Repower time for the 370

[xravenx]

I knew this day was coming, I need to repower my 370, starboard motor has water in the oil and some of the cylinders. I pulled the plugs and was able to crank the motor over and water shot out of the cylinders. Sucked the oil out and removed the oil filter, there was alot of water in the oil and filter. Pulled the risers and inspected them and the gaskets aand they looked like they did 3 years ago when I installed them. The experts on the dock yesterday were giving me thier opinions on where the water came from

I woild like your guys opinions on which way to go with this. Engines are RAW water cooled, carbed with 1100 hours. They have been great for the 10 years we have owned the boat. I want to keep this boat so I want to do this right. At the very least I would like to have fuel injection and fresh water cooled motors. What choices do I have, remaned 7.4s, 8.1s (expensive), Crusaders?

After doing a search here, there were lots of replies about buying motors from a third party and have someone install them. I don't want to do that, I want to keep a good relationship with my current marina or start one with a new marina, having some kind of warranty would be nice also. I wouldn't bring a steak to the Outback Steakhouse and ask them to cook it.

Hope to get a few estimates this week.

John

 

[Larry]

I don't see were you think you need a complete repower, just because you got water in the cylinders. Typicly water in the oil will come from an exhaust gasket or iron that has failed, you say your exhausts are only 3 years old, are you sure a gasket didn't fail? I have seen these fail in less time then this (are these exhausts OEM?). If your 100% sure the exhausts are all sound, then I would want to focus on the head and the head gasket, this could be tested with a compression test and or a leak down test, if you don't have equipment I am sure you could have your marina Service dept do this for you, should only be about an hour to two at most. There is just nothing in your original post that says to me you need to repower, if there are any underlying issues with the block or bottom end of the motor, then maybe I would consider a repower. It is also very important that you get the water out of the motor, especially the cylinders, if this stays in there then you are looking at a new motor. Spray the cylinders with lots of WD40 and crank it over a few times, this is VERY important!

 

[xravenx]

Thanks for the reply Larry,

I did pull the plugs and sprayed the cylinders with WD40, the riser gaskets looked great, I changed them anyway and put everything back together. I changed the oil and filter, started the motor, ran it for about 2 minutes, brought it down to an idle and it stalled and would not restart, like it was locked up again. Pulled all the plugs and just about all of them were wet, sucked all of the oil out and it looked like a milkshake, this is were I stopped. The first time I pulled the plugs, just the "outboard" plugs were wet, lots of water in the cylinders. I had the heads redone 10 years ago when we bought the boat.

I do understand about riser gasket failure causing water to get in, but what if it is a head gasket or like somone on the dock said - internally something in the motor has rusted thru.

 

[scoflaw]

A well known weak link of the big block even in automotive applications, is the exhaust guides seated into a water jacket. Add salt water for 17 years and yes I would look there first

 

[Jack380AC]

If you decide to use a mechanic, I can recommend a guy in Perryville.

 

[vandal]

Marine Power has 7.4 new for $5400.00 a week ago.

 

[Russ Calasant]

Been there, done that if you remember. After much consideration, research and "advice" I decided to buy reman long block from Merc and had my local Merc dealer install and warranty which by the way meant exhaust manifolds and risers (only a year old) in order for them to warranty along with some other misc parts. It cost between $12-13k by the time I was done, I did have them pull the heads, exhaust off the starboard and check everything too. As you can see I followed shortly after by selling her, although I did sell her to a good friend. it was the combination of opportunity and not wanting to deal with working out the bugs, although I did- it was the right thing to do. Also I felt that it would not be that long before I would be doing it again. I lost confidence in her and just had a feeling that 7.4 is just not enough for the 370 and requires that you push them too hard. Just my experience and opinion, for what it's worth. I wish you the best, always an adventure!

 

[sbw1]

8.1s, assuming you can find one is overkill. The 454s are very good power choices for your boat. A friend of mine had similar hours on his boat (a 390 EC) and had a failure of one engine last year. He replaced it with a remanufactured engine. This year, the other engine failed. 8.1s are hard to find now and doing one side might mean you could not do the other side with another 8.1 at a later date. All said, not a good way to go. If it were my boat, I would find new 454s if available and do both sides. This assumes you like the boat and really do plan to keep it.

 

[PlayDate]

John,

Given you are pretty sure that the exhaust gaskets are in good working order, I would be tempted to pull the intake off just to see if the intake gasket or intake manifold is the issue. It's a simple job which could result in a few more years of service.


