challenger454

I posted a few weeks ago about waterpumps (engine circulating), I bought one of out Miami that is aftermarket and was having problems from the get go with the plate on the back of the bump (454 BBC Merc). Water was spraying in little streams. I thought it was a bad gasket seal, tried a few things. Finally cut a new gasket out of FEL-PRO (light-blue) material and used Permatex Hylomar to seal it and torqued it to 15 lbs. I am still having problems with this. Now the boat has a Bravo one and I am not hooking the water to the drives. I have a hose hooked up to a length of hose that would normally attach to drive and I assume it is in line with the raw water pump so the drive is effectively bypassed. I am starting to think that there is too much water pressure in there. THe boat does not have a water pressure gauge so I dont know what I am dealing with. I don't want to start pulling things apart like thermostat housings and such because I dont know enough about this to really give reason to why this is happening. In short I was hoping someone could give some other things that are tell tale about excessive water pressure or something. This weekend I will try running water out of the drive I just didnt think that there would be that much difference. Also is it possible that the hose pressure is more than would actually be present if the boat were normally running in the water. Sorry for the long post but I am a pretty green boater....and need any help I can get. THanks

Kenny

challenger454

sorry for mispelling pump with bump...couldnt edit the post GOd I feel like an Idiot!!!!

Raypanic

I think that merc reccomends like 25 to 30 psi not sure on the exact psi but in that range. If your hose connection is sealed and not leaking I would think your house pressure (40 to 60 psi) is what the hose would bring to the engine. Now the flow has alot to do with it too but most of the psi would be dumped on the exaust circuit. I dont think the lower flow of a garden hose would come close to a bravo drive in the water but who knwos?

I do know this merc sells a water pressure bypass valve kit that bleeds off the spikes. You may want to try this. so try a search for bypass valve you should be able to find it.

challenger454

should I try a new thermostat??? Could this have anything to do with it. ALso I was thinking that maybe the fact that it is an old block (1989) that maybe my water passages are somewhat clogged??? It does flow water out the exhaust though. I also heard about some types of solutions that you can flush thru the engine....not Salt-Away but mild acids or something.

FloridianSon

I hope your problem is not the block and heads rusting but I will say that my old 1993 454 had so much flakeing is was almost hard to believe.had to scrap the heads and the block had become so bad that the cyl.walls gave out.The raw water pump is not rated so to speak as psi but flow.the belt driven pump should put out 7.5 qts in 15 seconds at 1000rpm.I do think that if your block-heads were not flowing it would put a lot of pressure on the circulating pump and the rest should be bypassing and going out the exhaust.If you think it might be rusting out just pull the intake manifold and if it is anything like mine well I will say no more.

candyman35

Are you sure the water is coming from the circulating pump plate? If you are running on a garden hose there will not be a high pressure problem. Check your hoses to make sure they don't have a small hole which is spraying water on the back of the water pump.
Dan