engine swap for Tollycraft 48

[Tollycrafter]

As part of a restoration project I am considering a swap from Detroit 671n engines to something cleaner and quieter.The Cummins 5.9 series seems to be what most people suggest on misc sites and also Yanmars as an alternative. Cummins has what seems to be a good choice with remanufactured engines.I would appreciate any comments or advice on what HP to choose between 315 and 370.Lots of weight to push here. Thanks in advance.

 

[ranger58sb]

Probably a "do the math" situation, followed by "how much cleaner?" and "how much quieter?" is it worth to you.

I could imagine a $40K cost (WAG) and the boat ends up being worth about $5K more (another WAG) than before. Or something similar...

-Chris

 

[Tollycrafter]

Thanks...I hear you on value added issue.I know that engine noise will bother my wife a bunch and the seemingly sweating of oil through the pores of the 671's would annoy me but I appreciate your input.Thanks

 

[O C Diver]

Do you know the HP of your 671? They came in a wide range. The original Grey Marine 671 that I had in an earlier charter boat, had a whopping 168 HP.

Would probably be a good idea to determine what speed you plan to cruise at and how much HP is required.

Ted

 

[ranger58sb]

Thanks...I hear you on value added issue.I know that engine noise will bother my wife a bunch and the seemingly sweating of oil through the pores of the 671's would annoy me but I appreciate your input.Thanks

Maybe additional engine room "soundproofing" could be economical?

Some of the DD guys make it sound like that theirs don't really leak like a sieve all the time...

-Chris

 

[Tollycrafter]

Thanks for your response.300 Jo on the 671n's...Low hours on rebuilds but looking for quiet.If someone has any ideas about how to quiet them down ( insulation of course) I would love to hear.Like to cruise at 15 to 17kts.

 

[mvweebles]

A good friend who works for a well known marine engine company used to live on a Tolly 48 with 6-71's that he de-rated. He could have re-powered reasonably inexpensively (he's done it before), but chose not to. After 5-years of ownership and 400-500 engine hours, he spent something like $50 on repairs (a hose or something).

That said, like many heavy-equipment mechanics, he's deaf as a door nail without his hearing aids. I can't speak to the noise factor except to say insulation is your friend whether DD or any other engine.

Peter

 

[Tollycrafter]

Thankyou.I'm planning to insulate with Soundown and various other products but would like to lessen the noise for other boaters and get rid of the oil leaking.Thanks for responding.

 

[soin2la]

I was going to suggest the Tolly Owners group, but I had to search to find it and it is not even remotely close to what it once was.

I think length of intended ownership should be a consideration.

671s will lower the overall value and limit the market annually going forward. The cost of replacement will increase correspondingly.

 

[sunchaser]

Years ago we sea trialed a T48 that had Cummins 5.9s rated at 310 HP. It was a perfect match with a nice easy plane at around 2000 - 2200 as best I recall. The boat really performed with a nice smooth wake at 18-20 knots.

The higher HP Diamonds would do fine too but with your normal cruise at say 9 knots or so I'd guess you'd not see the need for 370 HP too often.

Removing the 6-71s would save some weight, maybe around 1,000 lbs. Look out for soft core above sliding doors.

 

[C lectric]

New mufflers may reduce exhaust noise. Fast Fred often suggested hospital grade mufflers for serious noise reduction. Can't comment whether they are available suitable for a wet or seawater application, maybe not.
Examine the exhaust system and get some help as they can be quieted but back pressure must be kept low for these engines.

Soundown, I have used to help shut my old V555 down. It worked. THe single biggest change was made at the hatches with their foam 1" although 2" may be better, but it also sealed the gaps around the hatch perimeter which made a big difference.
They offer a good deal of info.

Do some reading as you will need to examine the cabin for any open holes into the E.R.

It only takes a small opening to allow a LOT of noise into the living areas. Any and all openings must be closed with at least removeable panels for service work when needed.

As for oil leaks examine carefully. Some leaks you may decide not to repair as they can be invasive. Valve cover gaskets are a common leak source.
Some engine seals are a bear but others may be relatively easily replaced to reduce leaks.

Old hoses can begin to weep even though they are still serviceable. New clamps in some instances or outright hose replacements.

