"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.

 

[RichNJKubota]

I've rebuilt and repaired alot of car engines - wet sleeved and no sleeve. Bottom line is that if there is a piston sleeve I'll put new piston, rings and sleeves in and if no sleeve then it's more time and money to do it right - by stripping the block down and taking it to the machine shop for re-boring. If the car is not worth the effort then it does not get done. It just gets new pistons and rings or possibly just rings and cylinder honing. You live with the potential issues of oil consumption, lower than optimal compression, shorter engine life, etc.

 

[Soundguy]

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.

Hmm.. I think you probably will have to narrow that 'engine' range down a bit.

I'll put tractor some tractor engine designs from the 60's on the table as lasting longer than some of the aluminum throw away junk that we are seeing now..... the very fact that these engines have survived in good running order with virtually no maintenance in some cases.. for? 37-47 years is a testament to their design..

Soundguy

 

[gemini5362]

I am sorry soundguy I wrote my post badly. I meant to say if you are talking about engines in general then car engines and pickup engines in the 60s and 70s were considered to be on the verge of worn out at 100,000 miles.


How would you compare mileage or hours as may be the case on a tractor engine versus car engine. Do you have any kind of idea what would be considered a risky amount of hours on a tractor engine where you would be figureing the cost of rebuilding it into the price if you were buying it ?

 

[Soundguy]

Actually.. that in and of itself makes a big difference.. IE.. rpm range. mostly old tractors are low rpm.. low compression engines..

That low rpm saves them a bit of wear and tear.

I am sorry soundguy I wrote my post badly. I meant to say if you are talking about engines in general then car engines and pickup engines in the 60s and 70s were considered to be on the verge of worn out at 100,000 miles.

How would you compare mileage or hours as may be the case on a tractor engine versus car engine. Do you have any kind of idea what would be considered a risky amount of hours on a tractor engine where you would be figureing the cost of rebuilding it into the price if you were buying it ?

Hours are generally only a flimsy guideline untill you get real high.... Actual condition of a tractor makes a better determination of fittness. Things like ' how rounded is the clutch pedal'... state of repair.. maintenance.. etc..

In general though.. I pretty much considder anything under 1000 hours as 'break in'.. and for cut.. would expect 4000 hours of use out of an engine... In larger diesels.. 6-8 is a good lifespan before rebuild. I've seen well maintained diesels in the 10k and 12k range that were just starting to get tired..

Soundguy

 

[art]

No matter how you look at it car engines and tractor engines are different in design. We have ag tractor engines reaching into the 15,000 hour to 18,000 hour range with good oil and maintence. This would equate to over 500,000 miles if, I say if a tractor engine ran at 1/4 throttle and 1/4 load!!!! So multiply that times four for an accurate comparison! Just think of over two million miles on your car!!!!!!! We have tractors in our area that are pushing the 40,000 hour mark with normal rebuilding of the components.

 

[Soundguy]

Reminds me of a 80 or 81 mack tractor ( semi ) that our company sold a few years back. We bought it used from a milk hauler.. had nearly 800K on it.. they gave us the service logs for it and it never had any work on it other than routine service. We dropped the mains and they were virtually at new tolerance levels... left the m like they were.

We ran it for years and got it to nearly 2 million when we sold it. All we ever did to it was a new air compressor, and the rear, rear diffy was replaced.. aside from regualr maintenance items...

That thing just always wanted to go.

When we sold her we replaced her with a western star that.. while more powerfull.. just didn't have the working spirt of that old mack. Sure.. at 2 mil miles she poured some black smoke out when hauling 80,000 pounds of heavy equipment on a flatbed... but she always started right up and newver broke down on us... They just don't make passanger auto engines like that...

Soundguy

 

[D7E]

Whith ford tractors just bore em out bigger and put sleeves in "Turn a ford into a cummins" LOL
But other brands like CAT or DETROIT i've wasted a lot of money rebuilding a dead duck , Recently $9'800 dollars rebuilding a detroit 671 turbo and still a peice of s@#t , you have to look at what it's going to cost , I usually do all our own work but i am not familiar with detroit "two cycle system" so i payed a very reputable shop and still got a bill of this size , I could have rebuilt a cummins or perkins my self for half of this and knew what i was getting or like my initial thought "Rip it out and put a cummins" But i got talked out of this .
I realy don't think sleeved or sleeveless makes a better engine ,I'm an absolute lover of every thing ford( diesel) and i've had good results with CAT 3208's but a sleeved engine you can rebuild yourself and labour is the killer .
Cummins build engine and thats all they do ?
Motor manufacturers , Theres no rule i've rebuilt 3000 hr JD's and i have Cummins 855's with 9'000hours and never had mains and don't burn a drop of oil ?

 

[glmf]

I have zero experience with tractor engines, but a lot of years with stationary diesels in gensets. Cat 398 and 399 were absolutely bulletproof. We had a 399 that ran a whole year with 23 hours down time. That was for oil and filter changes, and an injector or two. These engines were of the wet sleeve type and could be rebuilt nicely after some spectacular failures. Actual block repairs were very rare and if needed, very costly as it had to go out for those repairs. Also had Fairbanks Morse opposed piston, that was wet sleeved and again same types of plus and minuses. As stated, to determine which type is better would depend on wants and actual application,,IMHO