water pressure??????
 

how much water pressure is too much??? i think excessive water pressure is what smoked my engine tues and started the problem that i ended up with. is 30 psi too much at 125mph. if it is how are you guysgetting rid of it. please post thanks :D

30 PSI isn't to much, but at 125 running over some choppy water with short drives there were likely some pressure spikes in excess of 40 to 50 PSI. Pressure spikes occur so quickly the gauge may not even pick them up. Talk to "team Carrerra" about the cure. He will be here next week and I can send some parts back with him that should help lower the pressure and reduce the spikes. I have my pressure set at 25 PSI at 95 MPH and 6200 RPM. I think Corey is about the same. Hope the motor isn't to bad. Later, Craig

Wette Vette, Before I detonated one engine, (under jetted I'm pretty sure), I had switched from a standard crossover to a bypass crossover with a thermostat. I knew what it was going to do, but in 38° water, the water temp and oil temp wouldn't even register. Now I am pegging the needle on the water pressure gauges (over 35psi). The boat will only go 70-75 mph but it has the offshore pickups.

Was it you that posted a while back with a good cure?

I need some info. If you could help out here, I would appreciate it. I'll be a trailer queen owner for a while so there is no hurry, It'll just be easier to install with the engines out.

Thanks :)

Gary Grimes has the expensive cure. It is a pressure relief valve that tees right after the coolers before the thermostat or bypass. It works!! My pressure was in excess of 40lbs. Now it is a consistent 24lbs. I need to get different springs to drop it to 18-20. This is a picture of stock 365's with the tee valve installed.

:D

Candyman, what kind of price are you talking about when you say expensive? How much capacity does it have? Will I need one for each engine, or just one. I would assume you would need two.

I would also be interested in the price and what it includes.

The valve I use plumbs in in the same location as the valve pictured. It could go before or after the oil cooler depending on how you want to do it. It is much smaller than the one pictured and works great. All of the components including the transom dump and fittings will cost fellow OSO'ers $150.00. The spike reliever goes in before the sea strainer and can be bought for $135.00 dollars. Most pleasure lake racer boats do not need the spike reducer. I think the Grimes valve will cost $500 plus dollars.

Charlie;

My boat is at Kevins if you want to see the fix. Craig makes a custom "T" thats in the line between the cooler and the crossover. The "T" leads to a flow control valve that is adjustable...water dumps all the time. Pressure is 1-2 at idle and I have it set for 18 at 100+. Oh, and I run a thermostat also. Craig also has a fix for the "spikes" before the strainer...which I havn't put on yet. The whole thing is a cheap fix and it works.

The valves were around $500.00 each. :eek: I got sick of chasing the pressure problem and wanted a guaranteed fix so I bought them.

Wett Vette had a bunch of pictures posted in May of his system. It works on the same theory. I just wasn't sure it would flow enough water and was sick of this problem.

The Grimes valve is nothing more than a 1 1/4 stainless sleeve inside the valve that a piston rides in. The sleeve has two large ports cut into the sides. As pressure builds the piston is moved further down the sleeve exposing more of the ports. The ports can flow more than a 1 1/4" hose so there is no restriction there. The water then flows through the transom on to the top of the bravo. My water pressure will go to 24 lbs. and stop. My oil temp tops out at 220 on a 45 wot pass with this system. It would go to 240 before and I would back out. This system allows more water to go through the coolers without having to pass through the engines. I don't have Gary’s number here. I'll post it tomorrow.
Dan

Candyman, that sounds like an interesting valve. I was wondering if it was possible for contamination to cause the valve to stick open after a pressure spike and then the water pressure could go to zero or at least very low? Just curious if it is a "fail safe" solution.

WETTE VETTE,
I'm sure a large particle could hold the valve open. I don't think it could be held open enough to get zero water pressure. The rush of water I think will keep the valve clean and free of debris. It is a very simple design. I should have taken some pictures before installing it.
Dan

Jdnca1 and Wette Vette,
I have the same flow control valve Wette Vette suggested and have installed it after the stock Mercruiser oil cooler and before the Stainless Marine crossover. I use a custom fabricated Tee for the valve installation. It dumps over board.
My crossover has a bypass that goes to the T-stat housing.
What T-stat are you running and how many holes and what size holes are in it ,if any?
Does your crossover have a bypass?
I have been concerned about having enough flow to my exhaust while the T-stat is closed, therefore I use the bypass to address that concern.
I have experimented with a 1/8" orifice in the bypass all the way up to a 3/8" orifice, increasing at 1/16" steps. The bypass orifice is a 1/2" pipe plug shoved up in the rubber hose of the bypass.

The T-sat I was using for my testing is a 142 degree high flow T-stat purchased from CP Performance. It has two holes drilled in it that are .135" in diameter. I think it needs to have those holes enlarged to 3/16" and maybe two more of the same 3/16" size drilled in there also ( 4 total).
I was having over pressure problems with the setup. Had the flow control valve all the way open, T-stat installed (2 holes) and using a 1/4" orifice in the bypass. Temp was good.
I went to the 3/8" orifice and the pressure came down but the engine would overheat. I think due the water taking the "path of least resistance" which would be thru the bypass. Water was basically stalled in the motor. I backed down to a 5/16" bypass orifice but the engine would still overheat but not as fast.
My engine is a stroked 496" Gen IV (454), B&M 250, intercooled (Superchiller), witha single 1050 Dominator. Everyone I have spoke with tells me that nobody uses T-Stats in Blower applications. I now am setup with the bypass plugged off and a 5/8" restricter ( no T-stat) and no water pressure problems, but no temp( maybe 130 degrees).
Looking for suggestions and what you guys are running.
Thanks for any replies, Russ Withiam

To avoid confusion,
"The bypass orifice is a 1/2" pipe plug with a hole drilled thru it (1/8"- 3/8" diameter), shoved up inside the 3/4" rubber hose of the bypass".

Merlin540,

BW and I run relief valves on our Daytonas. He put his tee between the strainer and oil cooler and dumps out the back. I have seen him run 30 - 35 PSI. I have my tee inserted right after the sea pump and I run ~ 20 PSI and dump out the side. Both of us run oil thermostats and the relief valves are adjustable by turning a screw. We got the valves from Grainger.

One of the problems I noticed is the sea strainers are leaking after a complete cleaning and new gaskets. The sea strainer is the first thing to get the water. How does the spike eliminator work?

RLW, we are running stock 142 degree thermostats with crossovers that have a bypass. I would run the stock thermostat and get rid of the bypass restriction to keep your exhaust cool. If pressure is an issue you may need a 3/4" flow control. I made 50 of the custom tees you speak of out of stainless steel to go into the 11/4" hose and they have a 1/2" NPT outlet port that is plumbed to the flow control, if anyone is interested. You would only want to restrict your bypass if your pressure is to low.

Gary Grimes
 

770-475-5272
I have one also, works flawless

Merc relief valves
 

Merc now offers relief valves. I put them in. My water pressure gauges were pegged out at 35 psi. My hoses were ready to blow. I now run 20 to 25 psi max. They are $114. each. I'll give you the part # if you need it.

stainless marine also offers a strainer with a pressure releif valve in it......use them all the time....a strainer is also a very good thing to run at these speeds,they give you a reserve water supply when your airborne......theyll keep a constant 20 psi on the top and keep you from smokin impellers......20 psi is all you really want to run after that itll blow through headgaskets.....i can also have them custom built .....

offshor,
What motors do you have? I'm glad Merc finally realized they have some pressure issues. How many circulating pumps did you go through? Could you post the part Number?

Thanks,
Dan