Look into a crankcase vent system. Racor offers a good one although no experience in my case, just reports on B.D. and here.

Watch the crankcase oil level keeping a bit below the high mark. Often due to installation angle the oil may rise to much at the back of the engine sump so the crankcase will whip the oil into a froth which will make it way out of areas it would not if the level were maintained half way between the high and low marks.

The Cummins REcon engines may still be available as mechanicals. They offered a 1 year full wty. from the time of sign off. I have not kept track of them for availability or the costs but ask. Keep in mind that many things will need to be changed, engine mounts, electrical, fuel feeds, and so on so
be aware the other systems can add a lot to the costs over the engines.

 

[Tollycrafter]

Years ago we sea trialed a T48 that had Cummins 5.9s rated at 310 HP. It was a perfect match with a nice easy plane at around 2000 - 2200 as best I recall. The boat really performed with a nice smooth wake at 18-20 knots.

The higher HP Diamonds would do fine too but with your normal cruise at say 9 knots or so I'd guess you'd not see the need for 370 HP too often.

Removing the 6-71s would save some weight, maybe around 1,000 lbs. Look out for soft core above sliding doors.

Thanks for the tip on soft cores above the sliders.I think that Bounty in Anacortes makes replacement doors and windows but knowing that there may be an issue to fix is very helpful. Probably would not use higher speeds that much except running from the storms in the Bahamas ( which I have had to do)...thanks

 

[Tollycrafter]

New mufflers may reduce exhaust noise. Fast Fred often suggested hospital grade mufflers for serious noise reduction. Can't comment whether they are available suitable for a wet or seawater application, maybe not.
Examine the exhaust system and get some help as they can be quieted but back pressure must be kept low for these engines.

Soundown, I have used to help shut my old V555 down. It worked. THe single biggest change was made at the hatches with their foam 1" although 2" may be better, but it also sealed the gaps around the hatch perimeter which made a big difference.
They offer a good deal of info.

Do some reading as you will need to examine the cabin for any open holes into the E.R.

It only takes a small opening to allow a LOT of noise into the living areas. Any and all openings must be closed with at least removeable panels for service work when needed.

As for oil leaks examine carefully. Some leaks you may decide not to repair as they can be invasive. Valve cover gaskets are a common leak source.
Some engine seals are a bear but others may be relatively easily replaced to reduce leaks.

Old hoses can begin to weep even though they are still serviceable. New clamps in some instances or outright hose replacements.

Look into a crankcase vent system. Racor offers a good one although no experience in my case, just reports on B.D. and here.

Watch the crankcase oil level keeping a bit below the high mark. Often due to installation angle the oil may rise to much at the back of the engine sump so the crankcase will whip the oil into a froth which will make it way out of areas it would not if the level were maintained half way between the high and low marks.

The Cummins REcon engines may still be available as mechanicals. They offered a 1 year full wty. from the time of sign off. I have not kept track of them for availability or the costs but ask. Keep in mind that many things will need to be changed, engine mounts, electrical, fuel feeds, and so on so
be aware the other systems can add a lot to the costs over the engines.

Thanks very much..Good insights on potential issues that I was not aware of.No experience with old diesels, just MAN's, Cummins QSM 11's and Volvo D12's on my last three boats.I'm in a new world here so I really appreciate all the advice I'm getting on the forum.

 

[Ken E.]

I did what you are contemplating, replacing 8V71 Detroits with 5.9 210 Cummins. I reduced horsepower intentionally since I had no plan to run the boat at planing speeds and I don't care about any hit in market value from reduced hp. Send me a pm for any specifics you'd like to know about my experience. I used Cummins Reman engines, which come with a new-engine warranty. I was able to used my existing shafts, props, exhaust run, and sea strainers. In total, the repower worked out great and I'm happy I did it. The boat's normal use is up and down to SE AK each summer, and these Cummins give me the 8 kt speed that I want for the trip with reliability and good fuel economy.

 

[Tollycrafter]

Great,!..Thankyou so much.I'm really looking forward to this project and appreciate all of the comments and advice on my first day on the forum.I wish that I could carve out time to come to the rendezvous at Roche in June to see all the Tollys, meet the people et, and get ideas.I will try to figure out how to do a pm on this site.

