Deutz f3l 912 engine question

I purchased a duetz tractor (4006d) with the f3l 912 air cooled engine. The engine starts right up and doesn't smoke but has a metallic pinging sound when it runs. Best I can tell, the sound is coming from the top of one or two of the cylinder
sleeves where it meets the head. I'm thinking the piston is slapping the valves. I read online that there are shims that need to be used so this doesn't happen. Can someone school me on how to measure what size shim is needed? Does the
shim go between the cylinder and head or do you have to pull the piston and put the shim under the cylinder insert that goes into the block?

Steve
 
I made a video and posted it to rumble of the knocking sound. The URL is below. The sound does not go away after the engine warms up. When I crack open the fuel lines to cylinders #1 and #3, there is no change to the sound. When I crack #2, the sound pretty much goes away.

https://rumble.com/v1bjlpd-deutz-f3l912-knock.html
 
I have put a wrench on my share of Deutz engines so I will tell you what I know. If you hear a pinging,or popping sound while hitting the throttle its most likely a head to Jug leak. The old series didnt use a gasket, newer ones had a fire ring. Heads can be cut to fit a fire ring or relapped to seal if not warped to bad. If the engine sounds good cold, but starts knocking as soon as a load is applied it will indicate either excessive carbon on a piston, or the head to liner isnt shimmed correctly. 1.5 mm is what I shimm them at. All work on the pistons, rings, rod bushings, head, Liners, push rods,and rockers can be done from the top without pulling the pan. Not a hard engine to work on, just different from most US diesels. Al
 
The knock is present when the engine starts cold and doesn't go away after a few hours of work. I cracked open the fuel line to each cylinder one at a time and when I got to #2 the sound went away. The other two didn't make a difference. If I pull off the jug/liner, will I be able to get the piston back in it without removing the pan and rod?
 
I have seen a handfull of these tractors score a piston and then knock. It is almost always the next to the last cyl. from the front, the farthest from the blower fan, yet sandwiched between jugs. Are you getting a lot of blow by when warmed up?? I have worked on Deutz engines that have knocked for years after getting hot. They are truly a tough engine.
 
if you have narrowed it down to which cyl is knocking then swap the nozzle from that cyl. with one who isnt knocking. See if the knock follows the nozzle.
 
Gave this a shot and the knocking didn't follow the nozzle. darn it. I went ahead and pulled off the head and left the jug on the piston. I can tell from looking at the mating surface between the head and jug that combustion gas has been blowing out both sides so it isn't sealing. I must have an old style head as there is no fire ring between the jug and head. I looked at the cylinder and do not see any scoring so I don't think the piston has been slapping the sides of the cylinder. I also pulled the jug out enough to see if the wrist pin was loose and couldn't feel any looseness.

Is there a trick to getting the head and jug to reseal?

I appreciate your help as this is the first engine I've ever tried to fix.
 
Relapping the head to the jug can be done with lapping compound. I took an old jug and cut some slices in it with a hack saw like a tap would have. put compound on the jug and push down firm and twist back n forth. This works if the head has leaked a little. If it has leaked a lot you need to have the head cut to true it up for a fire ring. While the head to jug seal leaks it slowly eats away at the head surface. Sometimes you can feel the cut, almost like it was cut with a torch. I have a jig built to mount in a lathe to turn the head to cut these. The jug seems to never etch out, just the head. If you lap very much you do have to reshimm the jug to get the proper head to piston clearance. This should be 1.5 mm. Check your head bolts for stretch. If my memory is good it is 211 mm from the end of bolt threads to the underside of the head. If the bolt is longer get a replacement. I use 2mm solder to check piston to head clearance.
 
I went ahead and pulled the jug. The cylinder walls look good with a few minor blemishes down near the bottom of the jug that I cannot feel with my finger. Can these jugs be lightly honed?

However the piston has many more scratches. I've attached some files. What do you think? Replace this piston? How do you remove the piston? I don't think there is enough clearance to remove the wrist pin since it's sandwiched between the other jugs. Do I need to remove another cylinder first?

thanks for your help - I'm trying to learn,
Steve

cvphoto130667.jpg
 
Yes that piston would be considered junk. I would replace the jug n rings also. I was getting cyl. kits from Howards tractor in Lynn In. I know they changed their name, but for the life of me I cant remember to what. You do have to pull a snap ring out to slide the wrist pin out. I have 2- 14 thick by 2 inch wide by 6 or 7 inch long pieces of oak lath that I slide under the piston, above the block to hold the piston still while I slide the rings on and install the jug. I do use a band type ring compressor that uses a tool like pliers to compress the rings. Then the compressor splits open to remove from the bottom. Very easy once you learn how. Wrist pin bushings are presized so you can press a new one in using a threaded rod and fender washers. Al
 
The head's look fine to me. Will there be a problem lapping the old heads to the new jugs? The heads I have do not have the fire ring.

I'll be sure to measure the piston/head clearance using the solder method you described and add shims accordingly to get the 1.5mm clearance.
 
Yes they can be relappped. I used valve lapping compound, but is a very slow process. I built a jig from an old jug to be able to spin the jug while holding the Head. You lap until all of the black streaks are gone from the mating surface of the head. Also look for what will look like cracks in that area. These are actually torch marks from leaking combustion. I install fire rings when the heads are burnt this bad. Al
 
Thanks so much for sharing your knowledge with me Al. I'm sure I'll have more questions as I get further into this project.

Again, thank you for your help.
Steve
 
Head bolts are not torqued, they are tighten to 32lbs in a x pattern, then 45 degrees, 45 degrees, then 37 degrees. make sure you chase male and female threads first to clean them. Use just a pinch of engine oil for lube, not to much to case a hydraulic lock.
 
I noticed the fins on either side of piston are dirty.. could this be the reason for scuff marks on piston?
Is the dirt acting as insulation stopping heat getting out?
 
The backside of the airbox and the fins were completely clogged and I believe that was causing heat to build up and is probably what ruined the piston.
 
I have a 3 cylinder Deutz engine in a 60 ft Snorkel Lift we are going to scrap
I ll get the numbers and post them if anyone is interested
Hate to scrap a good running engine
 

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