While it is never an exact set of rules to follow.....think about it this way:

Getting water into all cylinders at the same time is usually the intake.
Getting water into one side or another is usually exhaust.
Getting water into the crankcase is usually a cracked block.

If it ends up that the block is cracked, the question of replacement comes down to quality, price and warranty. Everyone has their opinions about it. A big part of the thinking is also: How long do you plan on keeping the boat and what are your plans for the other engine?

-John

 

[xravenx]

John,

Given you are pretty sure that the exhaust gaskets are in good working order, I would be tempted to pull the intake off just to see if the intake gasket or intake manifold is the issue. It's a simple job which could result in a few more years of service.


While it is never an exact set of rules to follow.....think about it this way:

Getting water into all cylinders at the same time is usually the intake.
Getting water into one side or another is usually exhaust.
Getting water into the crankcase is usually a cracked block.

If it ends up that the block is cracked, the question of replacement comes down to quality, price and warranty. Everyone has their opinions about it. A big part of the thinking is also: How long do you plan on keeping the boat and what are your plans for the other engine?

-John

John, and everyone else, thanks for your replies.

I forgot to mention in my original post that the first time I changed the oil, there was water in it and the filter.

After a 3 year wait to get a slip at the yacht club we wanted to be in, it would take another 5 - 7 years (or longer) to a get a bigger slip that a bigger boat would fit in, so yes I'm keeping the boat. The other engine is original to the boat and uses about a qt. of oil every 5 hours. I would replace both at the same time. As Russ mentioned in his reply - "I've lost confidence in her" - age, hours and raw water cooling have probably taken thier toll.

I am pretty certain the gaskets were/are good, can the block be leaking internally like someone on the dock said?

 

[BRBSTA]

I knew this day was coming, I need to repower my 370, starboard motor has water in the oil and some of the cylinders. I pulled the plugs and was able to crank the motor over and water shot out of the cylinders. Sucked the oil out and removed the oil filter, there was alot of water in the oil and filter. Pulled the risers and inspected them and the gaskets aand they looked like they did 3 years ago when I installed them. The experts on the dock yesterday were giving me thier opinions on where the water came from

I woild like your guys opinions on which way to go with this. Engines are RAW water cooled, carbed with 1100 hours. They have been great for the 10 years we have owned the boat. I want to keep this boat so I want to do this right. At the very least I would like to have fuel injection and fresh water cooled motors. What choices do I have, remaned 7.4s, 8.1s (expensive), Crusaders?

After doing a search here, there were lots of replies about buying motors from a third party and have someone install them. I don't want to do that, I want to keep a good relationship with my current marina or start one with a new marina, having some kind of warranty would be nice also. I wouldn't bring a steak to the Outback Steakhouse and ask them to cook it.

Hope to get a few estimates this week.

John

John I have a pair of 7.4 MPI closed cooled motors great shape we repowered a 370 EC with 425's motors are complete drop in and go pm me if interested


Thanks Ron

 

[Larry]

That's a whole different story if your burning a quart every 5 hours... Then it is time to replace.

 

[PlayDate]

John,

You have a serious crack somewhere and given the oil use of the other engine....its time to change them. Nows a good time to get them done. The only issue is there someone you can trust the job to that has done them before and has a good reputation. I would also pm Ron and see how many hours are on his engines.


Fuel injection engines require some plumbing and electrical work to fit your boat. Some require a fuel return line and fuel pumps so make sure you find someone who knows what they are doing.

John

 

[RubberDuckeeToo2]

John,

You have a serious crack somewhere and given the oil use of the other engine....its time to change them. Nows a good time to get them done. The only issue is there someone you can trust the job to that has done them before and has a good reputation. I would also pm Ron and see how many hours are on his engines.


Fuel injection engines require some plumbing and electrical work to fit your boat. Some require a fuel return line and fuel pumps so make sure you find someone who knows what they are doing.

John

If Ron's engine's don't work out, I met a fellow CSR member today who is re-powering his 380DA with new 8.1s and has one good 454 with 70 hours on it. He's here in CT, but it may be doable if it's the right price. I have no idea what numbers are involved, but I can give you his contact info and you can PM here on CSR.

Been reading a lot about people having to re-power lately. Hope it's not contagious.

Gene

 

[xravenx]

Gene,

Probably the same guy I talked with thru PM and email, I saw Ron's offer as well. I'm going to sit down with the couple of the places I'm getting estimates from tomorrow. I'm sure the one (who will remain nameless) will not allow me to furnish the motor or motors, and I can't blame them. I want to replace both motors, hopefully have a little warranty and a place I could call if there are problems and get to me in a timely manner.

