Compression tests?? New rings??

[robsparky 0]

Before committing myself to buying a set of piston rings, i've done a complete compression test. Can someone verify my results? I think the readings should be 9 - 10 bar on each cylinder. All of mine were 4.5 - 5.5 bar. Am i right in assuming that i need a COMPLETE set of rings??

[Eat this 2]

could it be the headgasket??

do all the rings go at once i thought it was normally cylinders 1and/or that go first?

[robsparky 0]

I dunno, cyls 1 and 6 are using a lot of oil - but are no worse than the rest on the compression test. I've got no obvious signs of headgasket fault, -ie, using water, bubbles or oil in water.

[budgie 0]

i had my compression test on tues cyl 1, 2, and 3 were between 8 and 9 and the others were between 11 and 13 i was told this is def rings but because 1, 2, and 3 are low on my car it will only be oil control rings and that the bores should be ok. At the moment car running fine after new plugs, still dont want to use it too much as ive heard that the rings can break up if they are worn or weak.

[Project-VR6-38 0]

hi, did they carry out a "wet" compression test at the same time as the normal compression test? a wet test tells you if your rings are gone, r u burning oil? if ur not burning any oil then it could be your head gasket!! what mileage has the engine covered?

[robsparky 0]

Hi, no it was a dry test, i did the test myself. I assume by a wet test you mean putting a small amount of diesel in the cylinder and doing the test again? I wasn't sure to do both or not. i also wasnt sure if i should let the engine tick over and keep resetting the gauge or go with the first reading.

The car is burning oil, cyls 1 and 6. its got 118K on the clock. I sort of ruled out the head gasket as it runs too well and there are no issues with cooling system.

[SiGainey 1]

worth doing a leakdown test on it?

[robsparky 0]

I've re-done the compression test. I didnt start the engine this time, just used crankover compression. The readings came out between 135 - 155 psi. I then did a wet test which affected them all by about 10 - 15 psi. The odd thing is that the cylinder that burns the most oil was the one least affected by the wet test. Maybe there was already sufficient oil round the rings to provide some seal??

So it is looking like piston rings, but will try and organise a leakdown test asap.

[budgie 0]

my engine is being stripped down at the mo due to this prob with rings, like your car rob mine was running sweet but i was strongly advised to sort prob out soon as poss due to the weakness of the worn rings...

[robsparky 0]

What you havin done budgie?? is it full engine out job and then strip down and rebuild? If so, what sort of price you looking at... if you dont mind me askin?

[budgie 0]

sorry dude not been around, my car is being done by a vauxhall mechanic who will have car for about 2 weeks as work will be done in the eves and weekends.

At the mo the price is £750 inc parts, which is the cheapest i was quoted. this is a private job but this guys workshop at the bottom of his garden is 1st class and fully kitted out. He lives in watford hertfordshire.

I was quoted £2700+vat by stealth for a full rebuild.

the Phirm said when you strip down vr engines more probs are likely to be found and would nt give me a proper quote but said there prices are only guides. which is not much help

Personally mate i would book my car in with stealth for a complete diagnostics like i did this cost £60 they will tell you exactly whats wrong, your comp tests are not alot to go on dude and the cause of the low comp could be anything....once you know try to source somebody privately, it will save you money.

Also try talkin to mechanics at your local vw dealers and ask them if they are up for private jobs, it worked for me dude...let me know how you get on mate also i,ll keep you posted on any probs that we encounter along the way with my rebuild....peace!

[lee060 3]

are you losing power or burning oil?? if not , then why are you bothering with the rings? , 130-155 psi is fine .

[robsparky 0]

Hi dreamer, i've lost some power and burning oil. plugs 1 and 6 are oiling up badly. Like you say, compression isnt that bad, but theres oil getting in them cylinders somehow.

[lee060 3]

possibly valve stem oil seals?

Liam .

[robsparky 0]

with valve seals you tend to get smoke on cold start up, gear change and on deceleration. The only time i see smoke is when i boot it up the revs. It is possible, drawing oil down the inlet valve would give an almost clean burn and it would be a much easier job than changing piston rings.

