Piston Rings Worn Out, Time for a Rebuild

[Wildchild467]

That is the exact thing I am trying to do, document as much as I can and give lessons learned to help the next guy that decides to do the same thing as me. Its a big job so organization and attention to detail is key.

 

[74M35A2]

I'll be there with a CO2 fire extinguisher ready to stuff down its throat......

 

[Wildchild467]

It's not a 6-71.... it wont run away

I'll be there with a CO2 fire extinguisher ready to stuff down its throat......

 

[Wildchild467]

Last night I made some good progress on the truck. I got both heads off and put them on the bench. I also pulled the oil pan to see what things looked like under there. I was also curious as to what rod bolts I had in my engine, 6 point or the latest and greatest 12 point. I don't think my engine was ever apart because there is no rebuild tag and it has a date of 7-21-69 cast on the side of the block. Another thing I saw was my oil pressure regulator in the side of the engine is also the early style. So everything to me says the engine was never apart with the exception of me putting head gaskets on it a couple years ago (just as a PM). I did notice the idler gear of the oil pump felt loose as in it walked forward and back on the shaft quite a bit. I don't know what that is all about and it does not seem right, so i will need to investigate that further later.



Cylinder Heads:

After I got these on the bench I was able to look at these further. At first I noticed quite a bit of white powder on the cylinder heads (as shown in the photo) which I contribute that to burning WMO as fuel. I then used my valve spring compressor to remove the valve spring and remove the valve for inspection. I removed the valve and noticed quite a bit of black crunchy baked on oil or whatever it is on the intake valve. This seems odd because the only thing going in the intake should be air. Maybe my turbo is leaking oil a little bit? If somebody knew why I have crud on my intake valve, let me know, because all I can think of is a leaky turbo. I then pulled an exhaust valve I noticed some bad pitting on the valve where it meets the seat. I also wiped the oil off the valve stem and put it back in the head to feel if the guide is worn at all. I am estimating i felt .010' of slop in the valve guide. Just by feeling the valve stem with my fingers (not measuring) I could feel a little wear. So it might be time for new valve guides and exhaust valves anyway. The intakes felt a lot better as far as slop within the guides, which makes sense because they take less abuse. I did not investigate for any cracks on the heads yet between the valve seats. I heard that is a common place for them to crack, but I have not cleaned them up yet.


Above: Intake valve. The valve may look pitted, but its not... It is oil on the surface that I did not wipe off.



Above: Exhaust valve. Notice the pitting.

Above: Engine rear to the left, engine front to the right.





I might take tonight off from doing any major work on the truck. 2 nights of beating myself up working on it and I should take a night to clean the house and maybe grocery shop eating mac and cheese for the past couple nights gets old. haha! If I did anything, I could inspect the heads further and clean them up.

If anybody has any questions during my rebuild process, please let me know. I will try to answer them clearly if somebody has questions. Not many people dig this deep inside a multifuel. I will try to post as much information as I can for little tips and tricks I learn along the way.

 

[Wildchild467]

I went home for lunch today and checked my engine to see if it had piston oil squirters for piston cooling, and it does. My engine model on my truck is an LD-465-1 I believe. I will double check when I get home, but I know for sure it is an LD-465 anyway (not an LDT).


Piston oil squirters for piston cooling circled in red (shown above).

 

[Wildchild467]

I lied. I am working on the truck more today. I can't help it!

I just measured how much slop was in the one exhaust valve of the #3 cylinder. I did my best to measure it with digital calipers and it moved up and down somewhere in the neighborhood of .024" and .030". I measured the valve itself and it was worn about .004" compared to the diameter to the upper portion of the valve stem.

Here are the valve dimensions as In the TM 9-2815-210-34-2-2

 

[gimpyrobb]

Most of the motors I have worked on have the squirters(that I can recall). In the past I had posted they didn't, I was wrong. I am interested in seeing if the dual squiters will work in place of the single.

 

[rustystud]

The reason you have a oily crud on the intake valves is your guides are leaking oil. By the amount of wear you mentioned you where probably burning more then fuel !

 

[rustystud]

As far as the piston oilers go, all multifuel engines have them according to all the TM's I have read. Some have double squirters, most have single. The reason was the amount of heat build-up the pistons get due to the cup design that allows a slow burn of fuel. This means the pistons are exposed to a longer time of heat on them. Hence the oil cooling.
Many of the German built "MAN" engines also use oil cooling "squirters" on their pistons.

