Please, Iboats gods, why so hot??

[leshadow]

Long time follower of this forum, and I've learned so much, but I'm a bit stumped and wanted to be on the water tomorrow, so here goes! 1978 Sea Ray SRV 195, 228 Mercruiser, Alpha 1. Motor rebuilt professionally and new OEM outdrive by previous owner. Redid interior and exterior myself, then set about ensuring mechanical robustness. Fresh water boat it's whole life, but I'm at the ocean so I added SeaKamp FWC. Basically now at 99.5%, time to start using it more. Maybe 15 hours on the water thus far, and all has gone well. FWC, as per their spec, pins the gauge at the green/red line. Redid impeller and housing last month like a good boy, also removed port riser to peek at shutter (couldn't see anything) and replaced aftermarket blockout gasket with OEM stainless steel version sandwiched between 2 OEM gaskets. I'm busy building a house this year, so time is at a premium, but hoping to be on the water this weekend, so fired it up yesterday to charge battery etc. Runs like a top, but gauge gets into the red, and engine seems rather hot. Off with the outdrive, rechecked the pump/impeller, flushed and blew and inspected the power steering cooler, found a few of the previous owners impeller bits, but very little. Back together, run it up, seems slightly cooler, but after about 15 minutes idling on the muffs and hose, I noticed the heat exchanger and FWC hoses were quite hot, as was the exhausted water, in the past it's always been lukewarm at best. I'll have my stubborn little face in there again tonite, double-checking the riser gaskets this time, but thought I'd seek insites here, I'm always amazed at the depth and breadth of the knowledge base here! Thanks in advance!

 

[HT32BSX115]

Re: Please, Iboats gods, why so hot??

Howdy,

Well, it sounds like you're hot on the trail of the problem.

In a nutshell you have to have good water flow from the raw water pump (no bubbles) to the heat exchanger and then it has to exit easily thru the exhaust manifolds and/or risers.

If you have power steering and it's a V-8 you probably have oil and power steering heat exchangers. They must be clear of impeller fragments or other debris.

Your FWC heat exchanger must be clear of debris.

Your risers and manifolds must be clear of rust and debris.

ANY obstruction partial or otherwise in the raw water circuit can cause an overheat.

If your raw water pump and plumbing in the drive is not perfect, or has a hairline crack in a fitting or a hose you can suck air (if it's in the suction side or leak) which will ultimately reduce the amount of water flowing into the heat exchanger and out the risers.

How about the T-stat?


AND FIRST but not least........Your gage must be accurate. Just running in the "red" doesn't cut it. You MUST check it with a known sender & gage before you decide that it's even overheating at all.


Cheers,

Rick