Perkins 4-108 Nightmare

[cburger]

The Perkins is coming out of a Westsail 32. Are you sure the footprint is the same for the Yanmar as the Perkins? As far as the horsepower issue in terms of rating goes, I am specing based on cubic inch displacment, need at least a 100ci.

[CSY Man]

Also, remember that the 4-108 is WAY overrated in HP (37, 42, 50HP claims, and all that). It's a small engine, and only develops that kind of HP at high RPMs. IMO, it should be rated at about 25 shp.

At what RPM do you rate the 4-108 at 25 HP..?

The factory says 51 HP @ 4000 RPM, but at the old SAE rating (Society of Automotive Engineers)
That would be without anything hooked up, such as belts, transmission and such.

The other standard across the pond is DIN (Some German Industry Norm) Same power, less HP rating..Finally US cars changed to that..The old muscle cars from the 70s did not really develop 400 HP, more like 220.

The Perkins people says that the HP at cruise RPM (3000 or less) is less than the max rated RPM. (Surprise)
They also admit that the prop HP is less due to tranny losses and such.

I sail a CSY 33 with a Perkins 4-108.
I have also been on CSY 33s with Westerbeke 30s and with Yanmar 27s.

Not sure how Yanmar rate their engines, but I have far more power available than the boat with the Yanmar 27.
Also more than the Westerbeke guys.

The "top speed" of the CSY 33 don't vary much due to hull speed and weight, but it happens at a very different RPM: The 27 Yanmar runs at full throttle and barely gets 5 knots, the 4-108 at half throttle/RPM gets 5.3 knots.
The Westerbeke 30 guy somewhere in between.

Most engines are rated at full power, but ya think the 4-108 should be rated at a lesser RPM..?

only develops that kind of HP at high RPMs.

I "cruise" at slighty more than 5 knots, and the HP required at that speed would be around 18 to 20...Uh, should the engine be rated at those numbers as well?

Confused...

[hellosailor]

cb-
His labor doesn't sound out of line, either on the rate or the total, and apparently the big question is why he went ahead with so many hours of bead blasting and prep work before giving you the estimate.
I can see that if the block was rusty he'd want to get down to clean metal to see what was what...But there's still the matter of some 5000+ in parts, at some point he should have said "Well, an overhaul is usually from x to y dollars of labor plus five grand in parts, but it will take me $800 worth of time just to get in far enough to give you a closed estimate and see if the parts can be re-used."

I don't think anyone with experience and ethics would just ambush someone and say they're that far into the labor, before mentioning at least a ROUGH estimate based on just eyeballing the parts.

Not having been there...I don't know what was said by who.

I'm curious as to why he's apparently responding to a question of using RTV instead of gaskets. Like he says, engines are made with gaskets and RTV just isn't the right replacement for them. There are "form a gasket" special compounds that often work perfectly well--in some applications. Add the extra labor and prep time to use them though, and they're more a matter of "If you can't get the OEM gasket" than an alternative to using the right stuff.

Given the two price comparisons, I'd say to check what the total installation cost of a Yanmar will be--with all the work of the fittings, the bed, etc. and see just how much higher it goes, there's sustantial custom work to be done that may make it more reasonable to do the rebuild. If the numbers don't work out that way...Dunno, maybe the mechanic would be willing to take the old parts in payment for his labor, so you could at least walk away from them.

Reminds me of a shop that told me in order to give me an estimate on my car transmission, I'd have to commit to some $1200 in labor at book rate just to get it out and put it back in again. I found a better shop with a more rational attitude about estimates, instead.

[CSY Man]

As far as the horsepower issue in terms of rating goes, I am specing based on cubic inch displacment, need at least a 100ci.

Shoot, forgot my formulas: What is 100 ci?

Same as 1.63870 Liter?

The 4-108 is 1.8 liter if memory serves right, just a bit more than 100ci.

Stay with old faithful..

[hellosailor]

The web converters say 108ci=1.77L, your memory is still sharp enough for horseshoes. And gummint work.<G>

[cal40john]

Originally Posted by btrayfors

Perry,

If you do go with a new one, check out the Beta engines as well as Yanmar. They have a great reputation. Also, remember that the 4-108 is WAY overrated in HP (37, 42, 50HP claims, and all that). It's a small engine, and only develops that kind of HP at high RPMs. IMO, it should be rated at about 25 shp.

Good luck.

Bill

According to an diesel business owner/mechanic on another list the Perkins is derated by the factory to 40 hp @ 3000 rpm for use in a displacement hull.

John

[CSY Man]

The web converters say 108ci=1.77L, your memory is still sharp enough for horseshoes. And gummint work

Yeah, but my memory says 1.8 L for the Perk..

Aye, don,t make me walk on the boat to look up the specs..Too late in the day.

[CSY Man]

Here is a message from Perkins after I asked them about my engine with type and serial number as well as Horsepower.......

Our records show that engine ED22195U541655F was despatched from Perkins on
the 28th of April 1979 to an unknown customer in the USA. The rating was
51 BHP gross at 4000 rpm.

What has happened to the engine in the intervening 22 years will not be
known to us, if you are relating horse power to speed then , if the engine
is over propped then the rated speed will not be reached so not allowing
the engine to reach its full potential. So say then that at 3000 rpm the
power could be in the order of 32 BHP

With respect to the power absorbed by the gear box, whilst it is not in our
sphere of operation, we believe that 2-3% , should be deducted from the net
out put of the engine.

