Overheating and mayo on the dipstick

[drea]

About a mile from home last night, the temp guage started creeping up (usually sits at about 1/3). As my speed increased, the temperature went down again but I stopped getting hot air from the heater, even with the temp control set to max.

As I pulled onto the drive the temp guage shot to the top and all the warning lights came on. Had a feel of the rad pipes and the top ones were hot, but the bottom was cold. Went out this morning to have a look in the daylight and I've got a small amount of mayo on the dipstick, but I can't see any oil in the coolant.

Is it terminal Doctor?

I'm hoping it's the thermostat or water pump, but the mayo says head gasket (and expensive).

I'll be attempting to get it to my local specialist (Tom Ferguson, very good) on Monday, but I'd like to have some idea what to expect (and how much it's going to cost me)

The car's a '91 944S2 BTW, 102,000 miles.

Cheers,

Drea

[verysideways]

Compression check across the cylinders, and/or pressure check of the cooling system, should give you the information you want to know.
If you take off the oil filler cap is there mayo in there too?

Have to say, from symptoms sounds more like waterpump to me. Let us know when you find out eh?
Fingers crossed for you.

VS

[basil brush]

I hate to say it but had the same symptoms when the head gasket went on my old 944S at about 115k. Mayo in the oil filler cap happened a few times due to condensation but that was the only time it happened on the dipstick. Did your coolant hoses feel inflated?

[ninemeister]

Repeated from previous post:

99% of oil-in-water scenarios in the 2.5/2.7 944 engine are to do with the oil to water heat exchanger (oil cooler to you and me) located in the housing that mounts the oil filter. It will probably be one of the o-ring seals that go on the in/out stubs of the matrix, but in rare cases the matrix fails normally as a result of being frozen at some time.

The gaskets are around £50, the job takes an afternoon of swearing.

[basil brush]

ninemeister said:

Repeated from previous post: 99% of oil-in-water scenarios in the 2.5/2.7 944 engine are to do with the oil to water heat exchanger (oil cooler to you and me) located in the housing that mounts the oil filter. It will probably be one of the o-ring seals that go on the in/out stubs of the matrix, but in rare cases the matrix fails normally as a result of being frozen at some time. The gaskets are around £50, the job takes an afternoon of swearing.

But this is water in oil, not the other way round.

[drea]

verysideways said:

If you take off the oil filler cap is there mayo in there too?

Yup, there's a nice dollop at the bottom of the pipe. The cap itself has water around the inside. That might just be condensation though, it's very cold here today.

[drea]

ninemeister said:

Repeated from previous post: 99% of oil-in-water scenarios in the 2.5/2.7 944 engine are to do with the oil to water heat exchanger (oil cooler to you and me) located in the housing that mounts the oil filter. It will probably be one of the o-ring seals that go on the in/out stubs of the matrix, but in rare cases the matrix fails normally as a result of being frozen at some time. The gaskets are around £50, the job takes an afternoon of swearing.

This is water-in-oil in a 3.0 944. But it would be nice if it was something simple like that.

[ninemeister]

basil brush said:

But this is water in oil, not the other way round.

drea said:

This is water-in-oil in a 3.0 944. But it would be nice if it was something simple like that.

Ah, that's what comes of not reading the question properly. Thanks lads.

Water-in-oil = Head gasket. Sharp intake of wallet.

[basil brush]

I think mine cost about 700 quid to replace including new belts, but it was a few years back.

[rubystone]

Had you thought that it might be a simple airlock, is theh radiator uniformly hot? If not, it's possible that you do have an airlock and will need to bleed the system through

[Fatboy]

rubystone said:

Had you thought that it might be a simple airlock, is theh radiator uniformly hot? If not, it's possible that you do have an airlock and will need to bleed the system through

That wouldn't explain the mayo on the dipstick though...

Mine was a bugger to bleed

[drea]

Thanks for the diagnoses guys, it's not looking good

It's almost certainly the head gasket, but would that cause the cold rad bottom or is it likely that the thermostat and/or water pump's gone too and caused the gasket to blow?

[GreenV8S]

Heater not working is a pretty clear signal that you have no water circulation, which is a show stopper. This is consistent with the radiator being hot at the top and cold at the bottom while overheating. I would suspect that either you have run out of water, got an air lock in the pump, or the pump has mechnically failed (seems unlikely), or the stat has failed in the closed position.

[james_j]

It it's the head gasket (which I suspect) you may (if other cars I have seen this on are a guide, I don't know about the 944 specifically) see air bubbling up in the water header tank while the engine is running. If so, this would confirm the head gasket as the problem.

[Marquis_Rex]

Good luck, hope it isn't too expensive.

I HATE open deck cylinder block designs-given Porsches are the best of this type of design.
Witness aweful engines like the Rover K series-another "open deck" design....

[GreenV8S]

I thought the K series block was a design masterpiece, with zero bore distortion and all the high loads elegantly balanced out by the studs between the mains and the head. Unfortunately it seems that a lot of the details went wrong - totally inadequate head location, cross flow head converted to longitudinal at the last moment leaving major hot spots, somebody forgot that ally and steel expands at different rates so head clamping loads aren't maintained during warmup, the external cooling system design was ucked up. But the setting all the cock-ups aside, the basic design looks very clever.

[Marquis_Rex]

Green I was being flippant, the original 1.4 litre K isn't too bad, for it's application, but when they stretched it and went to damp liner- 1.8 there were alot of compromises.
Also, there was alot of hype with the K series because it is British, and alot of its accolades (sp?) are from a manufacturing point of view, such as being one of the first engines to use RTV type sealant instead of a gasket or having the big through bolts- good for assembly, to act as damping for NVH improvement on a paired down alloy block. But quality wise and durability wise, and use for performance upgrades and durability- I'm not so sure. ( and no I don't want to hear about performance one off pub-talk cars- one off applications are quite a different story to production line stuff)

[drea]

Just got it back from the garage and it looks like it was just the water pump causing the overheating.

The mayo appears to have been from condensation, as someone suggested, but I'll be keeping a close eye on it for a week or two.

Apparently the pulley on the pump was just spinning on the shaft (anyone else had this happen?). I haven't got the original one though, the replacement's an exchange job.

Good to be again.

Thanks for all the advice.

Drea

[Buster44]

Yep happened to me (but without the mayo) - impellor came off the waterpump.

Would have suggested this, but the last few times I have it has turned out to be something else such as the thermostat etc - sorry

Glad you got it sorted for not too horendous expense

[drea]

Buster44 said:

Glad you got it sorted for not too horendous expense

Not "Too" horrendous, still plenty of labour and parts. Did a precautionary motor flush, oil and filter change too.