Sludge coming from exhaust? 1992 40hp

Got my 1992 Mariner 40 hp hooked up to the muffs today to get it ready to take out. Haven't had a chance to use it yet this year and I wanted to make sure everything was in order. Took a while to start which I attributed to the fogging oil but when it did start it idled perfectly. However, after a bit I noticed a foamy like sludge coming through the hub. The sludge had no odor, and lessened after a minute or so of running. Any ideas? Fogging oil burning off? Faulty seal? A bit of sludge also was coming out from around the hub.

Please forgive the pic quality, the camera was trying to compensate for glare.

Re: Sludge coming from exhaust?

that to me looks like fogging oil , but i could be wrong

Re: Sludge coming from exhaust?

I initially thought the same, but the fact that there was a lot of the sludge made me have my doubts. So I drained the lower unit oil and sure enough, there is some water in there when there shouldn't be (changed it out before storage). I'm now thinking the oil seals on either the prop-shaft or the drive-shaft, but am not sure which ones.

Re: Sludge coming from exhaust?

Broke out the service manual and I'm fairly certain I have a prop seal issue. The only thing that's a little odd to me is why the lower unit would pressurize at idle, driving lower unit oil past the seal to mix with the exhaust.

If it does turn out to be the prop seal, it looks like I'll need to pull the prop shaft, is this correct? In that case, I assume I need a puller. Do I have to use the part listed in the factory manual or is there a generic puller that will work?

Re: Sludge coming from exhaust?

You might have two unrelated events here.

That doesn't look like gear oil to me, but there could be some there.

I would run a can of Merc's PowerTune through the motor to clean out the fogging oil and other cooties (5 bucks a can and just go with a few good shots into the carb throat until the motor almost "gags" - lots of crap will come out the exhaust).

The water in the case could be getting in from a number of sources including the the little rubber washers at the fill and vent plugs.

If it does turn out to be a bad propshaft seal that's a fairly easy one to change. You only need pull the propshaft bearing carrier. It has a pair of back to back seals where the propshaft comes through and a big o-ring around the lip of the carrier where it mates to the case.

You don't need to pull the gears etc, to do the propshaft.

And no, you don't need the "merc puller". Depending on the exact configuration of the bearing carrier I either use a gear puller or a harmonic balance puller.

If this is a Merc/Mariner the bearing carrier is just kinda (slid) in there, and held in by a plastic "cover nut" which winds out. You are not supposed to re-use the cover nut so you can be rough getting it out.

With the cover nut gone, a regular gear puller can grab hold of the carrier (if you can turn the the little hook ends to face out instead of inward).

There was also a version without the cover nut. Instead it had a cover held on by two bolts. You simply undo them and then use a gear puller to get it out.

Likewise the Yami/Mariners had a cover held on by two bolts, and then a gear puller would work...

Re: Sludge coming from exhaust?

Thanks Graham, top notch info as always....

A few questions/comments. First, I did replace the rubber washers on both the vent and fill plugs last fall. Also, I've only run the engine with the muffs on since so those two plugs have not been submerged since the seals were replaced. But yes, I agree it doesn't really look like lower unit oil and certainly doesn't smell like lower unit oil.

I'll run the PowerTune to clean out the garbage. Probably a good idea to do so anyways. If that clears up the sludge at the prop then I know one of the two issues has been addressed.

I've cozied up with the factory service manual and think I've got the general gist of how this all goes together. One thing is a little confusing though. When I pull the bearing carrier the service manual illustration shows the reverse gear coming with it. Is this correct? It appears to me from the schematic that the bearing carrier houses the bearing and then mates up to the o-ring which then mates to the thrust-washer. Wouldn't the reverse gear stay in the housing when I pull the bearing carrier?

I saw that I need to replace the cover nut, so I can abuse it while getting it out. However, the service manual shows a Cover Nut Tool. Will I need this to get the new cover nut in place?

In closing, I really appreciate your advice on this. You're saving me a boatload of cash by enabling me to do this myself. Plus I get to become more familiar with my engine, which is something I strive to do. If you're ever in MN, I owe you a beer.

Re: Sludge coming from exhaust?

Re: the bearing carrier, I think I have it figured out. The carrier houses the ball bearing and the reverse gear. The o-ring slides onto a groove between the the carrier housing and the gear. This o-ring should be replaced. The two oil seals are right at the end of the carrier housing where the propshaft exits the housing. These two will be replaced as well.

