Yanmar YSE Liner Question

[Wotname]

I am replacing the liner in a Yanmar YSE as part of an engine rebuild.

It isn't going exactly to plan or as per the manual but I am unsure if it is really a problem or whether I am over thinking the issue and being over cautious so I welcome you comments and ideas.

The essence of the issue is that the liner does not protrude evenly from the block. The manual states the protrusion should be between 2.5 and 5.5 thou. It does not states whether the protrusion should be uniform or not but I sort of expected that is should be consistent.

When I fit the liner, it protrudes 5 thou at the twelve o'clock position and about 8 thou at the six o'clock position.

Is this a real issue and if so, what is the best solution.


So far I have done the following.

1. Cleaned and inspected the groove in the block properly.
2. Measured the lip on the new and the old liner. Both are the same and consistent around the circumference.
3. Rotated the liner to several positions; the issue does not change.
4. Measured the fit between the head and the surface of the block without the liner or gasket fitted using plastiguage. It mates consistently all around with less than a thou variation.
5. I am unable to measure the groove in the block due to lack of accurate equipment due it does appear to vary in depth by a few thou around the circumference.

So I am thinking it what always like this before the rebuild but it does not match the requirements of the service manual.

The seal between the cylinder and the head is not affected as the head gasket provides that seal between the liner and the head but the seals between the water and oil galleries is my concern.

The seal near the 12 o'clock position should be OK as the gap is within the manual specs (i.e. less than 5.5 thou) but the gap at the 6 o'clock position exceeds the manual specs and the head gasket seems uncompressed at this position.

One solution is not to worry and use some 515 (or similar) gasket paste on the gallery sections of the head gasket to fill up the space.

Another is to fit the liner to the block and then have the protruding section of the liner milled down to a consistent height (say 4 thou). Of course the liner must then always be refitted in the same position.

The hardest solution is to have the grove in the block reworked to ensure a proper fit.


??????

[Cheechako]

I'm no expert, but that seems pretty wierd. It implies the liner was not turned on a lathe properly or something. How do you get the end of it not perfectly 90 degrees to the liner wall?
How hard to get it out? Return it as defective or take it to a machine shop to true up the end maybe?
Did you measure the land on the block where the liner goes into for equal depth? Maybe the block is just warped and you need to surface the top of the block?

[motion30]

I think I might just install it and then have the block decked

[Wotname]

Originally Posted by Cheechako

I'm no expert, but that seems pretty wierd. It implies the liner was not turned on a lathe properly or something. How do you get the end of it not perfectly 90 degrees to the liner wall?
How hard to get it out? Return it as defective or take it to a machine shop to true up the end maybe?
Did you measure the land on the block where the liner goes into for equal depth? Maybe the block is just warped and you need to surface the top of the block?

OK, the liner is (as best as I can tell), perfectly true and and symmetrical using a straight edge, engineers square and vernier callipers measuring to 1 thou). It is also identical to the old one as far as external measurements go.

As to the land on the block (see point 5 in OP), there is variation to a couple of thou but I can't measure it accurately. Perhaps the top of the block was milled in the past and it wasn't done square to the liner insert. Right now the block surface is flat when measured against a straight edge and against the head.

There is not enough material to mill the surface of the block, if that's done, the liner would protrude too far. The only way (as far as I can see) to rework the block is to rework the land/groove. At this stage I would prefer just to rework the liner top surface to get the protrusion back to book specs.

But I ain't no expert in engine rebuilding

EDIT: The liner is easily removed / refitted by hand and a very small hammer (to remove).

[Wotname]

Originally Posted by motion30

I think I might just install it and then have the block decked

Thanks, that's my thought at this stage but I could be convinced to do otherwise...

[boden36]

I would be inclined to just fit it if there is no evidence of past leakage. If it worked before, it should work again.

Regards,
Richard.

