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Merc 502 Timing Issue - any help.

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Old 07-13-2021 | 07:01 AM
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Originally Posted by Griff
Possibly worn dist gear and/or cam gear is much more likely than a timing chain issue.
I thought that but what about the low compression? I put my finger over #2 and it didn’t blow my hand away at all.
This week I’m going to investigate and get my compression numbers and check for loss of vacuum.
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Old 07-13-2021 | 07:13 AM
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Do leak-down test for compression loss. Borescope on your camera will tell a lot about your pistons/valves. Can also be helpful about your cam.
Good luck.
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Old 07-14-2021 | 09:38 AM
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Originally Posted by GLENAMY 242SS
Do leak-down test for compression loss. Borescope on your camera will tell a lot about your pistons/valves. Can also be helpful about your cam.
Good luck.
Ya going to get all compression readings today, check for any other noticeable issues, scan it with a Rinda tool and see if anything shows. Might do a smoke test to see if anything shows from that.
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Old 07-14-2021 | 05:23 PM
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Got the following compressions.

1-130
2-25
3-38
4-95
5-75
6- 50
7- didn’t check.
8- 80

Last edited by srdrago; 07-15-2021 at 09:41 AM.
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Old 07-14-2021 | 05:26 PM
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Originally Posted by srdrago
Got the following compressions.

1-130
2-25
3-38
4-95
5-75
6- 50
7-
8- 80
Might as well stop there. Engine needs to come out and be torn down to evaluate further.
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Old 07-14-2021 | 05:38 PM
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that might be a broken cam shaft
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Old 07-14-2021 | 08:40 PM
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Old 07-15-2021 | 06:38 AM
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Originally Posted by Griff
Might as well stop there. Engine needs to come out and be torn down to evaluate further.
Originally Posted by F-2 Speedy
that might be a broken cam shaft
oh ya. Can’t get it to the garage for couple days. Going to start tearing it down meanwhile to prep to pull out.
don’t think cam shaft being broken. The router spins, starter spins and front belts spin. So from front to back it’s intact.

anyone know if I can get the timing cover off without dripppig the pan?
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Old 07-15-2021 | 07:31 AM
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You may be able to pry the timing cover off of there, but if it is a gen 6 cover it will most likely break the corners off the timing cover. It isn't really feasible to do it without dropping the pan and dropping the pan in the boat is all but impossible. You would be much better off to spend the 45 minutes it takes to remove the engine.
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Old 07-15-2021 | 08:36 AM
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If #7 really has 0 pressure 95% chance engine has to come out to fix it. Much easier to work on on a stand.
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