The ball bearing on the carrier housing looks like it will remain sealed, so I assume I do not need to lubricate this. Is that correct? The needle bearing adjacent to the oil seals will be exposed when I pull the old oil seals. Do I need to lubricate this as shown in the manual? Or does the lower unit lube take care of this? Also, the manual calls for Loctite on the oil seals. Would that be to Loctite on the mated surfaces of the seals, and lubricant on the outer surfaces to slide the seals back into the carrier?

I guess my only question remaining from the previous post is in regard to whether or not I need a special tool to re-install the new plastic cover nut.

Re: Sludge coming from exhaust?

Yes, you have it. The reverse gear is held in place by the propshaft itself and the bearing carrier.

When you pull the carrier you can simply leave the gear (flopping) around on the shaft or take it out (along with the thrust washer if equipped). That will let you get a look at it (plus you can use a flashlight to get a look at the forward gear and pinion) just to make sure all is fine in there.

And yes, you replace the two seals at the extreme back end of the carrier (prop end where the shaft comes through) and the o-ring around the forward lip.

You shouldn't need to mess with the bearings unless they get contaminated with dust/dirt. If they do you can clean them with some solvent (I normally use gasoline) and then let them air dry, then just lube them with a bit of gear oil.

DON'T try and clean those bearings with compressed air, you can damage them (any "caged" bearings).

The cover nut can be reinstalled with a pair of channel lock pliers (like plumbers use for drain couplings) - you only need get it "tight" - it's not "waterproof" seal (the o-ring and seals on the carrier do that) - it's just there to keep the carrier in place - so anything you can jury rig to tighten it up is fine...

Re: Sludge coming from exhaust?

Excellent, I think I have all I need to proceed. I'll run the PowerTune through tomorrow night and the engine go under the knife this weekend. I will post back with results. Thanks again Graham, you've been an invaluable help...


Oh, one last detail...the Loctite shown in the service manual applied to the oil seals....is it applied to the surfaces where they mate together?


Thanks again

Re: Sludge coming from exhaust?

Update: Did the PowerTune treatment, and it seems to have made a difference. I treated it and then let it sit idling in the driveway for 15 minutes or so to let the crud clear out. At the end, the amount of junk coming from the exhaust had almost ceased. Still a little bit, but not sludgy like before. More of a thin foam and I'd guess less than 5% of the previous amount.

Before doing the PT treatment I changed out the LU oil to make sure it was fresh and clean. After running it for the 15 minutes I drained the LU and the oil was milky already. So it looks like I'm in for the propshaft seals. Parts will be ordered Monday. Thanks everyone for the help. While I was running it today I got the idle tuned to a purr, and the engine is running nice and cool. Once I get those seals changed out I'll be in good shape.



Runoff after the engine was shut down. Much less than before, and probably LU oil.



LU oil after today's run. Pretty milky for only running 15-20 minutes on muffs.

Re: Sludge coming from exhaust?

Whipped prop seal by the look of it.

Jeff

Re: Sludge coming from exhaust?

You say you ran for fifteen minutes in the drive? The lower unit wasn't submerged in water? Then I think water pump base needs looked at

Re: Sludge coming from exhaust?

Hmm, driveshaft seal or propshaft seal? I don't have the experience to rule out one or the other. Do I need to do both to be safe?

Re: Sludge coming from exhaust?

Agree, higher odds that it's the seal on the driveshaft (carrier) under the water pump.

Normally two seals back to back where the driveshaft enters (below the waterpump). The one closest to the waterpump is rubber (like a big washer kinda), the one below that is metal.

To get at both of them you have to strip down the whole lower unit (big pain), but with an o-ring pick (looks like a dental tool) you can get at the top (rubber) seal simply by removing the entire waterpump assembly.

That's what I would try first. At worst, if it's the lower seal or the o-ring around the carrier you have to tear everything down, but if that solves it (or even puts it off for a couple years - or until the off season) then you have saved some time which can be better spent on the water in the nice weather...

Re: Sludge coming from exhaust?

Thanks for the advice fellas. I'll cozy up with the manual again and get familiar with the procedure. I'm sure I'll have more questions, but thanks to you I'm getting a clearer picture of how everything goes together...