[Matsubob]

If you have tried the liner in different positions and the high's and low's always are in the same spot, the lilner is not at fault. There must be something left in the groove that is receiving the lip on the liner. A piece of rust, or even a piece of old head gasket or something. Gasket material will compress "enough" to allow it to align but rust will not. I would be very hesitant to just bolt it up and hope because diesels depend on good compression to run, and if there is the slightest protrusion or variation it won't produce that needed compression.
The block has been machined evenly so that groove "should be" precisely the same depth all the way around. I would check and recheck that before doing anything else. And I would definitely NOT deck the block with the crooked liner installed, because that would cause misalignment of the liner vis a vis the block, which would cause uneven piston and ring wear, as well as put sideways pressure on the wrist pin and bushings. No, it must align correctly with NO additional machining!
The only other possibility is that the deck itself is warped; if that is the case, decking the block itself "might" true it up. That can be determined with a reliable straightedge laid along the surface in a criss cross pattern while running a feeler gauge between the edge and the block surface. Any variation will show up there.
I would check the groove first, for any foreign material that might be lodged there. Then check the block surface for irregularity. The new liner, though, is not the culprit and should not be machined!
Good luck!

[Techtool]

My two Cents.
Clamp the liner in with 4 head bolts with long spacers the measure the protrusion. If it’s still unequal spin the liner 90 deg. and retry if you find a sweet spot mark it with a felt pen ..remove the liner install the liner seals and reinstall in the same place. If it won’t true up to within .001 variance you may have to have the liner seat in the block re cut. Not a big job it can be done in place. Just out of curiosity what is the protrusion variance on the other cylinders?

[Wotname]

Originally Posted by Techtool

My two Cents.
Clamp the liner in with 4 head bolts with long spacers the measure the protrusion. If it’s still unequal spin the liner 90 deg. and retry if you find a sweet spot mark it with a felt pen ..remove the liner install the liner seals and reinstall in the same place. If it won’t true up to within .001 variance you may have to have the liner seat in the block re cut. Not a big job it can be done in place. Just out of curiosity what is the protrusion variance on the other cylinders?

Thanks, I have tried spinning the liner but the protrusion variance remains in the same spot. Currently I am using either feeler gauges or plastiguage to measure the variance.

The YSE is a single cylinder engine.

I am curious to know how the liner seat can be recut in place, what sort of tooling is used? Not that it matters as the block is currently on the bench but nevertheless, I am interested in knowing how it can be done outside of a machinist's shop.

[Techtool]

I worked for Volvo, Cat and Cummins for 38 years but never Yanmar. Clamping is very important when measuring if the liner is not pressed into the seat in the block with bolts you wont get a valid reading. But if that is what your doing there is a manual tool arrangement that clamps into the bore and onto the deck. It has a depth adjustment, a hand crank and a carbide tool bit. All you do is set the tool bit so it just touches the block seat then crank the tool. it will shave off .001 or less at a time. you can slowly lower the tool bit into the hole as you crank. This may seem Flintstoneish but its still the way we square up most seats in the field.

[Wotname]

Originally Posted by Matsubob

If you have tried the liner in different positions and the high's and low's always are in the same spot, the lilner is not at fault. There must be something left in the groove that is receiving the lip on the liner. A piece of rust, or even a piece of old head gasket or something. Gasket material will compress "enough" to allow it to align but rust will not. I would be very hesitant to just bolt it up and hope because diesels depend on good compression to run, and if there is the slightest protrusion or variation it won't produce that needed compression.
The block has been machined evenly so that groove "should be" precisely the same depth all the way around. I would check and recheck that before doing anything else. And I would definitely NOT deck the block with the crooked liner installed, because that would cause misalignment of the liner vis a vis the block, which would cause uneven piston and ring wear, as well as put sideways pressure on the wrist pin and bushings. No, it must align correctly with NO additional machining!
The only other possibility is that the deck itself is warped; if that is the case, decking the block itself "might" true it up. That can be determined with a reliable straightedge laid along the surface in a criss cross pattern while running a feeler gauge between the edge and the block surface. Any variation will show up there.
I would check the groove first, for any foreign material that might be lodged there. Then check the block surface for irregularity. The new liner, though, is not the culprit and should not be machined!
Good luck!

Thanks and I concur with much you have posted, especially about checking and rechecking the groove for foreign matter and consistent depth. I certain it is clean as I cleaned it within an inch of its life and inspected the groove with a good light and magnify glass but it is worth doing again. The depth does vary but I can't be certain by how much although it is certainly a "few" thou. I will have to work a better way to measure it. I'm currently using the depth bar of vernier callipers which is not really suitable for the job.

