[jrd22]

Some of the engines we rebuilt in my business had the "broken" rods/caps, I always assumed it was so they could only be put together one way but don't really know. Might have been Perkins, or maybe JDeere, but we had a bunch of different brands.

 

[v40163]

I know that Perkins engines were used in a lot of different brands of equipment so they may have been the same!

 

[SloopJonB]

They were even used in the classic black London taxicabs.

 

[Capnblu]

Since the bearing surface that moves is on the crankshaft surface, and the bearings are stationary in the rods, wouldnt it make sense to get the undersized bearings, and turn the crank rod journals down the appropriate dimension, after determining your min/max. measurements with plastiguage?

 

[v40163]

I certainly could do as you have suggested and install 0.010 inch undersize bearings and then "tune" the crankshaft to match the installed bearings by grinding and re-nitriding (Tufftride is the proprietary name) the crankshaft. In fact I used to do almost exactly that on my race motors, although for entirely different reasons...I would have the machine shop finish the crankshaft to 0.0005 inch larger than I really wanted. Then I would hand polish the crankpins and journals with increasingly fine sandpaper and a shoestring to get the exact clearance that I wanted. But that is a lot of work, and I only did it because the engines ran in excess of 9000 RPM and bearing clearances were critical in order to make the motors live.

But crankshaft grinding is forever and in this situation I'd prefer to bring the engine back to new factory specs. Rods are available out there, and it seems that they are not ridiculously expensive.

 

[SimonV]

Perkins motors are every where in some form of another. In Vietnam they drive pumps in the paddy fields, supplied village water in Fiji, power in the Marquesas and my boat. I think I should start making a a coffee table book of Perkins 4.107/108 motors being used in domestic and exotic locations.
As for New 4.108 they are being made by a number of counties. China build,
Zhejiang Xinchai Co., Ltd. called the 4108BT they also build 4105BT which looks like the old 4.99 which was the original London Taxi motor.

 

[v40163]

Are the Chinese parts interchangeable with their British cousins?

 

[SimonV]

Are the Chinese parts interchangeable with their British cousins?

This I don't know but all those engines out there in asia are getting parts from somewhere. Perkins is owned by Caterpillar, and they support factories in India and China.

 

[v40163]

Have you by chance had any dealings with either the Chinese or Indian arms of Caterpillar? Any idea where I might start poking around?

 

[v40163]

SJB,

I found the answer to your question on rrconnectingrods.com's website: "The angled rod cap is used on small bore engines or for camshaft clearance."

Ray R

 

[eherlihy]

I wish I'd been around when you were rebuilding your engine. I am currently rebuilding a Perkins 4.107 and have found that the connecting rod IDs are out of limits. I'm trying to figure out what to do...I can't hone the big ends of the rods to accept oversize rod bearings because nobody seems to make them. Wish I could understand why.

Ray Russell
Valiant 40 163
Enshalla

You may want to look here: Perkins Diesel

 

[v40163]

Thank you.

 

[v40163]

More info on oblique cut connecting rod caps:

Because of the large diameter of the crankpin to increase bearing area and decrease bearing load, the width of the bottom end of the con rod is greater than the diameter of the cylinder liner.

So that the piston can be withdrawn from the liner, 3 different designs are used:

The con rod can be fitted with a marine palm as in the photo above.

The con rod can be split in two parts as shown opposite.

The bottom end can be split obliquely. Serrations are used to locate the two halves relative to one another.

 

[PorFin]

Thought I'd pass along a little news:

- My shipment from the UK arrived today ("improved" rear main seal and new Bowman end caps.)
- Also got a call from the diesel shop, seems my injector pump is ready for parole and re-entry to society (I'll pick it u[ tomorrow.)

So, all things considered I should be able to resume the narrative pretty soon!

 

[Faster]

.....So, all things considered I should be able to resume the narrative pretty soon!

'bout time!! We're going into withdrawal here!

 

[aeventyr60]

Thought I'd pass along a little news:

- My shipment from the UK arrived today ("improved" rear main seal and new Bowman end caps.)
- Also got a call from the diesel shop, seems my injector pump is ready for parole and re-entry to society (I'll pick it u[ tomorrow.)

So, all things considered I should be able to resume the narrative pretty soon!

Can you tell me about the new and Improved rear main seal?This project is looming in the next 6 weeks...need the real skinny!

Question, when installing the rear main seal does it go in dry or do you soak it in engine oil first? The scuttlebutt has it that if dry the seal tends to glaze and then leak quicker. Any opinions on this one?

 

[MedSailor]

Question, when installing the rear main seal does it go in dry or do you soak it in engine oil first?

Why would this matter? It's a perkins right? So once you start it up the brand new seal (along with the rest of the engine and bilge) will be soaked in oil.

But I'm not bitter.....

MedSailor

 

[HardTAC]

Thank you so much, PorFin, for posting your project in such detail!

I am new to the forum and am super impressed with all the information and contributors here!

My wife an I just inherited a '79 Morgan 382 with a 4.108M. The boat is in pretty good shape, but has been sitting in the yard for almost 5 years. The boat only had one owner (an aircraft machinist) who was pretty malicious about everything (including the engine). But he has passed away and I have almost no history on the boat.

Anyway, five years is five years. The engine was properly winterized way back when, but I'm still concerned about firing the Perkins up for the first time. I'm gonna replace the fuel, filters, oil, batteries, etc., before attempting to start. But, I'm wondering if there's anything unique to this engine I should be aware of before attempting to crank her up?

I know this should probably be it's own thread, but I got so caught up in your detailed rebuild, I thought you (and those following this thread) would have some good advice. Besides, if the engine proves to have a lot of issues, I'll be re-referencing all your steps as I go through the re-build process myself!

Thanks again everyone; I plan to be frequent visitor/contributor.

 

[SloopJonB]

I started my 4107 after it had been sitting on the hard for several years, after being neglected for many more before that while in the water. Did just what you propose - gave it a thorough service, oil, filters, belts, hoses, fuel, pumps, coolers etc. It fired right up and chugged exactly as it should.

Those engines are about as close to indestructible as any engine out there.

Before & after pics attached to give you an idea of how far it had sunk before I started on it.

 

[HardTAC]

Thanks, SloopJonB for the encouraging words. I'd say my engine looks like your "before" picture. Your "after" engine is beautiful! It's nice to know the Perkins is worth fixing up.

I've learned a lot about the 4.108 just by reading this thread. It has forced me to go through my workshop manual and (now maybe somewhat obsolete) parts book.

PorFin: You could put all your posts and pics together and make a book. I'd buy it!