Engine Overhaul Kama 554

[rayh]

ROB. Looking at your sleeves, There is a lot of wear. Be sure to replace them. Don't hone them out and reuse them. Put in a set of sleeves and pistons.
On a diesel, if you can feel the the top wear, replace the sleeves.
Years of experience
GOOD LUCK
RayH

[3RRL]

Thanks for taking time to check this thread out guys.
It looks to me that the consensus is I need better air filtration. In fact I do work in heavy, dusty environment most of time around here. It gets well over 100F in the Summer months and is very dry and dusty whenever I'm doing dirt work. (Which is what I do most of all)

I too am inexperienced at rebuilding and engine (correctly hahaha).
I rebuilt my first motorcycle engine at 15yrs old, then an old Pontiac in 1966 and recently a weed eater engine. They all ran but I don't know how good a job I did.
In my field of expertise, I know sometimes you have to live with imperfection. But I know the limits and what I can get away with if I have to. I also know where to draw the line and make it "perfect" because sometimes that's the only acceptable thing to do. Probably much like you guys when you see the engine torn apart. You know exactly what to do and what "will" work and what "won't" work and where to draw the line.
But not knowing about this stuff, I need to rely on you guys to tell me what is "OK" and what is absolutely "Not OK". You know what I mean?
Although not out of the question, I am trying to avoid taking the head in. If I can get it back in acceptable shape, even though not 100% perfect like described above, I would rather do it myself. I just moved up to this town and don't know any body's reputation here. It would be a crap shoot. Plus, being a Chinese engine, I'm not even sure if I have all the specs to follow.

The TBN guys also gave me some good information.
Bob Rooks told me there was a nice flame front on 3 of the cylinders but the 4th one looks like an oil pump (problem).

Note that I found on that last cylinder, that the connecting rod journal bearing was partly "squished". Perhaps that had something to do with that cylinder looking like it did? While working the tractor for the last time, I thought I heard a "knock". I saw the oil pressure start to drop and drove it immediately into the barn and shut it down. Right then was when I decided to tear it apart. After seeing the bearing, now I believe that is what I might have heard and that is what caused the low oil pressure. I called Chip and he is the one who told me that is a sure sign of oil pressure loss and that the pump is probably still OK.
I bought all new journal bearings from Chip and will install them. The crankshaft journals are OK, even that last one. There is no galling and they are clean and bright.

Both Bob and IH3444 said (and Larry too) the valves sitting deeper would not hurt except losing a little compression and most important was the rocker arm geometry would be affected...but maybe made up a bit by valve lash adjustment. IH3444 told me how to grind the valve stems to get the rocker arm geometry back into spec and check for valve guide wear.
I abbreviated his reply but here's what he said:
"... all you have to do is get the overall valve length measurement, and then grind the valve stem end a few thousands.
... Your valve seats are fine I'm almost sure due to the low hours. Just need to shorten the valve stems a little bit.
... Sitting that small amount in the head deeper is not a problem, it is very slight.
... you may want to check your valve guides for wear
... Do the rocking in the direction that the rocker arm presses down on the valve.
... there should be almost no play, and the valve should glide very smooth in the guide.
...The rocker arm geometry will mostly be unaffected due to the fact of the very mild lift and durations of these slow speed diesel engine camshaft profiles.
...If you are, and it's measurably out of tolerance, then a small shim under the rocker arm will most likely put you right back into the ball park."
A lot of information!
What I'm getting from his clipped quote is that the valves sitting slightly deeper will not necessarily hurt (except slight compression loss) and that I can grind the end of the valve to get the rocker arm geometry back to spec. I will also check the valve guides in the manner he suggested.

Assuming I lap all the valves so the all seat properly, I could then measure each one to see how much deeper it sits than spec, and grind off the end of each valve stem that amount respectively, right?
In other words, after lapping, I measure the valve depth and it is, say .020" too deep. Then I would grind off .020" off the end of the valve stem, right? That would put the rocker arm geometry back into spec, right?
If so, I can certainly do that easily in my shop.
Rob-

[3RRL]

Dec 13, 2009 13:15:12 GMT -5 rayh said:

ROB. Looking at your sleeves, There is a lot of wear. Be sure to replace them. Don't hone them out and reuse them. Put in a set of sleeves and pistons.
On a diesel, if you can feel the the top wear, replace the sleeves.
Years of experience
GOOD LUCK
RayH

Ray,
I have 4 new sleeves coming.
I did start to hone them out myself. Two of the sleeves I got rid of the "ridge" on top where is was not worn. Those two measured out at the high end of the tolerance ... the gap on the new piston rings was at the widest allowed. the other two were way over ... like .040" or more over the tolerance, so about 1 to 1.5mm OVER the maximum allowed gap in the ring according to the book.

