Eddie7295

Member
I have been looking at a 870 with a bad engine, owner says it spun a main bearing. I have not seen it in person what are the chances of the block being messed up? I know I am asking a lot from you guys but some of the mechanics that have seen a lot of bearing failure could shed some light on it. Trying to figure worse case scenario crank or crank and block.
 
About 10 years ago I bought a W14 loader which has the same engine as an 870. I knew it had engine problems that turned out to be a spun main bearing. If they are not to bad the crankshaft can be ground, and the block line bored. In my case it was bad enough so it would have left the timing gears, and piston clearance very tight. For the same money as the grinding, and line boring I bought a core engine out of an 870 and rebuilt that. On a tractor you have the option of pulling the oil pan, and the bearing to see how bad it is. On the loader the engine needs to be pulled before the pan can come off.
 


Depending on the severity of the damage to the block they can be line bored back to new condition. Likewise the crank could be turned to an undersize and be reused. I have seen main saddles built up with brass and rebored.

I guess from your perspective you do not really know the extent of the damage.

I would hate to see an 870 diesel go to waste, Good luck.

mEl
 
The block and crank are two items for concern. I would also be very concerned about the condition of the balancer, which could be OK, but when dealing with a stuck engine nothing would surprise me. The last time I needed one a few years ago it took 7 mo. for a good one to become available. Be sitting down if you need to price one. Rod.
 

1370,

Have seen some small journal cranks snap after a regrind, if the crank show bluing from heat that would concern me as well.

Purists may throw a fit but the 780 backhoes used a front main cap mounted oil pump and by machining the front cap the pump can be installed along with the piping from that engine also. Most farmers if given the option will go for the cheaper fix.

I have done several of them and there is a slight harmonic just above idle but smooth after that.

If I were pulling one of them the balancer would be the first thing to go, imagine what the balancer is doing at twice engine speed! Not to mention the power soaked up running it that fast.

The first of those series engines were not equipped with balancers and their reliability and durability cannot be faulted.
 
Mel, the fix you are referring too was that part of a case bulletin?

I have never heard of a fix like that before. Do you have more information, such as how the cap is machined or part numbers?
 
What if you where to take the crank new or used and have it
balanced at a machine shop like the high performance
diesels? If the crank was internally balanced this would do
away with the need of the balancer and then install the front
mounted oil pump? I don't know enough about the difference
between one with a balancer and one without we have two
870s and they both have the balancer in them. I do know in
order to balance the crank the vibration damper in the front
and the flywheel have to be on the crank when it is done. Just
throwing out ideas!
 
The balancer isn't about balancing the crank. It is about smoothing out the sudden stops that the pistons are making top and bottom.
 
Interesting Mel, I had no idea they could be run without a balancer. That gives new hope to reviving one of those engines. I am sure the day will come sooner than we wish when a good balancer will be near impossible to find. Are the oil pumps used in the non balanced engines similar to the 9-1070? Rod.
 
I once worked on a really nice white 870 that the balancer went bad in and they replaced it with a 1070 oil pump. That one shook over about 1500 rpm
 
RG, the thing that has always puzzled me, you would think a 4 cly engine that has 2 cly up and down at the same time would cancel out vibration forces. But as we know nothing could be further from the truth.
 
It is not my intent to argue the pros and cons, the simple fact is that the 780 engines did not have them. The cap needs to be milled flat ( believe the dimension is 3") to support the pump and one hole has to be enlarged to locate the pump dowel. None of the pre 30 series had the balancer and worked just fine. Just a thought, I wonder if the rubberized damper off of the later big 6s would be an advantage for those that think it is a problem.

We stroked a 730 1/4" by using a 870 crank with the rod journals offset ground and the mains turned to the small crank diameter, bored the block to 4 5/8 sleeve dimensions for 350 cubes.

It was the counterbalanced crank with the balancer drive gear removed and was smooth without the balancer, that one we used the standard cam driven pump.

If a customer brought me one to do I would do it without hesitation. and I have done several.

I will leave the rest of you to debate whether it is right or wrong. After bringing everything to the same weight with precision scales, bringing the pistons to the weight of the lightest and weighing the big ends and small ends and bringing the weights to the same, a 4 cylinder , even a DC can be made very smooth.

BTW, 730--830s before sn 8353500 had NO balancers, a quick look at the earliest on CaseIH parts search show the cam driven pump with the distributor drive on top.

I'll bet some are running these engines and don't know the difference.

The things I have posted I am not theorizing on, I have done them and probably all still running.

Some of my engines so done were to get rid of an arrangement gobbling up HP at twice the crank rpm for pulling purposes.
 
We have 3 870's of them in the scrap row ,some day they will be going to the scrap yard along with around 15-20 others/taking what we need & they will be gone.
 
Thanks for the info Mel, it is encouraging knowing these engines have been converted to run without a balancer. We had a Plymouth mini van with a four cly. and that engine even had balance shafts in the block. And then our 430 runs great without one, go figure. Rod.
 
Thanks for all the info, found a machine shop that will balance
the crank for 300.00. I am with Mel there is no doubt that they
can run without the balancer. I called case with the part # for
the balancer they did not have one and if they did it would be
3200.00. I would think if you where to completely balance the
complete rotating assembly like Mel said you could get rid of
the vibration.
 
Mel, now knowing about the 780 being produced without a balancer is really interesting. Have you wondered why CASE would go through the extra expense of installing them on some of the ag tractors. The HP they consumed was I factor I never really gave much thought to. Also thinking about it DB never bothered with a balancer and they ran quite smooth. Rod.
 

1370,

One could debate this till the cows come home, there are certain forces within the reciprocating assy of 4 cylinder engines that cause some vibrations but these are present irregardless of the balancer or not. The bigger the bore and longer the stroke the more pronounced the problem becomes. When you are after performance tradeoffs are made, a 7" stroke DC is certain to have more tendencies to vibrate than a 5.5".

If nothing else can be changed to engineer this issue out then it seems logical to assume that the balancer is there to simply mask the problem as the same forces are there whether the balance assembly is there or not.

Reading some online stuff it is theorized that the balancer may consume as much as 15 HP but nothing definative to back that up. Many newer 4 cylinder engines use balance shafts that run in the block rather than bolt in assemblies, I believe that JD has engines so designed.

Do not get me wrong, I am not advocating taking a good running balancer engine with no other problems and gutting it out, Just that the realities of the cost of a crankshaft/ balancer assembly as was the case when the three gear balancer was discontinued and the two gear introduced made good tractors otherwise sometimes uneconomical to repair. as with all controversial subjects there will be good people lined up on each side of the issue, that is what makes for good discussion.
 
Getting back to the original question, I think DCase is on the money with his advice. We had a Case 870 the year they came out. Turned it up to 100 hp and ran it hard for 12 years. Put on about 500 hours a year. It had mediocre maintainence. Maybe we were lucky. I know the tractor is running today.
Back to your problem. Assuming the block can be line bored, crank can be ground, rods reworked,
head redone, new injectors, check pump?
A core engine or takeout engine might look better and better.
Maybe I am prejudiced, but unless you can get the tractor dirt cheap; stay away from engines that have spun mains. Across all brands we throw away 2 out of 3 blocks with spun mains. Cost almost as much as a good used block to recondition.
 

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