 

[Comodave]

Click on the user name and a box will come up with some options, PM being one of them.

 

[jungpeter]

Probably a "do the math" situation, followed by "how much cleaner?" and "how much quieter?" is it worth to you.

I could imagine a $40K cost (WAG) and the boat ends up being worth about $5K more (another WAG) than before. Or something similar...

-Chris

Hi Tollycrafter. Chris' suggestions above are probably the closest "short answer" you'll receive. This is very much a "do the math" issue. Your boat, your money, you're choice. But some things to consider:

a. My WAG on cost is probably closer to $60K. If you're fortunate to be able to re-use your existing transmissions and associated running gear, you may be able to shave my WAG a bit. However, should your repower open up the WAY more typical can of worms, my WAG will seem like a bargain. If I were to contemplate a repower on what is probably a 40+ year old Tolly 48, I would certainly consider replacement of the four 150 gallon fuel tanks outboard of those engines at the same time. You will never have that opportunity again. Ditto prophylactic transmission rebuilds, assuming you can use your existing units. And the beat goes on...

b. Several of the systems such as electric and HVAC on a Tolly 48 run overhead in the engine compartment. To remove your existing Detroits, all must be cut and/or moved out of the way to lift the engines through the salon floor. And replaced when the new engines are replaced. When I contemplate dealing with THAT mess, I see labor dollars flying out the pilothouse door.

c. My Tolly 48 had CAT 3208s for power. While fine engines, I often pined for DD671s, simply for access reasons alone. You mention the DDs are noisy. Well, ANY engine will be noisy, particularly if you power for, and run your Tolly at 15-17 knots. You mention the DDs leak. Not so, assuming they are properly sealed by a knowledgeable DD mechanic, and are maintained appropriately. Don't lose sight of the advantage of mirror-image engines like the DD671s. ALL service items are accessible inboard, with the exception of the air box covers. Assuming those covers are sealed correctly, there is no need to be outboard of your 671s. Not so of any other engine, to my knowledge. I believe any Cummins or Yanmar repower will result in at least 1/2 of your service items (pumps, water lines, heat exchangers, zincs, turbochargers, blah blah blah being outboard on one engine, smack up against those pesky fuel tanks.

d. Removal and replacement of your engines obviously requires dynamiting your salon. Not a big deal, but you will also have to remove one of the salon windows to hoist out your engines. And the likelihood of damage to the existing window frame upon removal is high. Can this damage be remedied? I seriously doubt there are any OEM windows still around, leaving you with the high likelihood of having a custom frame and window manufactured by somebody (who?). Smart money looks into this BEFORE that window is damaged irreparably.

Repower of most boats is a big, big deal. Sure, there's lots of anecdotal evidence from the howler monkeys on the WWW that say "sure-piece of cake. I lifted an engine from my cousin's front end loader and stuffed it into my XYZ over the weekend. Cost me peanuts." Not so much anecdotal evidence of proper and realistic repowers, costing many thousands, and yielding universally satisfactory results. Hope you've got your eyes wide, wide open.

Regards,

Pete

 

[Comodave]

Are you planning on doing the work or have it done by the yard?

 

[Tollycrafter]

Hi Tollycrafter. Chris' suggestions above are probably the closest "short answer" you'll receive. This is very much a "do the math" issue. Your boat, your money, you're choice. But some things to consider:

a. My WAG on cost is probably closer to $60K. If you're fortunate to be able to re-use your existing transmissions and associated running gear, you may be able to shave my WAG a bit. However, should your repower open up the WAY more typical can of worms, my WAG will seem like a bargain. If I were to contemplate a repower on what is probably a 40+ year old Tolly 48, I would certainly consider replacement of the four 150 gallon fuel tanks outboard of those engines at the same time. You will never have that opportunity again. Ditto prophylactic transmission rebuilds, assuming you can use your existing units. And the beat goes on...

b. Several of the systems such as electric and HVAC on a Tolly 48 run overhead in the engine compartment. To remove your existing Detroits, all must be cut and/or moved out of the way to lift the engines through the salon floor. And replaced when the new engines are replaced. When I contemplate dealing with THAT mess, I see labor dollars flying out the pilothouse door.

