85hp Chrysler Lower Unit Oil Leaking from weep holes? Update Please HELP!

[prater]

So after a day of boating I got home and found some L/U oil leaking from the drain holes above the lower unit. This picture is from a different occasion but those are the holes the L/U fluid is coming out of. This wasn't leaking at the lake when I got it out of the water, only after I tilted it up and drove it home. What would cause this?

 

[Frank Acampora]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

Those are weep holes to drain blind cavities in the lower unit casting. Usually, it is unburned oil that drips from them. You need to smell it. If it smells like gas, it is unburned oil and normal. If it smells sulphur, it is lower unit oil and you need to check the seal below the water pump.

 

[prater]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

I smelled it, its gear oil, coming out clean too. I just replaced the impeller and gear oil, didn't replace the seals under the water pump.

 

[prater]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

Also, which seal is that, the one that comes with a water pump kit? Or something deeper than that?

 

[Frank Acampora]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?



NO! it doesn't come with the pump. Below the pump is a torpedo shaped plate held on with three more bolts in addition to the four from the pump. Remove this plate and you will see the drive shaft seal pressed in the bottom AND an O ring around the lower perimeter of the part that plugs into the lower unit casting. It COULD be either of these or could be the seal where the shift rod passes through.

However, the first place to check is the front portion of this plate where the shift rod is. There is an O ring set into a roughly triangular groove and this may be the culprit. Clean everything well and coat the Oring and both sides of the casting with Black silicone RTV. I recommend you buy a new O ring though.

I have a lower unit leaking in just this fashion and will be sealing it when I get a "round tuit."

In the first three photos, you see an assembled lower unit and three of the top plates. None of these plates has a sealing O ring in the front groove. The photos do show the O ring on the plug portion. Depending upon how old your lower unit is, the drive shaft seal will be different. Straight drive shafts have the large seal with a small hole. "Necked" driveshafts with a thinner center section have a larger seal area thus a larger hole in the seal. Two piece drive shafts have two seals pressed into this piece. You do not have a two piece drive shaft because you have a white lower unit.

Ignore the last photo.

 

[prater]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

First off, THANKS! That is one of the best responses I've ever gotten to a question.

Now for a couple of questions, the motor is a 1978 or 79 85hp Chrysler with a straight drive shaft that is fairly thick, not sure which one for sure though.

When I pull the lower unit I should be able to see where the leak is correct?

Do I need to get a full lower unit seal kit? If so where can I get one?

Do I need to remove the drive shaft or can I just slide the plate up and off the drive shaft like I do the water pump?

Do I need to apply black silicone around the plate before I reinstall?

Does the drive shaft seal require hammering in with a block of wood similar to a hub seal?

I can't tell by the picture where the shift rod seal would go, is there a groove for it?

 

[Frank Acampora]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

The plate slides up off the lower unit just like the water pump. However, a lot of them get stuck and there are no pry points. Sometimes you need to get on the side with a big screwdriver or a chisel and hammer a bit. If you can twist it some in its seat, then there will be a spot on each side to pry. Pry ONLY on the water pump (center) section. Front and back parts will bend and/or break.

After removing the drive shaft seal, then you must tap in the new one carefully and seat it. The shift rod seal is located above the holes showing in the front in the photos. You can clearly see it in the third photo. It also presses in. You set it in steel side up and rubber down. If it is not torn up, you should be able to re-use the original. If it is leaking slightly, just increase the pressure on the rod. You adjust the pressure against the rod by how far you press in the seal. You can adjust with the unit assembled. Slip a 7/16 socket over the shift rod then a long enough piece of pipe to clear the rod. Tap on it until the rod moves smoothly but snugly.

You do not need to buy a whole seal kit and in most marine supply stores they will not carry seals for this old an engine. Seals are, however, standard size and can be bought at a bearing supply house. Just be certain to specify all stainless construction. Do not let them BS you by saying all seals are stainless--not true. The seal you want to buy costs more--up around 25 bucks. In this case, you might be better to contact franzmarine@aol.com.

Shift rod seal is the same for engines up to around 1989 so they can be bought at a Mercury service shop.

