High Water Pressure

[RangerRob]

Have a 2004 115 TLRC and and for years the water pressure has stayed steady at around 15 -20 pounds when trimmed up and running. The last time I had boat out water pressure was up around 25 - 30 pounds. Why would water pressure suddenly getting higher?

[99yam40]

If this motor has a PRV then I would be checking it to see if it is sticking or not opening as it should.
Have you been changing pumps and T-stats like Yamaha recommends?
Sounds like something is restricting the flow out after the pressure pick up

[RangerRob]

How do I know if I have a prv valve and where do I find it. I purchase a Seloc manual but have yet to find it in the manual, there is nothing listed in the index? I have good stream of water coming out of motor regardless of rpm. I have 85 hours on the boat and have done nothing but changed my impeller twice and I just changed lower unit oil.

[boats.net]

It's number 19 in this link, 2004 115TLRC Yamaha Outboard CYLINDER CRANKCASE 2 Diagram and Parts

[RangerRob]

Cool, Thanks, That looks like a little more work than what I was planning for but it is what it is. Would you recommend just replacing, it is only a $ 6.00 part.

Thanks again

[99yam40]

replace it and the grommet if needed, but must check to see if it is sticking and causing the higher pressure. Look for corrosion swelling grommet and grabbing/ binding things up.Some of the newer PRVs were redesigned to help with the problems it had, but have no idea about yours
Make sure you are careful and do not lose the grommet inside the motor

[RangerRob]

Do you think I should go ahead and replace thermostats while i am in there. I onle have like 85 hours on the motor and other than this recent high water pressure problem, it runs really good

[jb123]

YES cheap insurance
try unhooking pressure tube, see if pres drops to 0

[RangerRob]

what if does ? what will that mean? and I am assuming the pressure tube is connected to the prv?

[jb123]

tube on gauge

[RangerRob]

Yes it does drop to zero

[99yam40]

no it is not tied to the PRV
PRV just opens up when water pressure gets above the pressure needed to push open the spring tension on it to relieve the excess pressure during high RPMs

[RangerRob]

Pressure Relief Valve

Ordered parts to replace a pressure relief valve and the old one is shown on the left. The new on on the right is quite different but is supposedly the correct part. Does anyone know if this was changed due to performance issues. I replaced spring and grommet also, hopefully this will bring my water pressure down to what it normally was last year.

[99yam40]

It was redesigned to keep the corrosion from under grommet from pushing rubber grommet and grabbing the PRV .
Did you find a problem with old one when you opened it up?

[RangerRob]

Prv Valve

The valve itself looked fine - the only problem I encountered was that I had to pull on it with pliers to get it out. There was some " mineral deposits" on the round edge part. Would that little bit of deposit be enough to make it stick and keep it from opening?