So I'm starting an A4 overhaul. The answers to my questions might be in the Moyer book, but I don't have it yet, just ordered it last week, so bear with me...
Backstory on the engine: Engine is out of a 79 Oday 27. It has not been well kept, but has been upgraded some- it has an indigo electronic ignition and some kind of aftermarket alternator, so it isn't like it's been ignored, but it's caked with rust... I pulled the engine b/c the head has a leak, more on that in the questions. Since I'm gonna be pulling the head off, I figure I'll clean the whole thing up and do whatever else I ought to do...
So. I started by doing a compression test to find out whether I should be dealing with pistons and rings or whether the head is gonna be my only worry. I did the compression test cold (b/c I can't start it up right now) with all plugs removed and the throttle held open. Results seem fine for cylinders 2,3, and 4 - all about 100psi. The first time I tested cyl 1, I got 85 psi, but after testing the others, I thought maybe I didn't get the compression tester threaded all the way down to the block and I ought to give it another go, but this time I got 65psi.
Questions:
1) Why would my cyl 1 have such lousy compression compared to the others? Anything I can do with the engine cold to be sure it wasn't a test error? Why the change in compression over the course of 5 minutes?
2) When the engine was running, there was water leaking from the head where the red circle is in the picture. I figured it was corrosion and that if I took a wire wheel to it I'd see pinholes, but I found none. Any chance the problem is with the plug on the top of the head right there? Water was coming out in a slow dribble- more than a drip, but not a stream. Any solution to this problem besides a new head?
Pictures:
Backstory on the engine: Engine is out of a 79 Oday 27. It has not been well kept, but has been upgraded some- it has an indigo electronic ignition and some kind of aftermarket alternator, so it isn't like it's been ignored, but it's caked with rust... I pulled the engine b/c the head has a leak, more on that in the questions. Since I'm gonna be pulling the head off, I figure I'll clean the whole thing up and do whatever else I ought to do...
So. I started by doing a compression test to find out whether I should be dealing with pistons and rings or whether the head is gonna be my only worry. I did the compression test cold (b/c I can't start it up right now) with all plugs removed and the throttle held open. Results seem fine for cylinders 2,3, and 4 - all about 100psi. The first time I tested cyl 1, I got 85 psi, but after testing the others, I thought maybe I didn't get the compression tester threaded all the way down to the block and I ought to give it another go, but this time I got 65psi.
Questions:
1) Why would my cyl 1 have such lousy compression compared to the others? Anything I can do with the engine cold to be sure it wasn't a test error? Why the change in compression over the course of 5 minutes?
2) When the engine was running, there was water leaking from the head where the red circle is in the picture. I figured it was corrosion and that if I took a wire wheel to it I'd see pinholes, but I found none. Any chance the problem is with the plug on the top of the head right there? Water was coming out in a slow dribble- more than a drip, but not a stream. Any solution to this problem besides a new head?
Pictures:
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