Do not be concerned if the replacement drive shaft seal you buy looks different. As long as the shaft size is correct and the seal presses into the plate, it is OK.

The front O ring may or may not leak when assembled so it is wise to coat it with RTV before reinstalling the plate. Before disassembling the plate, check around to see if the leak is at the front O ring seal or at the drive shaft seal so you will know.

 

[prater]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

So big problems now. While attempting to get the drive shaft seal out the plate came of the vice, and ended up breaking the plate off on one end. Is there anything that can be done to fix it, JB weld perhaps? It was on the pointed end that covers the water intake. I also thought about maybe finishing the job and installing the plate back on then having it welded in top while its all together. What do you think?

 

[prater]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

Also, the seal puller kinda marked up the sides and the lip of the seat, the marks on the sides don't really concern me but the couple of spots around the lip are worrisome as they could possibly rub the drive shaft if it touches that part, I'm not sure if it does, maybe I should smooth it with some fine sandpaper? The seal still fits in there, though I haven't seated it yet, it goes in and is tighter than a drum.

 

[Frank Acampora]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

The broken section of the plate covers the water intake passage. It has no real stresses on it and no pressure to seal. JB weld it together bit be certain it is perfectly flat. For reinforcement, sand the inside to bright aluminum and JB a plate there. When reinstalling, coat it with some silicone seal to be sure it will allow the pump to suck water. After installing, sand the top and JB another shaped plate to it.

Use a very thin coating of red Permatex (non- hardening) on the seal before installing. There is a bit of clearance between the driveshaft and the casting so a small nick or two where it passes through should not be a worry.

 

[prater]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

I got the new shaft seal and I got it almost seated, but once it got flush with the rim I cant seem to find good area to tap it with the hammer to drive it the rest of the way down, it still has 1/8 of an inch or a little more to go until it seats as it sits below flush. Any tips on how to drive it that last little bit?

 

[jerryjerry05]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

A socket the same size will work.J

 

[NetDoc]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes?

RTV or any sealant on an o-ring will probably cause premature failure. A dab of silicone grease should be all you need.

 

[prater]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes? Update Please HELP!



Did I put this seal in the right way, the guy at the shop said to do it this way. The little spring there has popped out once, not sure if that matters as long as I put it back in. It popped out when I was test it for fit on the drive shaft, I didn't seat it just kinda put pressure on it to make sure it would seal.

 

[NetDoc]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes? Update Please HELP!

As long as the spring pops back into place, you should be golden.

 

[Karla45]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes? Update Please HELP!

Yes you do have it going the right way. I was told that it does not necessary have be all the way down below flush, it can be flush and it will be okay. I used loctite 271 threadlocker on the that seal because it has metal and the manual and mechanice told me to use it there but that is up to you.

 

[jerryjerry05]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes? Update Please HELP!

Since you dug holes in the side of the sealing surface.You need to fill in with something that will harden like silcone.Thread locker is for screws.Normally any sealer would work but since you made grooves it needs to be filled with something that won't give way.Silicone will harden.
After you assemble it wait a while before you pressure test it.

 

[Karla45]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes? Update Please HELP!

Sorry I did not realize you had made grooves in the sides.Threadlocker will only work on the sides if they are smooth. I used the threadlocker on my lower with the metal encased seal and it worked out just fine but yours is a different situatioon.

 

[prater]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes? Update Please HELP!

Okay so I've got it all put back together, ready to install the lower unit but I have this weird nagging feeling in the back of my mind that the garter spring might have come off the seal when I installed the plate on the l/U. The first time I tested the fit of the seal but pressing it up against the drive shaft, the spring popped off. Is there any chance that spring could have come off from pushing the seal down over the drive shaft. The only way to know for sure is to pull the plate back off, am I just being OCD?

 

[NetDoc]

Re: 85hp Chrysler Lower Unit Oil Leaking from weep holes? Update Please HELP!

The garter spring should not come off during installation. If you have doubts, you might want to pull it apart to be sure. Listening to that little voice has kept me safe over the years. Ignoring it has almost always had consequences.