high water pressure
 

Just got engines back from being rebuilt, kept all stock, replaced Gils with KE headers, water pressure at idle about 7 , at 3500 rpm and up the needles get pegged at over 35 psi, some water leaking out of hose as if under high pressure, help what should I check for, HP500s carbed, normal water and oil temps.

if everything was the same then it's probably
 

the header restricting water flow out

I will try to figure out some way to check headers for restrictions. Could some thing be hooked up wrong, maybe wrong gasket? This occured on dyno also. The boat is an Outelimits and when doing a search someone mentioned OL putting pressure relief valves in- could they have left it off, where would I look?

jeffg
What kind of pressure did you have before the rebuild? To check the headers for the restriction you need to make up some tees and install them in the two water hoses that go to each header. I used the plastic tees that are used in underground sprinkling systems. Off of the tee install a gate valve and then some rubber hose running over the transom. While running have some one open up the gate valves at 3500 rpm. Try to open each equally until you have reduced the pressure to 20lbs. If you open both valves fully and the pressure won't drop then that rules out the headers.

Did you install a water crossover to replace the circulating pump? That has been known to cause pressure problems also.
Dan

You'll be needing some type of a dump valve. There are several threads on this in the tech section. I used a 3/4" valve and it's not bleeding off nearly enough pressure. My dealer has a propritary dump valve that uses a 1-1/2" port. That's my next step.

BTW-your engine might survive at 30psi, but it won't at 35. Don't run it up there or you'll be reparing it.

Is 33 at wot too much?
 

Just curious, never had a water pressure gauge before.
Stock power, was out last night it gets close to the
max on the gauge. Thanks JC

If the correct type of valve is used 3/4" is more than enough to lower the pressure. There are several guys using the dump valve system I came up with with great success and some of them were seeing 40 plus PSI. 30 PSI is ok but still overkill. Shoot for 18 to 22 psi at WOT. Send me a PM if you can't get it figured out.
Craig

Wet-I have your system on my boat. By 60mph I'm seeing 35psi! However, I do have an unusual application that is probably the cause for the high pressure. It seems to work well, but is simply overwhelmed in situation.

Cord,
What valve are you using and is it overwhelmed while being all the way open? Are you running an offshore style pick up or through the drive? Is the dump on the inlet or outlet side of the seawater pump? On most boat the 1/2" valve is adequate to relieve 10 to 15 PSI at WOT. Sounds to me like you may need the inlet and pressure side system. I would hate to see you have to use a huge 11/2" valve if it isn't necessary and will not eliminate spikes. If you have a lot of ram on the inlet side you may need to dump some water there at 5 PSI through a 1/2" check then the 3/4" valve will keep up. Just a thought. I run the 5 PSI inlet check on my inlet just to eliminate spikes before the sea strainer. Then I run a small 1/2" valve on the pressure side to dial in my max pressure.
Later,
Craig

It's the 3/4" McMaster-Carr valve. It's installed after the pump, before the oil cooler. The pickup is in the drive and is a single 3/8" hole. I have a crossover and have flow restictors that control the waterflow through the engine. I believe the water pressure is comming from a combination of the crossover and the flow restrictors. I'll be adding a transom pickup this weekend, so we'll see how much control I have over the water pressure.

What is this 5psi check?

Going to the thru transom mounted pick up is likely to further raise your water pressure. On my drive the water enters into a 5/8" hole, which really creates a lot of ram. I am a thermostat fan rather than the flow restrictors. That could very well be where part of your problem lies along with the McMaster Carr valve. The valve and tee I use likely has more flow capacity than the McMaster valve. Does your crossover have a bypass? If it does then my tee and valve system will fix your pressure problem as well as allow you to run a thermostat to maintain consistent temps whether idleing or running WOT. I have a couple of valves and tees left and if you are still having problems after your new pick up I will ship a set for you to try and if it works you can pay me, if not send it back. The check valves I have are preset at 5 PSI cracking pressures and tee into the inlet line before your strainer or sea water pump and dump water once inlet ram hits 5 PSi. The check limits the inlet pressure and stops spikes before they even get to youe sea water pump. Stainless Marine has a similar setup on their sea strainers. Good luck and PM me if you want to take me up on my offer.
Craig

I'll be in touch. The first thing is to get this back up and running. The transom pickup is being added because, even the low water pickup isn't low enough. I'm sucking air, buring up the pump and thus cooking the motor. Hopefully, the new pickup will induce some reliability.

Re: Is 33 at wot too much?
 

The 496 has a closed cooling system. I would guess your pressure is tapped off of a water line after the sea water pump. Since the engine cooling system is isolated from the Sea Water side the engine doesn’t see the high pressure. The coolers can take more pressure than the engine. If this is the case you will be fine. Let us know where Fountain is taking the pressure reading.
Dan

Duh, I should have known that
 

Thanks candyman, I'm concerned about nothing.
I'll check anyway to see where they tapped it. JC

The 496's are tapped @ the pump. Merc. has a low press. alarm, part of its guardian package if your's is connected. It includes drive oil resevoir, start-up squeal, etc. (mine stuff is in a bag where it belongs).

Wette;
How do I get information on your bleed off system?

Tantrum or anyone else interested just send me a PM with your phone number and I will call you to discuss your application.
Craig

Hooked garden hose up to headers and they flowed great (took sparkplugs out to be safe), will try "t" and valve tomorrow as its fathers day and wife can't say no to helping me.

HIGH PSI
 

Fresh water cooled, normal water pressures before rebuilds, did the "T" s with valves before headers, opened full and pressure dosen't drop, 2500 rpm 35 psi, 3000 rpm 45 psi approx, did this test with boat on plane and with boat in neutral to eliminate ram effect, any suggestions?

jeffg,
That eliminates the headers as the problem. What changed? Did you install a cross over to replace the circulating pump? Could there be a wrong gasket being used? Maybe some water passage is blocked. Are you reading the pressure at the same point you used to? Where are you tapping off for the pressure gauge? If it's not the headers then something had to change. It would be better to fix the problem than just install a dump like I did. My problem came from the factory. I still have no idea why my stock 454 mags had high pressure. I think that's one of the reasons Merc is going to closed cooling systems. Let us know.
Hope it can get figured out soon.
Dan

Thanks Candyman, no crossover, water switches same location, nothing else changed, now the water pump gasket is leaking, also its both engines so I don't think the the gauges are wrong, plus dyno guy said water pressure was above 50 psi. ??????? Guess I won't be making Thunderun.

I think I got this licked. Engine guy installed headers, they removed 2 of the 4 outlets for cooling water from on top of the thermastat housing and plugged it. Gils have fittings for 2 supply hoses, KE has 1, solution is to run 2 into a "y" fitting and then into header, hope this helps someone else out.

I hope that takes care of the problem. Who did your engines? Are you the 37' out of Worth?
Dan

Goodwin Competition in Omro WI, I'm downtown.

Hope you make the run this weekend. It's looking like we may get some nice weather. I think Obren's doing his warm weather dance.:p
Dan