6V92T- water in oil

chuckdrum · May 15, 2012, 11:30:55 AM

For those of you that followed a "searching for a 35 Footer" thread earlier this year, here's a follow up:

My 'new' 1979 MCI 5C ran great retrieving it from the previous owner in Minneapolis and driving to Seattle (1700 miles). I checked the oil frequently en route, including just 120 miles from home, and was pleased that the consumption was less than the 1200 mi./gal suggested by previous owner. About 10 days after I got home, I was about to leave for a local trip and checked the oil in preparation. It was gray and very high on the dipstick. I contacted Pacific Torque here in Seattle, and the bus has been there for the past week with no definitive answer about what's going on, other than there is water (coolant) in the oil. There's 94k on the rebuild, previous owner had no problems since he put it in (1999).

While waiting for an answer from the shop (the jury is still out on whether it was a wise choice of mechanic), have any of you had similar problems? Particularly with this engine?

On a possibly related note, the previous owner said he always just put the cruise control @ 59mph and suggested I do the same if I want the best mileage and life out of the rig. I experimented with various speeds on my return trip, occasionally running at 68-70 mph (1900-2000rpm). Any thoughts on cruising speed and whether changing driving habits from what the bus is used to could have caused a problem?
Thanks for any advice/suggestions!

bevans6 · May 15, 2012, 11:59:34 AM

I don't think your driving it at a slightly higher speed made any difference at all. The first two places I would think to look for water into the oil is probably the oil cooler and the injector sleeves. I have no idea how to diagnose either, unfortunately...

Brian

Van · May 15, 2012, 12:32:13 PM

What were the engine temps coming home? just curious.

RickB · May 15, 2012, 12:33:22 PM

Chuck, That's probably the O-rings in one or both heads. Did it overheat at all? Those O rings get brittle (especially if they sit for a long time or if they get hot) nand fail on a fairly regular basis in the wet sleeve motors. There are others here that know more but the fact that the first thing out of the mechanics mouth wasn't the O rings makes me a little uncomfortable. There are a couple schools of thought on what needs to happen when coolant comes in contact with bearings, I and others here recommend all bearings be replaced and if you're gonna go that far most would say at least an inflame rebuild and some would say an out of frame (complete) rebuild. Run it by Clifford (luvrbus), Don Fairchild and Tom C they are kind of the go to guys here for major issues. Sorry to be the bearer of bad news.

Rick

chev49 · May 15, 2012, 12:40:57 PM

if he had no water in oil on return trip, and only discovered water when checking the oil before starting - after only 10 days since getting home.. would the engine still need bearings if it hadn't run?

am gonna get lamblasted for this question....

luvrbus · May 15, 2012, 01:04:42 PM

If they oil is gray and milky it has been run with water in the oil the oil won't turn colors without a good mixing it would still be clear on the stick and he could drain the water from the oil and you know that Chev49 lol

Geoff · May 15, 2012, 01:10:45 PM

The shop is supposed to drop the oil pan, pressurize the cooling system and trace where the cooling is getting into the oil.

luvrbus · May 15, 2012, 01:21:01 PM

I found over the years liner o-rings don't leak much while running when the engine cools downs if they leak water runs out the air box drains his leak is probably up stairs too much racket is made about the o-rings on a 92 series if installed right they are not much trouble unless you cook one well done

chuckdrum · May 15, 2012, 01:28:31 PM

The engine never heated up on the trip. The mechanic DID mention o-rings initially (and said that they are known to fail occasionally on the 6v92), but has not committed to that. And they did drop the oil pan and pressurized the system. But they still haven't found the leak as of my conversation this morning.

I've only driven the bus about 8 miles since I discovered the problem, but not sure how many miles since the problem actually started. The maximum would be about 120 but it's most likely much less. So I'm really hoping I caught it before serious damage was done.

fwiw, the engine started, sounded, and ran just fine when I drove it to the shop.

chuckdrum · May 15, 2012, 01:31:18 PM

"never heated up" meaning that it stayed consistently at 180, regardless of terrain.

luvrbus · May 15, 2012, 01:32:25 PM

I never could find a cracked head with pressure testing seems like the head seals itself when it cools down but have found other leaks with pressure lol

Geoff · May 15, 2012, 06:10:29 PM

Quote from: Geoff on May 15, 2012, 01:10:45 PM
The shop is supposed to drop the oil pan, pressurize the cooling system and trace where the cooling is getting into the oil.

I have so experience at "water in oil" I could not even begin to tell you the stories.

What I posted above is just the start. If you have some num-nuts working on your engine you are in for a huge bill. I got my "DD-2-stoke" certification from the DDA so long ago my hair was brown instead of grey, I am ready to retire and I am the last of the crew that worked at Williams and Lane in Berkeley, CA.

--Geoff
'82 RTS AZ that runs perfect.

chuckdrum · May 15, 2012, 09:39:43 PM

Well Geoff, tell me some stories, then! In your experience, does having coolant in the oil necessarily lead to an in-frame rebuild? How common is it for 0-rings to fail after just 94k miles? Is a cracked head actually difficult to detect? If it's the o-rings, what kind of cost should I expect? If it's an in-frame rebuild what kind of cost should I expect? If head gasket?

Thanks!

Geoff · May 16, 2012, 07:18:03 AM

Well Geoff, tell me some stories, then!

In your experience, does having coolant in the oil necessarily lead to an in-frame rebuild?
--Not at all. The coolant could be coming from the water pump, the o-rings seals on the aftercooler, leaky injector tube... In that case youi just fix the problem and roll in new crank and rod bearings.

How common is it for 0-rings to fail after just 94k miles?
--I doubt it is the head gasket o-rings or the clyinder liner o-rings

Is a cracked head actually difficult to detect?
--I doubt it is a cracked head unless the PO overheated it after the infame rebuild.
You never said what your engine temperature was when you were driving it, if you had a cracked head it would have been very hot.

If it's the o-rings, what kind of cost should I expect? If it's an in-frame rebuild what kind of cost should I expect? If head gasket?

--I can't give you estimates on other shops work. The main thing is to find out what is causing the coolant to get into the oil, and go from there.

--Geoff

chev49 · May 16, 2012, 07:39:19 AM

Quote from: luvrbus on May 15, 2012, 01:04:42 PM
If they oil is gray and milky it has been run with water in the oil the oil won't turn colors without a good mixing it would still be clear on the stick and he could drain the water from the oil and you know that Chev49 lol

you are right of course.. now from his post, we find that he drove it to the shop....that is what i was wondering.. oil no water when parked, etc....