I am looking to get water pressure numbers from anyone who has a 95 and up 454 or 502. What is the highest water pressure you have seen from your engine? I am interested in engines with the newer thermostat housings. The thermostat housing has one water inlet from the seawater pump. One exit to the circulating pump and two exits, one to each of the exhaust manifolds. Any input would greatly be appreciated.

Dan

my max pressure is 14 psi. maybe 15 to 16 with new impeller when running. it was the big 0 when it was full of sand. this is on a 99 hp500.

just replaced water impelllers on 98 500hps at idle barely registers, at 2500-3000 approx. 12-15, wot 5200 22-25lbs readings are from gauges mounted in dash. hope it helps.

I have 2000 HP500EFIs: nominal at idle; 15-20 at 3000-4000 RPMs; 25-30 at wot - (trim making a difference on the water pressure at top speeds).

Dredgeking,
Maybe that sand would help me. My 35-lb. gauges are pegged by 4000 rpm. I estimate block pressure around 45-50 lbs. My pressure use to top out at about 35lbs and then fall as low as 8lbs. At that point I would lift and pressure would come right back up. I added the beloved dual water pickup drives over the winter as Jeff Harris suggested, at my expense. He was right. No more air in my system. I'm still waiting for Jeff to return my calls. I did get to speak to Wyatt Fountain. He is more than happy to trade me out of my 97 and into a 02. He sounded confused when I told him I had a deal worked out on a new boat and was waiting for an answer on the ITS system since the begins of December. He said we’d love to build you a boat with the ITS. He informed me that the ITS doesn’t perform very well on Fountains but would still put one on if I desired.

My solution has been to spend a bunch of money on a water dump system. When I step up to larger power it will come in handy. It shouldn’t be necessary for my current application.

I never new I had a problem until this board. My previous 4 boats did not have water pressure gauges. It never occurred to me that Fountain would sell me a boat that didn't perform perfectly. The water pressure going high and then low didn't mean anything to me. I had asked why this happens and was told it was normal. I never put any more thought into it. Then the board! I started lurking back in the board’s infancy. I read a post about high water pressure and gasket failures. A radiator cap is usually between 15-17 lbs. because that is what an automotive engine can take. I average about 70 hours before my circulating pumps start to leak. I have gotten sick of replacing them and have been gambling with just letting them leak some.

I still love my boat. Fountain builds a hell of a boat. The experts sending a boat out with this kind of problem is inexcusable. I am very uncertain how they propose to handle this matter. Now that I know better I have had a boat for 5 seasons that has never been correct. See what a little knowledge does.

Thanks for the responses and listening to me *****. Hopefully in a few weeks I can get back to important stuff like BOATING!

Dan

Candyman,

Consider this, Tee off the sea pump outlet to 1/2" line plumbed to one of those Innovative Marine (www.innovativemarine.net) outdrive coolers. I'm hoping the Tee to my Whipple Intercooler reduces some of that excessive pressure. I plan to plumb the outlet from the intercooler through the transom to the shower.

Also, do you plan on being out on lake MI during the Air and Water Show (I know, it's a long way off)?


Thanks, Mark S.

Breathe Later,
I usually go to all three days of the Air & Water show. Wally had organized a large group for last year’s show but Mother Nature didn't cooperate. I'm sure we'll all try again this year. I did get to watch Back4More doing passes on Friday. There was definitely some hang time going on.

With your intercooler dumping over the side your water pressure should be just about right. I took the plunge and purchased Gary Grimes pressure relief valves. I plumbed a 1 1/4" tee after the coolers and ran the line through the valve and out over the drives. I shouldn't have to do this but Oh Well! I did speak with Boat US and they are very interested in this problem I am having with Mercury marine engines. There has been a lot of circulating pumps dying way too soon on the late model engines.

I will post some pictures of the water dumps when I am finished.

Dan

Dan,

Thanks for your reply. I've not been out on lake MI yet and would appreciate going with a group to show me the ropes, etc.

Where do you like to launch? I've got a 27' with only 61 gals. and I'd probably launch from Winthrop Harbor. By the time I'm by the city, thats probably 1/2 gone. I know there's alot of marinas in the city, but where would be easy to refuel?

Thanks, any info would be appreciated.

Mark