In my experience with prochargers, your belt being worn on one side would make me think you were either losing a idler bearing in a idler on the tenssioner is getting worn and ;'cocked", which either one can rub its respective pulley on a angle on belt and wear outside unevenly. If you grab the tensioner with belt off and try to pull it in and out, if it has slop, its worn. Another thing I learned is anytime a seprentine blower belt slips under boost it leaves belt dust AND pulley shoots over 200 degrees, hot enough where you cant touch it without getting burned!

Arctic,

I checked the tensioner and pulley. There was no more end play or axial/radial runout to the pulley than the new one I had on hand. It spun smooth and free with no wobble to speak of. I was not up for the swap, given the extremely limited space there is to work with, so I skipped it. I'm betting there was something rubbing on it at one point in time prior to our owning the boat. There are a number of hoses and wire bundles in the general area that could have been the culprit.

Thanks. Brad.
(937)545-8991

Guys,

Having the new belt on, it's time to move on to the rest of the effort. My thinking is to go ahead and replace the plugs as I do the compression test. I'm thinking the plugs are going to be fouled beyond burning them off. This would enable a clean slate to check burn pattern on the plugs. Sound logic?

Also.... I'm assuming the engine should be warmed up before doing the compression test.....?

Thanks. Brad.
(937)545-8991

You can do a comp test on a cold engine. Numbers might be marginally less than when warm, but you're looking for cyl-to-cyl variation rather than being concerned with absolute numbers. So it's fine either way.

Leakdown is another story.

Griff,

Dang. That made THAT easy.

Thanks. Brad.
(937)545-8991

Guys,

Compression test complete.

L R
1 - 137 2 - 140
3 - 140 4 - 149
5 - 138 6 - 148
7 - 140 8 - 150

These are all guestimates, as the gage was an analog unit, with 5lb graduations on the dial, and I was trying to split hairs, reading between the lines. From memory, these seem like similar numbers to what I've seen others post here on OSO, but I really don't know if these are good numbers or not. I tried cranking the engine as consistently as I could. I had no way of watching the gage to see if peak was established or not, so I ran each cylinder twice, releasing pressure each time, before moving on to the next. I did notice that the right bank seemed consistently and, on average, higher than the left, so I went back and re checked two of them, just to rule out whether I was a factor, as I started on the left bank, and I might have gotten more confident in tightening the gage in the plug hole and cranking the engine longer. I was no real difference the second time around. This is my first time actually doing this sort of thing myself.

Thoughts?

Thanks. Brad.
(937)545-8991

Assuming those are accurate, you have less than 10% variation across the board. I'd say those are perfectly acceptable numbers, as far as consistency among the 8.

Did you have the throttle open while doing the test?
I’m not that far away from you. Just outside Camden Oh. is where we live. You probably go through here if you go to Brookville any.

Rosie,

Nope. Didn’t realize I should have. If somebody mentioned it, I’d forgotten. 😕

Thanks. Brad.
(937)545-8991

That’s why I asked. I didn’t see it mentioned and you stated that was your first time doing that.
The throttle blade will restrict airflow into the engine. You’ll likely see higher numbers with the throttle open.

How’d the plugs look? If the ignition side of things is getting weak you could be blowing the spark out under boost. I’d think you’re down on boost because you say you aren’t getting the rpm you did before.
Stay on the tighter side of the plug gap when you gap the new plugs.