coolant in outdrive oil

[arnettmark]

I have a 1979 Sea Ray I am trying to get lake-worthy. Mercruiser 470 I/O. I drained the outdrive oil to replace the raw water pump. First, clear water came out, then antifreeze, then oil/antifreeze mixed. I am guessing a bad heat exchanger is where the coolant is coming from, but is there anywhere ELSE it could be coming through. Given the lateness of the season, should I plan to do a gasket/seal job on the drive over the winter? Or should I just buy a reman and not mess with it? ($1200 ouch!)

My skill level: I've rebuilt several car engines, carbs, wiring, etc. built a couple race cars, NEW to boating. Manual in hand.

 

[stonyloam]

Re: coolant in outdrive oil

Wow! That's crazy! Is this boat new to you? Maybe from the exchanger, but how? Seems like that would be almost imposable.

 

[JustJason]

Re: coolant in outdrive oil

It is impossible to mix gear oil and engine coolant, as the 2 never come into contact with eachother.
Did you mean engine oil?

 

[Fishermark]

Re: coolant in outdrive oil

OR - are you mistaking the green gear lube for anitfreeze?

 

[crewscontrol]

Re: coolant in outdrive oil

First let me say that I know NOTHING about a Mercruiser 470 except to say that I have heard a lot of negatives about it from owners. As I remember the 470 was a Mercury designed aluminum block engine and not a converted automobile engine.

I have three boats with Mercruiser engines and stern drives; a 1964 Glassmaster 17 ft with 153 CI 110 HP Mercruiser, a 1986 Glassmaster 21 ft with a 350 CI 260 HP Mercruiser, and a 2002 Sea Ray 270D with a 7.4 Mercruiser and Bravo III. I am basing my reply on my knowledge of these three boats and not on my knowledge of the 470.

None of the Mercruiser engine - stern drive combos that I own have any common outdrive to engine "connections". By that I mean that there is no outdrive oil cooler on the engine where engine coolant can mix with the outdrive oil. Outdrive oil cooling is done strictly by heat transfer from the outdrive to the water it runs in.

In fact to the best of my knowledge, at least on the three Mercruisers I own, engine coolant cannot get into the outdrive unless somebody puts it there on purpose. But then maybe the 470 is a different animal.

I hope somebody else can diagnose this problem, because I just don't understand how that can happen.

 

[Eric 3.7LX Alpha 1]

Re: coolant in outdrive oil

If the exchanger was the cause it "could" drain coolant out the drive thru the water pick up slots, but would not mix with the lube inside the drive.

If you had clear water drain 1st, then there is definately water in the drive, that greenish color might be a mix of lube/water, then straight lube on top. Don't think water and antifreeze would separate like what you described.

Sounds like you should drain the outdrive and pressure test it and see if it holds. Here is a link to make a psi tester for the drive:
http://forums.iboats.com/showthread.php?p=1573303#post1573303

Hopefully the lower gears weren't in H2O too long.

 

[arnettmark]

Re: coolant in outdrive oil

@Fishermark: I've never heard of green gear lube, maybe that's what it was. I'll check it tonight.

There absolutely was water in it though, could that have come from a melted down water pump leaking raw water?

The heat exchanger is only a 3", and I have a 4" ready to install. Should I go
ahead and put it all together with a new water pump and heat exchanger, lube it up and give a it shot?

 

[crewscontrol]

Re: coolant in outdrive oil

@Fishermark: I've never heard of green gear lube, maybe that's what it was. I'll check it tonight.

There absolutely was water in it though, could that have come from a melted down water pump leaking raw water?

The heat exchanger is only a 3", and I have a 4" ready to install. Should I go
ahead and put it all together with a new water pump and heat exchanger, lube it up and give a it shot?

Mercruiser Premium stern drive gear lube is GREEN.

 

[Fishermark]

Re: coolant in outdrive oil

What he said. ^^^ (Well, actually it is the Mercury / Quicksilver High Performance Gear Lube that's green. The Premium Lube is a honey / golden color)

The "green stuff" is the good stuff. It's what I use in my outdrive.

 

[Don S]

Re: coolant in outdrive oil

Mercruiser Premium stern drive gear lube is GREEN.

The Premium is oil colored, the Hi Performance gear lube is green.

 

[arnettmark]

Re: coolant in outdrive oil

Upon closer and less panicked inspection, I think you are correct that it is green gear lube mixed with brown gear lube. However, given that there were two types of lube along with a fair amount of water in there, is there a good way to flush the whole thing out?

 

[Don S]

Re: coolant in outdrive oil

Before I would worry about flushing it, I would pull the drive, drain it, and pressure test the drive and find out where the water is coming from. If you have to take it apart to repair it, flushing at that point is called washing off the parts.
The fact that water was not mixed with the gear lube causing the gear lube to be milky means that it leaked in since the drive was used last. Have you checked the bellows for water? Drain plug gasket get reused or drain plug loose?

 

[arnettmark]

Re: coolant in outdrive oil

The plug above the trim bolt was missing altogether, so that's at least part of the problem.

 

[Fishermark]

Re: coolant in outdrive oil

The plug above the trim bolt was missing altogether, so that's at least part of the problem.

Do you mean the plastic plug that covers the access hole for the allen bolt that holds the trim tab / zinc on? If that's what you mean, then no, that's not a problem. That's more of a dust cover than anything. Has nothing to do with water in the drive.