Keep an eye on your Temps

[Capt. Rick]

I decided to give my old 20 Shamrock to my son. He is out in California and is actually going to drive cross country to come and trailer the boat home. I've owned the boat since 1985 when she was new - she is powered by a Pleasurecraft (Ford) 351 freshwater cooled inboard engine. I have been going over the boat, trying to make sure she is running tight before she goes. I've changed all the ignition parts on her for new. Other than that, I have noticed the engine was running a little hotter than normal. Normally she would be around 175 degress or so, and last few trips I noticed her around 10 degrees hotter. I knew I was overdue to change the risers so pulled them off. Have a peek.


After seeing this I realized it must have been longer than I thought, I ordered a set of manis as well. I really should have been keeping tabs on things like this by writing stuff down in a book and being a little more careful with planned maintenance items. So lessoned learned, pay attention to the signs your engine gives you. Granted there are many other reasons an engine can run hot, but my point here is to take care of the maintenance items like Manis and Risers and dont be the ostrich. You dont want a hot running engine.

[Hawkboat]

Did you have pencil zincs F/W side ?

S/W tears everything in it's path up.

[captjoekingcod]

pretty chitty lookin...

[jawz]

manifolds/risers-these are good for about 4-5 seasons,after that,you're asking for trouble...

zincs have nothing to do with the risers and the manifolds rusting out...

also,those ford engines,the block is freshwater cooled,the maniflods and the risers are where the sea water is exited-these are raw water cooled...

looking at those risers,as you can clearly see,the water passage,the surface is eroded away,allowing water to run back into the manifold-look at the sealing surface,you will see what i mean...this is bad,real bad.i would be willing to bet,if you perform a compression test on that engine,it's way out of spec-the sea water backing up,it rusts the exhaust valves,and causes a low,or no compression situation in that cylinder-you can see that's what's happening...


inexperienced boat owners believe they're prolonging the life of the manifolds and risers by flushing,not true...you can flush day and nite,these are the weak link in the system,and the max life is 4-5 seasons...this is the #1 cause of gas engine failure...

[Capt. Rick]

Good stuff Jawz I was hoping you would chime in. The engine seemed to be running real well and strong- but you are right about the back pressure, I noticed a had a drip from one of the hose connections to the end of the riser elbow above the heat exchanger. That was another sign that I didnt pay any attention to. Will have to test the compression once it is back together. What kind of readings am I looking for?

[jawz]

um...."back pressure" ?? what's back pressure ??

compression...old engine like that,you're really looking for uniformity-look for the compression the be within 10% of each other...

[Capt. Rick]

back pressure - what I meant was the sea water backing up and not circulating properly...