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Perkins 4.108M DIY Rebuild -- A Narrative

189K views 278 replies 46 participants last post by  eherlihy 
#1 · (Edited)
This Ought to Keep Me Busy...

So, glutton for punishment that I am, I've started a winter project:



That's our aux -- a reliable Perkins 4.108M that (as you can tell from the staining) has developed a bit of an oil leak problem that is even high by Perkins standards. We also were getting a pretty noticeable exhaust stain on the stern, which didn't indicate good things...

After a lot of deliberation about whether or not to repower, I decided to bring this lump home to tear her down and see just how bad is is. I'll do a complete inspection, measuring the components against workshop manual specs, to see what all needs to be replaced.

At this point, I figure that at best I can get by with a top end job. If the cylinders liners show significant wear, then those'll need to be replaced.

The deal breakers will be if the block, crank, head or other major components need to be replaced.

Stay tuned...

What fun!
 
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#33 ·
erps,

Cool beans. A new water pump's gonna run about $100; I follow in your wake to rebuild the current unit as a spare.

Your portable blaster sounds all too familiar -- I've got a very similar DIY soda blasting set-up myself.
 
#34 ·
I've got a very similar DIY soda blasting set-up myself.
I've seen the term soda blasting come up from time to time on Sailnet. I am a little embarrassed to admit that I don't know what that is. Is baking soda used instead of silica as the abrasive?
 
#36 ·
A few cents of experience;

Taking the block & head castings to an engine shop and having them hot tanked is a bunch easier and more effective than doing it yourself - all the little passages & hidden corners get cleaned and most of the old paint gets boiled off.

Spray Nine works incredibly well on aluminium parts - cylinder head carbon just disappears after an overnight soak.

Before you replace them, have an engine shop look at your valves - they can spot face the stems if they aren't too badly worn. You'll have to get the seats reground anyway and it can be done as part of that process.

As part of that process, have them check your pistons - a set of liners and new rings will be a lot cheaper than a full rebuild kit if the pistons are still good.

It's also a very good idea to get the mains line honed to ensure they are absolutely straight, or rather, concentric.

Glass beads work extremely well for blasting parts - they come out looking like new but the process won't mar machined surfaces.
 
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#37 ·
Speaking of cylinder liners, I was told by a diesel mechanic that long haul truckers use a heavy duty antifreeze rather than the green/yellow regular stuff that I've been using for years since the heavy duty stuff had more corrosion protection. Not knowing at the time whether my 4-108 had wet or dry liners, I removed the anti freeze and replaced it with the heavy duty stuff being careful to flush the system well. I then learned that I had dry cylinder liners and the change out was really not necessary. Don't suppose it hurt....my 2 cents.
 
#39 ·
Today's Installment:

Chapter 5: Hitting the Road.

Sorry that this post has no pics -- I'll do the upload & cross-link kibuki dance in future installments.

I've been trolling the internet looking at alternatives for overhaul kits and other parts. I sent e-mails and/or made phone calls to promising leads, and here's the gist:

o Several "authorized Perkins dealers" failed to respond to e-mails to the "contact us" address on their websites.
o Foley Engines also never responded (no shock there, and frankly saved me from having to seriously consider them as a supplier.)
o I did get a response from a local Perkins outfit. They don't stock kits per se, but would send me all of the parts a la carte -- estimate was $1774 + shipping. To be fair, this also included an oil pump (at $510), but still a little steep.
o E-bay outfits have kits in the $600-$800 range.

I elected to go with the reliable Trans Atlantic Diesels. Since they are (almost) local, I decided to drive down last Friday and actually put a face to a name. Sheri Moon and I have exchanged many e-mails over the last couple of years, and while she's been exceptionally helpful I've only once actually pulled the trigger to buy a couple of minor things from them.

Besides the latent guilt, I also was interested in seeing what gems their parts boneyard might surrender. I've got a couple of parts that while relatively serviceable, could stand to be replaced.

