88 Force 125 HP runs then kills

[vanfleetlh]

So I took my 88 Force out on the lake, got it up to full speed for about 5 minuets and it killed. White smoke was bellowing out of the exhaust ports. I was scared that I had blown a head gasket so I didn't try restarting it. I got home and did a compression test and all 4 cylinders showed 120 PSI. I tried stating it and it started and ran fine. I wondered if I had knocked the kill switch off so I took the boat out again and the same thing happened. I took the thermostat out and tested it. The thermostat opened at 145 Deg, it's rated for 130, is 145 too hot and could that cause my failure? I rebuilt the lower unit and replace the water pump this spring. I had it out once after the rebuild and it ran fine all day. Water is getting pumped, it's pumping better than I have ever seen. Anyone have any suggestions?

 

[jerryjerry05]

Welcome.
​White smoke sounds like it got HOT!!
Check the impeller even if it's new.
The pump housing is made from some kind of pot metal and can get pretty worn down.
Check for scorring and wear on the stainless plate.
Cheap impellers can be part of the problem too.

​IF?? you run in shallow water it's possible the power heads full of crud?

​IF???? you decide to remove the head be very careful when removing the head bolts.
​They can come right out or be a 5 hr. job.

 

[vanfleetlh]

This time around I replace the entire pump housing, impeller, plate.... It's pumping water out the pee hole better than it ever has. Can water come out the pee hole and still be clogged in the power unit, or does it need to pass through the power unit before it can come out the pee hole? Enquiring minds want to know ;-)

 

[jerryjerry05]

No Title

Yes the water from the pee tube just indicates there is flow.
But doesn't really tell the condition of the passages.
​This motor was peeing just fine.

 

[Stingrayaxe]

Wouldn't the overheat buzzer be going off if it got that hot?

 

[Jiggz]

Actually, the buzzer and thermo switch are designed to get off at 160 degrees. Additionally, these model of motors do not have safety shut down due to high temp. So the most probable reason the engine shuts down is due to faulty fuel delivery or electrical. This could have been subsequently caused by high operating temps.

 

[jerryjerry05]

The motor can shut itself down if it gets too hot.
The alarm system needs to be tested.

 

[vanfleetlh]

Thanks for the input, I took the boat for another test run and it did the same thing. I tested the compression again, this time I took all the spark plugs out and tested it with no plugins. This time the compression looks like this: 100, 120, 120, 30. I took the head off and the bottom cylinder has some pretty bad scoring on the piston walls. So the big question is, is it worth rebuilding it and if I do how much will it cost me in parts to do it myself? Thanks

 

[jerryjerry05]

A do it yourself job??
​Parts around $300 or so, machine shop $50-150??
​Getting it done? 1200-3000++
​You can replace one piston and do it yourself 2 weeks.
​If you don't have to wait on the machine.

 

[Jiggz]

You can start posting pics of the piston and cylinders and would probably get a better recommendation if it is worth fixing it or if you can DIY it. With 100 PSI compression, it can be surmised the cylinder is just lightly gouged if at all.

 

[jerryjerry05]

He said he had 30 in the bottom and had some bad scoring there.

 

[Jiggz]

Oh shoot . . . 30 is quite low meaning there is a serious gouge or a serious break on the ring. Again, photos will help a lot in proper diagnosis.