Perkins 4108 gearbox identification

[Compass38]

Hi
I was wondering if anyone could identify this gearbox on a Perkins 4108? I can’t find nd an identification plate anywhere?
Thanks!

[oldcal46skipper]

Looks like a Borg Warner Velvet Drive with reduction, which could be 1.5- 1, 1.9-1, 2.5-1.

These are very good, robust hydraulic gears. I went to school on them about 40 years ago. A new one will cost you about $4,500, rebuilt about half or repair is less. I have one on my Cal 46 that I rebuilt in 1987. It has 3,600 hours and is still perfect, but I change the oil as indicated.

If your prop shaft coupling is not aligned perfectly, less than .003" variance at 12, 3, 6 and 9 O'clock positions, you can damage the output shaft seal and the oil will leak out.
If you don't change the oil as directed or don't check it regularly you can damage the seals, bearings and clutch plates. Also assure the oil cooler is getting adequate flow as ATF starts breaking down over 190 degrees.

Hope this helps? Or contact me by PM

Tom

[coopec43]

Perkins don't make gear boxes so as OldCal46 says it is a Borg Warner.

There is a 1.9:1 and a 2.1:1 but one turns clockwise and the other anti-clockwise so that may help to identify the box.

My opinion is it is unlikely to be either of them and more likely a 2.5:1 in a yacht the size of a 38ft boat.

Clive

[GordMay]

Greetings and welcome aboard the CF, Compass.

[bletso]

Borg

Look at the first few pages at the drawings. Yours looks like you may still find the ID tag on it. I have a 1.9:1 on a 38 ft Globe

If you need more detail info go to manuals

[jewt]

If it is a velvet drive keep it! Better an old one than any of the new ones like twin disk.

just sayin',

jewt
S/V Bifrost on the hard in Beaufort

[coopec43]

Originally Posted by bletso

Borg

Look at the first few pages at the drawings. Yours looks like you may still find the ID tag on it. I have a 1.9:1 on a 38 ft Globe

Well I'm perplexed because when I was buying the prop for my yacht the prop specialist said the 1.9:1 or 2.1:1 ratio gearboxes were not appropriate for a displacement hull. He said I needed a 2.5:1 or 2.9:1 so that I could fit a large aggressive 3 blade prop to drive the yacht at hull speed.

He went on to say 1.9 or 2.1:1 gearboxes were suited for planing hulls where props are smaller and necessarily spin a lot faster. (I can't find anything about a "38 ft globe" but I assume it is a displacement hull?)

Clive

[Compass38]

Thanks everyone for your time. I’ve had a good look around for an ID plate including with mirror & torch but I’ll have another go. The Perkins I’ve inherited with the boat was supposedly overhauled a couple of years ago, but in a 2hr delivery leaked both water & oil. Then the remaining fuel leaked into the oil on the mooring (possibly through the lift pump diaphragm).The engine also has some blow by. I understand the engine & gearbox are strong quality units but wondering whether complete overhaul of 40yr old equipment worth a go, or repowering with Volvo or Beta 40/50hP. Waterlinelength 32’ and about 10,000lb displacement loaded.
Any thoughts welcome.Thanks again

[Uncle Bob]

Originally Posted by Compass38

Thanks everyone for your time. I’ve had a good look around for an ID plate including with mirror & torch but I’ll have another go. The Perkins I’ve inherited with the boat was supposedly overhauled a couple of years ago, but in a 2hr delivery leaked both water & oil. Then the remaining fuel leaked into the oil on the mooring (possibly through the lift pump diaphragm).The engine also has some blow by. I understand the engine & gearbox are strong quality units but wondering whether complete overhaul of 40yr old equipment worth a go, or repowering with Volvo or Beta 40/50hP. Waterlinelength 32’ and about 10,000lb displacement loaded.
Any thoughts welcome.Thanks again

Sadly there are those out there that think the addition of a coat of paint and some new hoses constitute an overhaul.

