306 Diesel Compression Results

[xudfanatic]

Good Afternoon Guys,

I've just finished a compression test and got a set of results that I wondered whether anyone could explain what could have caused these readings?

Cylinder 1: 400psi
Cylinder 2: 360psi
Cylinder 3: 400psi
Cylinder 4: 380psi

Many thanks.

Grant.

[Oldpug]

Could be lots of things?? most likely nothing to worry about,one is down 5% the other 10% on 400.I havn`t a clue what the psi should be as I`ve never tested one,never needed to.Why have you tested it? is there a problem with the engine? do you have water loss etc? how many miles has it done?

[xudfanatic]

We brought it with 9 months MOT and it has just failed badly, was trying to work out whether it was worth bothering to put it right. Our 205 got 375psi, as far as i'm aware 400psi was healthy. If the compression was low on a cylinder I was just going to scrap it. Thought it was probably nothing, but just curious. No engine faults or water loss, engine has covered 155,000 miles.

[spider]

The acceptable maximum difference is about 70 odd psi give or take a bit as far as I remember, so you're not that far off.

Could check valve clearances I guess ?

I'd not be concerned myself if it was mine and there was that difference if there was no sign of any other problem present, ie gasket failure etc.

[Peter.N.]

What has failed, what is the problem with it?

Peter

[Oldpug]

I would say don't worry about the engine.Put Forte engine flush in the old oil,Forte Diesel treatment in the tank,give it a good run,change the oil and filters and I bet the compressions will be about equal.Those old XU`s last for ever,whether the rest of it is worth spending on is up to you?

[xudfanatic]

It had a dodgy MOT I think last year as it failed this year on no less than 14 counts. I found it didn't even have a horn, and I removed a welded droplink...wtf! Failures lie in 3 main areas:

Adjustment of rear brakes and ceased compensator/bias valve,
Bit of welding,
Front lower arms are knackered.

Quoted £600 to put it right, decided initially to scrap it and brought another my brother had to get the Mrs on the road again. Then I sat down and worked out it will be around £150 to get through the MOT if I do the work myself when I get time, so the resurrection begins!

Cheers for the posts chaps.

[evilally]

I have an XUD workshop manual here. Minimum 290psi with no more than 70psi variance.

[xudfanatic]

Thanks for confirming, I'll make a note of that.

[Xsarahdi]

Failures lie in 3 main areas:

Adjustment of rear brakes and ceased compensator/bias valve,

306's always seem to suffer from this kind of thing!