Hey guys, ive done several inframes over the yrs on 855 s an it seems as evertime when I start running the over head procedure the motor tends to lock down, its allways locking the motor down an cant turn it over by hand, im constantly having to try backing off the valves an injectors ,, it seems eventually after screwing around with it for an hr or so, finally it will all adjust like its suppose too,,,, so now ive done an inframe on an 1974 gmc white dump truck an it has an cummins 250 in it. never seen one like this, its heads seem to bolt on sideways an not flat like normal. so when I started running the over head using the accessory drive marks I started out using the (A mark) an found witch valves were loose. so I adjusted the valves on number 2 valve an set the injector on the number 4 cylinder. an then I tried turning the motor over to the B setting mark, but then the motor locked down before I got there. marks injector valve A 3 5 B 6 3 C 2 6 A 4 2 B 1 4 C 5 1 IM HOPEING IM USEING THE CORRECT ORDER FOR OVER HEAD PROCEDURE, I LOOKED IT UP FOR A 855
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This may not have anything to do with your current problem. But if this engine is old enough to have an air compressor with the crankshaft that is one piece with the shaft that the accessory pulley mounts on and someone has replaced the compressor and not aligned the timing marks when it was installed you could have all kinds of problems trying to set the overhead. Not 100% sure what this means " its heads seem to bolt on sideways an not flat like normal. " Are you just saying the engine is leaning to the right like an old slant six Dodge engine?
LOL that was the first thing I though of aswell when I saw the block with the heads off,,, a dang old slant six that dodge put out, an yes the top of the block is slanted to the right. I have ran into the air compressor having a bad spot in it an locking the motor down before,,,,i hadn't looked at this one yet,,,, I know something did happen to this motor when it died,,,, when I took it apart I noticed that it had a bad elbow in the air filter housing an let a lot of dust go threw the motor an eat the pistons an heads up, an when I took over head off I noticed that there were 7 bent push tubes an there was oil mixed in the cooling system .
With out being there the best thing I can think of would be to back valve and injectors adjusters and make sure the engine does turn over. I do not have access to my old Cummins manuals since I retired in April, for got to grab them on the way out the door! But if you engine has the A, B, C letters on the accessory pulley there should also be a marking for 1-6 TC. You could pull #1 injector out and check to see if the piston is at top center when this mark is lined up. Well I did find a manual online to refresh my memory! http://http://www.liberatedmanuals.com/TM-5-2815-233-14.pdf This manual has basic info on just about all the Cummins engines so you need to be careful when looking at it that you are in the correct area for your engine! My first question should be how are you setting the injectors? Are you using the dial indicator method or using a torque setting? It makes a big difference at which position you set the injectors. If using the torque method while positioned for the dial indicator(injector travel method) would cause the engine to lock up while turning over. I prefer the dial indicator one myself but if you don't have the tooling the torque method will work, Also each method I believe needs to know if the rocker boxes are cast iron or aluminium.
been turning the acc drive to A spot an checking to see witch valves are closed then with the number 2 valves closed I adjusted them then went to the number 4 injector an ran it in all the way with a screw driver hand tite then backed it back out an then ran it in to 6 inch pounds, then when trying to turn to the b spot it locks down on me
1974 250 cummins Yeah chris , that's a "small cam" engine . You will set valves & injector all at the same time on a given cylinder . Say you on A ( 1-6 vs ) on the accessory drive . Both intake & exhaust are rockers are loose on cylinder # 1 . Set intake at .011 and exhaust at .023 . Now set the injector on number one . You need an inch pound torque wrench for this . Break the jamb nut loose on the injector rocker & back the screw out . Then torque it back down to ........ Book says 72 inch pounds , We stop at 68 .