[peanut 0]

had similar on a vr and changed the valve stem oil seals with the head on. Didnt cure it so now looking at changing rings and having head refurbed. No loss of power but it its charged and losing nearly 7psi, think this may be blowback. Did a compression test and although the rear bank were oily all ssemed within tolerance (but it was a dry test). Leakdown test wasnt conclusive

[Haydn 0]

Hello, another VR burning oil question. Head fully rebuilt, compression test ok, No smoke on start up just a puff of blue smoke now and again on de accelaeration after high revs? Any ideas?

[Haydn 0]

Forgot to say, from what ive heard this car runs perfect and pulls very well with no signs of water contamination and the engine has only coverd 2000 miles since rebuild. Thanks

[robsparky 0]

Hi Haydn, my vr has this fault too, but i havent done any work to it yet. when you deccelerate, the cylinders become a vacuum - because the air intake is shut off, the piston pulls air from wherever it will come from.. like the valve guides/seals and piston rings. It also pulls oil with it.

A common sign of worn valve guides or seals is to see a puff of smoke when throttling after deceleration or on gear change. This is because the air/oil has been pulled down the valve guide then burnt with the fuel mix when you accelerate. As you have had your head rebuilt, you should not have valve guide wear or bad seals.

Either the oil is being pulled up the bore passed worn piston rings or its coming through the breather pipes from the crankcase and in to the air intake.

If you have worn oil rings but good compression rings, it can give you the impression that the rings are good because the compression test shows good. You may be looking at rings like me.

How much oil are you burning? Remember all vr's burn some oil.

[Haydn 0]

Thaks rob, not burning enough oil to show on dipstick atm. The bottom end is the only part of the engine which wasnt rebuilt so it makes sense for the problem to be doen there. Early in the year i had an injector go making the car run very rich. Unfourtunatly i had to do more mileage than i wanted to get it fixed. The car wasnt burning any oil before this. Could this be related? recently the car hasnt ben burning any oil at all which adds to the confusion, but when it does it can usually be seen through the rear view mirror.

[lee060 3]

Thaks rob' date=' not burning enough oil to show on dipstick atm. The bottom end is the only part of the engine which wasnt rebuilt so it makes sense for the problem to be doen there. Early in the year i had an injector go making the car run very rich. Unfourtunatly i had to do more mileage than i wanted to get it fixed. The car wasnt burning any oil before this. Could this be related? recently the car hasnt ben burning any oil at all which adds to the confusion, but when it does it can usually be seen through the rear view mirror.

[/quote']

running excesivly rich could of caused a case of the old bore wash, dramaticaly reducing the life of the bore's and ring's .

[robsparky 0]

Like dreamer said, when injectors wear they start to hose (which means they let fuel run through almost constantly rather than a fine spray at the right time). This washes off the film of oil lubricating the bore causing the cylinder and rings to wear quickly.

It seems strange though that you aren't burning oil consistantly. My vr uses about 3 litres of oil in 1500 miles.

If your compression tests were good and your not using enough oil to notice on the dipstick, i wouldnt worry too much. just keep an eye on it in case the oil level suddenly drops.

If you can see blue smoke in the mirror at full throttle and high revs - its almost certainly rings.

[Haydn 0]

Thanks alot for your advise i really appreciate it. The car went all the way to club charlys belguim and didnt loose any oil but a few puffs of blue now and again(only when giving it a bit of stick and then on the over run it smokes a little) It never does it at low revs. I also did an oil change (synta silver) after the injector was replaced and the oil was black black maybe a result of high contamination??? as it hadnt coverd many miles. Ive been advised to put quantum blue 15w40in to see if it still smokes. If not then this would show ring damage. not to keen on running on quantum blue though. anyone back this up??

[EmkayVR6 0]

I'm havin the same problem with mine, but mines got to the point where i have smoke all the time and rich oily deposits in the end of the exhaust, Comp test also showed cyl 1,4,6 were low about 8-9bar and the others were 10-11.

Anybody know how much a set of rings and bearings are gonna set me back?

cheers

mart