YM336D - Started knocking loud while tilling

[kenmac]

Car doc,
As this thread is long and has sometimes gotten off course,,
I think I remember some talk about measuring from the deck ( top of block) to piston height to see if the pistons all come up even . If the rods have ever been worked . They may not all come up even. I had a race engine once & had a machine shop work the rods. They worked too much of the rod end which ended up dropping a couple of the pistons lower the others

 

[Car Doc]

Car doc,
As this thread is long and has sometimes gotten off course,,
I think I remember some talk about measuring from the deck ( top of block) to piston height to see if the pistons all come up even . If the rods have ever been worked . They may not all come up even. I had a race engine once & had a machine shop work the rods. They worked too much of the rod end which ended up dropping a couple of the pistons lower the others

You are right on kenmac all true and in these these the liners actually stick up above the deck .005-.007" and can vary from liner to liner and thats why I suggested the deck rather than liner tops since #2 is a low spot again. (I mentioned way earlier to measure the liner tops also...)

I am so almost absolutely certain he has 2 bent rods I wont bet my rep on it but thats what is off in the geometry imho....

 

[Barry 1]

Domush,
Got it running yet?

 

[Domush]

Got the freshly milled head back today. They had to mill it .011" in order to get it flat, which means it was nearly three times more warped than Max spec! (.004" is Max spec)

I cracked the exhaust manifold trying to pry it off. Welding cast iron sucks.

I managed to get five out of the six manifold nuts off using an acetylene torch, heating them red hot then coaxing them loose with whatever socket fit the uber rusted nut. One stud broke, which I'm hoping won't be a problem.

Tomorrow I'll be testing the injector timing with the injectors installed. That way I can know if an injector itself is firing too soon, now that I know the pump is properly timed.

I'll also be checking the piston heights at TDC in order to check for a possible bent rod.

Photos to come tomorrow. I know, an entire post without pictures! You can proceed to revolt.

 

[winston1]

Domush, I don't know how anyone could revolt against you. You have impressed everyone with your patience on this project. We are all ready for the big celebration of the final video. :thumbsup::thumbsup::thumbsup:

 

[clemsonfor]

Im thinking that Head was possibly your problem!!! Hope this works for you this time.

 

[Car Doc]

I have been wondering where you went Domush glad you are still with us and good luck on the project! :thumbsup:

You already know this but my .002 remember to step up the torques and I do a circle and X them around the center and out. I always split them into more than is required say it calls for 3 (or doesnt say anything at all just the final number) and I oil them under the head of the bolt as well as the threads in this case where they are blind holes.

I make it 4 or 5 steps so they are as even as humanly possible. Like lets say these are 135 (dont quote me) or whatever do 25-45-60-80-100-135 for example and go back over @ 135 to double check. :thumbsup:

 

[Car Doc]

Domush,

This is something I did with my engine when I had my head milled I dont think Yanmar recommends milling heads from my research but we do what we have to.

You may ask Hoye or someone on here that knows more than me may chime in.

But under the pre-chambers there is a single copper sealing washer (and one under the injectors above the chambers) I put 2 under all my chambers to account for the milling so the chambers set higher in the head to clear the pistons just in case.

I posted this earlier dont know if you caught it or not? It worked fine on mine fwtw.

 

[Domush]

Okay, I measured the piston heights at TDC compared to the deck height and found:

#1: .019"
#2: .018"
#3: .018"

I'm going to guess that extra .001" doesn't really mean anything vital in terms of final compression.

Here are some pictures showing how the pistons and sleeves line up (in order of #1 -> #3):

Sorry the angles aren't all the same, not much room to hold my phone below the block.

What does concern me is the fact milling .011" from the head makes the pistons much closer to the head, even with the head gasket. Seeing as there are dents in the pistons where the injector nozzles have hit the pistons tops it appears the nozzles are a major concern, especially now.

I hate having to remove those nozzles (never did remove them completely), but if that is what is needed, so be it. I was contemplating simply grinding a flat spot into the nozzles in order to make them flush with the head, as right now only one of the three sits below the head surface, and only about .005". That would not require much grinding. It seems every time i have to remove something else, something else breaks and requires another Hoye order.

Opinions on grinding the nozzle bottoms instead of shimming?

Freshly milled head. Removed .011" from the surface. I checked the accuracy of their milling, as it appeared they milled it at an odd angle, but it measures perfectly (.000" difference) from the top of the head to the surface on all sides.

Different angle

 

[Car Doc]

Domush,

Glad to hear the rods are not bent I sure would have sworn they were by the pics! Actually the head is the same distance from the pistons the pre-chambers and valves are whats closer fwtw. And no .001" wont affect anything compression wise anyway.

I would not grind the pre-chambers. The "dents" you refer to are simply wear and tear from the injection process not parts touching.