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  #151  
Old 04-01-2013
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

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Originally Posted by PorFin View Post


Of course, I got no one to blame but myself.
Yeah really, you are no good for that engine. If there was an engine protective services department I would have already have lodged a complaint and that poor engine of yours would have a home in a foster boat already.

I'm sure your Perkins is happily waiting for it's new presents to come in the mail.

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  #152  
Old 04-04-2013
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

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
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  #153  
Old 04-04-2013
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

Ray,

The job's still underway, so there's still more to come. I'm twiddling my thumbs waiting for my next parts delivery.

I'm no machinist, but it seems to me you've got a couple of possibilities:

1. Shop around for new (or lightly used) con rods.

2. Check with a machine shop or speed shop and see if it's possible to build up the inside of your big ends and then rebore them to specs.
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  #154  
Old 04-05-2013
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

Regarding machine shops and how to find a good one- visit at least two tractor dealers, ask their service manager who does their machining. Visit at least two local speed shops- ask who does their machining. The shop recommended by both is where to take your parts.
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  #155  
Old 04-05-2013
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

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Originally Posted by v40163 View Post
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
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That's what rod resizing is for. Take them to an engine machine shop and they can do it. They shave the cap mating surfaces which makes the big end slightly oval and then hone it back to standard size.
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

PorFin,
Sorry, I just signed up for this list last night when I sent my reply. I saw the 2007 date in your posts and assumed that that was the post date! It looks like you're doing a great job. I have been looking for rods but as of today haven't found any. Torresen Marine wants $300+ for new ones.

Bljones,
Thanks taking the time to reply to my post. I have a fair amount of experience with machine shops, having raced sports cars for almost 40 years. The problem is that I don't think that the rod and cap can be machined to accept standard size bearings, and I haven't been able to find oversize bearings for them.

SloopJonB,
Thanks, I do know that. I've had rods resized on other engines that I've rebuilt in the past. The problem with the 4.107 rods is that the rod and cap mating surfaces are serrated, not flat. So you can't shave material off the mating faces and then bolt them together and hone them out to accept a standard bearing shell. I've never seen another rod that's like that. And as I mentioned above the available bearing shells seem to be undersized for use when the crankshaft is turned down. But I could be wrong. I've got feelers out to the usual suspects- TADiesel, Torresen, etc. I'll post what I find.
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

Ray,

Another possible source is in the agricultural/industrial realm. The 4.107/8 family was used by Massey-Ferguson, New Holland, Bobcat and others in various applications.

Something else to remember is that Perkins' website links for retailers/distributers is pretty useless. There are many, many more operations that support Perkins products than the home page would suggest. I've had some success finding them after sifting through a lot of internet forums and search engine kabuki dances.

I've always been a little incredulous at Torresen's prices, and never used them (even when we were living in Michigan.)

Another possible (and I mention this with a lot of trepidation) is Foley. But before you call them, by all means do an internet search regarding their customer service reputation to see what you are potentially getting yourself into.

I'm a little curious: If the con rods are that pooched, what's the crankshaft look like?
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

I did an internet search, including the ag/ind sites with no luck. I did get an email from TADiesel this morning saying that they had the rod bearings that I was looking for, but after quizzing them a little they responded that the bearings were indeed undersized rather than oversized, which of course disappointed me! So I asked them to quote me a price on four rods. They came back with $150 each, so I'm going to go that route.

As for Foley, I approached them with an interest in purchasing a remanufactured 4.108 from them (listed at $7K). They originally agreed to take my Perkins 4.107 (the one that I am now rebuilding) as a core, but changed their minds after thinking about it overnight--they were only interested in a 4.108, not a 4.107. The core charge was $4K and that was too rich for me. So I wound up purchasing my major overhaul kit from them and I am embarrassed to say that I did no due diligence before doing so.

I did however read the complaints against them after the fact, and I must say that other than charging me about two times what the kit is going for on other sites they have acted honorably. They shipped the kit out promptly, it appears to be of good quality, and it was complete. My only issue with them as I mentioned was the price I paid, but that was my fault for not doing more research.

