73 Merc 850 lube problem

[dhauser]

Hello

Last year we picked up a boat with I believe a '73 Merc 850. Had it checked out, new water pump/impeller, clean carbs, etc. Ran great. At end of season I winterized it and the lube I replaced looked great, no signs of water, etc.

This year, I had the boat out about 6-7 times with no problems, before getting a new boat, so this one sat. My father decided about a month ago that he wanted to take this fishing for a weekend.

I told him to take it (I was up north at the time) but to check a few things including to check the gear lube. Well, as I've learned recently, he apparently removed the lower plug, and when the lube came pouring out, quickly replaced it. He didn't see any problem and just lost a bit so he went with it. Said he only ran it about 10-15 minutes or so to get where he need to go, then used the 20hp troller for the idle work.

So, here I am, in the process of winterizing it... I remove the lower plug, and get about 2 tablespoons of water. I immediately notice THERE IS NO GASKET on the lower plug!! The oil continued to come out with a slight mixture of water, then thicker. It doesn't look/smell burned, nor do I see any metal fragments. I also noticed there was less lube than there should have been coming out - meaning, noticeable, maybe a couple ounces.

So, now I'm wondering, what are the chances of damage? Is it likely that the water got in due to the missing gasket? Does the lack of fragments/no burning mean it may be OK??

I'd like to be able to sell this thing next year, and now I feel like I need to get it checked out.

Thanks

 

[Texasmark]

Re: 73 Merc 850 lube problem

Lower unit lubes have additives to make them sticky so that they will stick to the metal and resist washing away or letting water touch them. I have seen some pretty raunchy fluid come out of lower units and the units were still working just fine.

If you have water in the lube and it sits for a long time there is a possibility that the water could rust the spots where it's touching.

An 850 has a big gearbox and 2 table spoons of water is not much. Since the water separates from the oil and oil floats, your gears get the benefit of the oil, not the water.

Only problem MIGHT be with the water suspended in the oil causing some rust prior to coming out of solution and sinking to the bottom. But these are teeny weeny bubbles and even if it rusted you'd probably never know it unless you were looking at the parts in your hand.

If you are really concerned, remove the entire lower unit (might put in a new impeller while out), drain out all the oil, and by hand (vise grips to the driveshaft will work) rotate the shaft in F, N and R. Very slowly.

Listen and feel for any abnormalities. If it feels and sounds smooth, get some new lube, flush it out and put in more new lube with new gaskets and go for it.

If you have access to a pressure gauge you might do a pressure test on it. If you don't, and you drop your lower unit off at your dealer's he can run the test for you. Then you will know what kind of condition the seals are in and the new lube will stay new.

Mark

 

[dhauser]

Re: 73 Merc 850 lube problem

Well, I did go ahead and finish winterizing it yesterday, and changed the lube (with new gaskets!)/fogged/etc. I think now that it's winterized, I'm just going to schedule a visit in the spring, and have it checked out as you recommend. I'll need to have the impeller changed anyway, and want to have the thing checked over before I go to sell it.

I guess I'm left wondering how likely the missing gasket on the lower fill port would be the cause of the water getting in? There was no water in there last year, and according to paperwork from previous owner, the seals were changed in 2001. (I know, 5 years - but could be worse). Thanks again

 

[Texasmark]

Re: 73 Merc 850 lube problem

Usually a closed gearbox attempts to breathe with changes in weather. Trailer wheel bearings are especially succeptable as they are hot from rolling down the highway and then you submerge them to launch and all they do is make this gigantic sucking sound.

There also is a physical thing that occurs where a not hermetic container will ingest water with humid air. On exhale it exhales the air and keeps the water. BTDT

Course temp plays a part in that and if hot enough will evaporate the water.

Mark