Mk1 MX5 possible head gasket

[jaycey001]

Hi

My mk1 Mx5 has been running great and has been ridiculously reliable, however yesterday when i went to check the oil and water i noticed the expansion tank had alot of oil emulsion in it (light brown and thick;-(
There is no oil in the radiator and there is no mayo or water in the oil and no over heating, but i suspected the head gasket was the only possible cause. Speaking to my mechanic he suggested i clean out the expansion tank and top back up with water/antifreeze and run it around locally and keep an eye on it.

Is there anyway oil could get into the expansion tank if it want the head gasket? (the cam cover gasket weeps slightly and fouls the sparks, but i doubt this is the cause?)

Also is there anyone is Suffolk who fancys doing/working with me to do the gasket for some cash and plenty of cup of tea?
The car has had a recent cam belt and water pump, is there anything else i should replace if i go ahead with the gasket?
Just for info it is the 1.6 on a P reg with 136k on the clock and full history.

Thanks for you advice and comments

James

[kevin]

Its not too bad a job to do the head gasket on the mk1.
for some1 to do it you may be better asking at MXNutz

http://www.mx5nutz.com/

To be fair, most change the engine for a decent unit it the head gasket fails, they are available quite cheaply.

Kev

[Luxobarge]

I'm not familiar with the MX5 mechanicals - does this engine have an oil cooler in the radiator, or an otherwise water-cooled oil cooler (as opposed to an air cooled one)? If so, this is a common cause of oil and coolant mixing.

[Diesel Fionn]

I had a bad radiator failure on my wife's Eunos a couple of months ago.
All seems well now, coolant is the corect colour and no overheating, In fact the temperature gauge refuses to go above less than half way now which was common before. We recently went on small driving holiday in it. It was very good but the expansion tank was virtually empty after a particularly long hot run. We did use the air con a bit but not too much.
I topped it up, but I'm wondering is it normal for these cars to lose a bit of coolant. The radiator seems to be at a constant level.

[JPB]

Aircon doesn't use coolant, maybe the reason it won't reach half way up the gauge is that the thermostat is sticking open? No, unless it's an atmospheric cooling system with no pressure cap - as found on some really ancient cars - it shouldn't use coolant and if it does, then either you're overfilling the catch tank or there's a leak somewhere.

Am I right in thinking that this engine uses a pressure cap on the radiator and a flat one on the catch tank? In that case, perhaps you have a leak between the two. Last one of these engines I had any involvement with was a transverse version as found in an older Kia Vagentis, that had a more modern system with the catch tank pressure capped and a flat cap on the radiator.

[kstrutt1]

Yes they use the old fasioned pressure cap and catch tank, that said ours does not seem to use any coolant.

[Diesel Fionn]

Fairly sure the thermostat is fine. the pipe between the radiator and expansion tank is fine. I also suspect a leak but I can't find it.

[rich.]

can you get pressure test done?

[JPB]

Fairly sure the thermostat is fine. the pipe between the radiator and expansion tank is fine. I also suspect a leak but I can't find it.

Is the carpet damp and smelling of coolant? Heaters have been known to leak especially if they've been opened after a long period of being closed et vice versa.
If it's failing to reach the correct 90C running temperature then the thermostat is the most likely solution to that one but this isn't necessarily related to the loss of coolant unless the sender switch is responding to the air where coolant used to be, but by that time it would probably have overheated. Also, the rad itself may be leaking only when the car is being driven and not dribbling once it's cooled again. Are there any telltale signs of coolant staining on the matrix? Cars with pressurised cooling systems only lose coolant if there's a leak, either internally or externally so I'd go with what Rich suggested and put a pressure tester on it. This takes a couple of minutes and many garages will do it for the price of a contribution to the canteen fund.

[kevin]

On my mk1 1.6 MX5, if I am just tootling around locally, the temp gauge doesnt move up much. If I rag the car above 4k revs (where the useable power is) it will creep up to just under half way.
For the price of MX5's, I would just use it, keep an eye out for any obvious issues and if it goes pop, replace the engine for a decent one. Loads going for not much money on MXNutz

Kev