c. My Tolly 48 had CAT 3208s for power. While fine engines, I often pined for DD671s, simply for access reasons alone. You mention the DDs are noisy. Well, ANY engine will be noisy, particularly if you power for, and run your Tolly at 15-17 knots. You mention the DDs leak. Not so, assuming they are properly sealed by a knowledgeable DD mechanic, and are maintained appropriately. Don't lose sight of the advantage of mirror-image engines like the DD671s. ALL service items are accessible inboard, with the exception of the air box covers. Assuming those covers are sealed correctly, there is no need to be outboard of your 671s. Not so of any other engine, to my knowledge. I believe any Cummins or Yanmar repower will result in at least 1/2 of your service items (pumps, water lines, heat exchangers, zincs, turbochargers, blah blah blah being outboard on one engine, smack up against those pesky fuel tanks.

d. Removal and replacement of your engines obviously requires dynamiting your salon. Not a big deal, but you will also have to remove one of the salon windows to hoist out your engines. And the likelihood of damage to the existing window frame upon removal is high. Can this damage be remedied? I seriously doubt there are any OEM windows still around, leaving you with the high likelihood of having a custom frame and window manufactured by somebody (who?). Smart money looks into this BEFORE that window is damaged irreparably.

Repower of most boats is a big, big deal. Sure, there's lots of anecdotal evidence from the howler monkeys on the WWW that say "sure-piece of cake. I lifted an engine from my cousin's front end loader and stuffed it into my XYZ over the weekend. Cost me peanuts." Not so much anecdotal evidence of proper and realistic repowers, costing many thousands, and yielding universally satisfactory results. Hope you've got your eyes wide, wide open.

Regards,

Pete

Thanks...Good information.All of it and it does have me thinking.I expected that I wasn't looking at a simple task ( $$$) but you mentioned lots of things that I didn't even think of. The salon is going to be done over and I knew the windows have to come out..By the way all of the windows and doors can be had at Bounty marine in Anacortes according to Scott that worked for Tolly forever. On the noise I guess Soundown and earplugs are cheap..Thanks.

 

[Tollycrafter]

Are you planning on doing the work or have it done by the yard?

By a yard I'm sure.

 

[ofer]

you are now at 100k for two engines

 

[Tollycrafter]

you are now at 100k for two engines

Ouch!

 

[ghost]

Couple small points…

You can get windows from Bounty, but not really window. If you break one, the new ones won’t perfectly match. Not a problem when replacing all. By then once the window is out, I did not understand the comment that you might hit the remaining frame and need to buy a new one. When the window is out, it’s entirely out, no frame to run into.

If you Re power, it’s an easy job to replace fuel tanks while everything is out. Others have successfully removed tanks with engines installed. It’s tricky, but can be done.

If somebody ran ducting above the engine hatches, move it next to the fuel tanks. Ducting isn’t much to move anyway.

Personally, I would invest in soundproofing before Re powering engines with a long life still in them. I will say that there are likely some efficiency gains in getting rid of the detroits and the 48 hull can deliver some pretty nice economy when run slower. But, you won’t make back your investment.

On the plus side, good condition 48’s are bringing top dollar. They essentially stopped depreciating many years ago. I could get what I paid for mine 17 years ago today. I won’t get back everything I’ve invested above the purchase price, but still that’s more than pretty good for a 42 year old boat. That’s good condition in a market that pays a premium for Tolly’s. Run down boats, not so much. These boats are getting old, if a buyer perceives a whole list of old boat problems, YMMV.

 

[koliver]

Ouch!

That ouch was for an estimate of $100k.
I think that is low.
Over 20 yrs ago I had a client who had done a repower and was so unhappy that litigation ensued. His was the removal of a pair of brand X and an installation of a pair of brand Y. Naturally, the exhaust sizes were different, exhaust position was different, the shaft sizes were different, the engine lengths were different, widths were different, and so forth.
His saloon floor had to come out, he did nothing with his tanks, had a sliding patio door access to the cockpit so access was relatively easy, no window involvement.
Your proposal will likely include most of the changes noted above, and some others you have already noted, so the labour component will be at least as many hours, but at today's hourly rates, not those that my client was dealing with 20 years or more ago. His bill from the yard was over $100k. The cost of the replacement engines was in addition to the yard bill.