Technical Support Centre
--------------------------------------------------------------------------------------

There is no recommendation regarding a crusing "engine rpm", obviously if
the engine is to operate continously at full load then it is better to not
operate it maximum rated rpm. If the boat is " propped" at a lesser speed
however, then the engine will never be able to obtain 51 bhp at 4000 rpm.

If the engine was installed in a commercial craft for continous operation
then a prop would be selected the to limit the engine speed to 3000 rpm.

The gross power available through the the speed range would be in the order
of; 4000 rpm / 51 bhp 3800/50 3600/49 3400/48 3200/45 and 3000/44
bhp..

A speed needs to be selected to satisfy youself the design of the hull and
the prop. supplier

Technical Support Centre

------------------------------------------------------------------------------------

[David_Old_Jersey]

I am not a mechanical expert, despite having a 4107 (and years ago now my father had a 4107 for many years and then repowered to a brand new 4108 which he also then had for many years).......whilst I do like the Perkins and am happy enough with my Engine (now 37 years young ), from my experiances and more extensively via my father's, IMO once they do start needing major work then it is time for a repower, rather than drip feeding them money.

If they still made them brand spanking new straight from a Factory I would get another, cos' of it being a straight fit.........I would not get a recon or a 110% rebuild of mine - mainly due to a lack of trust in an Engineer but also cos' some parts would still be 37 years old.

But out of choice I would go for something brand new and Japanese, probably something based on the Kubota engine.......and bite the bullet on the additional installation costs.

But this would only be on a boat that I intended keeping long term so I got the use out of the new engine myself - if I intended selling in the next couple of years I would get the Engineer to fix what I had as best as he could and live with any new problems as and when they arose / keep my fingers crossed a bit more than I would be happy with.

No easy answers........

[never monday]

In the Wessail I'd look harder at the Universal 35 than the Yanmar 3JH. The Univ is 4 cyl and will be smother to operate.

[Heron]

I also own a Westsail 32 and fortunately it came repowed with a 4jh3e 56 HP Yanmar. I have owned several other vessels but this is my first Yanmar. I have never experienced an engine start so easily as the Yanmar does. It's almost like it anticipates we are ready to go and just starts running as I hit the starter switch.

It pushes the 10 ton vessel along at 6.5 knots without coming close to her cruising rpm. I generally run the engine at 2200 at we are moving along at 6.2 knots burning about .65 gallons per hour. If I do run the engine at her optimum speed of 3200, my stern digs in, the bow lifts up and we are "planing" along at 7.5 knots.
Saying that, I believe the engine is too much power for this vessel.

I was told by more than one mechanic that the more modern diesels like to be run at their optimum cruising speed. This is to maximize their efficiency and burn all the fuel cleanly which minimizes carbon build up. I do push my Yanmar at the 3200 rpm for a short duration if I am motoring along for a few hours at a time. What I do like about the 56 HP is that it can move the vessel along at 6 knots under heavy current, severe wind or whatever else may want to hold her back.

Even after a long cold winter, we launch the boat in May and it starts without the starter making a sound since she comes to life on the first "click". If I were ever to repower, I would most likely choose the Yanmar again but would opt for the next size down so that it is more efficient for the hull size and weight.

As far as rebuilding an engine, I did have a Westerbeke 32B rebuilt in 2001 in my prior vessel. I was quoted $3500. and when I came back to pick up the vessel, I was handed a bill for $6300. I was shocked but as we went over the invoice, the engine "needed" more work and I felt I had basically a new unit.

After 50 hours of use, it began leaking oil. This engine NEVER leaked oil since new. I brought the boat back to the "reputable" mechanic and he said he could pull the engine and replace the gasket for $1500. I couldn't believe his attitude but I was stuck since he gave me a 1 year warrantee and it was now 14 months old. He suggested that the leak was minor and I should just live with it until the engine needed more work!

If I were keeping your Westsail for several more years, I would repower. If you plan to sell the boat in the next year or so, save some money and rebuild.

HERON

[AnchorageGuy]

The Perkins people finally admitted to me that the rated HP for the 4-108 is 4,000 RPMs and that marine installations can not meet those RPMs. Those ratings are on a bench with no load. In addition, the exhaust is too small but can not be modified. This costs HP. There are several other issues specific to the Perkins not inluding the gear box. The Yanmar, My favorite by the way, Is rated HP at 3500 RPMs and Yanmar will not warranty the engine unless it is installed, propped, Etc. to turn the maximum rated RPMs.

[btrayfors]

According to the Perkins workshop manual dated 1983, the 4-108 puts out maximum torque (83 lbf ft) at 2,200 RPM. Using the formula to calculate HP from torque and RPM:

HP = rpm x T(torque)
5252(constant)


This means the 4-108 is developing 34.8 HP at 2200 RPM. This doesn't, of course, account for any losses from transmission, gearing, etc.


Sorry for the bold type....don't know how to get rid of it.


Bill

[CSY Man]

The Perkins people finally admitted to me that the rated HP for the 4-108 is 4,000 RPMs and that marine installations can not meet those RPMs.

Hmm, i get 4000 RPM when underway if I "floor" it, but not recommended in the long run.

I get 90% of that when tied to the dock, or 3600.

Max continous according to Perkins is 3000.

[micoverde]

Does anyone know a shop in the Brisbane area that does 4.108 rebuild exchanges (i.e. you give 'em your old engine and a lot of money and they hand you a rebuilt engine)?