1978 F25 Exhaust Risers

[jayn8yy]

Hey All.

1st thanks for the advice on the bow steer. the trim tab settings did help, as did the bottom cleaning.

New problem. I have a Ford 351 V8. The engine runs at normal temps at idle or just cruising. However, when i went offshore and pushed it to get it up to plane. The engine overheats to 190F. this is to hot i believe.

The only thing i can think of - is the risers need to be replaced, from the service log i see that the previous owner changed them about three years ago.

Is this a big job?? I am concerned about disconnecting them while the boat is in the water because of the water coming up thru the exhaust port.

Any advice is appreciated on this. if this is the thing to do and if it can be done simply..

Thanks....

Also -- what type of cruising speed should i be expecting from this boat. 15- 18 knots???

[chucka]

There are many possible causes of overheating such as a loose belt, waterpump impeller, thermostat , low coolant (if FWC) that seem more likely to me that risers after 3 seasons. Is the engine fresh water or raw water cooled? I changed risers while re-powering, (with the engine out of the boat, where I had plenty of room to work, this is not an issue. It is possible to remove your exhaust hoses from the risers while the boat is in the water, but you are correct to be cautius about this. Don't leave the disconnected exhaust hose laying on the bottom of the hull, as water can flow in through the exhaust and sink the boat. While working on my engine, I disconected the exhaust, but tied the hoses to the underside of the deck, so they stayed up high above the waterline, not permitting water to flow in.

I recommend following a standard troubleshooting guide on overheating before replacing the risers. http://www.skidim.com/Faq_TROUBLESHOOT.asp#RWTS
Good Luck,
Chuck

[jayn8yy]

Thanks for the advice. The things that lead me to believe that it might be with the risers is:

1.) The risers are hot to the touch while running
2.) The engine does not overheat while idleing only when a load is applied. If the impeller was shot - it would overheart pretty fast.

Thanks for the link it did provide me with help. I am goint to disconnect the risers and take a look.
I'll let you know and hopefully wont sink the damn thing.