SRobertson

I know I know... most likely a waterjacket crack from not getting all of the water out before this last winter... but it wasn't that cold??? (Wasatch Front, Northern Utah)

I drained the block (So I thought) unhooked intake, riser and petcocks to the block. Fired it up today and after 10 minutes or so it was trying to vent cream coffee into the intake. Motor is a 98 Indmar 350 with MPI assumed Vortec heads.

Boat is fairly new to me, I have owned it two years and the previous winter I didn't have a problem. Last year i did replace the intake manifold due to an oil leak at the rear, other than that it was good the last summer.

I have resigned myself to a cracked block and in need of a short block... OR... It could be something else that I am not aware of. Seems like a lot of water penetration in a short period of time to just be a water jacket crack. Perhaps a blown seal? I will start digging but any old or young wise guys on hear with an idea it would be greatly appreciated. I did hook up my plunger setup and it was tight to the hull so decent water pressure into the system? Wonder if a week seal let go and allowed pressurized water into the oil somewhere? Ran well when it started but went down hill 10-15 minutes into it.

If you're close and you're right I'll buy you a good bottle of Scotch.

Shane

pind

I know you replaced the intake gaskets last year, but the vortec engines were famous for leaks at the intake ends. It leaks internally, down into the block.

I would pop the intake again, and look for compromised gaskets at the cooling ports. If this is indeed the issue, then when you replace the gaskets, put a small smear of "the right stuff" around the water ports. That fixes it... period.

Other than that, bad head gaskets between the water passage and inside of the head, or perhaps oil return holes. Man, thats tough.

I know for sure that the intake gaskets can flow a LOT of water in a short time though.

Good Luck

Hvytrkmech

Does it have a remote oil filter mount with water cooling? (I moon light at a Searay dealer), If a block cracks due to freezing it usually pops right under the head externally. First thing i would do is what Pind said, pull the intake. Any pitting around any of the ports and its junk. A good machine shop may be able to repair it but usually the pit marks run to deep so the intake may be junk.

SRobertson

Thanks for the info... I have some hope now.

Was the vortec head leak still valid on the ramjet style MPI intakes? I hope so.

No it does not have a remote oil filter or cooler, but I may look at putting one just to make it easier. It does have the standard tranny cooler and then this one has fuel cooler before it is feed into the MPI rail.

This is in an inboard skiboat and from all of the dewatering I could do the only place there would have been water left was low in the block, but the left side petcock was fully open and compressed air put through it last winter with everything undone. Soooo if they typically crack up high that also gives me some hope.

Thanks again, and as soon as I can take the intake off I'll get some pictures posted.

Shane

Hvytrkmech

You have a block drain on each side of the block, and on both exhaust manifolds, most times you have to stick a small screwdriver in the hole to break up the rust that accumulates at the drain. You can use all kinds of air pressure but it won't break through the rust. Has this boat seen salt water at all? Also if you don't add antifreeze to the block after draining it you speed up the internal rusting. I always filled my ski boat, Merc 350 Magnum, with regular antifreeze for the anti corrosion properties, then drained it into the hull then captured it out the port hull plug during its spring commission.

scuzman00

Buddy of mine back in the day, had an Olds 455 jet boat that was notorious for the same problem. We tore her down numerous times, copper coated intake gaskets, reshaved heads you name it but it still produced milkshakes. When it was all said and done, the Indmar jetpack headers were allowing water to get sucked in and mixing water with the oil thru the exhaust... Go figure. It drove us crazy all one summer. Put on new headers and the problem went bye bye.

Grit Dog

Assuming you wintereized it the same last winter as the yr before, it SHOULD be ok. I've never had and engien freeze up and crack (knock on wood now). Have had 2 Indmars. A 'Vette LT-1 and now a MCX 350/350. ALways just drained the water, never added antifreeze.
If it did crack low on the block look at the side with the petcock, not the knock sensor side. The pecocks can get plugged up w/ sediment and not let all the water out. I repalced the petcock with a brass plug and always fish around a little with a coat hangar in the water jacket when winterizing.
What may have happened may not be bad winterization at all.
Did you turn onthe water to the fake a lake for any period of time before starting it? If so you may have filled the engine u with water and filled up the exhaust manifolds enought o get water back into the cylinders.

Hope you didn't crack it.