compression testing figureS on VR6

[Chris Langdon 0]

hi

 

i hoping to do a compression test on my VR tonight (borrowed mates compression tester) i was just wondering what sort of figure(s) i should be expecting from a good VR engine??? as i dont know, also i fitted the centre dials ages ago but dont know what sort of pressure a good VR engine should be at idle when at working temp?

 

any help and info i would be most gratful

 

regards

 

Chris L

[steve @ 0]

~2 bar hot (80-90

[Chris Langdon 0]

Cheers steve mines doing that 5 bar cold and 2 bar at idle when hot.

[CorradoVR6-Turbo 0]

Compression pressure in should be 11-13bar

[was8v 0]

The Bentley manual states when new the compression should read 11-13 bar and the wear limit is 7.5bar with engine at 30 degrees(F?)

 

Mine made 12-13 bar when cold the other day - full results here - http://www.the-corrado.net/.archive/forum/viewto ... 3&start=15

[Roger Blassberg 0]

Are these figures barg (gauge pressure)i.e. above atmospheric, or absolute pressure?

 

Best wishes

 

RB

[was8v 0]

Are these figures barg (gauge pressure)i.e. above atmospheric, or absolute pressure?

 

Best wishes

 

RB

 

 

No idea, its what my draper compression gauage said on the dial

[ProdigalSon 1]

Are these figures barg (gauge pressure)i.e. above atmospheric, or absolute pressure?

 

Best wishes

 

RB

 

No idea, its what my draper compression gauage said on the dial

I've got the same Draper gauge - the pressure readings are relative (ie. in addition to atmospheric pressure), the minimum reading is 0 bar, which is what you get when it is 'zeroed'! :wink:

 

The other useful thing to check is the variation between cylinders, if there is more than 3 bar difference between any of the cylinders, you have a major problem... :( My variance was about 1/3 bar 8)

[Chris Langdon 0]

im guessin you lot disconnected the injectors/fuel rail before carrying out the test, to stop lots of fuel being throw down the bores!!!

 

and is it best to do it hot as for the working tolerances

 

total agree with the above checking the difference between them

 

cheers

 

Chris

[was8v 0]

im guessin you lot disconnected the injectors/fuel rail before carrying out the test, to stop lots of fuel being throw down the bores!!!

 

and is it best to do it hot as for the working tolerances

 

total agree with the above checking the difference between them

 

cheers

 

Chris

 

 

yeah remove the bottom right relay and fuse 18 and disconnect the LV side of the coil. Make sure your battery is charged!

[Chris Langdon 0]

i guess the last one dont apply to me cos ive got a coil pack?

[A1 VR6 0]

Hope you allay your fears Chris and there isn't a problem with it, that's a nice car you have and I'm really looking forward to seeing it this year.

[was8v 0]

i guess the last one dont apply to me cos ive got a coil pack?

 

Undo the LV side of the coil pack then! lol I theres a similar LV (low voltage) plug on it, i.e. not one of the spark plug leads the little lead.

 

Basically you don't want the coils generating a high voltage as it wont be used - this could damage the coil pack/coil or earth through you while you are messing in the area giving you a shock.

 

And just check with your book that fuse 18 is the fuel pump and the bottom right relay is the fuel pump relay, if my memory serves me right it is.

 

Its a good idea to:

first take the fuel pump relay / fuse out
start the car a couple of time with the plugs in it will briefly run using up fuel left in the lines.
disconnect the LV side of the coil / coilpack
whip all the plugs out
screw your gauge in
turn car over on starter until its not going up anymore (I did it 7 times to be sure)
reset the gauge and take 3 readings for each cylinder and average them

 

if the readings are all within the range 11-13 bar then all is well. If a cylinder reads much lower than that somethings amiss. In this case repeat the above compression test but squirt a bit of oil down the cylinder this will temporarily seal the rings. If the reading is unchanged then you have a head gasket / cylinder head issue, if the reading is in the normal range or above then you have a piston ring / bore wear issue.

 

If 2 adjacent cyclinders are low then the head gasket may have gone between them.

[Chris Langdon 0]

Right here are my figures that i got from doing a compression test today. The Car cover 70000 Miles regularly service, me personally that looks like ok figures, would just like soone elses view.

 

Still NOT at the bottom of my oil consumption and sightly carboned no:6 Spark plug?????? Its starting to do my head in!!!

 

HOT

Cyl.1 160IB/11bar

Cyl.2 160IB/11bar

Cyl.3 160IB/11bar

Cyl.4 160IB/11bar

Cyl.5 155IB/11bar

Cyl.6 170IB/11bar

 

 

WET TEST

 

Cyl.1 180IB/12bar

Cyl.2 180IB/12bar

Cyl.3 160IB/11bar

Cyl.4 165IB/11bar

cyl.5 190IB/ 13bar

Cyl.6 165IB/11bar

[Chris Langdon 0]

Hope you allay your fears Chris and there isn't a problem with it, that's a nice car you have and I'm really looking forward to seeing it this year.

 

 

Cheers mate :D

[Kevin Bacon 5]

Those figures are fine.

 

When you were cranking the motor over, did you notice if one or more cylinders took much longer to stop the gauge than the other cylinders?

 

Is that Asim's old car? If it is I doubt it has anything seriously wrong as it was the most powerful standard VR6 Stealth have seen. 212hp!

[Chris Langdon 0]

no cheesewire, its not asim's, i brought it about a year ago in Bournemouth, the owner before me had it for about five years and looked after it,

 

christ 212hp i take it that is at the flywheel????

 

what should a standard VR be at the wheels?

 

Where is stealth i have heard of them, i fancy going to that rolling road day in april but im in Devon!!!!! :D

[Chris Langdon 0]

Those figures are fine.

 

When you were cranking the motor over, did you notice if one or more cylinders took much longer to stop the gauge than the other cylinders?

 

Is that Asim's old car? If it is I doubt it has anything seriously wrong as it was the most powerful standard VR6 Stealth have seen. 212hp!

 

 

 

Why do you ask mate? what would that indicate????

[ProdigalSon 1]

Those figures are fine.

 

When you were cranking the motor over, did you notice if one or more cylinders took much longer to stop the gauge than the other cylinders?

 

Is that Asim's old car? If it is I doubt it has anything seriously wrong as it was the most powerful standard VR6 Stealth have seen. 212hp!

 

 

 

Why do you ask mate? what would that indicate????

I'm guessing that if one cylinder took longer than the others, it might have a poor seal - not enough to loose significant pressure, but it wouldn't get the gauge up to the final reading as fast as the other cyls, no?