D650 head spacer?

[southernpiper1]

Hi All. I'm replacing a head gasket on a D650. I didn't really mill the head or block. Both are now within 1/1000" of flat. But I did take some off certainly not much. Never worked on a diesel before. Do I need a head spacer? A metal spacer .oo8" thick was in place when I disassembled it. Should I put it back? In what position should I put it if I do. I've read conflicting information. Some say next to the block, some say next to the head.
Thanks All. You've been a lot of help.

 

[85Hokie]

when you say "now" are within....
what was taken off?
and yes to the spacer - that was there probably due to milling before perhaps.
I would be careful here - you may need another "thicker" shim!
Location of shim can be affected by liners also

you have wsm to determine clearance?

 

[southernpiper1]

when you say "now" are within....
what was taken off?
and yes to the spacer - that was there probably due to milling before perhaps.
I would be careful here - you may need another "thicker" shim!
Location of shim can be affected by liners also

you have wsm to determine clearance?

I'm sorry to sound ignorant but what is a or are a wsm?
I just posted a group of pictures to someone who just mentioned the same question. Again, you all are amazing. I'm somewhat used to dealing with gas engines but I'm sure the tolerances are considerably tighter on a diesel. Thanks again

 

[southernpiper1]

I'm sorry to sound ignorant but what is a or are a wsm?
I just posted a group of pictures to someone who just mentioned the same question. Again, you all are amazing. I'm somewhat used to dealing with gas engines but I'm sure the tolerances are considerably tighter on a diesel. Thanks again

Could you look at the pictures on another part of the forum . I titled it b6100 removal of oil nub from block.
I didn't know it was called a pin pipe. He actually saw the evidence I was working on the block and asked me about a spacer. You all are a brain trust of information. Now if I can figure out what a wsm is....

 

[North Idaho Wolfman]

WSM = Work shop manual... AKA Service manual

Block, gasket, spacer, head

And don't forget the O-ring for the oil pin pipe!
And if you're into it far enough check the cam for a plug, the newer better cams will have a welded plug, if it's got the aluminum drive plug change it.

 

[North Idaho Wolfman]

And the Head spacer Test, using a "fuse", just use a piece of soft solder the kind for water plumbing.

 

[Lil Foot]

Block, gasket, spacer, head

Sean, I (and I suspect others) need a clarification:
Having never worked on an engine with a head spacer, I've always had a question:
If you need a gasket between the block & the head without a spacer, why don't you also need one between the spacer and the head?
They are both solid metal, true? And the spacer must be rigid/solid, because if it was soft/compliant, it would just squish, and not be a spacer.
It just seems like the spacer/head interface would be a likely place to leak.
Educate me, O Great One!

 

[85Hokie]

Bill

I ran across this the other day.....
Not sure if this applies 100%

 

[SidecarFlip]

Having never taken a Kubota diesel apart but plenty of Caterpillars and Detroit's and Cummins apart, what we always did if we did an out of frame and decked the block or in frame, milled the head was, we took the thickness of the removed metal (head or deck or both) and added that dimension to a new spacer plate and replaced the old one always (when machining a head or deck or both. Reason being is the static compression ratio is determined by the builder and to deviate from that is asking for issues.

In the case of a rebuild with no original spacer plate, we added one to the machined head/block to maintain the correct static compression ratio. If the machining (metal removal was small) we went with a thicker head gasket, again to maintain the proper static compression ratio.

You have to maintain that distance for a variety of reasons besides static ratio one of which is timing gear tooth clearance, especially on OHC diesel engines like DDEC's and Cummins ISX's. Cats were pushrod but Cats are no more.

 

[Lil Foot]

I get why you need a spacer.
It just seems counter intuitive that it would seal reliably.
For instance, if you can get a reliable seal (using this stack, Block, gasket, spacer, head) between the spacer and head, shouldn't it be possible to use a spacer of the proper thickness, plus the thickness of the gasket, and just assemble without a gasket using the extra thick spacer? If it seals on top the head, why not the bottom also?

 

[southernpiper1]

I'm sorry to sound ignorant but what is a or are a wsm?
I just posted a group of pictures to someone who just mentioned the same question. Again, you all are amazing. I'm somewhat used to dealing with gas engines but I'm sure the tolerances are considerably tighter on a diesel. Thanks again

Well even having been in the Army, I guess acronyms are not my forte. Sorry. I have one coming but it's not here yet. CD version do it shouldn't take too long

 

[GeoHorn]

I get why you need a spacer.
It just seems counter intuitive that it would seal reliably.
For instance, if you can get a reliable seal (using this stack, Block, gasket, spacer, head) between the spacer and head, shouldn't it be possible to use a spacer of the proper thickness, plus the thickness of the gasket, and just assemble without a gasket using the extra thick spacer? If it seals on top the head, why not the bottom also?

Because the block and the head have different expansion rates due to mass and coolant passageways. That’s why the gasket must be next to the block, to allow for that movement. The spacer being next to the smaller/less expansive head will remain mated better there.

 

[85Hokie]

Because the block and the head have different expansion rates due to mass and coolant passageways. That’s why the gasket must be next to the block, to allow for that movement. The spacer being next to the smaller/less expansive head will remain mated better there.

Winner winner chicken dinner !!! You explained it better than that article I read!

 

[Lil Foot]

Because the block and the head have different expansion rates due to mass and coolant passageways. That’s why the gasket must be next to the block, to allow for that movement. The spacer being next to the smaller/less expansive head will remain mated better there.

Sounds logical, Thanks!

 

[southernpiper1]

Sounds logical, Thanks!

Yep. Me too, Thanks

 

[southernpiper1]

And the Head spacer Test, using a "fuse", just use a piece of soft solder the kind for water plumbing.

Neat idea.

 

[southernpiper1]

Looking again, I think the D650/B6100 is done. The head is very pitted in the combustion chamber area and then there is the cracked block on top that I was going to try and TIG. I'll end up parting it out. Nice tractor to. What a loss.