4.3 crankshaft/housing oil leak - next steps?

[ShoalSurvivor]

In searching back for a more detailed answer to the question above, I believe we may have covered this area for you, maybe have a quick glance back and see if it helps here any, https://forums.iboats.com/threads/spark-plug-part-number.762750/#post-5822771

Yes - I use that all the time. It's bookmarked and has been my primary source of info. And, Thank you!

I was just trying to relate it to the factory and component spec's that Scott had in his doc.

 

[airshot]

Best job would be to pull the engine....otherwise it becomes a half added job and will probably be needed done again down the road. Had that same leak on my 3.0....bought oil absorbing mats that lay in the bilge and soak up the oil so bilge stays just water. When I calculated the amount of oil being lost it wasn't worth a half cost to fix it until it leaked more. I was using about a quart of oil thru one summer season. I watched and added when it got down about a pint. Never low enough to cause a problem, just looked messy. The oil absorbing mats were not that expensive, around 30 bucks for a case. Used one mat in about two weeks, still have over half added he case left, used those for two years to be sure the oil did not get pumped into the lake. Your call, but....pulling the engine and replacing the seals was not yet worthwhile for a box of oil absorb mats and a couple quarts of oil.

 

[Lou C]

Want to laugh, well my 4.3 still has the original 1988 short block and neither the front or rear main seal leaks! Kinda like my 1998 Grand Cherokee where both front and rear pinion seals still don't leak neither do the front and rear transfer case output seals. The only thing that leaks on that vehicle is the rear main and ALL those AMC straight sixes do that. I gladly feed its habit because it runs so well still.

 

[Jmunk]

If it’s the crank seal in the timing cover that’s an easy fix. Remove the balancer with the proper tool, you can rent from an auto parts store. Pop out of the old seal, get a seal for a similar year 4.3L at the parts store. Just pick an S-10 for them to lookup the deal. Install the new seal and oil the balance surface that rises on the seal and install the balancer with the proper tool, again rent from auto parts store. All in should be about a $10 seal.

 

[ShoalSurvivor]

Best job would be to pull the engine....

engine is already out. New timing cover and pan gasket on the way. I will try to pull the seal and consider replacing first, otherwise the cover will be replaced.
thanks

 

[Scott Danforth]

If it’s the crank seal in the timing cover that’s an easy fix. Remove the balancer with the proper tool, you can rent from an auto parts store. Pop out of the old seal, get a seal for a similar year 4.3L at the parts store. Just pick an S-10 for them to lookup the deal. Install the new seal and oil the balance surface that rises on the seal and install the balancer with the proper tool, again rent from auto parts store. All in should be about a $10 seal.

You realize the front timing cover is plastic and they usually do not survive pulling the seal, much less driving in a new one, there is more than one leak location

 

[Chris1956]

Check the oil pan for rust. They can rust thru pretty easily in the salt water. Obviously, they are easier to replace when the engine is out.

 

[airshot]

engine is already out. New timing cover and pan gasket on the way. I will try to pull the seal and consider replacing first, otherwise the cover will be replaced.
thanks

Getting the engine out and back in, is the hardest parts to do....good luck...make her ready for spring !

 

[ShoalSurvivor]

Getting the engine out and back in, is the hardest parts to do....good luck...make her ready for spring !

I was surprised at how easy it was to pull the motor. All of the connections are pretty obvious, and it only took a couple hours to document where things go and how they're attached. I've replaced or serviced virtually all of the connections already, so it was pretty simple.

The challenge was finding a cherry picker that would clear the gunwales, but luckily, my buddy has a forklift and that did the trick with ease.

 

[Lou C]

I think the oil pan on the newer 4.3s is aluminum, so might not be so prone to rust, I have sprayed my tin one with Boeshield/CorrosionX/FluidFilm etc many times, and it's still in good shape...

 

[Jmunk]

You realize the front timing cover is plastic and they usually do not survive pulling the seal, much less driving in a new one, there is more than one leak location

Yes, I know it’s plastic. My experience has been it’s fairly easy on the ones I’ve done.

 

[ShoalSurvivor]

Yes, I know it’s plastic. My experience has been it’s fairly easy on the ones I’ve done.

I'm gonna try
I've got a new cover w/seal and gasket on the way. if replacing seal works, great. If not, then replacing cover. Will also inspect pan carefully for corrosion, but seems wise to leave it alone if it's not the problem.

 

[Scott06]

I'm gonna try
I've got a new cover w/seal and gasket on the way. if replacing seal works, great. If not, then replacing cover. Will also inspect pan carefully for corrosion, but seems wise to leave it alone if it's not the problem.

I would think your 4.3 pan given the engine vintage is likely the ribbed cast aluminum one. While it could corrode, less likely than painted steel ones. If it is painted steel easy to refinish while its out and you can coat it with bed liner for long lasting finish.

 

[Jmunk]

I'm gonna try
I've got a new cover w/seal and gasket on the way. if replacing seal works, great. If not, then replacing cover. Will also inspect pan carefully for corrosion, but seems wise to leave it alone if it's not the problem.

Since you have the engine out, I’d just swap the cover. Re-seal the oil pan after verifying with a straight edge that the mounting surface isn’t warped. I take it you just got a GM cover from a parts supplier vs. the Mercruiser one with a high markup.

I swap out the crank seals when the engine is in the boat. Since you can’t drop the oil pan in the boat just R&R the seal makes sense, nothing to lose really.

 

[ShoalSurvivor]

Since you have the engine out, I’d just swap the cover.

Found the culprit. 25 year old part. Not sure how this would happen, except potentially age. Cover and seal have even replaced. Pan was in excellent shape. internal components look virtually new.

 

[Lou C]

some parts should be metal!

 

[Scott06]

some parts should be metal!

there may be a different issue didnt Chris (former mod here) have a years long thread on a front cover oil leak? I think he traced it back to casting defect on the pan that was cracking the cover. Had to get an updated GM pan etc , but took him 3-4 engine pulls to work through it...

 

[Lou C]

I remember that, the pan defect was putting pressure on the plastic timing cover, but metal can flex, the plastic can but eventually cracks. I don't like this trend on modern engines, plastic valve covers (warping, they get brittle and leak) nor oil pans, same thing, then when the leak they are one use only, etc.
Believe it or not my original 1988 short block still has the original front and rear seals with no leaks! Just a typical coating of old school Chevrolet oil seepage that kept the timing cover from rotting out lol.

 

[Scott Danforth]

There used to be a company making Billet timing covers for the 4.3. however I can no longer find them post covid.

 

[Scott06]

I remember that, the pan defect was putting pressure on the plastic timing cover, but metal can flex, the plastic can but eventually cracks. I don't like this trend on modern engines, plastic valve covers (warping, they get brittle and leak) nor oil pans, same thing, then when the leak they are one use only, etc.
Believe it or not my original 1988 short block still has the original front and rear seals with no leaks! Just a typical coating of old school Chevrolet oil seepage that kept the timing cover from rotting out lol.

the plastic doesnt bother me that much as most of the time I have had zero issues. On my dailies which are toyotas zero issue with plastic covers, wifes mini cooper the valve cover is chit and the engine temp they run at is a dumb idea. Mini also uses a tone of plastic in the cooling system. All on an engine the normal temp is like 220 F. The water pump is plastic ...

I guess what I am saying is designed appropriately and made correctly it can work just fine. On a car that they cut corners on like mini its probably not going to work out so well. At least they dont rust ..