Piston Rings Worn Out, Time for a Rebuild

[Wildchild467]

17:1 is the tractor compression ratio. However, this wouldn't 't explain the blow-by. A cracked head wouldn't explain the consistent low compression pressure. Are you guys even reading his posts?

I can't swe it being a cracked head especially since they were NOS when I put them on. I strongly believe the 17:1 pistons were a different shape and did not have the dish in the piston that we are used to seeing with the multifuel piston. The early 20:1 compression pistons were in early production engines and then eventually wereally replaced by 22:1 compression pistons for the rest of the multifuel production years.

 

[Wildchild467]

I can't see how it would be a cracked block. I wasn't losing water before the rebuild. Besides, the cylinder walls are sleeved (which were new with the pistons) so that wouldn't make sense to me anyway.

The heads were NOS.... not reman. They were brand new in the box and were the late style heads with the milled out porion between the valves to prevent cracking.

I am using the late style head gaskets with the fire-ring.

 

[gringeltaube]

..... If somebody else put these pistons in, I would love to talk to you....

See this post, pic #10.
Have you PMed Clay James? I see he has read this thread but that was one week ago.




G.

 

[JasonS]

I can't swe it being a cracked head especially since they were NOS when I put them on. I strongly believe the 17:1 pistons were a different shape and did not have the dish in the piston that we are used to seeing with the multifuel piston. The early 20:1 compression pistons were in early production engines and then eventually wereally replaced by 22:1 compression pistons for the rest of the multifuel production years.

I have no idea what pistons that you have in your engine; this you will have to figure out. However, the tractor and multifuel pistons are interchangeable because both have the same combustion chamber design. It is common for farmers to install the high compression pistons in their tractors to improve cold starting because they have the SAME chamber!

Again, if every hole has the same "wrong" compression pressure, every hole likely has the same problem. What every hole has in common is that you installed new pistons/ sleeves. Looking in my White D5000 rebuild book, the pistons do, indeed, look just like the multifuel's pistons. The D5000 pistons have two compression and one oil ring.

 

[JasonS]

The D4800 & D4800T book actually lists several different pistons:

3-ring: 380045

4-ring: 380407

3-ring: 40-3810302 (N/A engine)

3-ring: 40-3810301j (turbocharged)

 

[rustystud]

Jason even if he had the wrong pistons installed that wouldn't explain the "blow-by" problem. If the wrong pistons where installed he would just have a low power problem. The only thing that would explain the blow-by is incorrect rings or rings that have failed to seat. Or (and this is reaching) the wrong size liners for the pistons. If the pistons are "standard" and the liners where .010" over then that would also create this problem. Don't laugh either. I have actually seen this happen ! The mechanic who was installing the pistons just "assumed" the Parts shop had everything all set-up correctly. But the pistons did not match the liners, and the mechanic didn't check them like he should have done. It did rattle quite a bit though !

 

[JasonS]

Jason even if he had the wrong pistons installed that wouldn't explain the "blow-by" problem. If the wrong pistons where installed he would just have a low power problem. The only thing that would explain the blow-by is incorrect rings or rings that have failed to seat. Or (and this is reaching) the wrong size liners for the pistons. If the pistons are "standard" and the liners where .010" over then that would also create this problem. Don't laugh either. I have actually seen this happen ! The mechanic who was installing the pistons just "assumed" the Parts shop had everything all set-up correctly. But the pistons did not match the liners, and the mechanic didn't check them like he should have done. It did rattle quite a bit though !

Agreed (and I noted that in post 176 ). I don't remember (and I'm too tired to search); was there also an oil pressure issue after the rebuild?

 

[rustystud]

Agreed (and I noted that in post 176 ). I don't remember (and I'm too tired to search); was there also an oil pressure issue after the rebuild?

I don't remember. That's the problem with long drawn out threads. You start to forget what was said earlier. At least I forget !

 

[welldigger]

I don't remember. That's the problem with long drawn out threads. You start to forget what was said earlier. At least I forget !

Ditto

 

[Wildchild467]

I searched my pictures and found a couple pictures of the old pistons vs the new pistons I installed. These came in boxes with the NSN on them and everything. They were advertised as LDS pistons. Note the new piston on the right only has 2 compression rings where my old LDT piston on the left has 3 compression rings.




