"Parent Bore" vs. sleeved engines

[Bob_Young]

I see TC is pushing it's non sleeved (Parent Bore) engines as an improvement over sleeved engines. They identify "improved rigidity" as a feature. Of course virtually every iron block automobile gas engine made is non-sleeved so this isn't exactly earth shaking technology even if it does have advantages.

My impression was always that the sleeved engines were superior because they could be rebuilt an indefinite number of times; even after substantial cylinder damage. Non-sleeved engines, on the other hand, could only rebuilt until cylinder wall thickness was reduced (through wear or machining) to some minimum value. Debris (such as a valve head) bouncing on top of a piston can quickly reduce a non-sleeved block to junk while a sleeved block may only require a new cylinder sleeve.

So, TBN engine gurus, what's the verdict? Does the sleeved engine truly have better rebuild qualities? Since few Compact tractors will be rebuilt more than once, does it really matter if sleeves are better? (No point in paying for an advantage that might never be needed.) Are there advantages to the "Parent Bore" engines (such as lower cost, more easily maintained tolerances, rigidity) that make them better choices for the compact market?

To my knowledge, all compact tractors currently have non-sleeved engines (unless Perkins powered) while larger Ag tractors and most old Ag tractors of any size were sleeved (except Fords).

Just a rainy day question.
Bob

 

[scott_vt]

So, TBN engine gurus, what's the verdict? Does the sleeved engine truly have better rebuild qualities? Since few Compact tractors will be rebuilt more than once, does it really matter if sleeves are better? (No point in paying for an advantage that might never be needed.) Are there advantages to the "Parent Bore" engines (such as lower cost, more easily maintained tolerances, rigidity) that make them better choices for the compact market?

Just a rainy day question.
Bob

Mornin Bob,
Well I guess I can comment on wet sleeved engines. Both of my old Farmalls are wet sleeve. The biggest advantage IMO is that you could perform an in tractor engine rebuild without removing the whole engine and sending it out to a machine shop !

You are correct in that todays CUTS are non sleeved. But what you have to remember is that these modern day diesels can go thousands of hours before ever thinking about rebuilding ! The old gas Farmalls were worked hard in their day and even though they only had a top RPM of about 1400 rpm they did wear out when doing heavy tillage and such.

Hopefully this answers part of your question !

 

[art]

Bob, the parent bore engine can be dry sleeved to restore it back to near new condition. This is how they are fixed when they casting flaws where you might wear in to the coolant area or have a part flaw that might have gouged the cylinder wall.

Many of the older engines were dry sleeved, it was the first way that they stated making so you could rebuild a engine to new spec's on the cylinder bore. Today many of the bigger diesel engines are wet sleeves for tractors and trucks. There are advantages and disadvantages to this system of cooling. The cylinder liners are more consistant in thickness and they bring the coolent closer to the cylinder which alows it to cool the engine better. They are normally just removed from the top of the engine when it's time to rebuild. They have learned something new with this designed called cavitation which causes coolent leaks into the oil system. The sleeves often walk while the piston is going up and down and on the outside or coolant side they will pit and go through. This is normally caused from lack of maintence to the cooling system.

Not for nothing but there are many engines that have what I call "old tech" basically using soft metal for the crank which on some engines will nessitate the removal of the crank to have it turned at rebuilding time.

 

[Farmwithjunk]

Both technologies have their place. Parent bore blocks have an ever so slight degree of less machining and assembly time to reach a finished stage, making them more economic to build. Wet sleeve engines arguably have a longer service life, with ease of rebuilding extending their usable lifespan at a lower final cost. Expected life of the machine that'll see the completed engine installed plays into the need for each. As well, replacement cost vs. re-build cost play a factor in which is best for a given application.

Anyone with across the board statements that one is "better" than the other draw this comment from me. "Better" at what?

Advancements in metalurgy, machining , and assembly make modern engines much better IN THEORY. Built-in obsolescence in todays engines negates those advancements.

 

[Soundguy]

Junk hit on some points. A faster to manufacturer engine may be a parent bore.. and you coul;d always bore and sleave it at rebuild. Ford palyed around with this.. look at the ford 3000. Sleaves are part of the rebuild kit.. but were not oem.

Soundguy

 

[Woodbeef]

One thing is a wet sleeved motor has a bigger chance of being torn down for repairs before a parent bore.

 

[Bob_Young]

Woodbeef: Interesting statement. Do you know why a sleeved engine has a greater chance of teardown? To my knowledge, Perkins engines are sleeved (wet/dry??). They've got a great rep.

Soundguy: I knew the 1000 series Fords were parent bore but wasn't aware the 3000 had sleeves in the rebuild kit. Dry sleeves, right? Must be a lot of meat in those cylinder walls when cast.

For a good basic tractor, the 1000 series was tough to beat. That's what keeps Farmtrac's Ford clones near the top of my list.
Bob

 

[john_bud]

While I am not Woodbeef, I am guessing he means that it is so much easier to do (and cheaper) that when the engine gets weak, you would rebuild a sleeved engine. But a parent bore block may be run until it won't start or smokes so bad the neighbors call the fire department when you run it in the day light.

jb

 

[art]

One thing is a wet sleeved motor has a bigger chance of being torn down for repairs before a parent bore.

There are more parts that can cause the leak, but,,,, Then how about all the poor castings that get out and not till it's got ten years and a couple of thousand hours before it has "cavitation" or so they call it and they replace the engine.

 

[gemini5362]

I am not sure what you are talking about. If you are talking about tractor engines I do not know enough to talk about it. IF you are talking engines in general. I believe that todays engines have a lot longer life span than those of the 60s and 70s It used to be that a car engine with 100,000 miles was an egnine that you planned on rebuilding pretty soon. My 1998 chevrolet tracker has 150,000 miles on it and I am expecting an easy 200,000 this is a vehicle that was sold as an inexpensive little fun vehicle.