I recently bought a 79 int dump truck. It's a heavy spec truck. 20k front and 46k rears, it has a 17.5 box and can be permitted to 66k with no lift ax. I bought it with a non running 6v92 I replaced the head gaskets thinking that was the problem. It did not fix the problem. The motor runs fine with a little blow by then drops water into the base. I'm debating on digging deeper into this motor or pulling it and replacing it with a conventional straight 6. I have a sec truck with the same 6v92 350hp I can't say much bad about it other than not happy with power. This new truck is much bigger and heavier and I feel should have something around 400hp. I would also like a jake brake as ill be hauling 18-20 ton loads an plan on trailering a 30k excavator. I feel this is asking a lot of the 6v92 seein as its only backed with an 8LL. I was looking at a 60series or 855 cummins. I'm looking for any ideas or info on a conversion or if anyone knows what might be wrong with the 6v92. I don't want to dump a lot of money into that motor. I'm not sure what direction to go. The truck is a good solid truck and is in really good mechanical condition (other than motor) has good tires and almost new front floats. I spent about $3000 on the truck, $1100 into the motor in it and feel as tho its worth putting some more into just trying to get a good direction to point. A little other info, I have found a running take out 60series for $1500 from a wreck and a dump with a running 855 for about the same. Thanks
Well we have a t450 kw tri axle that weighs 26k empty with specs like your truck and we only have a 300 hp cat with a 8ll. we pull a 30k loader and haul 18 ton on some very steep and rough highways here in southern mo it is not fast but we get by just fine. I agree that 400 hp and a jake would be alot more desirable but if you can get any idea what it is going to take to fix your 6v92 that would be my first choice if it was me. second would be if it will fit in this truck a series 60 i think they are the best motor you can get overall for fuel milage and power.
Thanks I agree 300-350hp would not be bad I think the problem with the 6v92 is not the hp but the lack of low end torque. I have heard a lot of good things about the 60series as well. I believe there are a few diff sizes of these engines. The one I'm looking at is a Detroit 60 Good running cond. 12.7 L.Series II 370 hp,RTCO 14610B
I'm baffled how the truck was spec'd "heavy" (20K front, 46K rear) and ended up with a 6V-92? Heck, with those specs, why didn't some bone head put an 8V-92 in it in the first place? A question we'll never have an answer. I'm not a "re-power" guru, just thought I'd point out, if you go with something like a 60 series Detroit, or other 4 stroke turbo engines, you'll likely have to add an intercooler radiator that the 6V-92 configuration of present might not have.
Lapatra172 - Well, you're never going to get any substantial torque out of a 6V92. You know the old saying? - about Jimmys are best at turning diesel into noise and leaks? It's very true. You drive them like you just jammed your hand in the door. Having said that, they are one of the most reliable engines built, provided you can put up with the exhaust note, the lack of torque, and the need to keep the revs high. Essentially, the Jimmys became totally obsolete in the early 1990's when they had trouble meeting emission requirements and their basic inability to be very fuel efficient. The only thing really keeping them going is the huge number of military Jimmys still in use. The military Jimmys will still be around for another 20 yrs, most likely. I understand there's still several hundred thousand in military use. If you can cope with all of the above Jimmy traits, then the quickest fix is to purchase a good low hour 6V92 and slot it straight in. The engine you have sounds like it has some major problems that only a total disassembly will find. If you have the time and $$$'s to remove, strip and rebuild your engine, then that is the best solution. You end up with an original engine, with a rebuild, so that you know exactly what has gone into it. You could also "tweak" the HP, with your own rebuild. Fitting a straight 6 of any make is going to involve a lot of work. The 6V92 is a very compact engine, length-wise, and the installation of an L6 with 400HP capacity means, that at the very least, the transmission will have to be moved rearwards. There will be a heap of work arranging new motor and transmission mounts - and moving the transmission means moving the shifter position - and more importantly, shortening the driveshaft. This will run into more $$'s. You may have to even move the radiator and its mountings forward with the installation of an L6. There will be a heap of work re-arranging wiring, plumbing, hoses, and possible air-cleaner re-positioning. I'd be looking for a low-hour 6V92 if the cost of the fix is important - but if the cost is less important, and the aim is to keep the truck long-term and make it perform much better, then an L6 conversion may be warranted. The 855 Cummins is a big engine, physically - the Detroit Series 60 is probably a better consideration due to its smaller physical size.
If you can find a much later model 6v92 with DDEC (Detroit Diesel Electronic Controls) then the lower speed torque is much more in line with modern engines. At some point they also got a bypass blower which makes them run more efficient.
