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-   -   Merc 502 Timing Issue - any help. (https://www.offshoreonly.com/forums/general-q/372434-merc-502-timing-issue-any-help.html)

srdrago 07-13-2021 07:01 AM


Originally Posted by Griff (Post 4797230)
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.

GLENAMY 242SS 07-13-2021 07:13 AM

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.

srdrago 07-14-2021 09:38 AM


Originally Posted by GLENAMY 242SS (Post 4797254)
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.

srdrago 07-14-2021 05:23 PM

Got the following compressions.

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

Griff 07-14-2021 05:26 PM


Originally Posted by srdrago (Post 4797550)
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.

F-2 Speedy 07-14-2021 05:38 PM

that might be a broken cam shaft

SB 07-14-2021 08:40 PM

https://cimg6.ibsrv.net/gimg/www.off...079943694.jpeg

srdrago 07-15-2021 06:38 AM


Originally Posted by Griff (Post 4797552)
Might as well stop there. Engine needs to come out and be torn down to evaluate further.


Originally Posted by F-2 Speedy (Post 4797556)
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?

snapmorgan 07-15-2021 07:31 AM

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.

liberator221 07-15-2021 08:36 AM

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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