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Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I have twin 4 stroke 225 TRX engines. Both use the same fuel

Customer Question

I have twin 4 stroke 225 TRX engines. Both use the same fuel tank. Only the port side engine has raw sea water getting into the VST Tank from the vent hose on the top. The salt clogs the pickup screen on the high pressure pump at the bottom. I did change the pressure relief valve, and I may have put in on incorrectly, in the wrong direction. That seems to be the only place where vacuum comes into contact with the raw water for the fuel cooler. I have pressure checked the fuel cooler, and it is completely tight, no leaks.
A mechanic suggested I bore scope the engine to see if the raw water has eaten thru the block somewhere or bad head gasket casing unusual vacuum.
I have the relief valve assembly and the orifice, Air Vent completely corroded and need to be replaced.
Can you tell me if you have heard of raw water getting into the VST thru the vacuum lines and what I can do to fix?
Submitted: 2 years ago.
Category: Boat
Expert:  Jason replied 2 years ago.
Hello my name is ***** ***** am I speaking with?
The only place fuel and water come remotely close to each other is in the fuel cooler. How exactly did you pressure test it, and to what PSI?
Customer: replied 2 years ago.
I'm Stan. A mechanic put compressed air to the cooler, maybe 40psi or more. Couldn't feel any leaks in it. If no water can get to the vacuum, then why is the vent inlet on the top of the VST tank corroded? also the relieve assembly and vent orifice at the airbox is corroded.
Customer: replied 2 years ago.
also the VST tank had white, chalky deposits in it, and in the screen on the HP pump. It tasted like salt.
Expert:  Jason replied 2 years ago.
Hi Stan,
Are all of the hoses plumbed the correct way? When did this problem start?
Customer: replied 2 years ago.
Good point. I have had to pull the VST apart to unclog the screen so many times, I may have put the hoses on wrong or put the relief valve assembly in the wrong direction. This has been going on all summer last year. The mechanic at the yard kept cleaning the VST and putting in back together. I have done it atleast every 4 weeks. I changed out the relief valve on the water and fuel side end of last summer. They were both corroded and one was cracked. That may me when I noticed the salt water in the VST.
Expert:  Jason replied 2 years ago.
If you pull what you think is the vapor tank vent hose off, where does the other end of that hose connect to on the engine?
Customer: replied 2 years ago.
It should connect to a relief valve, then connects to the vent hoses on the top of the VST tank? I am 2hrs away from the boat. So I should contact you back on Friday when I get there. I can take pictures and possibly facetime you if that is possible.
Expert:  Jason replied 2 years ago.
You can definitely take pictures. I don't know what a facetime is. What you want to do is look at the vst tanks vent hose and see where the other side of that connects to. I have a feeling its in the wrong spot.
Let me know what you find.
Customer: replied 2 years ago.
How about the Vapor tank. I did change the Thermostats, and I recall having to disconnect hoses that go to the tank. I don't think I could have screwed them up, but you never know.Facetime is available for Iphone users only. I will take pics and send them to you.
Expert:  Jason replied 2 years ago.
Sounds good. Let me know what you see when you have another look.

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