I don't think compression will be affected if it was left the way it is. The head pulls up against the liner, not the deck (via the gasket of course). However the resultant gap between the deck and the head is not consistent, it varies from 5 to ~8 thou and I don't think the gasket will accommodate such variance and thus the water and oil galleries will leak (between each other and to the outside of the block). Especially as the manual states the max liner protrusion is 5.5 thou.

[Wotname]

Originally Posted by Techtool

I worked for Volvo, Cat and Cummins for 38 years but never Yanmar. Clamping is very important when measuring if the liner is not pressed into the seat in the block with bolts you wont get a valid reading. But if that is what your doing there is a manual tool arrangement that clamps into the bore and onto the deck. It has a depth adjustment, a hand crank and a carbide tool bit. All you do is set the tool bit so it just touches the block seat then crank the tool. it will shave off .001 or less at a time. you can slowly lower the tool bit into the hole as you crank. This may seem Flintstoneish but its still the way we square up most seats in the field.

Flintstoneish is good

Thanks for the info, this is good to know.

[Compass790]

Silicone will easily seal the oil & water galleries but the Flinstone cure is the one I know you are gunna go for. I'll be interested in the outcome & the process.

[Wotname]

Originally Posted by Compass790

Silicone will easily seal the oil & water galleries but the Flinstone cure is the one I know you are gunna go for. I'll be interested in the outcome & the process.

Hmm... maybe not - not sure yet. . There is a certain je ne sais pas quoi about using the simplest approach - if it works

Besides I don't have or have access to the Flintstone tooling, not even sure where to try. Not a lot of Flintstones in Southern Tassie but maybe I will hunt something out!

[jimbunyard]

Originally Posted by Wotname

I am replacing the liner in a Yanmar YSE as part of an engine rebuild.

It isn't going exactly to plan or as per the manual but I am unsure if it is really a problem or whether I am over thinking the issue and being over cautious so I welcome you comments and ideas.

The essence of the issue is that the liner does not protrude evenly from the block. The manual states the protrusion should be between 2.5 and 5.5 thou. It does not states whether the protrusion should be uniform or not but I sort of expected that is should be consistent.

When I fit the liner, it protrudes 5 thou at the twelve o'clock position and about 8 thou at the six o'clock position.

Is this a real issue and if so, what is the best solution.


So far I have done the following.

1. Cleaned and inspected the groove in the block properly.
2. Measured the lip on the new and the old liner. Both are the same and consistent around the circumference.
3. Rotated the liner to several positions; the issue does not change.
4. Measured the fit between the head and the surface of the block without the liner or gasket fitted using plastiguage. It mates consistently all around with less than a thou variation.
5. I am unable to measure the groove in the block due to lack of accurate equipment due it does appear to vary in depth by a few thou around the circumference.

So I am thinking it what always like this before the rebuild but it does not match the requirements of the service manual.

The seal between the cylinder and the head is not affected as the head gasket provides that seal between the liner and the head but the seals between the water and oil galleries is my concern.

The seal near the 12 o'clock position should be OK as the gap is within the manual specs (i.e. less than 5.5 thou) but the gap at the 6 o'clock position exceeds the manual specs and the head gasket seems uncompressed at this position.

One solution is not to worry and use some 515 (or similar) gasket paste on the gallery sections of the head gasket to fill up the space.

Another is to fit the liner to the block and then have the protruding section of the liner milled down to a consistent height (say 4 thou). Of course the liner must then always be refitted in the same position.

The hardest solution is to have the grove in the block reworked to ensure a proper fit.


??????

Have you tried installing and measuring the old liner? Does it have the same problem?

What is the thickness of the fiber portion of the head gasket?

Obviously, if you can get the tool that will cut the lip recess square and to the proper depth that would be the best solution. Depending on what the tool references on that may be harder than it seems.

Hate to ask again, but are you absolutely sure that there is no burr or contamination in the seat, or possibly further down in the bore, that is either keeping the liner from seating fully, or canting it to the side?

I would definitely figure out a way to clamp the liner and measure again, as suggested, if you haven't already done it.

You might also compare the OD of the new liner at the bottom with the OD of the old one, just for grins...