need help

i did a compression test on my mk1 jetta 1.3 l and i only had 20 psi in the 4th cylinder any help would be great none in the rest

none in the rest

what? - no compression on the other three cylinders?

NigelO said

none in the rest

what? - no compression on the other three cylinders?

none the gauge never moved i take it the engine im at a loose end with it

Could just be valve clearances poorly set, which means the valves are always part open. (Not sure on the small blocks if they have adjustable valve clearances or hydraulic tappets though).

paul_c said

Could just be valve clearances poorly set, which means the valves are always part open. (Not sure on the small blocks if they have adjustable valve clearances or hydraulic tappets though).

il tell you what i done i painted some parts of the engine to clean it up and i unpluged the temp sensor and then forgot about it then ran the engine and thats when the problem started running like a bag of nails dunno if this helps

Well, that would mean you wouldn't know if you cooked it and blew the head gasket, so it might have something to do with your lack of compression?

tyeness said

Well, that would mean you wouldn't know if you cooked it and blew the head gasket, so it might have something to do with your lack of compression?

is it worth trying to fix it or get a new engine

Well, you need to find out what the problem actually is first, lack of compression doesn't have to mean head gasket. Have you checked for Mayo under the oil filler cap? Are you down on coolant or oil? Does the exhaust smell like you're burning either?

There's always the option paul has mentioned above, or your piston rings could be shot on those 3 cylinders (though I'll admit this is unlikely).

As for whether you need to fix or replace it, that's up to you really  :dontknow:

There's always the 4th option - you did the compression test wrong. How did you do it, in detail?

paul_c said

There's always the 4th option - you did the compression test wrong. How did you do it, in detail?

it was with the screw in type i started with the cambelt side then work my way along the gauge never moved till i got to the 4th cylinder

i took the spark plug out then put the gauge in and took the coil lead off the dizzy i did that with all 4 off them is that right

tyeness said

Well, you need to find out what the problem actually is first, lack of compression doesn't have to mean head gasket. Have you checked for Mayo under the oil filler cap? Are you down on coolant or oil? Does the exhaust smell like you're burning either?

There's always the option paul has mentioned above, or your piston rings could be shot on those 3 cylinders (though I'll admit this is unlikely).

As for whether you need to fix or replace it, that's up to you really  :dontknow:

theres no mayo my water is fine so is my oil thats why im stuck its a weird 1

Dunno mate, honestly can't think of anything else, aside from mentioned above  :dontknow:

tyeness said

Dunno mate, honestly can't think of anything else, aside from mentioned above  :dontknow:

im stuck had a few people scratching the heads with it

mk1jetta said

tyeness said

Dunno mate, honestly can't think of anything else, aside from mentioned above  :dontknow:

im stuck had a few people scratching the heads with it

Its not weird, its all logical, its going one of:

- head gasket
- rings
- valves or their seals

Unless its some weird issue, like a chipped piston, cam not turning, head bolts not tight, etc but these are unlikely to happen if the engine's been running, etc.

The gold standard check is a cylinder leakdown test, which can be used to 100% determine what it is, before stripping apart or condemning the engine.

paul_c said

mk1jetta said

tyeness said

Dunno mate, honestly can't think of anything else, aside from mentioned above  :dontknow:

im stuck had a few people scratching the heads with it

Its not weird, its all logical, its going one of:

- head gasket
- rings
- valves or their seals

Unless its some weird issue, like a chipped piston, cam not turning, head bolts not tight, etc but these are unlikely to happen if the engine's been running, etc.

The gold standard check is a cylinder leakdown test, which can be used to 100% determine what it is, before stripping apart or condemning the engine.

thanks i will get that done first thanks to everyone for there help