Cooling Issues

[BassAckwards87]

1996 Nissan NS8B 8hp long shaft. Bought the outboard and the guy said it was making a funny noise and needed a water pump and he did to want to mess with it so I got a really good deal on it. After trying and failing to get the lower unit off ( yes I tried wedges and hammers ) I figured I'd at least see if it ran before I tried desperate measures and it started right up and ran perfect had plenty of pressure at the tell-tale. After getting my boat back together I put the outboard on and was ready to hit the water. I figured I'd run it one more time before then and again I have plenty of pressure at the tell-tale but when I went to feel the temperature of the water coming out it was scolding hot! Pulled the cowl off and touched the power head and it also was scolding hot. How can I have flow, good pressure and running perfect but the water temp is still so high? Please help and thanks in advance.

 

[pvanv]

May have salt/crud in the block/cylinder passages.

 

[Sea Rider]

Was scolding hot water beeing peed real scolding as to burn say your palm ? If so, being that old will second what Paul said, probably used on salt water and never or badly flushed after use. Ask seller if engine had sweet or salt water use to start with direct troubleshooting.

Tu cure the patient will need to remove cyl head and clean all water passages immaculate clean throughout the entire engine, install a new thermo along head gasket and plugs, take advantage to decarbon piston and cyl head interior, torque head to specs, it's the only way to have that 8 running as a champ again.

Happy Boating

 

[BassAckwards87]

Thanks fellas. I know it was run in salt water in its previous life, I just hoped I would get lucky. I guess it's time I order a head gasket and thermostat and get to work. I'll update this thread when I've completed the work and let everyone know how it went.

 

[Sea Rider]

You could flush engine on a barrel with 50/50 % of water and vinegar but will need gallons. Best is to tear cyl head and clean. Once crankcase is opened, squirt pure vinegar on all water passages and let soak for some time, with a sushi wooden stick rub all water passages evenly to get out the crud, salt formations, repeat as needed. That way won't scratch passages if cleaning say with something metal.

If wanting an excellent service done, remove side exhaust cover as well, has 2 thick gaskets. Probably are worn, burnt, dried out. Include them along other suggested parts. If pulling complete power head out, will need a new base gasket, which usually breaks when removed.

Happy Boating

 

[BassAckwards87]

Sounds like a plan with the exhaust. Pulling the power head is another issue due to the fact that the shaft splines must be rusted solid in the crank. I've been banging away at trying to get the lower unit off and so far I've only gotten about 3/4 inch of gap. Still trying and if so I definitely will pull the power head and thoroughly clean everything. Found a good website with decent prices for all replacement parts...wish I was fishing instead though

 

[dnhoogerwerf]

Are you sure the shaft spines are rusted? Sounds like you have not disconnected the shift linkage. The lower unit moves just enough (3/4") to take out the bolt that fastens the upper linkage to the lower linkage.

 

[Sea Rider]

Has already disconnected shift rod from lower leg, you definitely have a stuck, rusted shaft splines inside crankshaft, If you have already a large opening, insert a thick wooden or plastic wedge inside gap and with a rubber mallet hit wedges at both sides at same time, patience and hits should do the work...

If finding when removing cyl head bolts have too tigh space to work on, remove powerhead, take advantage to clean what's under powerhead, carbon, debris, etc.

Happy Boating

 

[BassAckwards87]

Well after breaking two head bolts and having to hammer a wedge in there to get the head plate off; you guys were absolutely right! There is all kind of corrosion in there. I plan to give it a thorough vinegar bath. Just wanted to stop back by and say thanks for the info! I'm starting a new thread due to another issue I ran into trying to remove the lower unit. Thanks again fellas...

 

[BassAckwards87]

No Title

That's after cleaning a lot out with a small flathead.

 

[Sea Rider]

Gee, finally opened the Pandora Box. Have so much rust in all water passages that engine will not cool properly in a lifetime use. Use a sushi wooden, plastic stick to rub/remove all crude, debris, rust out of all water passages, pre soak with plain pure vinegar.

Happy Boating