[FlyHiFlyLo]

Rob, the rocker geometry isn't that big of a deal. I wouldn't sweat it at all. The big deal the the spring seat pressure change. Make darn sure you shim the springs. Having a weak load on the valve springs will cause you BIGTIME trouble. You don't want to hammer the retainers and locks.... Then you will drop a valve.

The other deal is the crank and rod journals. They may be in spec but not round. Make sure when you plasti-gauge you do it in several spots (about 5) this will tell you if something in out of round (Rod, bearing, Journal or block/cap) Look for taper in the plasti-gauge too. Plus, MIC the shit out of everything in many, many places. You might be able to mico polish the crank and not need the next size up on the bearings.

Remember this. It is a Chinese engine build... So the crank polish probally sucks anyways.

Wow Rob! way to take this on!

[rayh]

Rob
Looking closer at your #4 rod bearings???Could you get a closer picture of these shells and a picture of the crankshaft journal for that cylinder. It looks bad from here, but further investigation is required. Is the hole in the crank journal plugged?

[GuglioLS]

Dec 13, 2009 13:11:15 GMT -5 rayh said:

Don't be fooled thinking oil bath are better at removing dust. If all conditions are perfect, they work good, but if they are slightly neglected, trouble can come quick. They will not work good on slopes. They must be level.
Dry filters are much more suitable for general use, but you need a good filter. I have found the Chinese filters to be not the best. They will allow dirt to come through. Find a GOOD - USA filter replacement. (BALDWIN or NAPA or FRAM) They have better quality control. If you are still afraid of dirt coming in, find a filter arrangement with a saftey liner (2 elements). Don't go backwards to an OIL BATH system. We threw them away years ago.

Ditto,

My 1990 Komatsu Dozer has a dual filter system one inside the other. My 1953 Ford has an oil bath, although it does seem to work quite well. Yes keep it level, fresh and never ever let it go dry.


As far as all the valve depths being out of spec, I seriously doubt they were ever in spec to begin with. Either the spec is wrong or the valve seats were not machined correctly or the valve itself is not made to tolerance. But I'm sure Rob considered all those variables already.

Larry

[3RRL]

Hi guys,
Got back yesterday from my 2 day a week job down South.
I wanted to start checking the everything that was mentioned above but Loretta had me put in a gate to her garden. At least I got some seat time on her Jinma and the post hole digger.

Chip is sending me the new sleeve liners and they should be here late today.
I will check the valves to see how good the guides are. As I recall, when the valve is almost closed there seems to be very little or no play, but I will check it again. I'll also blue-off the valves into the seats before lapping any more of them. After checking the blue off I figured on using a drill motor like you guys do to finish seating them. I have plasti-gage and several different kinds of impression blue in my tool boxes. I use that stuff all the time to check shut-offs on the plastic injection molds I build. I remember when I was an apprentice back in the sixties, I was working for an old journeyman top moldmaker. He used to light cigarette paper under the mold inserts and use the soot as impression blue off (black) ... pretty cool.

I've also decided to grind the valves to length to obtain the proper rocker arm geometry.
I have a set up in my surface grinder to do that. I can also grind a radius on top of the valve stems so that the rocker arm only hits closer to the center point of the stem. It won't be a full radius, I was going to leave about a .050"/.100" flat on the center of the stem. Right now the valve stems are just squared off. My plan is to measure the new valves with gage blocks and indicators. I have to determine an average over-all length. I presume since they are stock, I could use that length as a standard? Then, depending on how much deeper the valve sits in the head (than spec) I will kiss grind that amount off the valve stem. Although not a big deal, that should make the rocker arm geometry real good again (closer to spec). Since I'll be using the same valves, I'm going to make the assumption that I won't need to shim the springs. Other than the truly damaged parts, the rest all looks really good once it was all cleaned up.

Later this week I'll take some photos of the new parts before and after installation... still got some fencing to do for Loretta. I'm setting several posts in concrete and then have to run the chain link fence again.
Rob-

[stumppuller]

Rob - I'm not so sure about radiusing the valve stem tops. I seem to remember that the squared off end allowed the rocker face to rotate the valve as it swung through its arc thus distributing the wear evenly. It probably depends a lot on how the rocker geometry is set up for that to happen however. Plus a radiused stem will effectivly give you point wear on the rocker face as opposed to a less stressfull line wear of the square stem tip.

