Technical Yet another overheating problem

[Pep0]

Hi

Sei '98, decided to dump a quart of coolant out of header tank cap.

Refilled and blead, repeated, dump. Interestingly the heater and top rad hose were cool and not under pressure just before dump..only the little bleed hose to the header tanki was hot.

Replaced the thermostat, easiest to do but same synptoms so the water pump (10k miles from new) or both heat exchanger matrix or engine coolant passages blocked? The coolant did not look particularly mucky.

Probably the head gasket compromised, it is wet and windy so I'm going to have Sunday off...

Noel

 

[fingers99]

Compression test (or, if you can find somewhere with the kit) coolant pressurisation test. That'll rule in/out the head gasket (and the pressurisation test will find both that and where, if anywhere, you're loosing water from). Cheap, no-name thermostats are best avoided.

How's the radiator fan?

 

[rallycinq]

I wouldn't rule out a failed cap, either.

Cheers

SPD

 

[Pep0]

The fan fuse is ok, i'll hace to try pulling the connector and shorting the pins to see if it runs, suspiciously I have not noticed it come on for a while, but I dont get into traffic often and it is colder now. Should have done something earlier.

The fan may have been the start of the problem.

If the hoses dont heat up rapidly especially the heater hose then there is not much circulation. The fan only comes on from the rad switch and the rad is icy cool until after the geaser when it gets warm but not hot.

The water was only coming out the cap, as far as I could tell, the battery tray was wet.

The engine is running normally, there is no trace of steam from the exhaust, and the oil cap is normal, (as was the oil at the coil cover, which I remove to access the stat, sorry I'm chicken) the car only sees motorways, so does not get a lot of water in oil...

I'll remove the rad and flush it, or use a proprietary compound.

I'll scrap the current cap, and make/jury rig a pressure variation kit... If the cap was not pressurising then it could cause a geaser. But Id stil have expected the hoses to get hot and pressurise first...

The coolant that has come out to replace the stat has not been that badly contimated, catch it in large drainer.

The water pump was a fiat OEM pump new 10k miles ago, the stat I replaced may not be origonal, but replacing it made no difference, the new stat was 3rd party, all I could get Sat PM.

cats and dogs and I'm out in it...

Noel

 

[cc1]

Run the engine without the header tank cap and take the occasional sniff of the vapours in it. If the head gasket is blowing to a cooling chamber then fumes will be evident including bubbles.

 

[Pep0]

No bubbles or exhaust smells.

Drained coolant tried proprietary rad flush,with new cap, stopped engine when the hose fron the thermostst housing was hot but all the other hoses cold.

The heater hoses are supposed to get warm first... It was a pig to bleed as well, not normally this difficult.

Got new pump and new rad

So rad out next, dont want to swap pump unnecessarly looking at records it is an OEM pump fitted 10 months ago and 14k miles ago. I'll try to clear rad but Ive found it is not 100% effective.

The theromstat I replaced was also OEM, but had signs of wear in the rubber seal. May rebuild it like the low temperature stat thread suggests.

The weather here is still wet.

Noel

 

[Pep0]

Got the rad out, after removing several galled bolt heads with pad saw.

The rad seemed seemed ok except, it had been pushed off the rubber locators in the wing (horn end) by the fog lamp, nice witness mark. The fan motor was touching the oil pressure and TDC sensor, the fan had cut into the (throught) the plastic ducting at the base of the rad, and damaging its outer rim...

I had to remove the fan assembly to get the radiator out through the wheel arch.

Removed the fogs to allow more clearance for people who park by ear. Need to find round file to move the fan a little to the right to give more clearalce to the oil pressure and TDC sensors.

Bits I could access has a Calcium Carbonate deposit from hard water.

The little bleen nipple thing had to be cut off as it would not feed through one of the holes...

I'll replace the rad, but the fan seems ok, still ran ok when I shorted the temperature sensor switch.

Eventually I'll get to the problem.

Noel