 

[Tollycrafter]

Couple small points…

You can get windows from Bounty, but not really window. If you break one, the new ones won’t perfectly match. Not a problem when replacing all. By then once the window is out, I did not understand the comment that you might hit the remaining frame and need to buy a new one. When the window is out, it’s entirely out, no frame to run into.

If you Re power, it’s an easy job to replace fuel tanks while everything is out. Others have successfully removed tanks with engines installed. It’s tricky, but can be done.

If somebody ran ducting above the engine hatches, move it next to the fuel tanks. Ducting isn’t much to move anyway.

Personally, I would invest in soundproofing before Re powering engines with a long life still in them. I will say that there are likely some efficiency gains in getting rid of the detroits and the 48 hull can deliver some pretty nice economy when run slower. But, you won’t make back your investment.

On the plus side, good condition 48’s are bringing top dollar. They essentially stopped depreciating many years ago. I could get what I paid for mine 17 years ago today. I won’t get back everything I’ve invested above the purchase price, but still that’s more than pretty good for a 42 year old boat. That’s good condition in a market that pays a premium for Tolly’s. Run down boats, not so much. These boats are getting old, if a buyer perceives a whole list of old boat problems, YMMV.

Well....Since it is closing in on cocktail hour here in Port Salerno I think that I might get ready to pour one and mull over all of this information that I have learned today...Since one of the 671n's has 450 hours since rebuild and the other one 54 hours I think that I might back up my thought process.All this info from you guys is really helpful.

 

[Tollycrafter]

That ouch was for an estimate of $100k.
I think that is low.
Over 20 yrs ago I had a client who had done a repower and was so unhappy that litigation ensued. His was the removal of a pair of brand X and an installation of a pair of brand Y. Naturally, the exhaust sizes were different, exhaust position was different, the shaft sizes were different, the engine lengths were different, widths were different, and so forth.
His saloon floor had to come out, he did nothing with his tanks, had a sliding patio door access to the cockpit so access was relatively easy, no window involvement.
Your proposal will likely include most of the changes noted above, and some others you have already noted, so the labour component will be at least as many hours, but at today's hourly rates, not those that my client was dealing with 20 years or more ago. His bill from the yard was over $100k. The cost of the replacement engines was in addition to the yard bill.

See my reply to ghost below and thankyou for your input today.You are a very responsive group.

 

[Comodave]

Personally I think there isn’t much wrong with 671s, especially since they were just rebuilt. I would spend maybe $10K on a general cleanup and sound insulation of the engine room. Clean up the engines, steam cleaning is relatively easy if you can find a carpet cleaning person with a trailer and equipment. Then run them and look for leaks. Fix the individual leaks. Those engines should run for thousands of hours if you maintain them. I think that if you have the yard do the repower work $100K is a low guesstimate. And it will never add anywhere near that value to the boat. Spend the rest of the saved money on all new toys for the boat,, new electronics etc. Then enjoy the boat!

 

[Tollycrafter]

Personally I think there isn’t much wrong with 671s, especially since they were just rebuilt. I would spend maybe $10K on a general cleanup and sound insulation of the engine room. Clean up the engines, steam cleaning is relatively easy if you can find a carpet cleaning person with a trailer and equipment. Then run them and look for leaks. Fix the individual leaks. Those engines should run for thousands of hours if you maintain them. I think that if you have the yard do the repower work $100K is a low guesstimate. And it will never add anywhere near that value to the boat. Spend the rest of the saved money on all new toys for the boat,, new electronics etc. Then enjoy the boat!

This direction is making more sense right now.

 

[sunchaser]

TC
What did the "rebuild" consist of? What is the rating of the 671s? The higher HP versions if run hard have a short life span. As best I recall the 485 HP version was the top end. Several of those ended up in the T48s.

 

[Tollycrafter]

TC
What did the "rebuild" consist of? What is the rating of the 671s? The higher HP versions if run hard have a short life span. As best I recall the 485 HP version was the top end. Several of those ended up in the T48s.

Hi..The 48 is a 1982 and the engines are ,671n models with 301 HP..I don't have the paperwork history yet for the detail on the rebuild.