Stuck! Need advice ASAP 7.4 motor knock- need to get home!

mistercomputerman said:
Low oil pressure on one (turned out after the swap to be an anureysm in the external oil filter hose).
On the other one, an ECM wire shorted out on the valve cover while running along in the ocean about 3500 rpm. Sucked up a load of water and bent the inside of the motor. Every wire on each of the new motors is now in a loom.

A good rebuilder with some insurance and a good reputation may be worthwhile if he can find the blocks to rebuild. If you have any doubts, go the Mercruiser dealer route. If something runs off in the ditch during or after the process. you have one throat to choke and that throat is connected to a deep pocketbook.
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Thanks Rick, good advise that I have followed
 
Russ, if there's any extra cost for those two brand new crate motors, just send the bill over to spfortjohn.
 
rondds said:
Russ, if there's any extra cost for those two brand new crate motors, just send the bill over to spfortjohn.
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I am not trying to be a smart A$$ but with all the problems with rebuilds and the limited boating season it just makes more sense to go new and not worry about it. I know it cost more but what does it cost you to be out of the boat for half the season. Put a new one in this side this year and next year the other then you should be good to go for a number of years with no worries. We are about at that point with my dads 10 year old Formula. 10 years in salt and now getting all sorts or gremlins.
 
spfortjohn said:
I am not trying to be a smart A$$ but with all the problems with rebuilds and the limited boating season it just makes more sense to go new and not worry about it. I know it cost more but what does it cost you to be out of the boat for half the season. Put a new one in this side this year and next year the other then you should be good to go for a number of years with no worries. We are about at that point with my dads 10 year old Formula. 10 years in salt and now getting all sorts or gremlins.
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I agree with your basic logic. The two caveats - it's the end of the season up here and where do you find a new Merc replacement? I have all winter to work and pay. Merc does not have them, they are not making new ones.
 
7.4s went out of production in around 2001. The last 8.1 rolled off the line to much bally-hoo maybe a year ago. Where do these outfits like Marine Power and Jasper get their product?

The other thing to consider is that Russ already has a bunch of components that don't necessarily need to be replaced. Heads can be pressure tested and re-worked. Exhaust system components, heat exchanger, alternator, circulator and raw water pumps etc. are all bolt-ons and if they can be recycled, why pay for an entire new motor?
 
Michigan Mortz has Gen 6 for $5400.00 or $5500.00 7.4s have seen as low as $4700.00 in past year some one got molds and is bulding new short blocks.
 
I have a deal for you. Come down here and you can have my 8.1s.

The only catch is you have to help me "liberate" a couple of QSM-11s out of a 480DB that lives across the Bay, so I can drop them in my boat.
 
To "liberate" them you may need to solicit the help of Bobby Bacala, Richie the Arm and Nunzie.
 
Hey Ron,
These guys have been on vacation for a while. I think they're ready for a new adventure!

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I was thinking maybe this guy...
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And this guy...
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this guy too...
P1000863.jpg





DEFINITELY not this guy...
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IF and that's a big (GOD I HOPE NOT) IF, I would not go with Mercs. There are far better, stronger, and lighter out there.
 
dpmulvey said:
IF and that's a big (GOD I HOPE NOT) IF, I would not go with Mercs. There are far better, stronger, and lighter out there.
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David, what do you mean? If you were replacing both motors? You would pick another brand?
Buying a replacement long block or two even is a very different proposition than two complete motors, computers and the necessary hardware to swap to say Crusader or another brand.
 
Russ,

I was wondering if an engine flushing system would be good additional preventive measure? Or would the problem accur on fresh water boat as well?
 
In case I didn't share the plan, as it stands, the marina has ordered a long block from Merc and will assemble it over the winter and drop it in in the spring. Meanwhile they will inspect the exhaust on the starboard side and compression test the motor to take any corrective action needed.
 
Russ
Do you know the source of that longblock coming from Merc? ie: is it something they had leftover, is it rebuilt, or is it a casting they made. Just curious as these things are going to get harder and harder to find as time goes by and more of them fail :.-(
 
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