Compression test procedure

[Gasngo]

Hey there I have done many a compression test and various type of motors but I thought I would ask just to make sure Im getting it rt the first time.

1997 GTI is what Im working on. Both plugs out? Open throttle ? Crank till gauge stop? I dont see a grounding point for the plug leads. Make my own some how? Any input is welcome. I understand 145 150 are good #s to have. While Im on the subject I have a GTI LE RFI that I want to do it do also same way and what compression should I see on that motor.

Thanks Gasngo

 

[mikidymac]

The grounding lugs should be on the MAG cover, yes, you need to ground the plug wires.

You can either leave one plug in or take both out, won't make a difference.

Fully charged battery, fuel valve OFF, throttle held wide open and crank until the needle stops climbing.

 

[Gasngo]

Thanks for the reply Its a ski Im interested in buying and I dont see the ground lugs. Ill assume its been taken apart before and did not get put back on. I pull some gator clips out of the tool box. Anybody have thoughts on what I should get with the 03 GTI LE RFI

 

[mikidymac]

150 psi is perfect compression and at 120 it is toast.

On that ski they might be on the rear electrical box under the rear seat.

 

[Gasngo]

Thanks for the reply. I spoke with a buddy who knows the earlier GTI carb model and said 145 /150. I did some looking on the GTI LE RFI and at one point in time I thought I saw 130 on some literature but even that seemed low just by gut feeling. Speaking of feeling I have a feeling the the 03 GTI will need a top end job in the off season.

 

[B_Stew]

Thanks for the reply. I spoke with a buddy who knows the earlier GTI carb model and said 145 /150. I did some looking on the GTI LE RFI and at one point in time I thought I saw 130 on some literature but even that seemed low just by gut feeling. Speaking of feeling I have a feeling the the 03 GTI will need a top end job in the off season.

I’ve been told 130 and it runs, send it. Then in the off-season rebuild it because it’s on its way out.

 

[Gasngo]

Off season is close I figure another month. I have been told by my buddy in the biz that the RFI LE are a headaches if things goes south and if it runs good find a new home. It runs good but I also get the point its early gen tech and at some point in time once something goes its probably not worth fixing.

 

[mikidymac]

787 and smaller, 150/150 is perfect and 120 it’s done.

951, 130 I’d perfect and 110 it’s toast.