Flushing Engines

[fairpilot]

@fairpilot I have been running engines for 60 flashes In No-Wake mode, without supplying water. I have not had any overheat warnings while doing this and the engines get warmed up, hopefully drying out cooling system.
Like you, I always flushed for up to ten minutes after being on the water and still had overheating.
Last March after pulling both engines and cleaning the cylinder water jackets and oil cooler water jackets, I went on the water to test. No overheating. I flushed the engines as always and thought the overheating problem was resolved. But, afterward, while having the boat layed up, I periodically started engines and ran on hose for up to ten minutes each. That is where the problems began. I started getting overheating on engines that had only been in the water for a few a hours. I pulled both engines, again and found the cylinder water jackets and oil cooler water jackets packed with that jelly like substance you mentioned. Now, I am preparing to water test again.
Regarding tie valves: I do not think pressuring the cooling system to attempt better flushing is wise. There is barely a quarter inch space between water passage ways and cylinders. Water/steam could be forced into cylinders.

I have not had any overheating, the first time this happened it corroded away a piece in the manifold and water somehow got in oil, this time I have had a small water leak into boat which I decided to address so I pulled that engine and sure enough manifold was corroded to a point that any day was going to be an issue. Soni decide to pull manifold off other engine, sure enough center section has a corrosion spot that requires it to be changed.
Also the first elbow in in exhaust ( first big rubbber boot) is really corroded up. So I fixed that. As for the jelly substance, I really only find that in thermostat housings, I take them apart about every 6 months and the have it in them. The water jackets at manifold were mostly dried crusty salt and maybe what looks like some sand.
My problem now is I'm having a hard time finding a decent used inner manifold, a new set of manifolds is $870. If you know of a used center manifold from a FX 140 let me know. And thank you for all the information

 

[fairpilot]

Here is a pic

 

[Cobra Jet Steering LLC]

looks like corrosion from salt water, I recall that Yamaha did not have a good Rating years past for their lower units on the outboard engines being made of corrosion resistant aluminum, heat in the exhaust manifold could add to the problem but I have seen this on several mr1 engines in the past years as well I do not think it is related to flushing methods. remember back years ago Johnny O from the old site had the exact same issue with his 230. I will never run a trolling motor or any gas engine in salt water without ZINC anodes attached the battery connected to the ground on the engine supplies the metal with a negative charge to corrode things. Look at the bottom skeg of the trolling motor I made for my skies and you will see a round zinc anode

 

[WREKS]

Here is a pic

I have filled in a couple of corrosion pits on the manifolds with jb weld. So far jb weld has worked on the port cylinder head that had a corrosion canal.
The aluminum wedge was to hold jb weld in place if it loosened. No more milky oil.

Before and after

 

[Brad_Ct]

I have not had any overheating, the first time this happened it corroded away a piece in the manifold and water somehow got in oil, this time I have had a small water leak into boat which I decided to address so I pulled that engine and sure enough manifold was corroded to a point that any day was going to be an issue. Soni decide to pull manifold off other engine, sure enough center section has a corrosion spot that requires it to be changed.
Also the first elbow in in exhaust ( first big rubbber boot) is really corroded up. So I fixed that. As for the jelly substance, I really only find that in thermostat housings, I take them apart about every 6 months and the have it in them. The water jackets at manifold were mostly dried crusty salt and maybe what looks like some sand.
My problem now is I'm having a hard time finding a decent used inner manifold, a new set of manifolds is $870. If you know of a used center manifold from a FX 140 let me know. And thank you for all the information

I was able to find the exhaust parts I needed used on eBay from seller extrememoto and if I remember correctly he had the part you are looking for.

 

[Dfred]

Curious questions about this symptom:
1 - Would raw water strainers help (I see mixed mentions/endorsement of this mod on the forum, and from what @Cobra Jet Steering LLC says about sucking up sand, etc... why not?). Should folks look at adding those to prevent issues (if conditions warrant)?
2 - Shut-off “tow” valves at the intake seem to help tremendously in keeping the flush (whatever it is: hose water, soap, salt away, etc) going in the right place at max volume and pressure vs. just dumping it out the intake at the jet. This would seem to give maximum contact of flush with the engines cooling system channels. Why is this not standard design and OEM?
3. Would the closed-loop chemical flush (ie. @CrankyGypsy method) help?
Huge THANKS to all the veteran ol’salts on this site for your time and thoughtful guidance to all us jet boat newbs.

 

[WREKS]

Water is the biggest problem. A wet cooling system is a perfect environment for microbial buildup. It looks like whatever you want to call it. Active it looks like jelly; drying it looks crystal like, like big salt crystals, dead it looks like sand. It can really pack in. Cylinder water jackets Correction: when I say drying out the "cylinders," I mean the "cylinder water jackets."