Anyway, I took a day away from the garage to make a road trip.

In addition to the overhaul kit, I was also looking for a couple of other things:
-- Freeze plugs.
-- Expansion washers to reseat the combustion chamber inserts.
-- 10-tooth Damper plate for our Hurth HBW 100-2R gearbox. While my current one works fine, the springs are just starting to become a little loose. Since I've already got everything disassembled, it makes sense to pop a new damper on and keep the original as a spare.
-- And from the boneyard, a front plate and a timing gear cover, both of which are showing their age and aftermath of exposure. The rust damage to the timing plate is mainly cosmetic, since there's no damage to the inside or the gasket-side of the rim. The front plate, OTOH, has rust pits extending well into the area that would be under the gasket. Additionally, the bolt hole for the alternator adjusting arm has become both out of round and the arm has worn a significant divot into the face of the plate.

TAD stocks both OEM Perkins and aftermarket rebuild kits. I elected to go with an (MaxiForce) aftermarket kit, which saved me several hundred dollars.

I also picked up everything but the timing cover and the damper plate. They did have a new timing cover in stock, but that one was almost $300. A new 10-tooth damper plate was going to run me almost another $400 -- I think I need to do some more internet shopping.

All in all, I left happy and my wallet only hemorrhaging in a relatively minor way. My guilt about taking advantage of Sheri's good nature in the past has been alleviated.

BTW, on the drive back home I remembered a few things I also meant to at least check on...

Such is life.

Of course, the overhaul kit was just the initial gush of fiscal blood. The hemorrhaging will certainly continue...

Next Up: Anybody Got a Tourniquet?
 
#40 ·
Today's Installment:

Of course, the overhaul kit was just the initial gush of fiscal blood. The hemorrhaging will certainly continue...

Next Up: Anybody Got a Tourniquet?
I'd suggest putting up a list of current replacement engines with their prices on the wall of your shop. Whenever you get some sticker shock on parts prices for your rebuild, just have a look at the list. Don't forget to add a boat buck or three to cover the incidentals for a swap to any of them. :eek:
 
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#43 ·
That is a rare deal but don't forget - it's in Canada so it'll cost you MORE when the exchange rate is figured in. :D
 
#44 ·
Chapter 6: Anybody Got a Tourniquet?

As I posted last time, the overhaul kit was just the first significant wound in what I hope will not become a death by a thousand cuts.

The next major investment is my seeming adoption of the machine shop. I dropped off the head and block to have work done that there's just no way for me to do properly in my one-car garage.

o Hot tank and magnaflux both the block and the head.
o Pressure test the head.
o Replace valve guides.
o Face valve seats.
o Remove and replace cylinder liners.
o Bead blast the timing cover and engine mounting brackets.

Now mind you, I didn't just pick this machine shop after a random check of the Yellow Pages; they were recommended to me by several fairly knowledgeable gear-heads. Since I haven't had any major engine machine work done is a couple of decades, I guess I was ill prepared for just how much it was going to bite into my wallet. Getting the head work done is going to run about $150, and they are going to go ahead and include lapping in the new valves and reassembly of the head.

So far, I'm happy.

Removal and replacement the cylinder liners? About $750. I almost choked at that one (OK, not quite true... I did choke at that one.) What, you would be asking, does that include? Well, a little more than just R & R of the liners. The machinist is going to also have to fabricate a couple of things to do the job right. First off, he's got to make a plate to drive the liner out. Then he's got to fabricate a plate that will drive the new liner in, but stop while leaving the top of the liner 0.025" proud of the deck (which the guys who installed the last liners failed to do properly.) Once that's done, they will finish hone the cylinder to 3.125", and double check to make sure that the valve to piston head clearance is right. After that, another trip to the hot tank tank.

I'll post pics once those parts come back.

Of course, I wouldn't be in such a foul mood if this were the only setback.

