unit. Most times I have seen this, it has been a rad fault.

Another thought, I dont suppose the fan cowling is missing?

HTH

Alan.

Sounds more like a rad problem then a fan problem to me! quite common for a rad 2 get gunged up especially if the previous owner didn't look after it! Not sure if this is true, but apparently if you live in a hard water area, you're more likely to get gunged up coz the expansion tank is normally filled with chalky tap water which can settle in your rad!!! Whether that's a housewives tale I don't know...But if it anything like my kettle...???

Cheema,

I just bought a viscous coupling from GSF, SACHS part, no problems at all with it. Does the temp drop if your parked but then raise the revs? If so then the fan is definately suspect but you have a new coupling...hmmm. Remember, even if the engine is fully warm, if the air through the radiator is cool enough the fan will spin freely, it's only when the air hitting the fan is hot it will activate the viscous coupling and engage the fan, it does this in cycles as the temp rises and falls. 

I am sorry about the comment about the rad cap, It should have been, if it is faulty and won't allow the pressure to build correctly in the cooling  circuit then the water will boil at a lower temp therefore it will overheat quicker. You can also check the temp with a remote thermometer, one of those laser thingys, on the hoses, will tell you actual temp the water is at, just 2 be sure?

The other trick, if the fan is suspect, is to convert to an electric fan (Escort Turbo MK1 fan is a goody) on the grill side and then it becomes a blow through rather than a suck through, smutty comments on a stuck down envelope please    Then it's just down to the sensor or the fan and you know when it's working or not and you don't lose the couple of BHP the fan can use.

I would start with the radiator out and flush with water both ways and see if you have residue. Seen this more than once. Black cat is correct as well, in a hard water area the radiator can end up like your kettle without frequest flushes!!!  Check the core as well for dirt and crap jamming up the fins. Wouldn't be the first to see a core that was 3/4 blocked and next to no flow through the core. 

Rob

Edited by Madrab