Mercruiser 4.3 oil leak question

[AAJagerX]

I'm wondering if any of you guys on here have experience with the 4.3 Mercruiser.  I've found that I've got a small oil leak in mine and am having trouble pinpointing the source (it'd be easier if the whole thing wasn't painted black  ).  It looks to be on the front side of the motor, and is getting on one of the pulleys (oil spray is apparent on the top of the engine compartment cover... and just about everywhere else).  It's not leaking a whole lot, as I had to top off about half a quart after 4-5 hours on the water.   Overall the engine runs out great, I just want to identify and fix the leak.

I'm wondering if it could be the crank seal, but I'm not sure.  Apparently the timing seal ALMOST never leaks, so I've ruled that out for now.  Also, could it be that the crank case vent tube is clogged somewhere, forcing internal pressure to get too high resulting in oil being forced by the seal?  I read on another bbs that the vent clog issue happens from time to time but wanted some AHer opinions on this.  

I've degreased the engine, run it, and inspected again but still can't see exactly where it's coming from...  

[Shuffler]

When cool spray pam on the front of the engine... then white paint if you think it would help you to see it. Then rinse off with water.


I believe the spray you seeing is the oil thrown off the pulley.

[Rash]

I've used the oil dye, it showed me were my boat motor was leaking.

[morfiend]

I've used the oil dye, it showed me were my boat motor was leaking.

  Yuppers,quickest and easiest way to trace a leak, oh you'll need a UV light source too

  I would also change out the PCV valve,cheap insurance!  While you're at it might aswell change "ALL" the filters.  If it sat for any length of time you'll be doing yourself a favour by changing out the filters,amazing the things you'll find doing just that!

   Do a degrease of the engine before you run the dye,this will make the trace much easier.


     

[rpm]

I had one of those in a 28' Baretta. IMHO, Mercruiser makes great anchors.

[morfiend]

I had one of those in a 28' Baretta. IMHO, Mercruiser makes great anchors.

  Have any problems with the gimble in outdrive?



   

[Captain Virgil Hilts]

I'm wondering if any of you guys on here have experience with the 4.3 Mercruiser.  I've found that I've got a small oil leak in mine and am having trouble pinpointing the source (it'd be easier if the whole thing wasn't painted black  ).  It looks to be on the front side of the motor, and is getting on one of the pulleys (oil spray is apparent on the top of the engine compartment cover... and just about everywhere else).  It's not leaking a whole lot, as I had to top off about half a quart after 4-5 hours on the water.   Overall the engine runs out great, I just want to identify and fix the leak.

I'm wondering if it could be the crank seal, but I'm not sure.  Apparently the timing seal ALMOST never leaks, so I've ruled that out for now.  Also, could it be that the crank case vent tube is clogged somewhere, forcing internal pressure to get too high resulting in oil being forced by the seal?  I read on another bbs that the vent clog issue happens from time to time but wanted some AHer opinions on this.  

I've degreased the engine, run it, and inspected again but still can't see exactly where it's coming from...  

Entirely possible that the seal in the timing cover is leaking, and the harmonic balancer has a groove worn in the hub. You'll know that is the case if the back of the balancer is wet, and you'll see evidence of oil being slung from the hub and seal area, it will make "oil tracks".

Yes, the crankcase vent system could be blocked. In fact, the crankcase vent system being blocked will cause the leak you describe.

[AAJagerX]

Thanks for the replies.  From what you all are saying, I think I'm on the right path.  Fuel and oil filters are fresh, so that's out of the way.  I'll check the crankcase vent to make sure it's clear, degrease the engine again, and see what happens.  If I still get leakage, I'll degrease again and use the dye. 

I failed to mention this earlier, but the boat sat (winterized) for roughly 2 years before I bought it.  If the crankcase vent isn't a problem, I'm wondering if I may have an issue due to a seal drying out.  Is that also a possibility?

[AAJagerX]

I had one of those in a 28' Baretta. IMHO, Mercruiser makes great anchors.

4.3 in a 28 ft boat?  Are you sure it wasn't a 5.0 or 5.7?

[morfiend]

Thanks for the replies.  From what you all are saying, I think I'm on the right path.  Fuel and oil filters are fresh, so that's out of the way.  I'll check the crankcase vent to make sure it's clear, degrease the engine again, and see what happens.  If I still get leakage, I'll degrease again and use the dye. 

I failed to mention this earlier, but the boat sat (winterized) for roughly 2 years before I bought it.  If the crankcase vent isn't a problem, I'm wondering if I may have an issue due to a seal drying out.  Is that also a possibility?

  Yes !


   check what Virgil wrote and follow what he said.   Seal can and will dry out and this can cause leaks.

   

   PS:  could be a valve cover leak in just a bad spot.clean there first,should be easy to see if thats the problem.

[AAJagerX]

 Yes !


   check what Virgil wrote and follow what he said.   Seal can and will dry out and this can cause leaks.

  

   PS:  could be a valve cover leak in just a bad spot.clean there first,should be easy to see if thats the problem.

Will do.  I really don't want to have to yank the engine to do a crank seal...  I guess I'll just have to get used to being upside down for a bit trying to sort this out.  

I hope to get the leak squared away quickly so I can start on the cosmetic stuff (vinyl replacement and a good polish).  Btw, the boat is a 1990 Maxum 21ft sport cuddy.  I made a hell of a trade to get it ($0 out of pocket, just some extra guitar equipment that I probably paid too much for a few years ago).  The people I got it from bought it new, and switched to jet skis when their kids moved out.  It sat for two seasons in a heated building (right beside a 69 Camaro that he bought brand new) and he wanted one of my guitars and amps (and space in the building) to unload it.

Anyway, this is the boat.  I love the looks and layout of it.  She's gonna be sweet when I'm all done.



On the lake last Sunday

[CAP1]

I've used the oil dye, it showed me were my boat motor was leaking.

this

[CAP1]

i don't see "money pit" on the hull yet.

[rpm]

4.3 in a 28 ft boat?  Are you sure it wasn't a 5.0 or 5.7?

Yep. It was a POS and constantly in the shop. The routine was go to the lake, go to the boat shop, empty wallet, repeat. I sold it after 2 years and it was the best day I had while I owned it.

[homersipes]

  thats the first thing I thought of Cap.  Ah dont worry boats are fun I have a "money pit" too in need of a starter.