Need to re-power 7.4l efi

[joeyleggz]

Well the fat lady has sung need to re-power one of my motors it's a 1997 7.4 Throttlebody injected motor looking for some advice on what people have done in the situation with these Gen6 motors? Thanks for all the input hopefully a lot of people will chime in


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[Thornton69]

Sounds like at 20 years old, they long paid for themselves. If it were me and I was planning to keep the boat for several years.... Refresh them both with a couple long blocks and enjoy the fresh power.

 

[northern]

How many hours on the engines?

 

[joeyleggz]

Just around 500 hours seems that I was getting a little water reversion as apparently These 7.4 motors had problems with that in the past I do have the water lift muffler setup after pulling apart the motor I mushroom the valve and blew a lot of the seat material on the piston tops Port motor compression ratings were in the high 120s to mid 130s and seems to be OK but I'm scratching my head now on what I should do


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[joeyleggz]

Come on people !!only two comments but 175 views in 12 hrs


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[Adios Dinero]

Sounds like at 20 years old, they long paid for themselves. If it were me and I was planning to keep the boat for several years.... Refresh them both with a couple long blocks and enjoy the fresh power.

Sounds like a good plan! My Express has a bit over 600 hours on the 7.4L MPFI engines. New long blocks would be what I would do.

 

[joeyleggz]

I would expect these motors to last a couple thousand hours being fresh water cooled five or 600 hours is barely broken in very disappointed


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[joeyleggz]

Who has the best reputation for new long blocks? Also who would you recommend for remanufactured long blocks?


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[JBJ]

If the motors are the 310 HP L29 blocks you used to be able to buy new long blocks a year ago. I switched to diesels.

 

[Adios Dinero]

I would expect these motors to last a couple thousand hours being fresh water cooled five or 600 hours is barely broken in very disappointed


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Disappointed would be an understatement! I would be seriously pissed off if I had to repower my Express with those kind of hours. I would think they would go for a few thousand hours with the right maintenance.

 

[Sea Ray Mark]

If the motors are the 310 HP L29 blocks you used to be able to buy new long blocks a year ago. I switched to diesels.

I just replaced one of my L29's last year. It was a reman long block and I paid about $3200 for it.

 

[joeyleggz]

I just replaced one of my L29's last year. It was a reman long block and I paid about $3200 for it.

Who did you use in how's it going so far ?how many hours do you have on it?


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[Scott06]

I got a new partial engine (5.0) from Michigan motorz last year. They were real good to work with as far as customizing their package for my needs, quick ship, and resolved small issues ( missing small parts) very quickly. They also were one of the few that would give a warranty for the home installer vs requiring a certified mechanic to install. Bottom line had zero issues, had a great season on the water and would spend money there again. They als do remans if you want to go that route, but they weren't that much less - maybe $600-700 less on the long block vs new

 

[Jimmy Buoy]

Sorry to hear of your problem. Sure hope my engines last for 2000hrs or more, but I have to admit being more surprised than not each time I return to the marina with the engines still operating well.
I have seen 7.4's with over 3000 original hours, so there may have been some other issue as you've mentioned that caused its early demise. Reversion issues can still cause problems even with water lift mufflers. From what I've read it is the frequency of the exhaust pulsing at idle along with the exhaust elbow missing an important design element called the "hook". Somewhere along the manufacturing years, someone apparently decided to remove the little "hook" that stopped water in the exhaust from working uphill, around the bend in the exhaust elbow and ultimately down where the exhaust valves are located. Water and resulting rust of exhaust valves and valve seats can sure kill your engine. Once you shut the engine off, the water trail settles and does it's damage. That's the theory anyway.
Not sure how to check your exhaust elbows to see if this is the problem, but there are some interesting articles on the web if you plan on using the same engines with the same exhaust elbows...
Best of luck!

 

[joeyleggz]

I got a new partial engine (5.0) from Michigan motorz last year. They were real good to work with as far as customizing their package for my needs, quick ship, and resolved small issues ( missing small parts) very quickly. They also were one of the few that would give a warranty for the home installer vs requiring a certified mechanic to install. Bottom line had zero issues, had a great season on the water and would spend money there again. They als do remans if you want to go that route, but they weren't that much less - maybe $600-700 less on the long block vs new

I heard good things about Michigan motors actually spoke to them a little while ago at length very knowledgable definitely hanging onto his card definitely Will be a key player in my decision-making


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[joeyleggz]

Sorry to hear of your problem. Sure hope my engines last for 2000hrs or more, but I have to admit being more surprised than not each time I return to the marina with the engines still operating well.
I have seen 7.4's with over 3000 original hours, so there may have been some other issue as you've mentioned that caused its early demise. Reversion issues can still cause problems even with water lift mufflers. From what I've read it is the frequency of the exhaust pulsing at idle along with the exhaust elbow missing an important design element called the "hook". Somewhere along the manufacturing years, someone apparently decided to remove the little "hook" that stopped water in the exhaust from working uphill, around the bend in the exhaust elbow and ultimately down where the exhaust valves are located. Water and resulting rust of exhaust valves and valve seats can sure kill your engine. Once you shut the engine off, the water trail settles and does it's damage. That's the theory anyway.
Not sure how to check your exhaust elbows to see if this is the problem, but there are some interesting articles on the web if you plan on using the same engines with the same exhaust elbows...
Best of luck!

Thanks for the reply in a tough spot right now trying to figure out what's the best way to approach this ultimately it would be best to change both motors might be cost prohibitive for me at this point .the other motor did test out good but then again I believe last season my starboard motor appeared be good also .......priced out 8.1 crate motors I would be looking at the first cousin of $50,000 installed don't really think that's a smart move


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[BurgundyS24]

I also repowered with Michigan motorz


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[Gary B]

We had a 400EC with 7.4 horizons and had to replace the blocks. The marina used Jasper rebuilt or remanufactured (can not recall) long blocks. We through two replacement blocks on the same side in one season. Luckily we had an extended warranty that covered a good portion of the repairs. In the end, we repowered the boat with 8.1's.
Good luck with your repair. The 370EC is a great boat.

 

[KHE]

Why not repair the existing engine(s)?

 

[Sea Ray Mark]

Bought the engine from a local shop that gets them from the rebuilder so I don't remember the name of the company that actually built the engine. Only have about 10 hrs so far but all is well. I think if I was going to keep the boat for long time and put a lot of hours on it I may have gone in the direction of new instead of rebuilt. If not that I would have spent the extra money to have a trusted local shop rebuild the original engines so you have more control over what gets replaced and what gets reused. Good luck with whatever you decide.Mark