Ihave to agree with OzDozer. The 60 series is an electronic engine which brings another problem,making it work in a non electronic chassis. Your could be leaking coolant around the liner o-rings or the injector tube o-rings. Do you have any coolant coming out the air box drains? Pressurize the cooling system with the valve covers off & see if coolant leaks around the injector tubes. If not drop the oilpan with the cooling system pressurized & see where it's leaking. If it has been getting antifreeze in the oil for any length of time I would change the slipper bearing on the rods along with rod & main bearings. Hope this helps Mike
Thanks for the help and info guys. It does look like a lot of work repowering this truck. I guess I better see what's out there for strong running Jimmy's first. (How did they get that name) ill put some thought into this and let you guys know how it turns out. Maybe Ill post some pics of the truck if I can figure that out.
The nickname started from "GM Diesel" being the visible name put on the engines when they were first released in late 1937. So, people shortened that to "Gemmy diesels", then over the years, "Gemmy" became "Jimmy". When I was a kid, they were called "Gemmys" locally, but "Jimmys" appears to be the more common nickname in use in the U.S., although it's a recognised nickname elsewhere, too. GM ruined it all when they changed the name to "Detroit Diesel" - but they still got called "Jimmys" I'd guess WW2 and the widespread movement of soldiers, along with the ever-present GM diesels in all the WW2 landing craft, led to the nickname spreading.
Thanks for the fun fact. I suppose I better get aquainted with the old Jimmy's seeing as I know own and op 2 of them. I have just found an 88 haun pumper truck with a 6v92 with 25,000 original miles I think I'm going to head in that direction and simply replace the motor. I have heard fire trucks sometimes pushed the hp a little higher is this true? If not what can be done to push this motor closer to 400hp? I was told 105 injectors but that the timing and turbo also need changing.
Anytime I see a thread come up that concerns an old 2 stroke Detroit, it's incumbent for me to remind all that these Detroits are picky about the motor oil used in them. First of all, do not use multi-grade oil. Second, the oil should be SAE 40 grade with a sulfated ash content of less than 1.0%. The oil that best fits the specs is Delo 100 SAE 40, Delo 400 does not meet the spec, Rotella T is borderline meeting the specs.
When I was running a 6V92, the cyl. o-ring on one sleeve failed. An experienced Detroit Diesel mechanic told me to particularly check the sleeve next to the engine block heater and he was right. We changed all the liner seals and new gaskets and put it back together. I was being cheap and it was running OK otherwise. We found the leak by pulling the blower and pressurizing the cooling system. It was pretty obvious on top and dropping into the oil pan. It ran fine after that until the truck driver decided to drive it 15 miles with a big compressor oil leak. When I got to it I had to add 5 gallons of oil and it was junk.
Well I am now the "proud" owner of a fire pumper truck. I pick it up sat and start the transplant. Motor was one of the cleanest I've ever seen, ran great, even started well cold. Hope she runs for a while. If anyone is Interested In an Allison 4speed auto ill have one on hand. Also gonna have a 1500gpm pump and some other parts. Thanks again guys
What is the beat way to tell the HP of this new motor I'm getting? Do I need to pull a valve cover and check the injector size or is there some badging or tags to look for that may help tell how this motor is set?
I second the idea that it had to do with WWII. Do you know when the name Detroit Diesel was first applied? There seems to be a following of the rare 1-71 generator engine on the Internet these days. Fire trucks did indeed have higher power but that comes at the price of decreased longevity. Still, that is a great place to look since they were used well into the 1990s on fire trucks, are usually low miles and can be had very cheap. If it hasn't been destroyed, all the info you need should be on the stickers on the valve covers. Take a picture of the valve cover stickers if you can. Try to not destroy them with brake cleaner or whatever. Remember a candle that burns twice as bright burns half as long. 400 HP on these engines (I had a 1993 DDEC 2 motor at this level) is very hard on them and it is about the absolute max they are capable of. And that might be with DDEC only plus all the mechanical upgrades that came with it. Another great idea. I don't know if that Delo 100 straight 40 is hard to find now but when I had one to maintain it was easy to get from the local Chevron wholesaler. I don't think that Delo 400 straight 40 is that bad if the 100 can't be had, though, overall.
Thanks I will try to upload the valve cover pic once I have it. Prolly this weekend.
I second Willie on the oil selection. It's absolutely crucial to run the correct 2-stroke diesel oil in GM/Detroit 2 stroke diesels. Birken - The GM diesel became Detroit Diesel in 1965. Wikipedia gives a fairly basic timeline of the GM diesel product lines, although a lot of detail is lacking. http://en.wikipedia.org/wiki/Detroit_Diesel Lapratra172 - That's a good purchase. Firetrucks get well maintained, although they get hammered, pedal to the metal, from cold - so they probably suffer from higher wear, than engines warmed up properly.
Yair . . . A bit more trivia. As I understand it the original General Motors Marine versions of the screamers were painted grey and were known as "Grey Marine" engines thus maintaining the "GM" initialing. Cheers.
Scrub Puller - Sorry to blow you out of the water, so to speak - but the name is Gray, and it has nothing to do with colour of the engines, nor the GM name. The name comes from two brothers by the name of Gray, who were the sons of a banker, John Gray. The brothers commenced operations as the Gray Marine Motor Company in 1905. The Gray Marine Motor Company was formed with O. J. Mulford, president; Paul Gray, vice-president; and David Gray, secretary-treasurer. The Gray Marine Motor Company built its own engines, and went through a long and colourful history of changes before becoming an automobile manufacturer between 1921 and 1924, whereupon it fell into financial ruin. Mulford purchased the marine engine portion of the Gray company in 1924, and from that point, the reformed Gray Marine Motor Co became a marine engine conversion specialist. Gray Marines biggest coup was the deal (initiated in late 1936 and completed in 1937) arranged between Gray Marine and GM, to marinise the forthcoming all-new GM 2 stroke diesel, that appeared in mid-to-late 1937. WW2 saw Gray Marine converting 100 GM diesels a day to marine engines for the War effort. That would have been a "nice little earner", as Arthur would say. Neither GM nor Gray Marine were directly linked in any corporate manner, although GM tried to buy Gray Marine during late WW2. Continental became the preferred suitor. Gray Marine was acquired by Continental on June 14, 1944 for $2.6 million, and the company became the marine division of Continental. Gray Marine was closed down by Continental around 1967. Read more: http://gasengine.farmcollector.com/gas-engines/gray-marine-engines-history.aspx
Looks like the valve cover stickers are in good shape but not legible in that picture.
Well guys if your still following along. The motor an trans are out of the dump truck. (Not as hard as I had expected) the fire truck is here and I've started pulling that motor. I drove the truck 1 1/2 hrs home and it ran and performed excellent. (I was actually a little sad to start tearing into it) I looked over the motor and it is 350hp. A few other things look a little different too. I will still try to post pics of motor and valve cover. Turbo looks a slight bit different and the valve cover are grey an taller.(could this be for jake breaks?) I did not see a switch in the cab for one. I also have decided to ditch the 8LL for a 13speed I am told these make better use of the Jimmy's power. Hope this turns out to be a good ole truck when I'm done. More pics to come I will update Tomorow after another day of tear down.
I know you would need to change rear ratios, but did you consider using the automatic that comes with the motor? The 740 Allison that comes with a DD 6v92 is pretty near bulletproof and it will use the motor to its fullest potential as well. You already have it.
I did consider it but wast sure how it would do with the extra weight it would be hauling around also I would need to buy and plumb a tranny cooler as the one in the fire truck has seen its day. Also the PTO set up for the auto looks a little strange and not easy to refit in my truck.
The 740 is good for 80000+, it's really at the lower end of its range with the 6v92. It was used with all the full size 14 liter motors back in the day. You are right the cooler is an expensive item. The one I had to replace was on a very similar fire truck and it cost 900 bucks, I think. I don't know about PTOs, but you might have to buy one if you change transmissions anyway....
I must say up front, changing from original isn't my strong point. Some guys love it, and do some incredible work doing so, just ain't me. As for fitting the Allison, changing the ratio of a tandem axle truck will involve some expense. Then there's the aforementioned tranny cooler, additional expense. Then there is fitting the controller for shifting the Allison tranny. Expense is not the biggie here, just some reconfiguration. Again, just ain't my deal. But I do have a question, fitting an Allison, do they not require a throttle position sensor? If so, another thing that has to be fitted.
Lapatra172 - You do realise of course? - that in the year 2045, you'll be wailing to a bunch of buddies about how, "like the darn fool I was, I tore one of those collectable fire trucks apart, way back in 2012! - and look at what they're worth, now!!"
Oz-yes I have thought that and I find myself un bolting everything and being rather gentle I just can't bring myself to cut and beat the poor thing apart. Haha.
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I pulled one valve cover and there is a governor or something between the valves that is tied into the intake just below the turbo. What is this for?
I don't know about "tied into the intake", but there should be an injector between the valves.
