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986 overhaul

D

DTK

Member
Have 986 with 1 scored piston, no. 5. All other sleeves and piston in specs. according to IH mech. He suggests just replacing no. 5 along with rod and main brgs. O-rings and piston rings plus valve job. What are your opinions of this idea? Thanks DTK.
 
I would do the whole thing,you are going to have the head and pan off any way.You can buy a complete overhaul kit for not much more than buying bits and pieces.Don't waste your time and money.
 
Did just that on my 706D(310) 28 years ago.4000 hrs later it is still running.In fact it got a used sleeve,reused the old piston.Today it got more time on the clock.Over 11,000 hrs total.
 
Check your other sleeves. I bet they are full of cavitation pin holes about to penetrate thru the sleeve. Very common issue for those engines. In fact if you examine your scored sleeve I bet you will discover that's what happened to it. A hole went thru, coolant hit the piston washing away the oil causing it to score then the smearing aluminum resealed the hole. That's what happened to my 1066.
 
Completely different engine.

At less then 150 hours per year, was this tractor just used for loader work or to pull a wagon out of the barn?

I'd say from just the hours per year that this tractor had a very easy life and probably why it held up so well.

For the 986 I'd replace all the cylinders with sleeve kits (piston, rings, sleeve, etc), make sure their is a water filter on it or add one and put in the DCA-4 antifreeze additive. Should be good for another 5k-10k hours.

Check for cavitation holes as if antifreeze got in the oil I'd also replace the bearings. I'm assuming that the rod and main bearings don't have grooves or other damage and are with in spec.
 
it appears like he has done his homework by checking the others , so I would give him a go ahead.
just curious why only one piston is scored.
don't forget the shop foreman would be involved in this decision also, that's if its in an ih shop. unless the mech. is doing a side job.
like are u paying shop labour or mechanic's labour. like 120.00 vs. 20.00 is a big factor also. we never get full facts and reasons. but if all sleeves and pistons are checked then there is no problem what he is saying.
 
I agree with the guys if they are the original sleeves , I would do them all because of cavitation. The only way I wouldn"t is if the engine has a water filter kit on it . I installed #5 on my uncles 1066 years ago and with in a year we had to redo it because #1 sleeve started leaking antifreeze in the oil. The second time we completely overhauled it . I also installed a water filter kit and changed the filter at least once a year . He put nearly 7000 hours on it after that till he retired. The only thing done to the engine after the overhaul was rods and mains at 5000 hours since the overhaul. I would suggest putting on a water filter kit . If not check your coolant DCA level at least once a year, with test strips you can buy at the dealer or autoparts store. I use the Fleetguard strips, I get them at the CNH dealer or the Deere dealer. If the test strip shows the DCA level is low, I put a bottle of additive in. Good luck .
JJ.
 
dtk said that the mechanic was going to replace the O-rings... so when sleeves are out it is pretty easy to see cavitation. cavitation holes just don't start all at once... cavitation is happening when the engine is running. once the sleeves are out the story will be told, as the whole set being replaced is very possible. i am sure he would have made customer aware of this.
 
If your mechanic has pulled the other 5 pistons and sleeves there is no other way to see cavitation or bad orings. Was the piston ring gaps checked? Did he mic the crank? He's in there now.
 
Cavitation is caused by the reaction of the heated coolant to the sleeve metal. Small bubbles form and the corrosion process begins. Cavitation is not caused by the coolant being pumped across the sleeves.
 
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