1BIGJIM

Back to the basics. This problem should be easy to find if you have that much water. This is no hairline crack somewhere if you are filling cylinders up. First question, Are they the same cylinders each time? Did you take the center risers off and look for sign of water leaking down? If you are getting water in the cylinders you are getting water in the oil

Dirthead

When I said that I was not getting water in the oil was while the engine was running. After the engine overheated, got turned off, then you could hear the cylinders girgling and filling up with water, THEN yes you would have water in the oil after some time because it would leak down past the rings. But as far as driving the boat and checking the oil for water, there would be none. I have magnifluxed the heads and all look ok. I have sealed off one of the manifolds with a block off plate an pressured to 8 PSI and do not have any leak down. I am about ready to try the other exaust manifold now.

mcollinstn

***uming the heads are good (via your magnaflux test)
And the cylinder liners aren't cracked
And the headgaskets aren't leaking (you said they weren't)

Then you can only be getting water in the cylinders from the exhaust side or the intake side.

Cracked, or leaking exhaust manifolds should not cause overheating.
A leak in the intake water crossover can cause overheating.
The incorrect headgaskets (or the correct headgaskets put on "backwards") can cause overheating.
Incorrect coolant hose routing can cause overheating.
Weak springs in the popoff balls on the t stat housing can cause overheating.
An automotive thermostat (no air bleed hole) can cause overheating.


1) Pull the water hose from the t stat housing that comes from the oil cooler. With the outdrive in the water (not on muffs) fire it up and rev it to 2500 for a short spell. You should see an impressive flow of water. This will rule out any weirdness from the outdrive pickups, through the raw pump, and thru the cooler. Not safe to ***ume there's no problem there. Much better to witness the stream of water..

2) Since you are getting the cylinders full of water, there is either a crack in something OR you are overpressuring the block. Since all cylinders are filling up, my guess is a crack or bad gasket seal in the exhaust risers.

But that isn't causing the overheating UNLESS the exhausts are packed full of crap and are restricting the flow of water out of the motor,

best of luck

Bilgerat

Load that turkey up and let me fix it for you, i see a few opinions that are possibilities, however if you did a leak down you should have been able to draw a decent conclusion of where your leak down was going, it can only go so many places, too much disassembly not enough figure out was used in your search for a repair.

Gary Anderson

I'm guessing the overheat is due to a collapsing water line (before the pump) if there are no obvious restrictions. As Scott pointed out, the wrong line will collapse but the correct ones deteriorate too. I've seen normal appearing external lines with delaminated collapsing innards. BTW, they usually idle fine but only collapse/overheat at high rpm.
As for the water, was it in all the cylinders? That's acually hard to do! Overheats can easily cause failed head gaskets. Leakdown would be my first test.
Gary

1BIGJIM

Since both banks of cylinders are filling up with water I would have a hard time believing two head gaskets or two exhaust risers go bad at the same time. The overheating has to be related to water coming back into the cylinders. Gut feeling is, there has to be a restriction causing the water to NOT circulate causing it to overheat. The water must exit somewhere coming back into the exhaust. What are the chances something is causing it to backup in the Y pipe of the exhaust, forcing the water backup through the exhaust risers? Ok how about this you have one flapper in your Y pipe that is sticking. This could cause one exhaust manifold to fill with water. Water would then go thru the exhaust cross over in the intake manifold to the other set of cylinders. Far fetched?
I am land locked in Omaha . I also have a complete set of exhaust risers if you feel you need to replace them.
JIM

Dirthead

Everyone, thanks for the suggestions and please, keep them coming.

To Jim, I also thought that the flappers could be the problem, wither they were sticking open and allowing water to be sucked back into the engine after it got how and thus filling the cylinders... OR the flappers might be stuck shut and not allowing the exhaust water out thus causing a restriction. Because of these two possible scenarios, I replaced the flappers with a new style (the old flappers looked just fine and opened and closed freely) and the problem still exists.

Good idea though!!!

blue thunder

I'm pretty much with Gary. I would add the transfer tube in the outdrive should be looked at for twisting, collapse or clogs. See pic. I suspect the water is coming from the engines backspinning due to preignition when they are shut down in over heat mode. Eccentially your exhaust valves turning into intake valves for a 1/ to a 1/2 revolution. That is why you are able to clear the water and go again with no apparent issues, until whatever the root problem is recurrs. The only concerning thing to me if my scenario is true would be the quenching the exhaust valves are getting when they suck water back in. May make them brittle and untimately shatter at a most inopportune time.

BT

Dirthead

Blue Thunder,

On the pic you provided, I would like to check that hose inlet that you are pointing at. Can I simply take the 6 bolts (I think that is all it looks like there are) that are holding the drive unit to the housing, and pull the drive (if this is what I am to call it) out? I mean, is there any special way to disassemble or reassemble this or is it something a qualified tech should do? Mechanical handiness is not the issue, I just do not want to remove something that will cause more problems down the road.

One question I have always asked the marinas is that is seams to me that the first place I would look for a problem would be an obstruction in the Bravo 1 drive, where the water intake is. The first marina replaced the bellows boot, but since then, I do not see or recall where the other repair facilities have looked at anything in this area other than maybe a visual check. Where is the water inlet on the bravo 1? What should I look to check for obstructions? By removing the drive unit, will I b able to see the problems/ obstructions that might be there or could they be hidden in other areas in the drive that one can not easily access?

Thanks again for all the advise!!!

blue thunder

If you are handy I would definatly remove the drive and inspect this hose. While the drive is off you could also grease the ujoints, check the gimbal bearing and check engine alignment. As long as the engine alignment is ok, the only trick to removing.installing the drive is the shifter cable, shown on the right of my pic. I put my shifter in nuetral, remove the nuts and slide the drive back watching to make sure the clasp unhooks on that ball on the end of the shifter cable. Once it is clear the drive should come off easily. Of course you will have already removed the trim cylinder mounting bolts before doing the above. Reinstall in reverse order. Install new orings.

These are all things you need to learn how to do anyway. But if you don't want to do these now, remove the intake water hose from the transom inlet. Get a garden hose and shove it down the hose. Turn the water on. Start the engine and making sure water is flowing into the hose, see if you still have an overheating problem. It you do, the drive is eliminated as the problem. If the problem goes away, remeove the drive and start there. The water pickup point on the bravo drive is a series of holes at the leading endge of the housing on the left and right sides.

BT