Trojan with twin 454s overheating

[midlifemizfits]

25+ yr auto mechanic extremely new to boating but very mechanically inclined. I have purchased a 1974 Trojan F32, boat has sat in the upper Chesapeake for a couple years, went up this weekend and rebuilt carbs and have running excellent now but after about 10min the temps are getting up to 200+ temp, I know the water intakes may be barnacled up but does anybody have anything showing what the exterior intakes look like? Also I know that the fresh water pumps prob need rebuilt after this long to. Also need info on the purpose of the water pump on the front of the motors vs the fresh water pump ran by the belt on the accessory mount. Does it cool from both? If someone could point me in the right direction with a site or vid it would be very much appreciated. I'm 450mi from its current location so when I do make a trips up they need to count. Thanks so mush in advance!


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[LakeSuperior]

I have twin 454's in a 1978 Bertram.

The belt driven pumps toward the bottom of the engine are your sea water circulation pumps. They pump cool sea water through your heat exchanger to cool the engine circulation loop. This water is combined with your exhaust downstream and exits the exhaust outlet. Therefore, water should be coming out the exhaust pipes.

The engine coolant loop is exactly like your car loop.

Odds are the rubber impellors in the sea water pumps are no good. In fact, vanes may have broken off and gone into your heat exchanger. Hope not as you may have to fish them out if they block the exchanger. They really take a beating for the pump design.

When you install new ones make sure you prime the system by letting the air out of the intake water filters. This will reduce the amount of time the impellors run dry. Running dry for even less than one minute will score them. Use lube when you put the new ones in. I replace the impellors every two seasons.

[a64pilot]

OK, you have some learning to do.
First there is no radiator of course, what replaces it we call a heat exchanger, basically a big piece of pipe with a bunch of smaller tubes running in the middle of it, raw water flows on the outside of the tubes but inside of the pipe and exits out the exhaust.
The other water pump pumps the raw water, think of it as your radiator fan and the heat exchanger as your radiator.
There will be a hole in the boat that the water is drawn through, in this hole there is a valve and connected to that valve there ought to be a strainer basket. I would first clean the strainer basket as it can block water flow.
In truth go out and buy an hour of a Marine mechanics time to walk you through and explain stuff, it's not hard at all and you will immediately pick up on it.
I think you will end up cleaning the strainer baskets, replacing the raw water pump impeller and disassembling the heat exchangers and cleaning them. Not challenging work if you can get to the stuff, as an auto mech you already have the tools and the general knowledge, just gotta learn the boat stuff, and truthfully, it's easy.

[Lepke]

Normally marine engines have either a heat exchanger or keel cooling. 2 water pumps usually mean a heat exchanger. The auto type pump circulates coolant. The 2nd pump draws salt water and circulates it thru the heat exchanger, pulling heat from the coolant. The salt water pump has a rubber impeller that in yacht engines usually gets changed every year. Do this first.
Engines sitting in salt water can have all types of marine growth in the salt water part of the cooling system. I use Rydlyme for flushing. It dissolves things like shells.
Do this second.
The fresh water (coolant) side could need flushing if a rust inhibitor wasn't used.
Do this third.

[jamhass]

A friend has a similar setup, and it tubed out that his heat exchangers and exhaust risers were partially plugged. Since it is an older boat, unless you have a reliable service history, I would recommend pulling the heat exchangers, oil coolers and exhaust risers on both engines and cleaning all thoroughly. A good radiator shop can do so nicely, but DIY is possible. While you are at it, double check the condition of all hoses, etc.

[Shrew]

1) Make sure intakes are clear

2) Replace impellors

3) How long have manifolds and risers been on? More than 5 years? Time to replaced them too.

4) Is heat exchanger blocked?

Those are your 4 most common culprits in order and account for 98+% of engine overheating issues.

[Three Sisters]

That is the coolest floorplan for a 32 footer. Here's an article with several photos showing the thru-hull variations of the strainer at the hull bottom.

Remember that the transmission coolers can also pick up debris and clog.


Choosing a High-Speed Intake Strainer | Boating Magazine

[midlifemizfits]

Thank you all very much for your replies, you have all explained the system very well in great detail for me, giving me an understanding of the system that I can easily understand now. Thank you all for your help.


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[ranger58sb]

Originally Posted by midlifemizfits

Thank you all very much for your replies, you have all explained the system very well in great detail for me, giving me an understanding of the system that I can easily understand now. Thank you all for your help.

In addition to what everyone else said...

There are at least two environmentally-acceptable products that are useful for flushing the raw water cooling system, Rydlyme and Barnacle Buster. You'll probably have to do some disconnecting to find left-over bits of impeller in the raw water passages anyway, perhaps even impeller bits from several changes ago...

But once you've done that, you can clean the system reasonably well with these products. One way is to fill/soak/flush, and a slightly better way if you can cobble it together is with a recirculating system. Imagine a transfer pump, input fittings from ther maybe into your raw water pump (impeller removed), discharge fittings maybe from your heat exchanger, back to the transfer pump, something like that. In either case, you'd need to analyze your system to be sure the mixture would discharge as expected, not back-feed into your manifolds and valves and so forth.

It's not a substitute for a thorough off-engine service on your heat exchanger. It's also not a sub for aftercooler service (if you have those) because the mixture won't reach into the air passages. Still, it's pretty good, and would go a long way toward helping you diagnose your overheating issue. And the fittings will be useful for winterizing anyway, assuming you're still here on the Chesapeake.

There may be a Trojan owners club on line somewhere; if so, and if active, you could find that to be very valuable!



Looks like your engines are blue, in the pic. If so, maybe Crusaders... and you can probably get engine manuals and so forth direct from Crusader (probably given your serial numbers).

-Chris

[captlloyd]

You have received some good advice and guidance here. Please post your results, sometimes we all learn something on these types of post.

[midlifemizfits]

Captlloyd, excellent advice I have received, due to my boats long distance it will be a week or two before I make the trip up again, I was planning on taking it down the ICW to Beaufort NC the 1st of October but now it has a ways to go to get ready so we'll see how that plays out. I will update as to what I find and its progress with great appreciation to the advice I have received. Thanks to all again!


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[midlifemizfits]

Thank you all for your info, it helped tremendously. I just spent 2 days drive and 5 days work on the cooling system as well as many other systems problems. Turns out she had been sitting in the water for six years and basically untouched for the last 2 so I had my work cut out for me. But thanks to all your info my twins are cooling great. It had an extra Sherwood pump on board and after a quick glance at the ones on the motors I assumed they were the same so I ordered 2 kits and picked them up at West Marine(horrible experience) on my way back up on Thurs. Rebuilt the extra Sherwood at the Hotel and went to put it on and rebuild the one I take off to then put on the other motor. Well guess what, the twins had Jabscos. Mount and appear to work the same so at least I had 1 (the Sherwood) to use. Luckily after studying it over night and taking more measurements I find that the Jabsco impellers were the same, installed them and loaded them up with dish soap for initial lube and cleaned the strainers I was in business.
Thanks for your replies and I'm sure I'll call upon your help again!

[a64pilot]

When you take her on a trip, unless you go slow, it will eat an incredible amount of fuel.'
Here is a trick to minimize that, look behind you, are you creating waves? If so the energy to make those waves is coming from your fuel tank, slow down to where the waves are small and you will burn lots less fuel.
Just like a car which in truth these engines are, you want to blow them out before the end of the day for a couple of minutes.

Oh, next time you run them, does one run backwards?