Engine Compression Test

[StevieNicker]

I wasn't convinced the Earlybay id just bought was running on all 4 so I thought Ii'd do a compression test.
Its a 71 but has an 1800 type 4 engine in off a later model.

Compression result were as follows:

Cylinder 1 (OS Rear) - 85
Cylinder 2 (OS Front) - 110
Cylinder 3 (NS Front) - 90
Cylinder 4 (NS Rear) - 85

As you can see 3 cylinders aren't playing ball. I re ran the tests for 1,3 and 4 with a bit of oil in the cylinder to see if was a piston ring issue. Re-run results were as follows:
Cylinder 1 (OS Rear) - 120
Cylinder 3 (NS Front) - 115
Cylinder 4 (NS Rear) - 170 (WTF!)

To me that points to worn piston rings, but with 3 being gone would you think it could be something else, i.e the Head or valve issues?

 

[Paul Weeding]

1800... Could well be cracked heads as well!!

Biggest valve heads that vw did apart from the Porsche 2l out of the 914...

Of all the heads I've looked at, 1800 ones seem to be the worst for cracking through the exhaust port into the head!!

Good luck with it :smile:

 

[jonboylaw]

If you can get hold of a Leak Down compression tester you will quickly identify the problem.
This type of tester uses compressed air and measures the leakage in the cylinder. If the rings are worn you will hear the air in the crank case. If the valves are leaking the you will hear the inlet or exhaust hissing. You can pick them up off eBay for £30 and well with the money.


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