Compression Test Results

[RAF_gti 0]

After suspecting HG failre on my 1.9 I got myself a little compression tester yesterday.

 

From left to right I got 120, 80, 120, 160, the spark plug on '80' was very 'dry', the other three were similar in having a sooty end and being slightly oily.

 

I also checked the coolant and the level was fine and it did look a little murky. Also, I've used a fair bit of oil since it was changed 800 miles ago, it is now half of min/ max.

 

I'm I looking at a big repair here? please say no!

 

ps the plugs and oil was changed 800 miles/2 months ago.

[Mikey S 29 1 Cars]

After suspecting HG failre on my 1.9 I got myself a little compression tester yesterday.

 

From left to right I got 120, 80, 120, 160, the spark plug on '80' was very 'dry', the other three were similar in having a sooty end and being slightly oily.

 

I also checked the coolant and the level was fine and it did look a little murky. Also, I've used a fair bit of oil since it was changed 800 miles ago, it is now half of min/ max.

 

I'm I looking at a big repair here? please say no!

 

ps the plugs and oil was changed 800 miles/2 months ago.

 

 

have you tried a spoonfull of oil down the bore, then try compression testing it again?

 

as a rule of thumb, if the pressure readings increase with oil down the bores then suspect the piston rings at fault. if they stay roughly the same, then it usually will be down to a headgasket/valve/valveseat problem.

 

hth

 

mike.

[RAF_gti 0]

have you tried a spoonfull of oil down the bore, then try compression testing it again?

 

as a rule of thumb, if the pressure readings increase with oil down the bores then suspect the piston rings at fault. if they stay roughly the same, then it usually will be down to a headgasket/valve/valveseat problem.

 

hth

 

mike.

 

 

Ah no I've not tried that, look's lilke another wee trip down to the garage is in order then!

 

cheers

[pee vee 1]

did you do it when the engine was warm? sorta running temp?

 

number 2 seems low!

[RAF_gti 0]

Aye it was at a decent temp, 10mins of idling followed by a quick blast up the road.

 

I'm also rather concerned that no4 is high!

 

What are the recommended Pug specs?

[mattmk1 0]

160 is healthy, the others are fairly low. What condition is the engine in? Does it smoke / use oil? Generally 150 a cylinder on a used engine is good and 180 + on a rebuilt one.

 

Worth noting that some compression testing kits arent the most accurate and you need to make sure that its being used properly - but as you've had a garage do it i assume it was.

[RAF_gti 0]

160 is healthy, the others are fairly low. What condition is the engine in? Does it smoke / use oil? Generally 150 a cylinder on a used engine is good and 180 + on a rebuilt one.

 

Worth noting that some compression testing kits arent the most accurate and you need to make sure that its being used properly - but as you've had a garage do it i assume it was.

 

 

Matt sorry, the test I did myself with a new Gunson kit.

 

The engine was rebuilt ~10K ago and I would of said in very good condition, it pulls well throughout the range and has been very reliable for me, the engine needed an extra one litre of oil over 6K miles so not excessive use IMO.

 

I'm going to redo the test tomorrow with a drop of oil to achieve a better result, I also forgot to do it at throttle wide open!

[mattmk1 0]

Matt sorry, the test I did myself with a new Gunson kit.

 

The engine was rebuilt ~10K ago and I would of said in very good condition, it pulls well throughout the range and has been very reliable for me, the engine needed an extra one litre of oil over 6K miles so not excessive use IMO.

 

I'm going to redo the test tomorrow with a drop of oil to achieve a better result, I also forgot to do it at throttle wide open!

 

sorry chap, i was reading through quickly and not paying full attention. The Gunson kits arent generally that bad, your results will be massively different on wide open throttle. Let us know what you get !

 

If it pulls well, doesnt smoke and doesnt overheat you have no worries in my opinion. Always nice to see what compression the engine makes, but much like oil pressure gauges they can cause some unneccesary worrying!

[Miles 331 1 Cars]

Something's up, even on full throttle you won't gain 80 or 40 psi from the other cylinder's, If it's been rebuilt do you know what was done?

[RAF_gti 0]

Something's up, even on full throttle you won't gain 80 or 40 psi from the other cylinder's, If it's been rebuilt do you know what was done?

 

 

Miles

 

The rebuilt was done under the previous owner and carried out by DES, I've the invoice here but nothing mentioned other than 'full rebuild' it cost about £1.2K so I would imagine to be fairly comprehensive.

[Miles 331 1 Cars]

Thats a shame as it's handy to list what was replaced and what make of parts as I do, A full rebuild could be from new or recon parts