blown head gasket

[JB3]

My 96 ps190 blew a head gasket and as you can tell by the photos, didn't leave the motor in good shape. This is a std TBI350, non vortec motor. The exhaust valve burned and also the top of the piston on one side. I cannot tell if the cylinder walls are scratched or if it is above surface material. Cylinders #4 & 6 both have the same damage. The rest of the cylinders have 150psi. I would like to get a few opinions, should I repair the damaged cylinders, put in two new piston/rings and repair the valves? Buy a new long block ? upgrade to a newer vortec engine with more horsepower? The boat is primarily used for slalom course skiing, with the occasional friends/family outing.
The other head gasket was getting a lot of blow by and looks like it may have blown any moment. This was in the same location as the one that did blow, between the two center clyinders. Some history on the boat, had about 1100 hrs on it and was rebuilt due to the oil drain line developing a leak. I bought the boat after the rebuild was done. It ran great all last summer, then started running rich. I didn't think much about it until the gasket blew. We were about 5 miles from the dock when this happened, the motor still ran so we limped it back to the dock. Probably wasn't the best move, but we did it any way. The head gaskets were Felpro and not sure if they were marine grade.
Can you help with what direction to go ?

[erkoehler]

Your going to want to talk with JimN or Engine Nut. Sorry to hear about the engine, but hey.....you could always drop in an MCX.

Bump. 11 characters...

[east tx skier]

I hate it for you. Sorry to hear about your troubles. Were it me, I'd weigh the cost to rebuild/repair versus one of those nice mpi GT40s that always grab my attention in the skidim catalog. Anyone know if there would be clearance issues dropping one of those in?

[JimN]

An MCX will cost a lot more than a long or short block, or just repairing this one.

A piston head is cheap, so is a valve. Speaking of valves, that one looks like it broke, not burned, at least on my monitor. When they burn, usually the burn starts near the outer circumference of the cylinder and wears toward the center, but it'll be easier to tell once it's removed. You should have noticed that it idled badly (lumpy) and bogged a bit on acceleration once the valve started to go. Also, if you had problems with two adjacent cylinders, those plugs should have looked like crap when they were checked. This motor should run very smoothly when there's nothing wrong with it. Andy issues like these would be noticeable.

I don't know if you plan to tear it down yourself or if you have a friend who will do it, but it's not the worst job, it just needs to be reassembled correctly. It'll need a full marine gasket set (Fel Pro are fine) and the block would need the deck flattened, cylinder (s) honed (for the low cost/cylinder, do them all) and a new piston head and maybe a new set of rings (they're cheap too, and the pistons all need to be removed to flatten the deck and hone). Maybe have it magnafluxed first to see if there are any cracks- this will determine whether you need to repair or replace it. The head will need to be milled flat and if you do one, you should probably do the other, too. That way, if they had been milled before and only one has had ~.007 removed (the range where compression is affected), the compression won't be as consistant.

Ultimately, it's your call, but you may save money by rebuilding. However, you get a warranty with a rebuilt or reman. Another way is to go with a GM Performance Parts crate motor. They offer a good warranty and it's a totally new motor and it can go to any GM dealer for service. The one caution is that car/truck dealers may not have the marine cartridge for their diagnostic equipment and if you go with anything other than the original setup, you'll need a recal.

I would call the place that rebuilt it last year. It shouldn't have blown up. Was gasket sealant put on the heads and intake manifold mating surfaces? If it was, that's the reason it went away. The gaskets have a sealant on them that softens with heat and when the motor gets hot (or too hot, like when there's a restriction in the raw water flow from weeds clogging the oil cooler), the sealant flows and can be blown out by the in-cylinder pressure. I worked on a Nautique (mentioned in another thread) that had this done and it needed a total tear down.

[JB3]

Thanks for the advice. I agree with you that the valve looks broke, but hard to tell. The boat was running great, then started losing power all at once. The gaskets did not have sealant put on them.
If we rebuild this motor, I will do it myself, minus the millwork. I raced moto-x for ten years and did all my own work and have built a camaro motor once. I am very mechanically inclined and have resources to most any tool needed.
You mentioned a GM crate motor, are they marine? Where would I look for them?

[MYMC]

Best bang for the buck is to use a rebuilder like Jasper and turn your engine in for the core exchange. As long as there are no visable cracks on the outside they will give you full value. Jasper and others have great warranties now a days and some even cover the cost to remove the engine from the boat!

To rebuild this the right way will run $3000 minimum not to mention the value of your time. Using a rebuilder you could be back on the water this week.

[SKI*MC]

WOW! 3 k just to rebuild. I think the MCX is around 3k, new engine. GM Vortec marenized by Indmar. Heres a link for that engine.

http://www.indmar.com/engines/engine...ame=mas_57_MCX

Edit: I just looked up the price for an MCX engine, it was $2,355. it was in a boat, so I don't know if the price will change if all you were buying was the engine.

[JB3]

Where did you find the MCX price? I clicked on the link, but just took me to indmar?

[MYMC]

A 5.7ltr long block from Indmar is $9090 (MSRP plus truck freight), at MYMC discounted price it is still $7150. The "option" price on a new boat is not a very good representation of the "part" price.

WOW! 3 k just to rebuild

When it comes to machine work you get what you pay for... I guess it could be done for less...but that would depend on what your goals/standards are. Mine would cost $3000 if I were doing it for myself.