[Mk2] [Turbo] rev 2 compression results advice

[dylan5084]

Ok so I bought a cheapo compression tester and got the results 65 80 65 75 psi, I realise this is really poor, is it possible I've done the test wrong? I know its highly unlikely but I'm hoping I've done it wrong

Car doesnt seem down on power, last time on the rolling road it was making 240 bhp at the wheels but hitting detonation flat out at higher revs, cars been off the road since due to a hole in the gearbox..... Advice please?

Thanks Dylan.

[Slarty]

Did you have the throttle fully open?

[dylan5084]

Nope, I take it I was supposed to?

[Slarty]

Nope, I take it I was supposed to?

Yep otherwise you're trying to draw air in through a closed flap. Try it again and see if it makes a difference

[dylan5084]

Ahh sweet, will go again 2morro

[Slarty]

After you've tried again, try it one last time but with a couple of squirts of oil down each plug hole. A largeish (10-20 psi) jump will indicate worn rings/bores.

[dylan5084]

Opening the throttle only gained 30 psi per cylinder, put the oil in and got the jump in psi, worn rings/ bores it is then

[Slarty]

100-110 psi still seems very low, even for worn rings/bores

[dylan5084]

Was losing 20% in each cylinder to the crank case in a cylinder leak down test

[dylan5084]

im in 2 minds what i want to do now- im at the point where ive spent a wee bit money fixing it and fixing it and now theres a hole in the gearbox and my compression is crap, which would mean a rebuild, or another engine and the body work aint great either

[gnzyza]

If you want to keep it standard then fit a known good engine in there, maybe a rev3 if you can get hold.

Worth doing a leak down test to be sure of the exact cause.

[3sgte]

20 percent leak down isn't massive did you isolate the fuel pump from injecting whilst cranking as that can make a difference too
At 65 psi I'm amazed th thing starts even.

[dylan5084]

20 percent leak down isn't massive did you isolate the fuel pump from injecting whilst cranking as that can make a difference too
At 65 psi I'm amazed th thing starts even.

I didnt, I think ill let some one else have a look at it lol...

On another note, is it possible to check the bores for wear by taking off the sump?

[dylan5084]

Or could someone list the do's n fonts when testing the compression

[dylan5084]

Ok so I've done the test right now with the engine up to operating temp injectors disabled all spark plugs out a full battery and spark disabled, and wide open throttle, with the results....

100 112 105 100 psi, which I know is pretty crap. Also noticed oil on no 3 piston when I looked in but am unsure if its still there from the last time I tested her and put oil in one of the chambers to see if there's a jump in the compression ( which there was)

I've also read that if all the pistons are within a certain amount of each other it can't be possible they all have the same problem which is confusing me.

Also does any of the additives actually work to help the problem?

I was using a cheap eBay gauge too.......

[bobhatton]

I was using a cheap eBay gauge too.......

There is your problem then.

Never buy anything from Ebay, it is all crap and made in China.

[dylan5084]

turns out it was a duff gauge, reading 50psi out, turns out my engines within the limits

[dawesy]

I was using a cheap eBay gauge too.......

There is your problem then.

Never buy anything from Ebay, it is all crap and made in China.

not totally true. i have brought a few branded tools that were cheaper than most other places and they are genuine items.
not everything on there is tat.