Here's something I missed on first inspection. That's my crank pulley, and yes that's a crack right through at the edge of the keyway. No way that's going back on with much hope of survival. TAD's got one for about $380; there's a retailer in the UK that has a new one for GBP 60 -- I think I'll do my part to stimulate the UK economy as well as the US (just call me an internationalist ;))



Here's what the rocker assembly looks like assembled. A little wear on the tips, but otherwise looks pretty good.







And here's what the shaft looks like after I finally managed to get the thing disassembled. Why the struggle? I'm guessing someone too cheap to invest in a torque wrench cranked the crap out of the mounting bolts at some point, and really REALLY compressed the pedestals onto the shaft.







I think we may have found suspect #2 in our search for the top end oil leak.

My initial (naive, it turns out) thought was "OK, just replace the shaft & arm bushings, easy peasy..." As Lee Corso would say "not so fast!"

I've been searching high and low for a replacement shaft. TAD's got a reconditioned shaft for $350. I've widened my search into the other equipment with 4.108's installed; it turns out that Massey-Ferguson, New Holland, Bobcat, and Gehl all built skidsteers with the 4.108. BTW: The M-F 811 parts manual is better than the Perkins one -- the diagrams are better, the parts descriptions are usually more detailed (including fastener sizes & thread types), and is has both M-F and Perkins parts numbers. Of course, the industrial 4.108 build excludes the marine raw water cooling adaptations, but it's still a good resource to have.

After a ton of time on the internet, I found a company in CA that will rebuild the entire assembly for $187. This will include a replacement hard chrome plated shaft, new bushings, reface arm tips, reassemble, and ship back ready to bolt back on the head in about a week. We'll see how that goes -- I'll post results once it gets back.

Next Up: (Depends on what I wind up doing this weekend...)
 
#45 ·
Chapter 7: Cosmetology & Elective Surgery

Well, with the head and block away at the machine shop, I can turn my attention to the more mundane tasks.

If you recall, I was thinking about replacing my timing cover since it's been victimized in a hostile work environment.

Here are a couple of pics of the damage. You can clearly see where the oblong washers sat under the nuts, and the areas around them that have been pitted by rust. After bead blasting, I'm not too concerned about further decay, but paint ain't gonna cover these acne scars...







So, being a cheap (er, miserly) guy, I decided to do what any shade tree mechanic would do: The next best thing. Instead of the ~ $300 for a new cover, I spent ~$5 for some JB Weld.

After cleaning the bejeebers out of the pitted areas, I gave them a skim coat of the JB Weld.





Let it dry overnight, then faired it this AM. Once again, the Fein MultiMaster came in really handy. Getting that radius from the edge to the pan was a chore, since it was hand work all the way.







Stay tuned for end results after I start painting...

Speaking of which, prep for painting is also starting in earnest.

Here's the valve cover. After stripping off the old cork gasket and digging all the sealant out, I took a little time to go back and true up the rim a little bit. Nothing radical, just took an adjustable wrench and did a little controlled bending, then sighting along the flats to check that it was all more or less copacetic. After straightening, I began the drudgery of feathering out all of the chips in the existing paint. Again, all done by hand.



Next patient on the table was the lift pump.





I took a toothbrush and Spray-Nine to it, and the paint was flaking off like a bad case of dandruff. The body of the pump (like many of the components on this engine) is made of aluminum, and when they painted this the first time, they just used standard red primer.

After I got it fairly clean, I disassembled it (sorry, no pics) to check the diaphragm. It looked almost new. I put it back together and then began getting all that old paint off. I could have used the soda blaster on it, but decided not to deal with the compressor noise. Instead, it was old school -- dental tools, marking knife, and brake cleaner for the body; and wire wheel for the steel fuel lines.

Here it is mostly clean. There are still a few specks of paint there that I'll have to get off before painting.





