Imminent head gasket failure?

[pimkeirle]

I have noticed a build up in pressure in the radiator of my Elan +2S 130/5. I have owned the car 3 years, and covered 7,000 miles. When I check water level after first starting the car and running it for a few moments, there is an audible release of pressure when I remove the radiator cap. The car is running well and there are no other signs of head gasket failure, such as mousse on the oil filler cap (perfectly clean) also, the car never overheats, even when driven hard. The car has always used - or lost - a little water as long as I have had it (about half a litre over a 100 mile run) but this is no worse than it has ever been, and is rather less than my old MGB uses (I've had that 25 years!). Am I being paranoid, or would other owners recommend further investigation

[alaric]

Hi. Sounds normal to me; water expands as it gets hotter so the pressure in the system increases. As long as it returns to the original level on cooling down you're ok. Unless there's no pressure in the system of course, in which case there's a leak and the water might boil.

Sean.

[paddy]

But the original post said there was pressure after running "for a few moments". I think I would be suspicious of that.

I would do a compression test - it might confirm there is a head gasket problem or might not tell you anything. You might also be able to take it to a rad specialist who can do a pressure test of the cooling system in situ.

My guess is that if it builds up pressure that quickly then you do have a problem and you'll start to see the other telltale signs soon enough

Paddy

[alaric]

Oh yes - apologies for that.

Sean.

[types26/36]

I agree with Paddy if it builds up pressure in a few moments then it needs investigating, I had a similar problem where an engine would also build up pressure straight away although it did not overheat or loose water. Compression checks showed it was O.K. eventually I made up a fitting to screw into the plug hole and took off the radiator cap, connected the fitting to my compressor and sure enough it would bubble through the radiator when testing no.2 cylinder.

Now in my case it was a cracked head and I can only assume that when it got hot the crack closed with heat so it did not over heat or loose water.

I'm not being a prophet of doom as yours is likely to be a weep at the head gasket but DON'T use radiator/block crack additive.....its a waste of money, it doesn't work and just gums things up!

So my suggestion would be to do a leak down test as well as a compression test.

[65 Lotus]

An idea: The radiator cap is double sealing, the inner seal opens up at the rated pressure and allows coolant to dump via the overboard tube (at least in my S1), but the outer seal reamains sealed.

You could place something soft between the inner seal and the radiator thus cracking the inner seal to the open position but keeping the outer ring sealed. Remove the overflow tube and seal a balloon around the tube outlet tightly with a rubber band, then fire it up.

Balloons inflate at 1 psi or a little more, so you could see just how quickly it starts inflating and if it's a constant rate of inflation, i.e., the engine is pumping it up.

If you're just getting a bit of quick local heating, I would think it might inflate quickly just a bit, but then stabilize before continuing to slowly inflate. If it's like you hit it with an air compressor, then I'd say you have your answer. You might even be able to see the piston inflation "pulse" in the balloon.

You can usually see bubbles right away in an engine with a blown head gasket, but that would be a little tough to do on the S1 with the offset spout.

[kstrutt11]

Easiest way is to put the radiator overflow into a clear bottle, and run the engine up to operating temp , if the head gasket has gone you will see a constant stream of bubles when the engine is warmed up, if not the flow should drop off once the engine is warm.

[Jason1]

Hi

Have you thought about trying this?

http://www.frost.co.uk/item_Detail.asp? ... ock+Tester

?40 and you will be sure, it detects exhaust gas in the radiator.

Jason

[pimkeirle]

Thanks to all concerned for their helpful advice. I have taken the car to Plymouth Radiators (very helpful guys) who say it is likely that I have either a very slow head gasket leak or a small crack in the cylinder head head! I shall prepare for the worst and hope for the best! - anyone know if heads are still available if it comes to that?
Mike

[Jason1]

They are but not cheap. ?3,525.00 (inc.Vat)

https://www.burtonpower.com/product_main.aspx?home.aspx

You are better getting it repaired if it is possible.

Jason

[billwill]

Thanks to all concerned for their helpful advice. I have taken the car to Plymouth Radiators (very helpful guys) who say it is likely that I have either a very slow head gasket leak or a small crack in the cylinder head head! I shall prepare for the worst and hope for the best! - anyone know if heads are still available if it comes to that?
Mike

I was about to say the same.

Pressure in the cooling system very shortly after starting from cold, implies that combustion gasses are being forced into the cooling system. This can be a head gasket or worse a crack in the head or even in a cylinder wall.

I'm in the same boat, after having had my head welded & repaired twice It prompltly cracked again. You won't know for sure until you take the head off, though in my case after taking out the spark plugs I could see water in cylinder 3, as it can suck water in in another part of the stroke.


See my thread in Things in Common. called Cylinder Head kaput.

[billwill]

They are but not cheap. ?3,525.00 (inc.Vat)

https://www.burtonpower.com/product_main.aspx?home.aspx

You are better getting it repaired if it is possible.

Jason

Slightly cheaper from QED.

[pauljones]

Just a quick thought,I came across an article in one of the latest car mags, classic and sports i think.try www.cylinderheadshop.co.uk they may be able to help repair/modify for a better price.

they are nothing to do with me and i have not used them,its just a thought.

Paul