This is why I feel that way..............I've had a few customers in the past that have supplied thier own a/c equipment, chillers, cooling towers, etc. some approaching six figures, we install it, make nothing off the equipment, needless to say they are not a priority when they call for service.

John

 

[xravenx]

Update, I went with remanufactured Mercruiser 8.1s. They bolt right up to the existing transmissions and have a 3 year warranty thru Mercury. Another guy at the marina repowered his early 90s 350 Express with the same motors last year and says his cruising speed is a lot faster while fuel usage has decreased. My original carbed 7.4s would cruise at 21-22 mph at 3250-3300 rpm, don't know what the fuel burn was. What do you guys think I should be seeing with these new motors? The marina is dropping it in the water this week for a check out.

Also, anybody have the Smartcraft gauges in the picture below? I did a search and can't come up with anything........what type of info do they display. I also read somewhere that some of the new
Garmin stuff will accept the Smartcraft inputs...........thanks.

John

 

[hottoddie]

A well known weak link of the big block even in automotive applications, is the exhaust guides seated into a water jacket. Add salt water for 17 years and yes I would look there first

I agree. Raw water cooled in salt water for 17 years = repower with fresh water cooled.

 

[xravenx]

Thanks for the info Scott..........if I could get 25-26 mph, even using the same amount of fuel I'm used to burning this would be very nice.

 

[kaz911]

Update, I went with remanufactured Mercruiser 8.1s. They bolt right up to the existing transmissions and have a 3 year warranty thru Mercury. Another guy at the marina repowered his early 90s 350 Express with the same motors last year and says his cruising speed is a lot faster while fuel usage has decreased. My original carbed 7.4s would cruise at 21-22 mph at 3250-3300 rpm, don't know what the fuel burn was. What do you guys think I should be seeing with these new motors? The marina is dropping it in the water this week for a check out.

Also, anybody have the Smartcraft gauges in the picture below? I did a search and can't come up with anything........what type of info do they display. I also read somewhere that some of the new
Garmin stuff will accept the Smartcraft inputs...........thanks.

John

Those are the old Merc SystemView displays. I think you can find manuals online.

If you are thinking of "upgrading" wait ... Mercury has announced VesselView 4 and VesselView 7 - The VV7 is based on Simrad NSS7 display - with full Simrad/Lowrance integration if you like their gear. So it will work with them and be able to use their accessories like sounder and radars directly. It should be shipping between may and June.

Simrad's parent company Navico already makes the Mercury NMEA 2000 Gateway, the MercMonitor and other Mercruiser NMEA 2000 units for Mercury.

So I do think the tightest integration will be with Simrad & Lowrance (both Navico owned brands)

 

[Henry Boyd]

Update, I went with remanufactured Mercruiser 8.1s. They bolt right up to the existing transmissions and have a 3 year warranty thru Mercury. Another guy at the marina repowered his early 90s 350 Express with the same motors last year and says his cruising speed is a lot faster while fuel usage has decreased. My original carbed 7.4s would cruise at 21-22 mph at 3250-3300 rpm, don't know what the fuel burn was. What do you guys think I should be seeing with these new motors? The marina is dropping it in the water this week for a check out.

Also, anybody have the Smartcraft gauges in the picture below? I did a search and can't come up with anything........what type of info do they display. I also read somewhere that some of the new
Garmin stuff will accept the Smartcraft inputs...........thanks.

John

Those are outboard devices. They will "work" with the 496 version, but I'm not sure the feature set will be that useful for the 8.1 version.

Converting to Smartcraft is a chore, but doable. The replacement 8.1s should drop right in and connect to the existing gauges via the ten pin round engine harness plug.

Going to SC means new rigging and gauges. Merc wants SC conversions to be all or nothing. The issue is that SC (and engine ECM) run on 5 volts dc and boat is 12. By having a mix of analog 12v gauges and digital SC 5v gauges there is a risk of feeding 12v back into the ECM via a shared ground and frying it. The ECM is in excess of $1000.00.

I converted all of my gauges including fuel. Some folks here have done partial conversions with no adverse consequences. To each his own.

A back of the envelope guestimate for DIY SC will add about 2K with cables, gauges and Display. Cabling in only a Merc monitor for data export to a NMEA 2000 mfd might be possible, but I personally would still be worried about mixing 12 and 5 volt devices.

I've done the full conversion and think it has paid for itself in terms of fuel monitoring. I'd recommend it if the budget is there. I'm also leery of putting too much stuff on the MFD screen. Sure having engine gauge displays are great, but why use mfd display area to replicate gauge data at the expense of reducing chart and radar display?

Henry

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