Next Up: A Woodworker's Approach to Engine Repair
 
#47 ·
Inspired?! I am exhausted by your work, PorFin, but also in awe. Nice work on that timing cover! Appreciate the looksee into your project. I couldn't help but think that if my wife ever saw me with our engine in pieces like that, she'd never trust it again. :D
 
#48 ·
Using JB Weld as engine Bondo was a stroke of brilliance. :cool:

Let the aluminium parts soak overnight in Spray Nine - they'll come out almost spotless. Spritz them thoroughly wet and put them in a zip lock freezer bag.
 
#51 ·
Anyone who enjoys doing their own work on boats, cars etc. should do it at least once. I built a high performance Chevy engine for my wife's car 20 years ago and it was a source of endless satisfaction - from seeing it completely dressed on the engine stand to the first time I lit it off to every time I stood on it afterwards. :D

The first time it lights is absolutely exhilarating.
 
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#54 ·
The rear main on a 4-108, has a spiral cut on the crankshaft, to pull oil back in as the engine rotates. So it is actually designed to leak... to get it to stop leaking, or slow it, you need to ensure crankcase vacuum, from the valve cover to the air intake. :)
 
#53 ·
Por: Great narrative! I have an old 4.107 - nearly the same engine, but not anywhere near the number/range/choices for repair/overhaul parts that you have!

Glad to see that you are biting the bullet and having the machine shop do the valve guides and machine (grind) the valve seats. Whenever you replace valve guides (or even take the head off for that matter) it is always a good idea to have the valve seats professionally ground. Notice - I said ground, NOT lapped. Lapping valves into seats has pretty much fallen out of favor in the diesel world (I was a diesel Chief Engineer on oil tankers for 30 years). Standard practice now is to grind the seats, then "blue" (check) the seating of the new valves into the new seats. Grinding ensures accurate concentricity of the valve to the seat - lapping can damage that concentricity. New valves/seats will also "wear in" to a certain extent when the engine is run and everything heats up.
The bottom line is: since you have everything apart, now is the time to do the job as best as you can (including replacement parts) - as long as your wallet holds out! Thanks again for sharing your experience!
 
#55 ·
Anyone still interested? Hope so...

Got a call late yesterday that the machine shop's done with the block and head; I'm going to pick them up Monday. I stopped by earlier in the week just as they were getting done doing the finish honing of the new cylinder liners, and I gotta say after the initial hot tank the block looks pretty good.

After way more hours than I'd care to admit, I'm getting close to the point that I can start painting.

I am, though, faced with a decision or two -- which I hope some of you will be able to assist me with.

As I mentioned in an earlier post, many of the bolt-on parts of this engine are aluminum. I really, really want to get a paint job on this this that will last. With that in mind, I've been researching my options:

- Engine primer.
- Self-etching primer.
- Zinc chromate primer.
- Epoxy primer.
- Alodine, followed by one of the above primers.

It could very well be that I'm overthinking this, but I'd love to hear what you folks would recommend.
 
#56 ·
Porfin- great thread, nice that you are taking the time to share with everyone.
I'm no expert on priming aluminum, but when I talked to a reputable auto paint store about it they said the only way to go is the self etching. I used it on a part I made (5086 alum. IIRC) and top coated with an automotive paint and it looks as good today as it did 5 years ago when I made them. That said, I've also had excellent results on aluminum sterndrive props with the zinc chromate spray primer (Moeller?).
 
#57 ·
I'm a fan of Zinc Chromate on aluminium. I've never had a finish lift when it was on top of ZnCrO4. I've never put it on anything that got really hot though.

It's the standard coating on aircraft internal structures so it can take ultra cold but, as I say, I don't know about hot.

I presume you are referring to things like the heat exchanger tank, thermostat housing & so forth? If so, they should be no problem. Anything close to the exhaust ports or manifold could be though.

One tip I learned the hard way - don't paint the major parts individually before assembly. I did that once and ended up with small areas that were exposed with no paint on them. Bits of the block deck that the head didn't cover and so forth.

Once you have the long block assembled, paint it and then put the hoses, clamps etc. on so they don't get covered in paint the way the factories do.

