140 Oil leak--What gaskets/seals to replace just to be safe?

[cheburashka]

I have a pretty serious oil leak from my '72 140 HP. The oil ends up in the bilge. It seems to leak most when I rev the engine up toward WOT, but I haven't been able to find the leak. I'm assuming it's the main seals, and that the oil only comes out when the crank ends deflect at higher revs.

I'm going to be pulling the engine and replacing the mains and the oil pan gasket, since I'm certain that they're original to the boat. Any other ideas regarding what other parts should be replaced just as preventive maintenance as long as the engine is out?

Is there a kit that has the right gaskets in it, or do I need to pick them all out individually?

Thanks

 

[Don S]

Re: 140 Oil leak--What gaskets/seals to replace just to be safe?

Find where the oil is coming from, it may not be a seal or gasket. Could be a pin hole in the oil pan (above oil level) or timing cover. They get rust pin holes very easily.

 

[cheburashka]

Re: 140 Oil leak--What gaskets/seals to replace just to be safe?

Find where the oil is coming from, it may not be a seal or gasket. Could be a pin hole in the oil pan (above oil level) or timing cover. They get rust pin holes very easily.

This is a freshwater trailered boat. I know a saltwater boat can get rust holes, but I've looked at the oil pan and it appears to be very solid. Very shiny, and no surface rust or other signs of damage to the pan.

The other thing is that I've got the outdrive off and I hadn't planned on running it again until Summer, so I'd just as soon pull the engine and replace whatever seals tend to go out before the season starts.

 

[Don S]

Re: 140 Oil leak--What gaskets/seals to replace just to be safe?

The all tend to go out at some point. You have a 37 year old motor. Replace them all.

 

[cheburashka]

Re: 140 Oil leak--What gaskets/seals to replace just to be safe?

That's what I figured. So it's 18-1206 (short block gasket set) plus an oil pan gasket. Is that it as far as lower end oil leaks? Anything else along the lines of preventive maintenance?

The upper end has been covered. New head, riser and manifold two years ago, along with head gasket, manifold gaskets, riser gaskets, etc. New water and fuel pumps last year as well.

Thanks for the help.

 

[fishrdan]

Re: 140 Oil leak--What gaskets/seals to replace just to be safe?

When you remove the pan check it over well as the baffle in mine (72 140HP) had a couple of cracked spot welds. I speculating, but if the baffle could crack a weld I assume one of the spot welds on the pan could crack and leak oil.

All of the seals you need to replace can be picked up at an auto parts store (68 Chevy II, 153CI) but they won't have the nice 1 piece marine oil pan gasket. I did pick one up from Car Quest, but they had to order it from their marine Fel-Pro catalog. You could use the 4 piece automotive set, but the 1 piece gasket works much better, probably seals better for the long haul also. $50 for a complete automotive engine gasket set or $50 just for the 1 piece marine oil pan gasket, your call. I didn't want to have leaks, so I popped for the $50 gasket.

I'm guessing you're going to re-seal the engine and do the timing cover at the same time. The manual says you need a special alignment tool to center the timing cover over the crank, but I cheated and used a roll of electrical tape. (I'll probably get bashed for this, but here it goes) Tape the crank until a roll of electrical tape slides on snug, then peel tape off a new roll until it fits snugly into the seal. Cut ends of tape on crank and "alignment" tape roll need to be 180 degrees apart so the crank's seal is as close to centered as possible. Tighten down timing cover slowly and evenly, then remove the electrical tape roll and unwind the electrical tape off the crank... worked for me

Since you're in there, might as well replace the oil pump. Stock flow, don't use a high volume or high pressure oil pump.

 

[fishrdan]

Re: 140 Oil leak--What gaskets/seals to replace just to be safe?

Your 72 engine has a 2 piece rear main so you need to use the Sierra 18-1271 Short Block Gasket Set when ordering from Iboats. This was in the description for the 18-1271 gasket set; For motors with 1 piece rear main, use kit # 18-1206.

The 18-1271 kit says it comes with the oil pan gasket set, 4 piece.

 

[bigbob_FTW]

Re: 140 Oil leak--What gaskets/seals to replace just to be safe?

are you sure its not outdrive oil?

 

[chiefalen]

Re: 140 Oil leak--What gaskets/seals to replace just to be safe?

I just did this with the motor in my signature.

When you do pull the pan hold it up to bright sunlight, see any pin holes, pay attention to the lip. The lip rusts also.

Timing gear cover hold that up to the bright sunlight.

You do indeed need the four piece oil pan gaskets set.

The bottom of the timing gear cover, to install the gasket has nubs that must be inserted into tiny holes that will be clogged up you need to ream each hole with a tiny piece of wire.

Don't hurt to replace the front and rear main seal, while you have it out the motor.

Before reinstalling the old pan or the new pan, paint it 3-4 times, on the outside.

Same with the timing gear cover.

Good luck.

 

[fishrdan]

Re: 140 Oil leak--What gaskets/seals to replace just to be safe?

You do indeed need the four piece oil pan gaskets set.

Hmmm, now you have me wondering about the 1 piece oil pan gasket. My machinist told me to use it 10 years ago, it fit correctly and it never leaked a drop on my 72 140HP. I looked and the only 1 piece gasket I see is for 90 and up 3.0's?

Either I got lucky or they don't make it anymore...

 

[chiefalen]

Re: 140 Oil leak--What gaskets/seals to replace just to be safe?

Dan it don't leak than don't sweat it .

Bottom of the timing cover is a byatch where the holes and the nubes have to go into them.

 

[Cptkid570]

Re: 140 Oil leak--What gaskets/seals to replace just to be safe?

As everyone else said. Take a serious look at the timing cover. Very common place for oil leak on these engines. I had mine rust out on my 3.0, replaced it. Then replaced my engine with a used 3.0 liter and that one had a rusted out timing cover too.. and it was a freshwater engine.

 

[cheburashka]

Re: 140 Oil leak--What gaskets/seals to replace just to be safe?

Thanks for the help everyone. I'll be checking the timing cover and the pan carefully. This was a Puget Sound boat before I had it, so there could easily be corrosion that I didn't see.

It's hard to think about getting out on the lake when it's covered with 4" of ice.