J.A.R

Member
Just got done rebuilding a m670 super diesel with new heads. Problem when trying to start it I can hear/feel air puffs come out by rocker arms on #2 cylinder. Is this normal? No other cylinders are like that. Haven't got it started yet but working on it.
 
Got it running but it has a miss to it but seems like it's firing on all 4(really only misses when over 1500rpms). I can feel the air coming by the push rod hole. The last pushrod on the 1st head. If it is a compression leak what would cause that. Brand new heads and gaskets with more than enough time to properly torque and recheck everything.
 
No pressure on block to jug gasket but there is a small mist of oil it looks like from breather on valve cover. But I also oiled everything good only have had it running for about 30 45 mins now
 
Just looking at a head gasket. Has to be leakage in head gasket between #2 and that port.
Maybe warm up and torque again. What are you torquing at?
 
Torqued em to 135 and 175. Haven't readjusted the valves yet but will when I retourque. Would that have something to do with the miss.
 
Leaking compression around an injector? If the seating surface in the head was eroded away it will not seal.
 
Would doubt it. Were blocks planed? On a diesel if your compression is down usually misses
until warmup and get white smoke. On a diesel I use the thin block gaskets and thinner head
gaskets. Brings up compression to start better.
 
Chris, they are new heads that have been pressure checked and magnifluxed but I will pull that injector out and check the copper o ring just to make sure it seated right. I will get back to you guys and let you know what I find. Thanks for the help.
 
It starts alright when warm but the smoke never really goes away but the hottest iv had it was around 160-170. It is kinda bluish smoke but it does lessen when it reaches that temp. Block was line bored and planned for squarness.
 
Hope for your sake it's the copper rings around the injector. I had that on a 97 Massey. My machine shop had failed to remove the old copper rings. When I started or attempted to start the machine I was shocked by the sound of escaping compression. Old rings removed, mating surfaces cleaned up, new copper rings, all set!
Curt
 
Pump was not rebuilt but new lines made pressure and return also injectors were rebuilt. Sometimes tho that back pressure valve on top of pump for the return gets plugged.
 
Anytime the top pump return fitting plugs the injection pump needs repair SOON! The retainer ring is breaking apart inside, and bits are plugging the valve. Keep cleaning the fitting and running the pump and soon it WILL shear the retainer pins, locking the hydraulic head, and break the drive shaft. When guys bring me pumps like that it gets much more expensive than it needs to be. IF only they had removed the pump sooner..
 
I guess I don't know who named any Moline engine a long life motor because after 4800 hrs and at least 1 major overhaul and all the thousands of dollars and time spent on this tractor....its got to be the worst tractor ever made. For some reason parts are extremely hard to find and if you find them they cost 3 times the amount any other manufacturer costs. Always thought jd was expensive but after this money pit that ain't worth nothing...should have bought a oliver diesel. Least you can get power outta them and find parts for a reasonable price.
 
I guess lol just didn't think that this thing would have cost me an arm and a leg. Wasent a seal or moving part on this thing that didn't need to be worked on. Apparently it was well abused.
 
A 670 super diesel is an awesome tractor. When you have it done, the money won't feel nearly as wasted. I'm rebuilding a 1966 right now. Only needs a motor, radiator, PTO, ampli torc, wiring, steering rebuilt and hydraulics gone through.. although that's pretty much the whole tractor.
 
Know of a real late 670 diesel. Guy bought it new. Has nothing but trouble with it. He
finally parked it. In real nice cosmetic shape. Was always scared to buy it dueto it's
history.
 
Finally got a chance to see what's going on. I can see oil bubbling out from every injector where the copper gasket is. I put a dab of grease on each one 2 make sure they didn't fall off during installation. Would that cause the problem? I also retourque the injectors I think they are only suppose to be at like 14 ft lbs. Don't seem like enough to me.
 
I had a special reamer made to clean up and cut out small pits in the head for the seat of the injector. If your injector seats are not good and smooth somebody sold you a bad set of heads.
MMDEL
 
Not sure of the relevance but I did injectors and pump on the 670 or 900. Don't remember which but when I replaced the injectors I noticed part of a seal or gasket material in injector ports. I new enough that I had to clean the old material out to get a good seal of the injectors. I was able to find a wood bit from and old hand brace. By inserting into the injector port and turning the bit by hand I was able to clean all old material out. Must of worked because no leakes and tractor ran just fine.
 
Guess I'll give that a try cuz I just ran it now for an hour and popped the valve covers off. Still got a leak on #2. Shoulder have to touch the heads as I spend 1800 bucks on them. Plus I looked everything over before I installed them. It just pisses me off and is quite sickening. Just hope that's all it takes. But thanks guys for the help and suggestions.
 
Part of the reason for the cost is they have been out of business for a few
decades. Parts are expensive which isnt ever a good thing but at least they are
still available.
 

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