Repower Options
 

I posted yesterday about my issue with water in the oil. I haven't given up hope just yet but I am considering that its very possible I have a cracked cylinder. In the tradition of bench racing and considering it's winter time so I have a few months to figure out where to go I'll open this topic? If my 96 GenVI 7.4L Mag is toast what are my 'reasonable' cost options?

A) Replace the block and rebuild. Stay 4" stroke or go 4.25". Keep the original heads (assuming they aren't the problem).

B) Replace the shortblock entirely. There are quite a few brand new Dart 540 shortblocks on the market for just over $4k. Will the stock rect port heads and MPI support a 540? What cam?

C) There are a couple of brand new GM NOS Marine 502 Mag long blocks out there for about $7k.

D) My mechanic wants to jump right to the brand new fully dressed 8.1L Vortec. That might bust the budget.

Any other ideas for E), F) and G)?

The boat is a 96 Formula 252LS. Its a heavy boat and I'm not looking for absolute maximum speed but fast cruising and occasional wake boarding are typical. The 7.4L was adequate but why not add HP when the checkbook is on the table?

Not sure I'd let your mechanic do anything. He put 15 gallons of antifreeze into the engine before he noticed a problem.

Engine blocks don't just crack for no reason. Did it freeze hard before you took it in to be winterized???? or did the engine overheat recently????

I would just buy the fresh 502mpi in the swap shop or a low hour stock takeout engine.

There is some nice Ilmor 625hp gently used product out there in the marketplace right now that can be had for the $12-$15k range. Most of the product has around 100 hours freshwater use. Not sure how that fits into the budget or blows it......

Any links to these?

Not that I am aware of. I may be able to get you a phone number if you have a serious interest level.

Call 602-820-0965. Ask for Brett. Cautious on his advertised price. It may or may not be consistent with current market conditions.

I've got a friend selling a 496HO with StageII Whipple reprogram and low temp thermostat. Complete dropin ready to go.

http://www.offshoreonly.com/forums/s...96-mag-ho.html

i have a basically drop in stock 7.4 mpi 225 hours out of a 1998 Ed 419-721-1778

Im with Griff. this is what I did and couldnt be happier.

I posted this on your other thread. You are ready to toss what you have and go with something else with unknown history before you know what is wrong?

Either you are having trouble relaying what was said from the mechanic to you or the mechanic full of BS.

See my latest post on the other thread. I'm not taking anything at face value. I'm taking in all information and processing to figure out what to do. I'm starting to think there is a head gasket and/or crack somewhere. Not sure an external (like oil cooler) is adding up. I will continue to think this thru but I am entertaining the idea of a new motor. Right now the new GM 502/425 is sounding real attractive if a repower is needed.

The main issue I see is leaving the milky oil (water) in the motor for months. If you do decide to use your old motor for a rebuild it will be f__ed by the time you do. An oil change is not going to get it all.
Second I would find out what happened before I would move on. You will kick yourself to find out its a bad manifold or gasket is why you just spent 10 grand.

I already said the water/oil is gone and fresh oil in the crankcase

Was it run with clean out then oil changed 2 more times and even if I bet there is still water in there.
I've been there and have seen where it goes and what it can do.

It usually takes 2 or 3 oil changes to get all the water out and the engine has to be run up to temp.

and the hotter the better (within reason) .....m

From my experience, the first thing to check is the oil cooler. The #2 suspect would be the intake manifold(especially if you're running in salt). Third is a gasket. I'd try to eliminate those before investing big money. I also agree with other posters on multiple oil changes. At least two or three times.