Not sure why the link I posted does not work but Google "http//www.liberatedmanuals.com/TM-5-2815-233-14" and the first hit should be the link to the manual. Page 59 is about where the tune up shows. As I said cast iron rockers show different spec's than aluminum. You say you have A,B,C on the pulley, so A= 1-6VS, B=2-5VS, C=3-4VS With The "A" lined up and valves loose on #1 you first should be setting the injector on #1 to 71 inch pounds for aluminum rocker housings or 48 inch pounds for cast iron housings. Then after the injector is adjusted you set the valves on #1 also. Again depending on the rocker boxes aluminum you set intakes at 0.014 and exhaust at 0.027 inch. Cast iron go 0.016 and 0.029. Next turn to "B" and #5 valves should now be loose. Set injector and valves on that cylinder. Next turn to "C" and #3 valves should now be loose. Set injector and valves on that cylinder. Now back to "A" set #6, then "B" set #2 and last "C" and set #4. This should get you to the point you can run engine and after that you can do hot sets if you want. One thing I just noticed and did not think of before, what type of injectors are you installing? Are these top stop injectors? That would make a difference so let us know before you go any further!
OK, back to this engine tune up! After a break to do some work around the shop here is what to do if you are dealing with "TOP-STOP" injectors. Back off all injectors and make sure engine turns good now. If it does try the following: Bar engine over till the "A" is lined up on the accessory pulley and then check the valves on #5 cylinder. If both are loose on #5 you are ready to start if not turn engine one more turn to line up "A" then check the #5 valves. With engine at this point set the valves on #5 and adjust the injector on #3 to the 6 inch/lb setting. Next turn to "B" and set valves on #3 and injector on #6 Turn to "C" and set valves on #6 and injector on #2 Turn to "A" and set valves on #2 and injector on #4 Turn to "B" and set valves on #4 and injector on #1 Turn to "C" and set valves on #1 and injector on #5 This should work for the "TOP-STOP" injectors if that is what you have.
Hey friend, I tell ya I feel like a complete dumb a-- ,,, ive built several 855 s ,,,, I went back to the truck today an got all my facts rite,,, my motors a NTC 290,,, an cpl is 353,, ive come to decision that the motor will turn over with the rocker boxes off,,, so I put the number one box on an turned motor to the correct mark an adjusted the number 2 valves,,, after adjusting them 2 valves only I turned the motor over an it locked down, so I got upset an pulled the heads up an looked at the valves an I swore they look as if there hitting the pistons, I compared new to old pistons an they differ. part numbers but look the same, I though maybe my helper put pistons on the rods backwards but they look as the valve cut outs on the pistons face look the same on both sides, an now that ive read how ur telling me to adjust the overhead ,,, I was adjusting the overhead the other way,,,,, with A on its marks an adjusting injector 3 an valves on 5 then turning to B an setting injector 6 an valves on 3 an so on.
thanks for ur help with my NTC 290 issues,,, I was setting the over head in the other a,b,c pattern an setting injector to 6 inch pounds but whys there a big differ in the injector setting big gap in 71 an 6 pounds.
If I'm following your question correctly the different settings of 71 inch pounds and the 6 inch pounds is related to what type of injectors you have. For lack of proper terms off the top of my head if you have injectors that the plungers will slide out of you have "non-top-stop" injectors. If your injectors have adjustment collars on the top that stop the plungers from sliding out those are "top-stop" injectors. Now the key reason for the difference in the adjustment settings is that the "non-top-stop" injectors are adjusted with the cam follower sitting on the top of the cam lobe and are set so the plunger is seated in the bottom of the injector. That is why they are adjusted on the same cylinder as the valves when piston is near top center on the compression stroke. Now if you have "top-stop" injectors, they are adjusted with the cam follower on the base circle of the cam. So they are adjusted on a totally different point than when the valves for the cylinder is adjusted. The 6 inch pound setting is so low because you are just trying to remove all the play in the cam follower, push-rod and rocker arm system. You do not want to actually be moving the injector plunger at all. All this talk about injector adjustment seems to be off from the problem you seem to be saying you are now talking about, pistons hitting valves? Now it's starting to sound like you have a problem with the cam not being timed correctly with the crankshaft. Was the cam out of engine and someone used wrong marks on gears to install it? Or like you mentioned, pistons on rods wrong or rods on crank wrong? I'm just guessing here as I can't see your engine, but there seems to be something very basic wrong with this assembly.
