A Head's Up......Mercruiser Transmission Oil Cooler Failures

[fwebster]

For you guys who own boats with Mercruiser gas engines and V-drive transmissions, there have been several transmission failures due to transmission oil cooler leaks in our area (salt water on the Gulf coast) lately. The problem seems to be occurring with Hurth/ZF V-drives in 300DA's up to 380DA's. Cummins, Yanmar, Mann and Caterpillar powered boats are not involved.

Mercruiser is using a cheap stamped metal transmission oil cooler and the interior tubes are breaking down or corroding. When they fail, the transmission essentially pumps all its oil out of the gear case thru the leak inside the oil cooler and into the exhaust cooling water and on out of the boat via the exhaust . Once the oil is gone, the transmission fills up with water. Unfortunately, this usually happens at running speeds and the transmission is a goner. Local repairs are usually not cost effective. The only reasonable repair is a new or re manufactured transmission.

This is apparently a system wide problem for Mercruiser since they have no replacement transmissions in stock and owners are now waiting for 6-8 weeks for a new one if a replacement cannot be located at a quality reman facility.

The experienced technicians at our dealer admit that the Merc oil cooler is a "cheesy " design and they are recommending that owners replace the oil coolers at the same time they check their risers. The replacement oil cooler is about $275. Compared to the cost of a new transmission and labor at about $5500, this one seems obvious to me.

In the meantime, check your transmission oil regularly and be sure you look at the fluid not only for the amount in the gear case but for the color and clarity. If you notice the transmission gaining oil, stop and investigate. For more complete and/or better information you should check with your local Sea Ray/Mercruiser dealer.

 

[osd9]

Good heads up Frank. :thumbsup: This happened to a friends Cruisers 3750 ACMY two seasons ago. His first clue was the oil in the exhaust. It was too late when he realized what was actually happening. Cost him, out of pocket, one new transmission and two transmission oil coolers...plus of course the labor and down time... :smt013 .

 

[Hampton]

Frank,

What's a good time frame for this heart burn? Are they suggesting we replace them with the same piece?

Thanks,

 

[Hampton]

Who knows of a good source for replacement coolers?

 

[fwebster]

I didn't ask, but I'm conservative and know what is involved to remove and replace a transmission on a 340DA. I'd start checking risers at year 3 and replace the oil coolers then.

While they are still good, it is just a matter of removing bolts and hoses, so it should be an easy do it yourself job.

As far as replacements, those the marina are doing are all under warranty so far, so Mercruiser is supplying the same Mercruiser part. You may do some research since I know others are available. know my oil coolers are heavy duty and have cast bronze ends.........but they cost about 3X what a Merc one does.

My guess is that Mercruiser will do as they usually do and improve the design pretty quickly. Staying with the Mercruiser part gets you another 3 years and a part that bolts up to the existing monut

 

[Hampton]

3 years - I thought that was about what you meant. I'll talk to Roland tomorrow.

Thanks again, Frank!!!!!!!!!!!!!!!

 

[Hampton]

They claim at TI Marina to have called Sea Ray and that they haven't had any unusual failure rate.

Here's one of mine:

I flushed them both out to get the tiny weeds out:

 

[Hampton]

Judging from the color, mine are copper. Does that mean I'm safe?

 

[Hampton]

Coincidently!!!!!!!!!!!!!!

My neighbor is here. He is a retired Navy nuclear aircraft carrier commander. He has a story on a troller. They had to stop for transmission problems. The cooler was leaking. The transmission fluid was pumping into the cooler due to the transmission pressure being higher than the cooling water pressure.

The low fluid level caused the transmission to act up. He changed the cooler, then added fluid, and they were on their way.

MORAL!!!!!!!!!!!! If the transmission is acting up a little, STOP, investigate!!!!!!!!!!!!! When I take my tranny dip sticks out, air pressure rushes out. I'm guessing that's to keep salt water out in case of leaks. Great Story from Jim.

 

[Alex D]

Coincidently!!!!!!!!!!!!!!
When I take my tranny dip sticks out, air pressure rushes out. I'm guessing that's to keep salt water out in case of leaks.

My Hurth 63V do the same. I always wondered why since they seem to be vented via a simple transmission and gearcase vent. Go ficure ... :huh:

 

[fwebster]

John,

Treasure Island had 3 transmissions down at the same time last month, all due to Mercruiser oil cooler failures.......that seems a lot like a significant failure rate to me......

Asking Sea Ray if they have an unusually high failure rate on anything is like asking your preacher if he beats his wife.............

 

[Hampton]

Not that there's anything wrong with that......(Preacher/wife beatings).

I agree completely, but I wanted to get their answer. I didn't quote my source, but I described him as "Highly credible." I didn't get to talk to Roland - he was off last Fri, but Jim returned my call.

Frank - what do you think of that pic? Is that a Merc cooler? I'm sure it is. It is copper, but that doesn't make me safe does it? It looks good to me so far, how 'bout you? That being said, an ounce of prevention.... still need a change, agreed?

 

[fwebster]

John,

About all I am is the messenger in this alert. I just saw and observed what appears to me to be a potential land mine for unsuspecting owners of gas boats with v-drives. When I asked the mechanics about it thay referenced a "cheap stamped component in the design. Copper does not make you immune from corrosion or degredation from salt water growth.

You really need to go by and talk to Jay Bodner in the shop...just don't stop at the office and walk on by those guys to the open shop door, Jay is the shop forman and is where the rubber meets the road. Jay normally isn't very forthcoming, but tell him I asked you to come to him to get the right answer and it may cut thru some of the "overhead".

 

[Hampton]

Thanks.

I'll give it a try.

 

[Alex D]

Whre did this all of a sudden come from??? Never heard a lot about it before here or elsewhere. :huh: