Overheated my 1989 OMC 5.7

[cohiba54]

Long story short I ran about 20-30 minutes after leaving a sandy beach-head then one of my passengers said something smells, I glance at my water temp and it was pegged, I shut down the boat. We ran @ idle speed about half that time and about 15k rpm for the rest. Anyway got home, pulled the impeller and found about 30% loss, probably due to when I was approaching the beach-head. Yea, I know I was dragging the lower in the mud/sand. No big deal so far at least in replacing the impeller but one thing kept bugging me. Where did all the muck go? So I disconnected all the lines at the engine on the thermostat housing and flushed them out but no sand or anything but clear water coming out the out drive. So I pulled the drive off of the boat and found a mess on the exhaust port of the out drive (see pictures). This stuff looks like sprayed melted nylon (the white color) and soft rubber, like some type of rubber gasket about ¼” thick (the black color) and all that blown and stuck to the vertical shift rod.

What the heck could all this be? If you have ever come across something like this on the exhaust port please let me know what you think it was.


Thanks
Rene

 

[Boatin Bob]

Re: Overheated my 1989 OMC 5.7

No idea about the white stuff but the black rubber could be the melted rubber lining off the flex hoses that attach the risers to the Y pipe.

 

[Don S]

Re: Overheated my 1989 OMC 5.7

If you go back and edit your pictures and hit ENTER between each picture, they will be inline (Up and down) instead of side by side, and a lot easier to see.
Also easier to read your text without scrolling from side to side.
Looking at your pictures, I would say your drive hasn't been off for any kind of maintenance in YEARS and YEARS.
Do you ever run and flush it with fresh water?

 

[cohiba54]

Re: Overheated my 1989 OMC 5.7

No idea about the white stuff but the black rubber could be the melted rubber lining off the flex hoses that attach the risers to the Y pipe.

Yep thats what I think too Bob, I'll be exploring the complete exhaust at least from the manifold to the transom collector to see what melted. I'll keep yall posted.

Thanks
Rene

 

[cohiba54]

Re: Overheated my 1989 OMC 5.7

If you go back and edit your pictures and hit ENTER between each picture, they will be inline (Up and down) instead of side by side, and a lot easier to see.
Also easier to read your text without scrolling from side to side.
Looking at your pictures, I would say your drive hasn't been off for any kind of maintenance in YEARS and YEARS.
Do you ever run and flush it with fresh water?

Don- Thanks for the tip on the separating the photos. As far as maintenance I'm not sure, I just bought the boat in July. I had all drive fluids & engine oil drained and replace as I surveyed the mechanical of the boat, plus we did a compression check on the cylinders and every one was within specification and the drive was also pulled and the spline shaft inspected. For a boat thats 17ys. old I thought that the steel and aluminum parts were all in pretty good shape. Some degradation should be expected at that age, as far as flushing I was told the boat lived most of its life as a fresh water boat. I'll probably keep it that way too, I'll have to buy some other type of boat for saltwater fun...

Any ways thanks for the comments and help on the photos..

Rene

 

[Don S]

Re: Overheated my 1989 OMC 5.7

I can't tell just by looking at the pictures what that mess is. But I would suggest, before you mess with it, you get someone who knows to look at it and determine what that stuff is. Lots of things in those pictures raises red flags to me.

 

[bruceb58]

Re: Overheated my 1989 OMC 5.7

That sure doesn't look like a drive that lived in fresh water all of its life. I used to get a build up of white deposits in the shift bell crank area but never in the exhaust area.