Hey again,,, well I went back to my night mare again today ,,,, an don't remember I I told you guys or not,,, but when I pulled the over head off after motor went bad, I had 7 bent push tubes,,, that's kinda got me puzzled,,, (never seen 7 at one time to be bent) an when we did the inframe my guys said that there wasn't any marks on the pistons other than the cummins part number ( wasn't any marks or arrows pointing to the front of the motor like normaly see), but the pistons have the 4 machined out spots were the valves sit in top of piston face. we actually questioned ourselves bout the pistons in wrong but the valve machined areas seem to be evenly spaced ,an the rods are on the crank correct cause the dowels in the caps are faceing the rear,,, an when I pulled the heads back off after I though the valves were making contact I noticed that it looked as if the valves were over traveling an the middle of the piston is leaveing marks on the valves. ( the came hasn't been removed either dureing inframe job) so after fooling with it for few hrs today I removed the compressor an pt pump the pulled the roller rockers outta the block, we then turned the motor over an watched the cam turn ,,,,,(then we noticed that there were 3 cam bearing that had seized up to the cam an were spinning inside the block ,,,,an the cam had turned blue from heat around the bad bearings. so in one way this is a major issue here but then motor turns freely as long as the rocker boxes are loose, but still didn't figure out whats making the valves hit. so I have to get another cam an bearings,,, I have turned the motor over for numerious times trying to look at the gear timeing mark,,, the only thing that ever lined up was the crank an cam an they were 0 to 0 my accessory gear has a dot on it but I never saw it line up with the cam gear, been studying bout what bent the 7 push tubes cause what ever it is is why its locking it down now. also I did notice when I pulled the front cover off the motor , the brass thrust washed that go s infront of the access. drive hub had fell down an I had noticed the washer was split into an bent into a letter U shape. thanks for ur time an replys
OK Now this has me thinking that the cam gear has spun on the cam when the bearings seized up letting the cam be out of time there by giving the pistons hitting the valves. As I said I don't have the correct manual for your engine but do have an older one from 1965. The instructions on the timing marks are I believe the same as for your engine: 1. Bar engine over to #1 top dead center and the cam and crank gear timing marks will be aligned. 2. Continue turning in direction of rotation 90º, now the two dash marks on the cam gear will be aligned with the two center punched marks on the gear for the fuel pump drive/compressor drive. Maybe some one who has a newer manual can confirm this for me. If you look at the front cover there will be, I believe, a 3/8 inch pipe plug right where these gears mess so you can check this with out pulling the front cover. But from the sounds of this engine's problems I would be looking for a good used engine to swap in as I have serious questions about the rest of the engine's condition, but only you know what you have to work with as far as time and money go. Seems like as common as these engines were there should be many sitting just waiting for a new home.
This sounds like a complete basket case. These engines are about as basic as a Briggs and Scrapiron. Pull the front cover and there will be 4 dots on the gears. One on the crank, two on the cam and one on the acc. drive. Make the cam dots touch the other two. That will put everything at TDC. Your injector should be firing and the valves loose. After all the rigamarole I would heat the cam gear up and give it a tap to remove it and check the key for shearing. The woodruff key, it should be offset. Make sure to put it back it the same way! You can get a aftermarket cam for $4-500. The cam bearings were probably installed in the wrong journals and burned up because the oil journal was blocked. They are labeled what hole they are drilled for.
Sounds like the " in frame " overhaul just went out the window . Time to yank her out & strip the engine down for a trip to the machine shop . Do you have a spare cummins ?
I Agree that this engine should be scrapped. Sure anything can be fixed all it takes is time and money. Question to answer is how much money you want to spend? If cam bearings have spun in block the chance you can press in new ones and have them fit right is slim to none. Then there is the problem of cleaning all oil passages out. Bare minimum would be to strip to bare block and thoroughly clean all passages. Then if the bores for cam bushings are damaged to salvage the block it would need to be line bored and sleeves installed the the sleeves bored to bring it back to standard. Like I said it can be fixed but don't see it as worth the cost for what should be a very common engine available used in many places.
That's exactly what will need done to repair the block . Good machine shop can take care of that easy enough . Is it just me ? 3 cam bearings spun is a little odd . Oil passage not lined up when cam bushing was installed ?:beatsme
Yea I though it was odd aswell bout the 3 bearings cooking to the shaft,,, even turned shaft blue in few spots, just wander if when it all glued up wander if the cam gear spun on the shaft an that's what bent 7 push tubes, an now if it is spun on shaft if that's why my valves are hitting pistons while running over head, and they may also be why when I turn my accessory drive to the timeing mark letter A an my number one is never at top nor is number 6 up there. either way ive got a new cam on way.
Yeah chris , A , B , & C on the accessory drive is for setting the overhead . Clean it off good . Should also see a " TC" mark between A & C . That's the Top center mark . Is this a small cam 290 ?
its a big cam 290, ive located all the A B C marks on the hub, never found the TC mark
Not to muddy the waters too much but does the Big Cam engine have the shims to adjust injector timing on the cam follower boxes like the small cam engines? Did many of the "small cam" engines but where I worked we never had a "big cam" engine. KTA1150(KTA19) and the 1710's used off set keys on the cam gear, did a few of those also. Does the new cam come with a new gear? If not have you checked the old gear? I would be very worried about anything that has oil passages in them. When cam seized and spun the bearings crap could have gone anywhere. Into crank, cam followers, rocker boxes, air compressor...... If this engine is not stripped down to every last part it could be a time bomb just waiting to fail again. It's the old "Pay me now or pay me latter!" thing.
took cam to machine shop today an we pressed gear off an found that when cam locked up an the gear spun on the shaft an sheared the key ,,, so that's why my valves were hitting pistons an that's why I had 7 bent push tubes as well, so now im gonna go threw the oil galleys in block an make its all free of crap an no blockages.
Yes , The cam followers use shims to set timing on Big & small cam engines . Cam wont come with gear on it . Both engines are similar with exception of the cam journal size . Hence the name Big & small cam . I fully agree , That engine needs completely pulled down & cleaned / blew out . I'm puzzled about the 3 spun cam bushings ? This is an early 1980's Big cam II we were swapping injectors on a job site . They are " Top Stop " . HeavyEquipmentForums Do the injectors look like that in your 290 chris ?
So I hit it right back in post #12? The next question will be how much damage was done to the bores in the block for the cam bearings? And maybe even more important is why the heck the cam seized in three bearings in the first place. In working on diesels of all kinds over 45 years only saw one with a seized cam bearing, that was a 1710 V-12 Cummins that we got that way. Forget if we were ever able to be sure why it did that. That one had to have block bored and sleeved for a new bearing to fit. One more thing is how is the crank and main bearings?
well crank looks good, bearings did turn to the gold color a lil ,,, wasn't any heat coloring on crank, but there was coloring on cam , an yes it did get the block were one of the bearings spun, it does need to be sleeved in that one whole.
I have a 230 cummins in a 74 Dodge that I am setting the overhead on. Do you know if this would be top stop injectors or not?
Is this a 1974 dodge pick up truck, or heavy duty truck. Most dodges I’ve ever seen were 5.9 Cummins or also known as 6bt. If this is ur motor then no you don’t have top stop injectors. An the valve settings for a 6bt are intake .10 an exhaust is .20 Easy to set over head
Take a look at my profile pic,that is the truck.
No sir on the 6bt, lol. Not many of these ole girls still out an about. You prob have a big cam Cummins, maybe a 290 or a 300. An yes it should be top stop injectors, they adjust out at 6 inch pounds. Fairly easy to set , set valves too since ur already in there. It’s a special procedure to set the overhead, timeing marks on the pulley of the air compressor (accessory drive pulley) clean it off on the edges an look for 3 marks 120 degrees apart an there will be letters beside each mark. There will be a Either A , B ,Or C on each mark. There the timeing marks. If this looks rite to ya let me know an I can give ya a chart to go by that will tell ya witch valve or injector to set for each letter
You must not have read my first comment,I already know what engine I have,and itis NOT a big cam.