540 BBC, Big Cam, 14-71 Blower, Alum Heads, CMI headers

So everything was good until I change prop..My RPM went from 5000 to 6000, boat was running like a champ! (BUT) Breathers are foaming at the mouth! WTF?? Complete engine has less than 20 hrs on it. Compression check is good. Header had a small leak..sent and repaired. Pressurize block..not good, can't hold more than 5 mins. Replace intake gaskets..re-pressurize..alot better but still had a small leak. Replace Head gaskets and intakes again.and take out..1st day..mild on the throttle (under 5000 RPM) all is good. 2nd day..WOT on/off all day..foaming out the breathers again. Figure to much intake pressure, put relief valve and water pressure gauge..at @ 110 MPH pressures @ 20 PSI. Pull intake off again..gaskets look good no leakage noticed @ water ports.

Trying to make Havasu but these oil changes are killing me!! 12qt pan..take in about 1/4 qt water every outing.

What's my next move?? Send heads out and get pressurized??

PS. I have bypassed my oil cooler to rule that out and to build oil temp to evap water..No change.

Thanks in advance!

Check to make sure that one or more of your intake bolts isn't to long allowing the intake to lift just enough to pass water at speed. When you removed the heads did you check them to make sure that they were flat? If neither of these are the problem I would have the heads pressure tested. One more possibility would be a crack in one cylinder wall that opens up when the engine gets warm but I kinda doubt that is the problem. Good luck, Rob

Thanks..yea, I have never had a problem with the motor getting hot..or even warm..with the cooler I run temps @ 140 for water and oil. I by-passed the Oil cooler to try and help get rid of some of the residual condensation and am lucky to get 180. Oh, and all bolts are ARP and perfect size.

what are your camshaft specs?

One thing I tried to do to see if I could psi test the motor dry.. The intake gaskets would leak air but not water when I ran the motor.
I tired to block off the intake and psi test the block and heads. Hard to do without a wedge shaped device to compensate for the intake bolts being on an angle. Any way, the idea was to seal of the heads at the intake flange and put pressure to the block. I ended up putting some metal plates with rubber gaskets over the water passages and bolt the intake back down to hold them. I never did get a good seal, so the test wasnt very valid. But in your case if you could make plate that would allow you to clamp a gasket to the intake flange of the head. It might help locate where the water is coming from..
Although the first day at below 5krpm.. seems things were ok. Then WOT and water intrusion.
Has to be getting in somewhere. Are you sure it was only 20psi at WOT?? Can you trust your gage is what I am saying. Any spikes when you bump off a wave and reenter?? How about running a bypass valve on the water to the block.. Say a ball valve to bleed off some of the water, then go WOT and see if it stays dry.. That would tell you if you had a leak due to high pressure, instead of a leak due to heat..

Trying to think out loud.. Hope you find it.. It took me five weeks to find out the intake gaskets wont hold dry air.. and about 6 sets of gaskets experimenting.. Good luck, dont get frustrated!!

Dick

Dick..I like the thinking out loud..It's hard for me to believe I have a crack in the heads or the block and am thinking intake myself. That's why I went with the relief valve and gauge. It bounces..but 20 is what I'm seeing..The thing is..this boat has seen several motors and has never had a leak before..or had a relief valve on it..why now??

I'm still trying to get the build sheet but have not seen it yet..all I know is it is a Teague Cam.

but my guess is 306° Intake / 318° Exhaust

Duration @ .050'' Lift: 244° Intake / 256° Exhaust

Gross Valve Lift: .632 Intake / .632 Exhaust

Lobe Separation Angle: 114°

i was thinking reversion,then i reread your post and noticed you have headers,so it must be something else.i had a similar deal one time,it was pushing water past the head gasgets,as dick recomended,put a ball valve&dump some water overboard,less water pressure,hope that works.do you get the water from the drive or a seperate pickup?

Yes, I have installed a relief valve..I think I will re-torque Head gaskets even though the are MLS gaskets..and really seal those Intake Gaskets and try running min. intake pressures. If it comes back.. I will send the heads off to have them checked..if that comes back OK..I guess the motor has to come out

What heads are you running? I had a blown 540 that I chased a water in oil problem for weeks and it ended up being a porosity problem in the head casting. The leak would not show up under normal pressure when we tested them so after installing them again with new gaskets we removed them and increased the pressure dramatically and warmed the heads and finally found the problem. The heads were new and the manufacturer went good on them. Just another thought for you. Another thing I have seen on a problem like this is the part of the head gasket at the front and rear of the block where the intake seals to the block in some instances protrudes past the block and keeps the intake from sealing correctly. Only seen this with cometic head gaskets and it kept the intake from sitting correctly. What kind of boost pressure are you getting? You must be getting more boost at 6000 than at 5000 and this might be lifting the heads or if they aren't flat the extra boost might be just enough to get them leaking. Just some more thoughts for you. Rob