Re: Sludge coming from exhaust?

Did my homework with the manual last night. Looks like a bunch of steps, but none of them seem to be all that difficult. Remove the lower unit, remove the top half of the water pump, the gaskets that seal the water pump halves, and then the bottom half of the pump. At the bottom half of the pump will be the o-ring, and the two seals will be set into the bottom half of the pump housing (#s 15,17 and 18 in diagram). Graham, you mentioned that getting to the seals was a pain. The manual makes it look pretty straightforward. Am I missing something?

Also, while I'm in there should I replace anything else like the impeller or the nylon seals on the water pump output? I'm going to order parts today and would like to replace any and all common maintenance items while I'm in the guts of the lower unit. Should I be thinking about the oil seal on the shift shaft? (#s 44 and 46)

Re: Sludge coming from exhaust?

It is straight forward, but still a pain

With the waterpump removed but the driveshaft still in place you can pick out number 18.

But if you want to change 17 you need to pull the driveshaft.

To do that you have to partially disassemble the lower unit - so pull the bearing carrier and remove the thrust washer and reverse gear. Then fiddle around in a very very tight space to remove the pinion nut, which will then allow you to pull the driveshaft to get at that lower oil seal under the waterpump base.

"A Pain"

If you go that route, you will need a torque wrench that can fit in the case to retorque the pinion nut OR a special socket that goes over the crank end of the driveshaft splines. If you don't get the torque right you will burn out your gears in short order.

Taken down that far I would also replace the o-ring on the bearing carrier and consider doing it's seals as well since you have it out (it's under 10 bucks for the 2 seals) and I would throw in a complete waterpump kit if what you have there now is more than 4 years old...

Re: Sludge coming from exhaust?

galamb said:

It is straight forward, but still a pain

With the waterpump removed but the driveshaft still in place you can pick out number 18.

But if you want to change 17 you need to pull the driveshaft.

To do that you have to partially disassemble the lower unit - so pull the bearing carrier and remove the thrust washer and reverse gear. Then fiddle around in a very very tight space to remove the pinion nut, which will then allow you to pull the driveshaft to get at that lower oil seal under the waterpump base.

"A Pain"

If you go that route, you will need a torque wrench that can fit in the case to retorque the pinion nut OR a special socket that goes over the crank end of the driveshaft splines. If you don't get the torque right you will burn out your gears in short order.

Taken down that far I would also replace the o-ring on the bearing carrier and consider doing it's seals as well since you have it out (it's under 10 bucks for the 2 seals) and I would throw in a complete waterpump kit if what you have there now is more than 4 years old...

Click to expand...

Lovely ,
the service manual just shows the two seals pressing into the base of the waterpump, but I'll be prepared to pull the driveshaft if need be. The job has to be done one way or the other, so I'll just dig and deal with what presents itself. Thanks very much for the tips, I'll post pics and results.

Re: Sludge coming from exhaust?

Just thought I'd update this thread. Today I finally had time to tackle this job. I basically ordered every part necessary to rebuild the impeller housing and replace all the driveshaft seals. I pulled the lower unit, replaced all the seals, gaskets and impeller, and put it back together. Ran it for about 10 minutes on muffs and though there was still a little gunk at the beginning, it gradually tapered off to almost nothing. Then I drained the lower unit oil and was very happy to see no water in it. So I'm reserving judgement until I've run it in the water for an hour or so, but right now it looks like the problem is solved.

A couple things I learned for anyone who reads this thread and decides to tackle this job themselves. First, do not overtighten the nuts that tighten down the impeller housing. The housing is plastic and will warp, not allowing the lower unit to properly mate to the leg. Second, make sure that if you happen to rotate the shift shaft you make sure you rotate it back when re-installing. I re-installed the lower unit and because I had inadvertently rotated the shift shaft the engine was in forward when the throttle arm was in neutral. I had to re-pull the lower unit to adjust. Third, when if your driveshaft splines are not aligned properly on install, rotate the flywheel instead of the prop shaft as recommended in the manual. It't both easier and the lower unit doesn't have to be in gear.

Thanks to everyone who helped me out with this. I saved a ton of dough doing it myself and now have the confidence to tackle other lower unit repairs. It's really not that compilicated once you get familiar with what's going on in there.