Compression Problem On St185 Any Advice Welcome.

[phfactor]

Just picked up a 1990 ST185 with an engine problem and wondered if there are any wise men (or women) out there who could give me some advice. I did a compression test this morning and low and behold there's virtually no compression on cylinders 1 and 2. On 3 the reading was around 135 and on 4 around 150. A few possibilities are going through my head but I wondered if anybody has any gems to share with me. Grateful for any contribution as to what the problem might be and where I go next.

Thanks, Paul

[GTForbes]

well the standard head gasket is infamous for blowing at anything above stock boost so that would be a first port of call, what signs and symptoms is it showing except running like a bag of boots

[phfactor]

well the standard head gasket is infamous for blowing at anything above stock boost so that would be a first port of call, what signs and symptoms is it showing except running like a bag of boots

Well I must admit that was my first thought but there are no obvious supporting symptoms. Water is clear, oil is clean. no blowing around the gasket etc. Plugs maybe a little oily. I trailered it home as the previous owner said that it had been running fine until the week before Christmas when it started to miss and he thought he heard a light knocking from the engine. He made it home gingerly and had not started it since. It's pretty unmolested as far as I can see.

I thought I'd strip it down but couldn't resist turning it over to see if there were any clues. It'll fire, I suspect only on 2 cylinders but won't run or pick up. Lot's of spluttering through the carb. I wondered if somehow it could be valve timing but I couldn't make that add up. It'll turn over ok and I can't hear any particularly nasty noises coming out of the engine.

[GTForbes]

i very much doubt it'll be a timing issue considering it's lost compression in 2 cylinders, i'd be aiming towards bottom end. i hate to say it but knocking usually means big ends.

was the oil or water level lower after you turned it over, i know that would be a long shot on such few revalutions of the engine.

probably better to strip it down and see exactly for yourself the root of the problems, but then it could be cheaper to buy a new (second hand) engine

[phfactor]

Well at the end of the day, you could be right. I'm still throwing around the idea that it could be a top end problem. Maybe because I'd prefer a top end solution :-). Is there anyway of explaining the problem by way of cambelt slippage or maybe camshaft damage? It just seems a bit odd to me that one minute it's running fine and whilst being driven at, what I'm led to believe, was a slow speed, suddenly there is no compression on 2 cylinders.

Oh and I forgot to add the car is only showing 70K miles and although this can't be taken as gospel, there are signs that it might be right.

[dawesy]

a knackered valve would create a misfire and loss of compression but to get two valves in adjacent cylinders is unlikely.

it could be that the HG has gone between cyl 1+2. id take off the head (just about possible with the engine in the car) and get it checked over install a metal head gasket and ARP studs and at least its an upgrade. i would get the oil pressure checked as well. ST-185's do suffer from oil problems and they are best caught early as they quickly take out the crank. bearing shells and oil pump are changeable with the engine in the car.