1998 Merc 7.4 MPI won't start

[SDSeville]

Well, it didn't budge with 24 hours of PB Blaster. I do realize it could be the drive. However, I need to make a decision on potentially replacing the motor before I have her pulled out of the water. Here are my choices are so far. What do you all think?

Crate motor - Marina is suggesting a 383 350 HP for about $12,500 installed. 3 year warranty. Marina does all warranty work. I am not sure this will have enough torque for my application and the price is a little steep for me.

Long block - they are suggesting a remanufactured long block from Mercruiser for about $9,000 installed with new Merc risers and exhaust manifolds. I could use Sierra risers and manifolds for about $1,000 less. 2 year warranty. Marina does all warranty work.​

Have mine rebuilt - there is a reputable shop about 20 minutes away that will pick up my motor (removed from the boat and stripped to long block by the Marina) and rebuild it (including heads) with marine parts/gaskets for $2,500. Marina would put rest of the motor back together (including new Sierra risers and manifolds $750) and reinstall in boat. The guy at the marina gave a rough estimate of their work for this option at about $1800. Total $5,050. 2 year 240 hour warranty on rebuild. However shop does not cover labor to get the motor back to them. Risky, but almost 50% cheaper than long block.​

 

[alldodge]

I would not go for the 383, nice motor but IMO not in your app. The 12500 installed is a good price but comes with catalysis exhaust

I would go the rebuild route, the only thought is 2500 is kind of low, where normal is around 3 to 3500. If this includes bore, new pistons, grinding crank shaft, etc. Sure there is always the issue of after its taken apart something is found which needs to be replaced, but the price is a good deal. A 2 year warranty is normal.

 

[scoflaw]

Why would you make a decision before you know exactly what your problem is ?

 

[SDSeville]

Why would you make a decision before you know exactly what your problem is ?

I always think of what-ifs. ...and if the engine does need to come out, I may as well rebuild or replace. I would like the peace of mind knowing it is new. I only have the previous owner's word (no hour meter) that this 20 year old engine only has around 350 hours.

 

[SDSeville]

I would not go for the 383, nice motor but IMO not in your app. The 12500 installed is a good price but comes with catalysis exhaust

I would go the rebuild route, the only thought is 2500 is kind of low, where normal is around 3 to 3500. If this includes bore, new pistons, grinding crank shaft, etc. Sure there is always the issue of after its taken apart something is found which needs to be replaced, but the price is a good deal. A 2 year warranty is normal.

Thanks. The shop did say it includes all that stuff. This is from their website. http://www.mjmengines.com
[FONT=&quot]Every rebuilt engine and re-manufactured engine we build begins with thorough cleaning, inspection and machining of all re-manufacturable castings. All cast iron components are magnaflux to guarantee integrity. Engine blocks are precision bored, decked and diamond honed to the specified RMS. Crankshafts are ground and polished to an 8-12 RMS finish. Valve seats are precision cut to three angles, and heads are resurfaced and vacuum tested. The following components are replaced as part of the manufacturing process:[/FONT]

• New Pistons
• New Rings
• New Timing Components
• New Freeze Plugs
• New Installer Gasket Set
• New Main Bearings
• New Rod Bearings
• New Cam Bearings
• New or Reground Cam Shaft Cam core may apply
• New Hydraulic Lifters
• New Oil Pump
• Remachined Block, Crank Shaft, Connecting Rods and Cylinder Heads

 

[SDSeville]

Does anyone know if this engine has a roller cam or flat tappet?

 

[alldodge]

Does anyone know if this engine has a roller cam or flat tappet?

It has a roller cam.

The 454 MPI is a 454 block with 502 heads on it. I have a Merc reman with slightly over 100 hours on it and it spun a bearing. It's all about how good the machine shop does their job

 

[scoflaw]

On 11/17 you said the motor was cranking over slowly. In the 5 days that have past I'm sure the motor isn't seized up to the point where you can't free it.
​I'm also sure that someone with some mechanical savey could get this sorted out for you
​How did that motor run before the starting issue ? Smooth/quiet ?

Unless your hell bent on spending money, I wouldn't give up on this one yet.