 

[Wildchild467]

I pulled a bearing cap off last night and checked with plastigauge the clearance on the rod bearing of #5 cylinder (it was the easiest to get to). I measured between .002" and .003" clearance. The bearing showed some signs of wear, but it was not scored at all. I have to check the TM and see what the proper clearance should be. I also noticed a date code of "2 91" on the back side of the bearing. So I now think that the engine was apart once before... at least after February of 1991. I have the 6 point head on my rod bolts also, so it raises the question to me, when did these newer 12 point rod bolts get introduced to these engines? Anyway, chances are I will just put new rod bearings in it and not main bearings. Main bearings would be a pain to put in, especially if I have to pull the flywheel to put the main bearings in.



Below: I also rotated the engine about 1/16th of a turn and noticed the piston liner came up with the piston on the #1 cylinder. This makes sense because #1 had the most compression out of all of the cylinders which means the most ring friction. Also some pistons might have been on the down stroke, but still, This is just an observation

 

[Wildchild467]

The reason you have a oily crud on the intake valves is your guides are leaking oil. By the amount of wear you mentioned you where probably burning more then fuel !

Well the intakes felt good, the exhaust were the ones really worn. These engines do not have valve seals either, which I don't understand why they do not.

 

[74M35A2]

Well the intakes felt good, the exhaust were the ones really worn. These engines do not have valve seals either, which I don't understand why they do not.

There are no valve stem seals because there is no vacuum on the intake side. Pressure on both manifolds is either zero or positive.

 

[74M35A2]

Hey, nice starter Jerry! That MF'er looks like one of those expensive, lightweight, long life, gear reduction units. Totally high speed!!!

 

[gimpyrobb]

Thats a pretty poor pic, try this one...

 

[Wildchild467]

There are no valve stem seals because there is no vacuum on the intake side. Pressure on both manifolds is either zero or positive.

I agree with the positive pressure all the time on the valves, but what about the non-turbo deuces? I don't think they had valve seals either. Also does that explain the oil/crustyness buildup on my intake valves?

 

[74M35A2]

Non-turbo same thing, no vacuum.

There is always yuck on intake valves. There is "reversion" of flow during operation due to harmonics, and thus slight spit-back occurs.

 

[Katahdin]

Hey, nice starter Jerry! That MF'er looks like one of those expensive, lightweight, long life, gear reduction units. Totally high speed!!!

Actually the Delco clones are inexpensive, and cheaper than NOS units and more reliable in my experience.
http://www.steelsoldiers.com/showthread.php?78375-Replacing-my-starter-with-a-gear-reduction-style

 

[74M35A2]

Actually the Delco clones are inexpensive, and cheaper than NOS units and more reliable in my experience.
http://www.steelsoldiers.com/showthread.php?78375-Replacing-my-starter-with-a-gear-reduction-style

They will work short term, but not long term, and they do not meet the requirements for OEM use (corrosion resistance, water intrusion, cycle count, over-running clutch performance, contact welding, pinion hardness, etc...). Probably OK for what we use these trucks for, but $70 more you can get an OEM unit designed and tested to last a minimum of 50,000 cycles (70,000 cycles typical), has O-ring seals, and 5 different types of grease inside depending upon load/speed/moisture/temp/etc of each area lubricated.

 

[74M35A2]

Stopped by to help Jerry at lunch today. Not sure he made it back to work, but here are the updates for this thread:

Pulling up cylinder sleeve.

We laid the truck on its side to pull the sleeves. Why is this sideways?

Piston cooling oil squirt line visible, look closely.

Best way to get over one, is to get under another! Jerry with his pre-marital smile, attempting to make his arms match his shirt.

Brokenrings.com, girly drinks too....

Uh huh.....on right had decent compression, left little piggy had none.

 

[Katahdin]

They will work short term, but not long term, and they do not meet the requirements for OEM use (corrosion resistance, water intrusion, cycle count, over-running clutch performance, contact welding, pinion hardness, etc...). Probably OK for what we use these trucks for, but $70 more you can get an OEM unit designed and tested to last a minimum of 50,000 cycles (70,000 cycles typical), has O-ring seals, and 5 different types of grease inside depending upon load/speed/moisture/temp/etc of each area lubricated.

My experience has been different. I purchased a NOS OEM starter for $440. It got stuck cranking almost immediately, I had to pull the dogbone to stop the cranking. I paid (my dime) to ship it back to the seller, he shipped me another NOS OEM that failed after maybe a dozen starts in less than year. That's when I gave up on OEM and purchased the new gear-reduction starter, its been 100% reliable for 3 years. In any event, lets not derail the thread further. Back to the engine rebuild!