You also don't want paint in the grooves of your pulleys or they can slip. A trick for painting them is to hold them with an old V-belt in the groove while you spray them.
 
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#61 · (Edited)
Kevin,

As originally designed, the intake valves have o-rings that fit into grooves on the valve stem just below the retainers. The exhaust valves have no seals.

The overhaul kit I purchased came with umbrella seals for all eight valves.
 
#59 ·
PorFin - another tip on painting the engine - don't paint it Perkins blue, do it white instead. It shows up leaks right way and makes them easy to trace. It also brightens up the engine compartment which I presume is the usual gloomy hole. :)

See the before & after of my last engine.
 

Attachments

#65 ·
Chapter 9: An Engine Family Reunion

Some of you may have been intrigued by the title of the chapter I promised earlier. OK, so shoot me -- things change... (but I will use that title for a forthcoming chapter.)

So here's a quick show-and-tell of the stuff that's now back from the machine shop.

Head:











Block:





Some may have noticed a gray residue on the surface; that's all gotta come off before painting. If I had a pressure washer, I'd be in a lot better shape than I am now. I spent several hours with a wire toothbrush attacking it, and it's coming off albeit slowly. I've still got a couple of hours of work left to do. The outside of the block is the easy part -- all the nooks and crannies on the inside are what are giving me fits.







I also prepped the rings for install on the pistons. Here's drill:

Put ring in cylinder



Use a piston head to get it level in the bore



Verify end gap is within spec (0.009" - 0.017" for this engine)



Out of the 20 rings (five per cylinder), only three had gaps of less than the 0.009" minimum which were easily corrected with a diamond grit honing paddle. None are more that 0.012".

That's the latest -- there's a lot more to follow (but not today ;))
 
#66 ·
That pic is the single best illustration of the dumb design quirks that cause British engines to be such notorious leakers.

Note the almost complete absence of a raised rail or lip around the rocker area. That pressurized area is almost entirely dependent on the rocker cover gasket for sealing. When the engine is running there will almost certainly be pooled oil higher than the sealing surface with only a cork gasket to keep it in the engine.

:rolleyes:
 
#67 ·
I use RTV silicone to adhere the cork gasket to the valve cover, then coat the bottom surface with never seize. Works very well with no leaks, and makes valve adjustments a breeze. Shhhh it's a secret, don't tell everyone, ok? :)
 
#68 ·
An old hot rodders trick to keep gaskets from sticking is to rub lip balm on them. It's mostly used when the valves are being lashed regularly though. Once a diesel is set up the rocker cover doesn't (or shouldn't) come off very often.
 
#69 ·
Pofin - another trick you might want to do is to paint the INSIDE of your engine with "electrical" paint. I used Dolph red polyurethane electrical insulator paint. It is the colour of red oxide primer. I have NO idea what it's used for in that industry but it is extremely durable inside an engine.

Spray all the exposed surfaces that are washed with oil inside the block, head etc. Wipe off all the machined surfaces with paper towels wetted with lacquer thinner. It's easier than it sounds. ;)

It speeds up oil drainback to the sump by reducing "cling" on the internal surfaces. It also keeps the oil dramatically cleaner - I'm sure you know how rubbing oil on bare cast iron turns the oil and your finger black in no time.

I found my oil remained golden between changes - it has a quite dramatic effect. I would take the time to do it on any engine I built.
 
#70 ·
Pofin - another trick you might want to do is to paint the INSIDE of your engine with "electrical" paint. I used Dolph red polyurethane electrical insulator paint. It is the colour of red oxide primer. I have NO idea what it's used for in that industry but it is extremely durable inside an engine.
Funny you should mention that...

All that residue is paint. Hard to tell from the early, pre-machine shop pics, but the inside of the block and oil pan were both painted with a very durable black paint. I've been contemplating whether or not to go to do it again.
 
#74 ·
Chapter 10: Heading Down the Back Stretch

Although some of you may have been worrying that I'd bailed on the project, I have not!

The work has been delayed by our recent cold snap. While I can function fairly well in colder temps, paint does not.

