Trojan Boat Forum

So I'm almost done replacing manifolds risers and elbows on my 87 F36 and I got to thinking with this newer style manifold that eliminates the 2 inch spacer, for freshwater application why not move the stainless steel plate from being sandwiched between the manifold and riser to be in between the riser and elbow. Additionally rather than freshwater circulate through a fitting at the top of the manifold, it could circulate through the fitting previously designated for seawater entrance into the riser. Finally sea water could be rerouted and enter into the top of the elbow. This would allow for freshwater cooling of the riser and very minimal if any deterioration and slower deterioration of the elbow since there would never be any sitting Salt water in the riser. Any thoughts? Anybody ever tried this?

Passage ways are open on the riser so your coolant would end up going out the exhaust .If you want longer riser life ,Why not install a fresh water flush ?

I have Crusader 350's (7.4 L) engines as well, The manifold is fresh water cooled and the riser and elbow are raw water cooled, I wanted to have the riser on the freshwater side, but there are not any threaded ports on the Osco riser. the Stainless block off plates are between the manifold and lower inlet of the riser. I installed Groco bronze flush kits just after the strainers and I flush the raw water side of the system with salt terminator or salt away after I run the engines in salt water which leaves fresh water with a mixture of the salt away in the raw water passages, hoses and heat exchangers . I pulled off the risers and elbows from the starboard engine last fall and the internals look near new, after 2-1/2 years.

It takes a bit of discipline to flush after every run, but as you know, the cost of a full exhaust replacement it very high.
I made up a bucket and hose assembly that I fill and leave the hose running into while flushing, I connect this the the flush kit, I close the sea cock and draw from the bucket and just pour in a bit of salt away. DO NOT connect dock pressure directly to the flush kit, you will blow the raw water pump shaft seal out of the pump and destroy the bearing, ask me how I know , if you have a Sherwood pump - you know you don't want to buy more than one. $$$

gettaway wrote:DO NOT connect dock pressure directly to the flush kit, you will blow the raw water pump shaft seal out of the pump and destroy the bearing, ask me how I know , if you have a Sherwood pump - you know you don't want to buy more than one. $$$

Interesting. Our boat came with a flush system connected to the house water system, with multiple ball valves protecting from raw water getting into the house water, kind of like an air lock. We have not had any problems with the pump seals, but there is also a water pressure regulator keeping high dock pressure from affecting the house system. Maybe that is what is protecting us from seal damage?

I'll have to check the actual water pressure with a gauge and see what it is set to. It is certainly lower than the pump coming off the water tanks...

the dock water pressure on our dock fluctuates dramatically, I guess I could put a regulator on the hose and make up a pig tail, but I have gotten used to the system I made up, I can also check water flow of each engine by how quickly the bucket drains if I turn off the water supply.

I have thought about doing the same with mine (some sort of flush system ) not only do add life to the risers , the heat exchangers and coolers (oil and trans ) will benefit too . And in my case the after coolers

You can also use a flush system to "blow out" your intakes if you cap the hoses to the raw water pump. Sure beats diving in cold water...

When I change my risers and elbows I will be changing to the way my last F32 was set up.

It used the 2" spacer with the hose connection between the riser and elbow as the outlet for the closed cooling. The stainless block off plate goes between the 2" spacer and the elbow and acts as the barrier between the closed cooling system and the raw water.

On a side note I have a mini shop vac on board that I use to blow out my thru hulls if necessary.

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