Force 1989 85 hp Overheated while WOT

[lgaytan]

Hello,
this is my first post but I've been following this forum for over a year and it has been very use full, now it's time to make my own question.
I've seen several questions about overheating problems in this engines but I don't find one for a WOT over heated.
Last week I went to a local lake with an old Bayliner Capri 1989 with a force 85HP, I had issues with the battery so I connected the battery from my truck to the boat in the shore, I get it running but didn't notice it picked up a lot of mud, I went offshore for about 1 mile or less notice it wasn't going as fast as usual and that it was making a strange noise, the motor was with out it's cover so when I looked back I noticed smoke and burnt oil smell. I shut it down and waited for the tide to get me to the shore again.
I didn't tried to strat it again, but I cranked it just to see if it still moved and it did.
As I'm in Mexico I have a 2 week delivery time for spare parts so I tried to get what I considered basics of this repair now, and not wait till I have all the analyzis done. So for starters I bought the repair kit of the water pump, the head gasket, a compression gauge and some honing stones (expecting worst case).
My plan for the repair is as follows,
1. Rebuild the water pump
2. Check compression of head
3. If compression is low change the gasket
4. If compression is still low hone the cylinders, can I hone them with out removing the block, pistons, etc? Or do I need to take everything apart?
5. Recheck compression

do you suggest using any chemical? Seafoam, deep creep or something like that? Should I start looking for rings, this boat was owned by an uncle before me so I'm pretty sure it has original rings and pistons.

Any help will be appreciated.

 

[foodfisher]

It didn't seize, that's a good thing. I'd clean the cooling system and check compression before making any other purchases. Maybe you'll get lucky.

 

[jerryjerry05]

Do the comp test FIRST.
Then fix the overheat buzzer.
Change the impeller.
In the case of sucking up mud, the mud settles in the low spots and hardens.
Run it in the BIG barrel and add dawn soap.(amazing what Dawn does)
Run it for a while.
Then pray the muds gone.
Try the motor in the water.
The exhaust chest is where most of the crud settles. Remove and clean and install new gaskets.
When removing the screws be VERY careful the heads twist off just looking at them.

 

[lgaytan]

Update:
I just got the spare parts this weekend and I replaced the impeller seals and played of the water pump.
I cranked the motor to take compression measurements, I noticed the motor cranked slower than usual, the readings were 100, 35 and 100... Reality low the mid cylinder. I took the head off and inspected the cylinder walls, I didn't noticed deep dents actually top and middle cylinder are really smooth and I don't notice any damage, the third cylinder did have a dent, but as it is giving me the same reading as the top one I decided not to do anything to it yet.
I changed the cylinder head and rebolt it I applied 225lb in, but didn't followed any order to bolt it I just did it crossed. I tried again and the middle cylinder now reads 50 psi but still cranking slow, as I'm stubborn I decided to fire it, it wasn't easy but after some time got it running, it sounds almost the same or the same as before the overheated incident, it idles good, Igor it running for over 40 minutes, the water pump worked really good, I added tide soap to the barrel to clean the water passages. After this I retested compression, the motor cranked faster but I don't feel it as before the incident, now the mid cylinder reads 90 psi.
Any suggestions? What should I do next?



Thanks

 

[jerryjerry05]

The slow cranking is from the uneven compression.
The gasket hasn't "set" yet so loosen and retighten in the proper sequence.
Do a decarb.
I use Mercury's Powertune or OMC's Engine Tuner.
Follow directions.
One thing I do is after it's stalled out I remove the plugs and add more decarb in each cylinder and let it soak for 24-48hr.
It sounds like the rings are stuck on #2.
The decarb might??? help??
If not then you can do a ring job on all 3 or just the middle one.
Some of the guys do just one cylinder without taking the head apart.

 

[lgaytan]

Thanks Jerry, what will be the sequence for retight the head?
I have ordered the seafoam, I saw several videos on YouTube where it is applied directly to the carbs but I read here that you can apply it directly to the gas an run the motor, what will be the best procedure?

Regards

 

[UtahBoating]

The way I personally use the seafoam is as follows: I idled my boat in the driveway in a tub of water and sprayed about half a can through the intake, your motor will almost stall. Then I shut it off and removed my plugs and sprayed seafoam into the cylinders. I let it sit for 1-2 hours. I grounded my plug wires and cranked the motor over to get the seafoam out of the cylinders. Then start up engine and let it idle for several minutes. It will smoke like crazy and the fire department may show up.

On my next outing it also smoked like a mad man when we first fired her up, it was actually kind of embarrassing at the boat launch, took the boat out and ran her hard. I am not sure if this is how others do it but it raised my compression up over 15 psi on every cylinder. This is kind of how I have also used seafoam whether it be on my snowmobiles or auto or whatever.

On the boat I also add a few ounces to every tank of gas for the time being. I always did this on my snowmobiles and it worked wonders.