Here's the latest update.

As SJB suggested, I decided to seal the areas of the block and head with Glyptal. Lots of varying opinions out there in the interwebs about the wisdom, utility and benefit of doing this; some folks swear by it, others raise worries about the paint coming loose and plugging up the oil pump and/or oil galleys. Others raise worries about the paint's insulating properties retarding heat transfer from the oil out through the block and oil pan. What ultimately swayed me in favor was that it had been done to this engine before and it looked to be holding up just fine.

After taking an air gun to the block and head, I began by masking off the areas I wanted to keep clean. Now some of you may absolutely dread masking, because trimming the edges of masking tape with an Xacto knife or razor blade is a tedious affair -- it doesn't have to be.

First, clean your surface and apply the tape.



Next, run a round screwdriver shaft lightly along the edge of the opening. The pressure will cleanly cut through the tape and the excess can be pulled off.



Another tool that can be used is a ball peen hammer, just like you'd do to cut a gasket.



Here it is all masked.



I did have to fashion some plugs for the tappet bores and the fuel lift pump shaft. I used wooden dowels bulked out with tape. (No pics -- sorry)

Anyway, once it was masked off I then sprayed the bejeesus out of it with brake cleaner to wash off any remaining oil residue or other contaminants. After double checking to make sure the tape had not lifted I began to paint. Nothing fancy, I just went at it with a chip brush, and a couple of smaller art brushes I picked up at Michaels. Here's how she looks now.











A few comments about Glyptal. First, this is an alkyd enamel that was developed for use as an insulator for electrical coils and armatures. It has a very high resistance to heat, and plays well with oil. It's also pretty viscous -- 60% solids by weight. Unfortunately, after many, many hours of searching I've never been able to find any user instructions. The can itself has almost no instructions, other than generic warnings to "thin with proper thinner for spraying" and "use the right brush" for those who apply by brush.

I did two coats, about 90 minutes apart. This stuff skins over pretty quickly, but as thick as it is it will take a while to actually set up enough to apply another coat without disturbing the one below. I probably could have smoothed things out even more if I had applied a third coat.

For cleaning up a few spots where I did actually color outside of the lines, I used brake cleaner sprayed on a lint-free paper towel. It worked very well.

We're getting close to reassembly -- WOOHOO!
 
#75 · (Edited)
As SJB suggested, I decided to seal the areas of the block and head with Glyptal. Lots of varying opinions out there in the interwebs about the wisdom, utility and benefit of doing this; some folks swear by it, others raise worries about the paint coming loose and plugging up the oil pump and/or oil galleys. Others raise worries about the paint's insulating properties retarding heat transfer from the oil out through the block and oil pan. What ultimately swayed me in favor was that it had been done to this engine before and it looked to be holding up just fine.
I had the same concern about it flaking. After I ran the engine for the initial 20 minute break in period I changed the oil & filter. I cut the filter apart and found a few small flakes and that was it. It doesn't affect heat transfer to any measurable extent. I first learned about it decades ago from racers who did it primarily to speed up oil drainback at high RPM's. They wouldn't continue to do it if any of those concerns were valid.

Somehow I suspect the people expressing those concerns have never done it and experienced the benefits. :)

Anyway, once it was masked off I then sprayed the bejeesus out of it with brake cleaner to wash off any remaining oil residue or other contaminants. After double checking to make sure the tape had not lifted I began to paint. Nothing fancy, I just went at it with a chip brush, and a couple of smaller art brushes I picked up at Michaels. Here's how she looks now.
Very nice job. I used spray cans rather than brushing though - is Glyptal available that way? Spraying with brake cleaner is a good idea. I wiped it down with lacquer thinner which also worked well but was much more work.

I'll be interested to know if it keeps the oil as noticeably cleaner in a diesel - I've only done it in a gas engine.

P.S. Don't forget to do the inside of your sheetmetal parts - rocker cover, front cover, oil pan etc.
 
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