[rbk]

Originally Posted by Compass38

Thanks everyone for your time. I’ve had a good look around for an ID plate including with mirror & torch but I’ll have another go. The Perkins I’ve inherited with the boat was supposedly overhauled a couple of years ago, but in a 2hr delivery leaked both water & oil. Then the remaining fuel leaked into the oil on the mooring (possibly through the lift pump diaphragm).The engine also has some blow by. I understand the engine & gearbox are strong quality units but wondering whether complete overhaul of 40yr old equipment worth a go, or repowering with Volvo or Beta 40/50hP. Waterlinelength 32’ and about 10,000lb displacement loaded.
Any thoughts welcome.Thanks again

It will run you north of $20k for a new engine after you buy the engine, controls, gauges, alternator, transmission, shaft, prop, cutlass (cause, why not), and re-do the engine beds. Or you could do a real overhaul (not just an oil change, belt and some paint); start from the top down, depending on hours chances are the block is fine and you’ll end up lapping the valves, cleances, new lift pump and maybe a new inj pump all for less than $2k if done yourself and with 4108’s you can do the above yourself, maybe get a hand installing the inj pump if you’re not feeling up to it.

[jewt]

Finding the proper prop for your boat is a "Black Art" at best. After much trial and error and 15 yrs. I finally got the "correct "prop for my 41 Morgan, full keel, CB sloop weighing in at 24,000#. For the Perkins 4-108 and a 2.5-1 velvet drive it was a 16x12 3 blade. When I repowered with a Beta 43 with a 2.5 -1 twin disk I had to open the prop aptaeure to take a 17x12 without prop tip hull inference. The dealers had recommended a 18x12 but it would not work and had to be cut down at the prop shop.

It appears prop "programs" are not very accurate predictors of proper performance for sailing vessels. If you can find someone that can change props in the water "great" otherwise it could take several haul outs and a number of prop changes.

jewt

[coopec43]

Jewt

And on a Mauritius 43 ft I am building my prop is a 21X15(?), 3 blade. (That was a recommendation by a propeller expert with many years experience). I have a Perkins 4-108 but with a 2.9:1 Borg Warner. (I'll let you know how it goes after I launch)

You'd reckon Halberg-Rassy would get things right with their HR 42 ft:

Engine
Volvo Penta Diesel 31A. Output 46 kW (62 HP) at 3.500 rpm. Four cylinder Diesel with direct injection. The engine is fresh water cooled and equipped with oil cooler. Reverse and reduction gear type Mono Shift 2.4: l.
Propeller: 3-blade, pitch 16”, diameter 15”, left hand.

[freelandken]

If it’s a Borg, you should find an ID plate on the starboard side of the main transmission. It’s mounted horizontally and will have all the info on it.

[oldcal46skipper]

Originally Posted by Compass38

Thanks everyone for your time. I’ve had a good look around for an ID plate including with mirror & torch but I’ll have another go. The Perkins I’ve inherited with the boat was supposedly overhauled a couple of years ago, but in a 2hr delivery leaked both water & oil. Then the remaining fuel leaked into the oil on the mooring (possibly through the lift pump diaphragm).The engine also has some blow by***

. I understand the engine & gearbox are strong quality units but wondering whether complete overhaul of 40yr old equipment worth a go, or repowering with Volvo or Beta 40/50hP. Waterlinelength 32’ and about 10,000lb displacement loaded.
Any thoughts welcome.Thanks again

I would rather have a 40 year old Perkins than anything sold today. Having rebuilt over 200 Perkins 4.108's in the last 13 years plus seeing customers with newer "screamers", i.e. high RPM to get their power at less weight...

A completely rebuilt 4.108 Long Block, (send your email and I will send my 2 page description of "Long Block". With your rebuild able Long Block for $6,995 + shipping or a new "XXXX" for $22,000.

More info on request off this forum. One engine builder threatened to sue me because I told the truth about their POS engines.

[coopec43]

Originally Posted by Compass38

Thanks everyone for your time. I’ve had a good look around for an ID plate including with mirror & torch but I’ll have another go. The Perkins I’ve inherited with the boat was supposedly overhauled a couple of years ago, but in a 2hr delivery leaked both water & oil. Then the remaining fuel leaked into the oil on the mooring (possibly through the lift pump diaphragm).The engine also has some blow by. I understand the engine & gearbox are strong quality units but wondering whether complete overhaul of 40yr old equipment worth a go, or repowering with Volvo or Beta 40/50hP. Waterlinelength 32’ and about 10,000lb displacement loaded.
Any thoughts welcome.Thanks again

Surely that indicates the gearbox heat exchanger is at fault and not the gearbox? (But maybe the engine was leaking oil and water?)

Clive