Note: My previous posts (post #44 and #4 shows a piston WITHOUT the black coating on the top. This piston was the first one I opened and was not like the other pistons I received. The other 5 pistons I received had the black coating on the top and looked like a smoother,better machined piston on the top. I told the supplier about this and they mailed me another piston to match the other 5. I just wanted to let people know this if there was any confusion.

 

[Jeepsinker]

I see its shorter too, no skirt legs.

 

[Plane Fast]

It's hard to tell from the pics,(with no skirt as well) but are the wrist pins the same distance from the top?

almost looks like just a slight difference. (May be just an optical illusion)

i dont know, I looked again. They look the same.

 

[Wildchild467]

The distance from the wrist pin to the top of the piston was the same.

 

[rustystud]

Did you actually use a "micrometer" on the piston to make sure the liner was the correct one ?

 

[Wildchild467]

The piston/liner/rings came shipped to me in sealed individual packages with the piston installed in the sleeve and the rings on the piston. They were not ordered separately, rather as a kit. So they were assembled in each other when I opened the package. This tells me they are the correct ones.

 

[welldigger]

The piston/liner/rings came shipped to me in sealed individual packages with the piston installed in the sleeve and the rings on the piston. They were not ordered separately, rather as a kit. So they were assembled in each other when I opened the package. This tells me they are the correct ones.

I'm just taking a shot in the dark but could cylinder pressure be bypassing the outside of the cylinder liners? The reason I say this is I remember there being 2 or 3 different sizes of liner and piston kits mentioned in the tm. Something about an x and a y designating the size.

Don't know if that matters one way or another but maybe some of the sizes were miss matched? As many new parts as you used I'm stumped as to why your still getting so much blow by.

 

[Jeepsinker]

You know Jake, that is an interesting idea. I forgot about that entirely. Seems plausible. And it would explain why some reman engines have a lot of blowby from the slobber tube, and some have almost none. If they weren't properly observed and replaced with properly sized liners during rebuild

 

[rustystud]

The piston/liner/rings came shipped to me in sealed individual packages with the piston installed in the sleeve and the rings on the piston. They were not ordered separately, rather as a kit. So they were assembled in each other when I opened the package. This tells me they are the correct ones.

Having been in this business for over 36 years I don't know how many times I have seen parts totally screwed up even straight from the manufacturer. You must always verify the measurements. I vividly remember an engine that had the heads machined and the "proper" shims sent with them. This was from a well known shop that was known for their excellent work. Well they messed up. The right bank ended up with 18:1 compression and the left bank had 9:1 compression. Mind you this was a gas engine ! The engine literally tore itself apart ! I once installed a new crank in an engine with the supplied bearings. This was a good company and the crank was a "kit" so the bearings should match right ? So I didn't measure them, I just installed the crank. Well it ran great. Started hard but I thought that was due to the starter going bad. The engine only lasted 600 miles before it lost all oil pressure and the rods started coming out through the block. After tearing it down I found the bearings where for a .010" ground crank-shaft not a "new" shaft. I had "assumed" it would be correct since it came from the "manufacturer" and they never make mistakes ! That was a costly mistake on my part ! but I learned to always check for myself. So yes shops and manufactures make mistakes. So I say again you must always check and verify the measurements.

 

[gringeltaube]

I suppose these are the piston/sleeve kits in question, and that they all came in their original box, all nicely wrapped and still sealed in plastic?

Of course I could go and open all of mine and measure, but I know beforehand what the results will be...
Still, for peace of mind I might check the only one I had cut open so far, to take those pics.

It's hard to believe that all 6 of the OP's pistons/rings were too small. Or that no-one else has reported similar symptoms like low compression and excess blow-by, if these kits were somehow problematic.



G.

 

[gringeltaube]

...... Seems plausible. And it would explain why some reman engines have a lot of blowby from the slobber tube, and some have almost none. If they weren't properly observed and replaced with properly sized liners during rebuild

No way; not for the -465-family of Multifuels at least: the liner has a 4.75" O.D. with a 1/8" protruding rim (5.0" O.D.) which fits into a recess in the block, and sitting exactly flush with the deck surface.
Either the modern 1pc-head-gaskets - or the fire rings, for the older style HGs - keep the liners firmly pressed down in place- and sealed, of course.



G.