The crankshaft looks surprisingly good. All the journals and crankpins miked out very close to nominal and showed very little wear. The original main bearings showed showed no wear other than some scuffing on the upper (block) forward side of the #1 bearing shell and a little scuffing on the lower (cap) rear side of the #2 bearing shell. The #3 shell looked good. They miked out very close to nominal, within a few tenths. I attribute the scuffing to someone (not me-most likely a previous owner) tightening the double alternator belt too tight--a common problem as I understand it. The engine room had a lot of black belt dust in it when I bought the boat 9 years ago. I found the alternator to be a half inch out of line, corrected it, and gave it no further thought until now. I will probably install one of the serpentine belt arrangements that are available in order to reduce the bending on the crankshaft.

And speaking of crankshaft bend, I measured it as part of the removal process. I pulled the #2 main bearing shell from the block, set the crankshaft back in, and used a dial indicator that measures to a ten thousandth to measure the bend. Bend measured 0.0004 inch, which is right at the spec limit. I rotated the crankshaft until the bend was "up" and let the crankshaft sit suspended on the #1 and #3 bearing shells for a couple of days while monitoring it periodically. As I expected, the bend decreased over that time to about 0.00025 as near as could interpolate between the tenth marks. At that point I was satisfied, so I removed the crankshaft, fabricated a "liner puller", and removed the cylinder liners, which was pretty much the last part of the disassembly process.

The connecting rod bearing shells were different animals entirely. They all showed pretty significant scuffing and one (#4) showed obvious scoring from debris between the shell and the crankshaft. But as I mentioned, the crankshaft looked great. The #2 shell (in the rod) showed evidence of overheating--not surprising since the engine had overheated due to a hose coming loose according to the guy from whom I bought it four or five years ago. That's how I was able to buy it so cheap ($500 complete with heat exchanger, high output alternator, etc.). He told me that he had just had the cylinder head rebuilt and had about six hours on the engine before the hose problem. He said that the engine had "a bad cylinder" and would need new liner o-rings on one of the cylinders. I assume that he (or more likely his mechanic) noticed seepage from one of the weep holes in the block. That was the first thing I noticed when I began the disassembly. I did a leakdown test on the engine before I started the teardown and found that the #2 cylinder was leaking into the #1 and #3 cylinders, and it was the #2 weep hole that showed the evidence of leakage, so it was not a surprise to me.

I checked the cylinder head for flatness and found two interesting things--first and most obvious was that whoever had rebuilt the head had gone over it with a belt sander and left longitudinal scratches all over the head surface. The second thing was that the head had a low spot between the #2 combustion chamber and the pushrod holes. So I had a machine shop mill it as little as possible to clean it up. I will measure the piston to valve clearance when I get to that point and compare it against the Westerbeke 4.107 engine that's in the boat before I decide whether to use that head or the one from the Westerbeke.

What's wrong with the Westerbeke you might ask? I fell victim to the old "raw water pump seal failure". I changed the engine oil in the fall of 2011 as part of my annual "put it to bed" maintenance and let it sit over the winter. I started it up in the spring of 2012 and it ran fine for 2 or 3 minutes and then--it stopped and wouldn't restart. I pulled the dipstick and found the crankcase full of water. I did the usual things--changing the oil and filter three times and pulled the raw water pump. It and the fuel injection pump gear were rusty, so my guess is that it had been failing gradually over time and I just hadn't noticed it. So I figured it was time to break out the spare Perkins 4.107 engine and rebuild it.

Sorry for the book... )

Last edited by v40163; 04-09-2013 at 03:34 PM. Reason: Error corrections (6k to 7k, four to two)
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Old 04-05-2013
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

V40, don't apologize - the more info the better IMO - that's why we're all here.

You obviously know your stuff - much more than was apparent from your first posts. I have a couple of questions about your rods;

First, I assume the serrated mating surfaces are/were machined? If so, they should be able to be done again, the same as flat surfaces, only more involved. It doesn't seem like it would be much different than cutting splines on an axle. Might well cost more than the $150 you're paying for new rods though.

Next, I asked this question before but got no response from anyone - do you know why the Perky rod caps are "broken" on the bias instead of straight across, like every other con rod I've ever seen?
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

Thanks for the kind words. I'm the new guy here and my reply kinda turned into a narrative of its own!

Serrations: Hmm, good question. I guess they were machined, I can't imagine that they were forged with the rods-wouldn't be accurate enough IMHO. The rods are still together with the new bearings in them for mic'ing. I'll look at them and report back when I take them apart. I imagine that you could fabricate a jig to allow them to be "match" machined, but I think that the setup required to match the serrations to the cap and rod would be prohibitive...

And to your question about why the cap/rod separation point is the way it is puzzles me as well. I too have never seen that until now.

Ray
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