No Compression

Tonks4x4 · 08-11-10, 05:40 PM

Hi Guys, what on earth would cause loss of compression on 4 out of 5 cylinders?

Timing correct, Injectors opening fine, Cam chain and belt intact???

It was running fine followed by big cloud of light grey smoke and loss of power. No nasty noises, no fluid loss (Oil and water)

Does anyone have a bore scope I could borrow to take a look???

4v6 · 08-11-10, 05:46 PM

Snapped camshaft?

rich.r · 08-11-10, 05:48 PM

are the valves good or have they kissed the pistons as i pressume the engine turns over

just wonderd

missfire · 08-11-10, 05:59 PM

head gasket blown between the cylinders? like 4 blowing into each other? if you know what i mean? dont know how the hell it would happen though

AAN 5pot · 08-11-10, 06:01 PM

cracked head????????

Tonks4x4 · 08-11-10, 06:18 PM

Just find it really wierd I would expect a cracked head or bad headgasket on possible 2 cylinders but to get
No.1 4bar
No.2 4Bar
No.3 0Bar
No.4 4Bar
No.5 9Bar

The dizzy is still spinning so the inlet cam is ok. I will have to get the inlet and rocker off to see. but it's pissing down tonight and I can't be bothered....

It's a 7A by the way....

vag80 · 08-11-10, 06:31 PM

you may have a burnt out valve or seating prob on No3,dose the car run

kerker21 · 08-11-10, 06:33 PM

cam belt slipped around a couple of teeth

AAN 5pot · 08-11-10, 06:38 PM

voodoo??

Booty · 08-11-10, 11:55 PM

I was thinking the valves have 'kissed'. Last year at Race Retro a certain A2 owner had the same issue. The crank bolt was not tightened, came undone, and the second it was felt the ignition killed. However, on scrutiny all was ok, everything turned, no grating or gravelly feeling. But the valves had kissed and that was enough to lose all compression.

08-11-10, 06:31 PM	#7
vag80 Senior Member Classic Audi Club Member Join Date: Oct 2008 Location: Bracknell Posts: 1,967	you may have a burnt out valve or seating prob on No3,dose the car run __________________ nothing like a bit of deep dish 200k club member 87-b3 80 83-4000 2 door

08-11-10, 06:33 PM	#8
kerker21 Senior Member Classic Audi Club Member Join Date: Jul 2007 Posts: 1,412	cam belt slipped around a couple of teeth __________________ chairman of the quattro owners club 85 UR WR Quattro 52 ford transit faf specialised big hit mtb ex Z1000R owner ex KTM Duke owner

08-11-10, 11:55 PM	#10
Booty Moderator Classic Audi Club Member Join Date: Sep 2007 Location: Deepest darkest Shropshire Posts: 5,077	I was thinking the valves have 'kissed'. Last year at Race Retro a certain A2 owner had the same issue. The crank bolt was not tightened, came undone, and the second it was felt the ignition killed. However, on scrutiny all was ok, everything turned, no grating or gravelly feeling. But the valves had kissed and that was enough to lose all compression. __________________ 1987 Audi Coupe quattro - Clarion Tribute Car 2012 Audi A6 Allroad 2004 Mercedes SLK 350 2017 Mercedes GLA 220

08-11-10, 05:46 PM	#2
4v6 Ex Member Classic Audi Club Member Join Date: Dec 2007 Posts: 5,565	Snapped camshaft?

08-11-10, 05:48 PM	#3
rich.r Senior Member Join Date: Jul 2010 Posts: 1,832	are the valves good or have they kissed the pistons as i pressume the engine turns over just wonderd

08-11-10, 05:59 PM	#4
missfire making wooden things Classic Audi Club Member Join Date: Dec 2009 Location: cow land Posts: 8,156	head gasket blown between the cylinders? like 4 blowing into each other? if you know what i mean? dont know how the hell it would happen though

08-11-10, 06:01 PM	#5
AAN 5pot Grown up member Join Date: Feb 2010 Posts: 683	cracked head????????

08-11-10, 06:18 PM	#6
Tonks4x4 4 ring whore! Classic Audi Club Member Join Date: Oct 2008 Location: Huthwaite, Nottinghamshire Posts: 2,607	Just find it really wierd I would expect a cracked head or bad headgasket on possible 2 cylinders but to get No.1 4bar No.2 4Bar No.3 0Bar No.4 4Bar No.5 9Bar The dizzy is still spinning so the inlet cam is ok. I will have to get the inlet and rocker off to see. but it's pissing down tonight and I can't be bothered.... It's a 7A by the way....

08-11-10, 06:38 PM	#9
AAN 5pot Grown up member Join Date: Feb 2010 Posts: 683	voodoo??