Bruce

[3RRL]

Dec 18, 2009 0:16:05 GMT -5 stumppuller said:

Rob - I'm not so sure about radiusing the valve stem tops. I seem to remember that the squared off end allowed the rocker face to rotate the valve as it swung through its arc thus distributing the wear evenly. It probably depends a lot on how the rocker geometry is set up for that to happen however. Plus a radiused stem will effectivly give you point wear on the rocker face as opposed to a less stressfull line wear of the square stem tip.

Bruce

You're right Bruce,
Thanks for pointing that out. Boy, without these forums and shared knowledge from ya'll, I could sure screw things up if left alone. I think I can get away with a tiny radius just to remove the dead sharp edge. Maybe like a .005" radius. I could do with a stone just to break the edge, right?

Scott,
About shimming the springs, I have never done that.
What's involved and how would you know the correct spring pressure? Do you think that perhaps my springs are alright due to the low engine hours? Plus, these diesels run at such low rpm compared to gas motors. I'd like to avoid shimming if you think it's probably OK as is.
What are your thoughts on that?
Rob-

[rayh]

Shimming the springs on these engine is not necessary. There is so little change. Make sure the springs are good, no breaks and just put them back on.
High RPM engine require precise spring tension, not a 2500 RPM diesel.

[3RRL]

I measured all the valves ... old and new.
Turns out that the old valves are the same length as the new. In fact, the old valves measured within .002" and the new valves, one was about .009" shorter than the rest. After depth mic'ing the all the valves, I found that only the very first one was sitting deeper in the head than the others. That was the one I based my judgment about having to grind the ends of the valve stems. Turns out all the other intake valves were only slightly deeper than spec, from .003" to .008" deeper. And all the exhaust valves are within spec (.027/.044 deep).



With that in mind, I decided not to grind any of them. Instead, I replaced that first intake valve with a new one which sits closer to what the other intake valves were. I also tested each valve when it was almost all the way in for play or slop. All of them except one exhaust valve had almost zero movement. So the valve guides were all good. I tried a new exhaust valve and it seemed to fit tight in the guide, so I decided to put a new one in that 2nd cylinder.
That means I only replaced 2 valves ... intake on cyl #1 and exhaust on cyl #2.

[3RRL]

Then I started to lap the new valves in.
That went pretty well after I cut my lapping tool in half and turned a shank that would fit my drill motor. I got the new valves lapped in with a nice finish. I checked after lapping with blue and the band around the shut off was nice and even. I pushed the valve home by hand then tapped it a little with a nylon hammer. (less pressure than the valve springs I believe). Even without tapping, I could see a witness all around the valve seat bead, so I'm confident they were lapped properly.



I also lapped the old valves to be certain they were seated and fit properly.
After thoroughly cleaning everything off, all lapping grit and blue, I re-assembled the valve springs. Tomorrow I'll do that kerosene test as described in the manual. That means pouring kerosene into the intake and exhaust ports to see if any leaks out through the valve seating bead.

[3RRL]

Tomorrow I will install the new sleeve liners.
I'm going to paper the engine block first, where the "O" rings slide in so they don't shear. Then I can pretty much start re-assembling the tractor. That is after I help Loretta get the rest of the chain link fence around her garden.

Below are some of the new components for this rebuild.
Not shown is the new piston(1) for #3 cylinder. Then new valves(8), new sleeve liners(4), new journal bearings for the connecting rods(4 sets), new "O" rings(8), new set of rings(12) for 4 cylinders, all new gaskets. If my math is right, I spent approximately $150 bucks buying some of those items last year. Adding in the new stuff I bought this month, the total is under $500 bucks for everything.
Rob-

[bradblazer]

Nice work Rob. This is a great tutorial.

$500 - not too bad for restoring the engine to "as new" or better. I'm sure you can't wait to hear Huge shout to life again.

Does your air filter have a pre-cleaner? Mine has a dust-bowl ingestive type like this:
www.sy-klone.com/mm5/merchant.mvc?Screen=PROD&Store_Code=SI&Product_Code=NW-S9-SNOW09&Category_Code=NW

The Belarus has a crude-but-effective looking ejective one.

Here's another ejective precleaner:
www.donaldson.com/en/engine/support/datalibrary/000207.pdf

[3RRL]

Thank you Brad,
This is a good learning experience for me as well.
Documenting and sharing not only is fun, but I sure got an education and good direction from guys who are experienced with rebuilds like this.
Also, my Kama does not have a pre-cleaner. I would love to install one. I presume I could use the air intake opening in the large filter housing...connect a pre-filter to that, right?
Rob-