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Discussion Starter #1
Started up my tandem a couple weeks ago and saw a few puddles on the floor under the exhaust and from behind turbo piping. This is beyond my scope to tear into so took it to a truck shop and looks like they found the leak into #5 cylinder. Initially they pressurized cooling system and everything was fine, then dropped pan, turned crank a bit and that uncovered the hole.

So they will pull heads and see where we go. It's a 76 KW and as far as I know, it's original engine as have had truck for 20 years.

Shop is a little worried about what they will find given the age. It ran fine, oil pressure 65 psi when hot at 2000 rpm, used no oil. Just needed water now and then. If its too far gone, how hard is it to swap in a newer engine. I don't think it's a Big Cam, do the BC's interchange easily? Truck gets 1000 miles a year, plan to run it another 20 years, looking for some insight as to when a guy throws in the towel on the engine and what he is getting into looking for a transplant.
 

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First off I hope these mechanics have actual experience with those older 855s, the simple fact they are saying they are worried about what they'll find concerns me, big deal you got cavitated liner by the sounds of it, cracked possibly, throw a cylinder kit(slug and jug) into just that hole at min, the one beside as well since that head is off already and given its age, roll a set of shells in the bottom end rods and mains, reset the top end and go. Whether the other two heads need to be pulled and the other four holes done is something that can only be determined by actually looking at the condition of the engine and I can't do that long distance. It takes an experienced set of hands to properly set one of these up so I am hoping your mechanics are familiar with these engines. Not as sensitive to settings as a two stroke Jimmy but it does effect performance.
Anything that needs to be done can all be done in the truck.
One thing that concerns me is if it has been run much with water in the oil, that could somewhat raise **** with bearing journals on crank, but again can't say with actually looking.
76 is probably Small Cam, reason for names given is a SC has a 1/2" smaller cam shaft diameter than a Big Cam. Same basic block externally and engines do use some common components but not all. Heads are the same I believe, but followers and rocker boxes ect are diff. Yes they can be interchanged as a complete assembly fairly easy.
Guess this is kind of short and blunt, sorry bout that, I'm tired lol.
Anything else, ask, tomorrow is another day.
 

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First off I hope these mechanics have actual experience with those older 855s, the simple fact they are saying they are worried about what they'll find concerns me, big deal you got cavitated liner by the sounds of it, cracked possibly, throw a cylinder kit(slug and jug) into just that hole at min, the one beside as well since that head is off already and given its age, roll a set of shells in the bottom end rods and mains, reset the top end and go. Whether the other two heads need to be pulled and the other four holes done is something that can only be determined by actually looking at the condition of the engine and I can't do that long distance. It takes an experienced set of hands to properly set one of these up so I am hoping your mechanics are familiar with these engines. Not as sensitive to settings as a two stroke Jimmy but it does effect performance.
Anything that needs to be done can all be done in the truck.
One thing that concerns me is if it has been run much with water in the oil, that could somewhat raise **** with bearing journals on crank, but again can't say with actually looking.
76 is probably Small Cam, reason for names given is a SC has a 1/2" smaller cam shaft diameter than a Big Cam. Same basic block externally and engines do use some common components but not all. Heads are the same I believe, but followers and rocker boxes ect are diff. Yes they can be interchanged as a complete assembly fairly easy.
Guess this is kind of short and blunt, sorry bout that, I'm tired lol.
Anything else, ask, tomorrow is another day.

x2 on that plan, given that low usage I would just make it work again without fluids going where they shouldn't. And it dont really matter a rats ar** if the rest of the engine isnt 100%, 95% is good enough. As long as it starts and runs for 1000m(1600km) you dont need or want to be spending a lot on it.
 

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The truck shop where I worked had a rule "any head off is pressure and crack checked"
also we sometime did "pistonless inframes" on the newer engines with stainless steel pistons. Yours won't have stainless pistons but with so few miles used you might just change the rings, liners and bearings.
 

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It sucks when the old reliable lets you down! But other than what has happened with a cavitation hole I think is what you are saying, those engines are going to run a long time doing what we do with old farm trucks. They don't need to be in perfect specs to run ok and do the job for 1-2,000 miles a year. I agree with AB and the others, change the cylinder kit, maybe two, make sure the bearings are good if antifreeze has gotten into the oil, and evaluate whatever else you have opened up in the process for condition. Good luck with the fix. I have a NTC 350 about late 70's or early 80's vintage that drove into it's current parking spot about 12 years ago that I would part with pretty cheap if you get to that. I kept it for a spare just like what you may need.
 

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In a perfect world the coolant would get changed on equipment more often but we all know how that goes and certainly the seldom used engines get the least love because so few hours get put on them. A neighbor had a friend of his do an in frame this winter on a C15 as it had been pressuring up the cooling system and I wasn't quite sure if it ended up being a crack in the head or a liner that caused the issue but I got to see the old liners and that was rather scary. In that case every one of the liners had cavitation issues "worm holes" I'll call them drilled into the outside of the liners, some liners more affected then others but it was a wakeup as to what can take place in an engine. When that liner is pulled you will see what the culprit is and make a decision at that point as to how far to rebuild the engine to give you more years of life. I would guess if you are using extended life coolants in other equipment that it goes that way as well to avoid mixing and then never use a coolant filter with DCA in it again in that case.
 

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Discussion Starter #7
You summed up the reason I posted AB, i get a little leary when someone uses the "opening can of worms" angle too much before starting on anything. Although, on the flip side, guys that run a decent business do get frustrated when telling customers the job could get expensive and then when it does, the customer is pissed off and giving the shop a bad rap. So I think it just comes down to how many people are easy to deal with this days as to what comes out of a mechanics mouth initially. Will have to see how it plays out.

I never had water in the oil previously, always clean. But the leak certainly accelerated this spring so may have got a little just sitting at shop, dipstick looked fine to me the day I drove it to the shop. If it did have some coolant in oil that my eye didn't notice there was not much run time and not much load.

Figured if I get some news next week that raises my eyebrow I would start posting to ask for thoughts so decided to bring it up now. Low miles per year is one thing, the other is need to freshen things up now to make sure that age doesn't take its toll in another 10-15 years. So I would prefer doing all 6 liners, maybe check the heads (they were redone not too long before we got truck), put a water pump in too. I don't think bearings, rings are an issue as age doesn't do much to them vs what run time does.
 

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If your looking out 10-15 years and this can’t let you down in season then might as well do an inframe. They’re pretty economical to overhaul but even with some cheap labour still looking at 10K.
 

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Them old Cummins are pretty tough animals. We have a big cam 400 that dropped a push rod after being over revved. Pulled the pan off took out the rod in 3 pieces. In all put 3 new rods in set the top end and away she went. Any truck shop worth it’s salt should have no problem with a leaky liner. Heck around here running take outs can be had for 3-5000 dollars
 
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