# Compression Test Results



## slinx (Jan 15, 2007)

Hi,

I've had a compression test done on my 225 today, here's the results:

No.1 - 135psi, 9.5bar
No.2 - 120psi, 8.5bar
No.3 - 142psi, 10bar
No.4 - 152psi, 10.75bar

They do vary a bit! It states that the acceptable rane is 7-13bar/100-185psi. The guy in the garage said the factory figures should be at 140psi.

I also read somewhere that it should be at 80% of the factory figures, which means the 2nd cylinder is at about 85%. It also said on the site that there shouldn't be too big a variance between the cylinders.

Has anyone else had a test? can anyone confirm the correct factory figures and the allowable figures? I trust the guy in the garage and am happy he's gave the ok, it'd just be interesting to get others opinions! It also gives others something to compare against.......

Thanks.


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## JAAYDE (Aug 15, 2006)

I will be doing this soon..

i'm also interested in other results..

whats kind of mileage have you got..?

I'm also interested in what kind of bore wear that the 1.8T blocks get, if any..


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## slinx (Jan 15, 2007)

The car's done 78k at the moment. You'll have to post your results when you get it done.


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## slinx (Jan 15, 2007)

I've been told that the compression results are too low, especially on number 2, and that they should be at around 170-180psi.

I've tried rining a local Audi garage, and Audi UK, but neither of them will give me technical information. Does anyone know what the factory pressures should be ??


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## slinx (Jan 15, 2007)

I've done a bit of research and from what i can find is that it has a compression ratio of 8.9:1.

The compression pressure should be 17-20 times the ratio, so should be between 151.3psi and 178psi. With a maximum 10% tolerance between the cylinders. Therefore a 15-18psi difference maximum.

Can anyone confirm?

Looks like i'm f%$^$Â£.


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## slinx (Jan 15, 2007)

Please can anyone help with the figures?

Halfords don't have a haynes manual and i've trawled the web, but no luck!!


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## UK225 (May 12, 2002)

Cylinder leak test is much better than a compression test.. however according to my factory data for compression test results

New 10-13 BAR

Wear Limit 7 bar

Permissible difference between cylinders max 3 bar

Hope this is of some help.

Cheers
Morgan


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## Black Knight (Jan 16, 2007)

you dont really need the factory specs, noone bothers with that. the tests arent that standardized either to be compared to an absolute spec... when you do a compression test, either all cylinders are the same or close in which case that means a good engine.. or some are low.. that means a fukked engine.. yours is pretty close to being fukked..


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## slinx (Jan 15, 2007)

Yeah, that's kinda what i thought. Time to bang it on ebay or trade in for a newer one.


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## HighTT (Feb 14, 2004)

As Morgan says, get a leak down test done;
it will tell you much much more than a compression test.

Was your compression test done dry or wet?
Was the engine hot?
Was the throttle fully open?
Was the cranking speed constant?

Although your variation is too much, it could be something simple,
don't throw your car away just yet


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## slinx (Jan 15, 2007)

Ta for your replies.

To be honest i left the car with the garage to do the test, cos i had to go to work.

From what i remember him saying, it was just a dry test and mentioned keeping it a 2000 revs. I can give him a ring and ask exactly what he carried out.

Whats a leak down test involve?

Also, are you suggesting the variance could be down to something that won't cost me Â£Â£Â£Â£ and might not be valves/pistons or whatever.

In a previous thread i mentioned that he told me my turbo was letting in too much oil and needed replacing (the odd bout of smoke & oil consumption), but the compression results stopped me from getting it replaced incase it was something even more serious.

I also mentioned a sort of cranky noise under decceleration, which i thought was the turbo, but have read this could be the divertor valve?.

Thanks for your input.


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## Mike TT (Jun 5, 2006)

Having read all the comments, I think it might be best for you to have the car checked by someone who knows a little more about what they are talking about.

A compression test is done at cranking speeds- Thats some powerful battery/starter motor that can crank at 2000rpm. Also, the comment about whether the throttle was fully open or not really relates back to when throttle pedals opened the butterfly, an ECU is responsible for that now.

The comment on wet/dry however is relevant as this will help highlight whether and compression leakage is via piston/bore wear or headgasket/valve seating.

A cylinder leakage test is a good choice but in my opinion, should be done in conjunction with a compression test.


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## HighTT (Feb 14, 2004)

Mike TT said:


> A compression test is done at cranking speeds- Thats some powerful battery/starter motor that can crank at 2000rpm. Also, the comment about whether the throttle was fully open or not really relates back to when throttle pedals opened the butterfly, an ECU is responsible for that now.


 I raised the throttle open aspect because I don't know how
an ECU would know to let enough air in at cranking speed to carry out a meaningful compression test :? .

I've only done this sort of thing on 'old' cars that have carbs.


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## KenTT (Feb 20, 2005)

HighTT said:


> Mike TT said:
> 
> 
> > A compression test is done at cranking speeds- Thats some powerful battery/starter motor that can crank at 2000rpm. Also, the comment about whether the throttle was fully open or not really relates back to when throttle pedals opened the butterfly, an ECU is responsible for that now.
> ...


A nice row of SU's :?: 8)


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## HighTT (Feb 14, 2004)

KenTT said:


> HighTT said:
> 
> 
> > Mike TT said:
> ...


No ... a nice row of Dellortos (DHL 45s) 8)


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