I really don't know that much about ski boats, but I'm sure eleven skiers is a lot.

Personally, I'd still be inclined to perform a bottom end rebuild even with 420 hours. Intake and heads are already off, and a few ancillary items removed it would be almost ready to pull. Are they difficult to separate from the leg?




Terry

 

15 idle is not that bad. The 40 at WOT could be better. How many rpms does it spin at WOT? Pressure is not bad enough to make a higher grade mandatory but it's not a bad idea. At this point you may just look for a trend for as long as the oil stays clean. If pressure holds up, I would leave it alone. Generally you will see a much larger difference in pressure from cold to hot as the clearances open up.

 

His is direct drive so there's no leg. Just a 2 speed trans. At this point unless you have your heart set on stroking it to 383, I'd pull it since your half way there and replace the mains and possibly oil pump.

Differences between marine and auto are generally cam's. From what I understand intake mani's and heads are different too. Things like water pumps will bolt right up, but will not last due to sediment in lake water.

as for oil, my 5.0L Volvo (gm) specs straight 30W full syn.

 

11 is a shit load.

I fully plan on a rebuild, i just need/hope it gets thru the summer. then ill tear it down and do a fresh build (want to help, ive seen your work)

 

full throttle im spinning 4900-5100 depending on water and passengers.

 

Thats what im trying to avoid with the holiday weekend

I have NOTHING against pulling it and rebuilding it. I just want to find whats causing this stupid water issue. Its driving me nuts.

Heads on the motor are typical Vortec heads. The water pump is completely different than auto water pumps. You can see it off the crank in this pic. I pretty much have to replace the plastic impeller every other year.

 

That's the impellor housing, is there not a circulation pump too? The top pulley there, is that driving power steering or a circulation pump, I can't tell from the angle.

 

yea, what was i thinking. Its been a long day. You can see the pump in the 1st pic i need sleep!

 

I'm still a little confused.

Just to clarify, the boat does not have a water to water heat exchanger with it's own closed loop cooling system? I don't know much about boats but it's hard to believe it circulates lake water through the water jackets and heads. The exhaust I could understand.

 

Draws it straight up from the lake to the motor, then it finds its way out thru the exhaust. If you look at the first pic the hose on the left goes to the bottom of the boat where it draws the water in. It goes up to the pump(the hose on the right), where it then goes over and to the water pump. from there it circulates thru the motor then its final exit is thru the exhaust manifolds and out the exhaust (thermostat regulates the block temp and expels into the mani)

 

boats typically draw cooling water from the lake, closed loop cooling is more exotic and often reserved for salt water applications. This is why it's very bad to start a boat out of water without muffs and a garden hose. The impellors are rubber and will burn out in a few seconds without water. The impellors are rubber because when at speed the flow of water over the intake is sufficient to cool the motor, so the blades literally fold out of the way and allow for free flow, when hull speed is lower the blades will draw up water to feed the circulation pump.

 

Very interesting. Thanks for the info!

 

Were you able to get her back on the water for the long weekend? I found a rock with my prop yesterday

 

Well after replacing the head gaskets, riser gaskets and intake gaskets, i put it in the water and it ran great Friday and Saturday, THEN Saturday night it started taking on water again. Im beyond irritated. Motor will be pulled by me sometime this week for a full rebuild Im going to start out by having the head on the side we continue to have a problem with fluxed and looked for a crack. If that comes out fine the block will under go the same procedure. Im hoping its a head problem.

Now i need to start sourcing engine parts. Looks like Jegs may be good friends with me for a little bit here unless someone can recommend someplace better?

 

Bummer. Something you can have straightened or you need a new one?

 

I guess that's a lose-win? What's your plans for the build? Small over bore and heads?

I could have it repaired, but it would be damn near the cost of a new one. I already pulled the trigger on a new one from Iboats, they had them 25% off, and I was able to pick up some other odds and ends that have been sitting in my cart for awhile. I went down 2'' of pitch and up to 4 blades from 3 so hopefully I'll get to plane faster with load and not loose much top end.

 

Im going to go .030 over and turn it into a 383 stroker with a new crank, rods and pistons . Im planing on some nice roller rockers too.

 

Sorry to hear it didn't work. You can always start small with the intake manifold and work your way down, starting with the heads.

I don't want to sound ignorant but my memory is real vague. I remember reading an article one time on someone that had the exact same issue as you. They could not stop the water even after having the heads and block magnafluxed. It turned out to be a pipe plug in one of the heads that only the marine engines have. This was a Chevy based engine. I know it's a long shot but if you can spot any pipe plugs under the valvecovers it may be a good place to start before pulling the engine.

Do you plan on keeping the same cam and untouched heads with the stroker bottom and building a torque monster or are you going to open it up a little to support the new displacement?

 

Yea, im going to start of with the heads (not sure what or where to start with the IM) the same head gasket keeps blowing in the same spot on the starboard side (drivers side on a boat) between cyl 4 and 6.
I will look to see what i can see and see if i can see these plugs?

As for the cam, i would like to upgrade. I need to find out what the actual spec is on the cam thats in it. I have asked Indmar (the company that makes the motor for my boat) a few times but they wont tell me the actual specs on it. I would like to open it up a little. Any more HP that can be gained easily i will do.

 

Did not know it was blowing headgaskets. Really it comes down to head and block flatness. Get the heads surfaced and/or the block decked. Only other thing is if one of those cylinders if running lean and detonating.

 

It only does it once water gets in the oil. The head was checked once before for being warped. Im not sure if it is. It will be rechecked, along with the block

 

Chances are the water is getting in from the headgasket before it's obvious that it's blown. Does it use a metal gasket or some sort of composite?

 

http://www.jegs.com/i/Fel+Pro/375/17030/10002/-1
Stainless Steel

 

If you change cams you have to be very careful with the lift and duration to ensure there's no overlap between exhaust and intake.

 

i have already looked into cams, and all are marine cams.

 

Well i brought the head to the machine shop. it wasnt warped. There is a crack inside it between the 2 center cyls between the valves.

Time for a (or 2) new heads

 

Glad you found it. Hopefully those are run of the mill SBC heads. If they're standard Vortec you're probably looking at <$100 for the head plus the reconditioning like a valvejob, seats, guides, and seals.

So what are the plans? Even though there's a chance you hurt the bottom end, it may not be a bad idea just to get a good baseline of what the oil pressure is without water in it and trend it to see if it's falling off. Do the cylinders still have the crosshatching?

 

They seem to be. I need to get the head back to see what the casting # is, but im pretty sure its the standard 906 casting vortec head. Im seriously considering 2 reman heads with all new components. I can get them (pair) for about 2 hundred more than a single used head and reconditioning

I would like to put it together and get it running, do a compression test and check the oil pressure. I cant recall if they still have the cross hatching. Ultimately i want to rebuild it this winter regardless if i can wait and get all new bearings and internals. The kids are being a real pain with no water toys.