Nope I'm not talking about the injector. You have your three sets of valve and injector rockers then this is kinda stuck In there too between two of the sets. It is linked the the throttle rods with some linkage and there is a small line prolly 1/8" that is plumbed out of the head and up to the intake above the blower but under the turbo. Didn't these motors come with some sort of governor to prevent smoking and over fueling if the boost pressure wasn't spooled up? I believe that is what it is. I should have taken a pic but I wasn't thinkin that far ahead. Also any of You guys know what a low mileage Allison or a good working 1500gpm pump might be worth? Just curious. I'm hopin I can recoup some of the money I'm doing into this truck. Thanks.
I've seen that on a turbo'd 3-53. It senses the airflow from the turbo. Okay, now I'm going on unsteady memories: I think it provides more or less fuel for starting. I think it works by a vane in the intake moving the rack slightly, and when RPMs are up, it has no effect. I give myself a 70% chance of having remembering it right. I'll try to remember to look it up when I get back in the office.
I believe this is to lower fueling until turbo spools up. The older turbocharged engines didn't have these and would put out a big puff of black smoke when the throttle was snapped open. Looked cool but the EPA frowns.
Damn EPA can't have anything cool anymore.
I think you are describing the throttle delay system. It keeps the rack from going into full fuel until the boost pressure reaches a certain point. It is to help keep it from blowing black smoke when you stand on the throttle. It works like Cat's rack limiter or the aneroid on the older Cummins. If it came disconnected, it would smoke more at low boost-full throttle application, but would be more responsive . I don't know if you would have a problem where you are, but up here there are a lot of driptroits that had the delay taken off. I know what I would do if it were mine,bye-bye delay Isaw that the fire truck engine has the mini by-pass blower on it. It opens when turbo boost is higher than the spring in the valve[little cylinder on top of rear blower end plate] allowing turbo air to by-pass the blower rotors, giving more air to the cylinders.
How do I go about taking the delay off? Is it as simple as unhooking the line to the intake manifold or should I remove the valve cover and remove the entire unit? Is the bypass you speak of good or should something be done with that as well? We don't have a lot of problems with smoke regulations and as I said before the truck is running mostly local and a lot of farm use. Thanks.
It will use a little bit more fuel disabled. Our last Detroit also had the reservoir under the engine to catch the drips from the air tubes. Can't have any spots on the ground you know, and we did have a commercial customer who was insane about drips on their property. Remembering, seem as if you just disconnect the tube it will retard the rack all the time as it requires boost to let the rack open up. I think if you look at the way it works it will be pretty obvious. I just cant remember as it's been a while.
Ok thanks. Ill look into it.
I take it off the rack control tube & plug the boost line. With it off it runs the same as an engine without it. As far as the mini bypass,you want that. Without the bypass the turbo can only get so much air past the blower rotors.
Ok sounds easy enough, I did the heads on my other motor so I'm familiar with the injector tubes. Sounds to me this motor should feel a lot better than that tired 79 that I pulled out. I'm anxious too see how a newer tighter jimmy runs. My other truck had something like 500,000 on it so I'm sure that old girl is tired too.
I'm sure your old one is getting tired, that's alot of miles for a 2 stoke Detroit. Here in Alaska you would consider yourself really lucky to get 200,000 out of one.
I've been following this thread with interest! I drove an old White Road Commander tractor with a 6V92TA in it for a few years and I actually got to like driving it. I hauled freight for a grocery chain and I was able to keep up with the Fords with the 300hp Cummins in them on the hills, on the flats I ran away from them. I hope when this is done you can post a video of the truck at work!
I can recall advertising blurbs for the 71 series Jimmys in the early '60's, where GM was bragging the Jimmys in the Greyhound coaches were doing 500,000 miles between overhauls - and upon pulldown, the bore wear was only around .003" to .004".
I've heard mixed things as to reliability. Some praise them and a few local guys I know say your lucky to get 40,000 before she comes apart. I thought my old motor required minimal maintenance and service and after working on this one although frustrating at times it's fairly simple and straight forward. The parts haven't been outrageous ether. I keep telling myself I'd like a 60 series or a big cat but in all honesty these motors have given me nothing to complain about. I will follow up with some more pics and videos. I believe I have some of my old truck hauling off dirt from a pond we dug on our property.
I know it's been a while. The truck is running good and I've been using to haul grain in from the field for a couple weeks now. Still working out a few bugs with some lights and other previous owner butcher jobs but I have been very happy with the drive train. I have some pics and I will work on some videos. I'm having a hard time uploading. It says my files are too big and seeing as I use my iPhone for all this I'm not sure how to resize them. I will work on posting them for you guys tho. Again thanks for all the help.