 

[SDSeville]

On 11/17 you said the motor was cranking over slowly. In the 5 days that have past I'm sure the motor isn't seized up to the point where you can't free it.
​I'm also sure that someone with some mechanical savey could get this sorted out for you
​How did that motor run before the starting issue ? Smooth/quiet ?

Unless your hell bent on spending money, I wouldn't give up on this one yet.

It hasn't cranked since 10/18. Ran a little rough but not horrible last time I started it beginning of September. Not sure what else can be done until it is out of the water.

My thought was to have the mechanic at the marina take a closer look at the drive and motor before pulling the motor out. If they find something else that would be great, but once the motor is out, it will be rebuilt.

 

[cableguy1979]

I just had a similar issue and mine turned out to be water in the fuel system... caused rust on the plugs because the injectors were injecting water. I used the Schrader valve and blew out all the water and a seperate tank of gas and it fired right up..... mine turns slow as well its the 454 mag. It first would only make a light clunck but after cleaning all connections it turns slowly but doesn't take half a turn to fire....ise the Schrader valve right in the front on the manifold and make sure its got fresh gas. If you had that much corrosion on your starter and light corrosion on your plugs im betting you had enough water in your boat to make it to the fuel tank. Use that valve to drain as much as possible and get it fresh gas. Dont give up on this until you find out what it is....if you don't have water in the oil and you have compression chances are your problem isnt that big.

 

[SDSeville]

I have a Merc reman with slightly over 100 hours on it and it spun a bearing. It's all about how good the machine shop does their job

Wow, that's too bad. Is it still under warranty?

 

[alldodge]

Wow, that's too bad. Is it still under warranty?

No, was to many years went by. It's in my barn but belongs to my buddy. My point is even getting one from Merc doesn't guarantee it will last. Most of the remans to my understanding are done by the low bidder, not Merc

 

[SDSeville]

OK, so since there is water in the cylinders, this is something I should jump on right away right? Will the water eventually make my block and/or head not suitable for a rebuild?

 

[tpenfield]

Yes, get it done by yesterday

 

[SDSeville]

Yeah, I was hoping to wait until after Christmas to do it, but will get it done ASAP if I am risking further damage.

 

[SDSeville]

Going rebuild option. Marina is going to check the boat out this week and get me an exact estimate for their part in this process. I will hopefully be in dry dock next week.

While I am at it, what are your thoughts on adding closed cooling and a fresh water flush system for exhaust?

Thanks for all the help everyone.

 

[Benny67]

Going rebuild option. Marina is going to check the boat out this week and get me an exact estimate for their part in this process. I will hopefully be in dry dock next week.

While I am at it, what are your thoughts on adding closed cooling and a fresh water flush system for exhaust?

Thanks for all the help everyone.

Just reading quickly through this thread. Is the motor confirmed bad?

It seems that the whole thought process going from a bad starter, checking the distributor ect and THEN making the call that the engine is toast before it has even been pulled from the water is just silly.

Sometimes things are not worst case scenarios...

If possible can you post the conclusion after the guy looks at the boat?

I'd be curious to see exactly how this drama ends...good luck

 

[Benny67]

...as far as "closed cooling" or freshwater cooling, in my opinion it's the only way to go.

Seems to me the only motors that appear to last over 700 hours are not raw water cooled.

 

[SDSeville]

Just reading quickly through this thread. Is the motor confirmed bad?

It seems that the whole thought process going from a bad starter, checking the distributor ect and THEN making the call that the engine is toast before it has even been pulled from the water is just silly.

Sometimes things are not worst case scenarios...

If possible can you post the conclusion after the guy looks at the boat?

I'd be curious to see exactly how this drama ends...good luck

Just spoke with the marina and they confirmed that the there is water in a few cylinders and the engine (or drive) is frozen. Can't tell me any more until it is in dry-dock. Drive will come off 1st (of course) and will be checked prior to removing engine. I will certainly let you all know how this ends.

 

[Benny67]

Just spoke with the marina and they confirmed that the there is water in a few cylinders and the engine (or drive) is frozen. Can't tell me any more until it is in dry-dock. Drive will come off 1st (of course) and will be checked prior to removing engine. I will certainly let you all know how this ends.

Sorry to hear that...again, good luck