JD 855 Won't Start

jbarker855 · Mar 11, 2011

Your troubleshooting seems sound, and I cannot think of a better reason for it not to start. BUT.......I gotta say, it makes no sense at all that your engine loses compression overnight. If it ran when you put it away, I highly doubt that a rebuild is necessary now. Hold tight, talk to more people before you go through with this total rebuild you are considering. I second the ether comment. Just disable your preheater when doing this.
-Jay

Mechanos · Mar 13, 2011

YesDeere said:
I know your not supposed to do this but, hit it with a little ether. If you can get it to go then you can rule out everything else. Only use a little bit. When starting turn the key to crank right away so the heater doesn't have a chance to get hot. Once it is cranking then spray. Done this many times on older trucks and reefer units that had low compression.

Got a little pup trailer through thanksgiving time this way. Would not start on it's own. Gas it and go. Although it did have over 20,000 hours

jbarker855 said:
Your troubleshooting seems sound, and I cannot think of a better reason for it not to start. BUT.......I gotta say, it makes no sense at all that your engine loses compression overnight. If it ran when you put it away, I highly doubt that a rebuild is necessary now. Hold tight, talk to more people before you go through with this total rebuild you are considering. I second the ether comment. Just disable your preheater when doing this.
-Jay

If you're going to try the ether.... do as jbarker suggests and remove the air heater control module. Simply turning the key to start real quick won't keep the air heater from getting hot. If it's below 40 degrees, the control module while energize the air heater. After 15 seconds, the dash light will go out, but the air heater will continue to operate for another 45 seconds or so.

David-Davies · Mar 13, 2011

I was told by a machinest, to use wd-40, to start a diesel, if that doesn't work then use starting fluid. I spray the air filter while it's turning over. I should say not spray, but squrt, small squrt, you can allways spray more, but you can't get it back, once the engine is running.
Dave

Dennisfly · Apr 30, 2011

Follow-up

I removed the head and the pistons. The engine is extremely clean inside. No sludge at all. The head gasket looked good - no sign of a blow out. No obvious problem with the head like cracks or burned valves. The cylinder ridges were composed mostly of carbon and after using some emery paper, the pistons came out easily without using a ridge reamer. None of the rings were stuck or broken. The ring lands were in perfect shape and the ring to land clearance was in spec. The was no scoring on the cylinders and no galling or scoring on the pistons.

Off to Harbor Freight to buy a set of Mics, telescoping guages, and a digital caliper. I must say I'm impressed with the quality for the price. The 6" caliper was only 10 bucks with the Inside Track coupon and it is accurate to .001" as advertised and compared to the mics and the mike standards. I was shocked!

The cylinder taper was minimal and within spec for all cylinders. The piston skirt measurement was within spec, as were the conecting rod bearings and crank journals. Now I'm beginning to worry that I can't find anything wrong. I put the used rings back in the cylinders to check the end gap. Each gap was approximately 1/8" or .125". The spec calls for new rings to be .008 to .016 with the maximum allowable .059 - Bingo! Worn rings as suspected.

I honed the cylinders with a flex hone which worked great - a nice 45 degree crosshatch pattern. The end gaps for the new rings were all .008 to .016 per spec. I installed the new rings, new rod bearings, and sent the head to a machine shop for a valve job. Three new intake valves were required, as each had a wear ring on the face and the valve would be too thin if ground. The valve guides and exhaust valves were good. The head flatness was out .005" so it was resurfaced. Talking to the machinist, he thought the ring and intake valve wear were caused by the engine being run at some point in dirty conditions with a damaged or defective air filter.

I got the whole thing assembled yesterday, bled the fuel system, and it started quickly on the first attempt and ran perfectly!

Costs:

Machine work $270, parts $550 but $220 was for a new injector that the machinist ruined getting it out of the head. I could't remove it with a slide hammer puller and he ended up heating it with a torch and damaging it to get it out. All parts were from the John Deere dealer. Tools $300 including a 2 ton engine hoist.

Hopefully, it will last a long time.