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Top Stop vs Non Top stop...

DW818

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Hello...Just obtained my first military rig...I recovered a 1970 kaiser m818 w/winch with a 1970 nhc 250 cummins power plant from the lower part of ohio...Truck was only reading 1277 miles when I picked her up...Checked all fluids and headed for home about 300 miles away. 5 hrs and some change later I rolled into home base...What a ride! On arrival i did a post trip inspection and noticed that I had developed an external coolant leak on the rear head... Truck never over heated ran a steady 175 to 180 degrees with an 80 degree outside temp...Dipped a rag into the surge tank and found that the coolant was brown and smelled of diesel and had a slick film on top of the coolant... Drained all the old coolant and started into my disassembly. Luckily I was able to track down a upper end gasket kit for a very reasonable price from a local cummins dealer...Everything came apart smoothly and with much of the very useful information I have found on this site aided me in my teardown...I made the decision to replace all injectors while i had the top end torn down to this point. I have tried searching the site but couldn't find an answer i was looking for...Is it possible to use newer top stop style injectors in my engine if it originally had the non top stop style injectors? I ordered non top stop but received top stops this is why I ask...The business end of the injector all lines up but the top end of it,where the jam nut is located, is a much different dimension... It is Much taller than the non top stop...I would like to thank everyone who is a part of this site for all the time and info they have put forth to make this such a useful website...Thanks again.
 

DW818

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Sorry no pics yet...but its close to an inch or more longer then the non top stop. The injector hold down doesn't fit over it like the non top stop injectors that i removed today...I guess if they won't fit this year engine i'll try and return them for the correct set if they are available...I was glad i decided to pull them for inspection because almost all of the sealing o rings around the injector body were either rotted 75% or flattened to the point where they look like they were not sealing properly...ill snap a shot hopefully sunday or monday...thanks
 

grunex125

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While the injectors are out you might want to check the copper sealing cups around the injector body. when I put the new injectors in my 250 I had to pressure check the heads and found also that the coppers where bad. about $375 to have them redone per head. If you have any other questions feel free to ask, I know for me it wasn't as simple as just slapping in new injectors and putting the rockers back on, the biggest thing for me was getting the injectors timed correctly as I had never done it before.
 

DW818

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Again thank you for the replies/info. How did you go about pressure testing the heads to reveal that the copper cups were indeed bad?...I have all the heads removed and cleaned up and had them checked for flatness at a machine shop where I work...Is that something you could do yourself or is it something best left to a professional with the correct tooling to do so?...I'm trying to get the ole girl back to a safe running condition with out breaking the bank...which i might find out to be tricky...I only paid 3500 for the truck. if this puts things in a budget perspective...More or less this is my big toy....people have boats, motorcycles, atvs...and well...i have 20,000 pound ex-military tractor...:)
 

grunex125

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pressure checking can be done by any machine shop that does work on cylinder heads, I think for me it was about $75 to pressure check them and that was all, the reworking of the coppers had to be taken to a local shop that specializes in Cummins engines. The guy I went to had the special tooling required to expand the coppers inside the bore and seal the injector tubes. the coppers themselves are not very expensive, and you may be able to put them in yourself if you have an expanding mandrel to do so, but I wouldn't suggest that as once the coppers are installed you will need to machine a small amt to seat the injectors correctly. As a machinist myself (vo-tech training mostly) I know where you are coming from, but sometimes one just has to say ok.........I'm not all that familiar with this process and let someone who knows how to do it handle the project.
 

DW818

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I agree with your statement of letting a pro handle the copper cup install issue...From what I've been told by some local diesel techs is that they have to be done with precision and only the correct tooling to achieve a good sealing surface against the head and injector body...Somewhat unsure what to do at this point...Wasn't exactly planning on this if you know what I mean.
 

grunex125

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it's all surprises sometimes isn't it? I think the thing that was hard for me to get used to was when I put the heads back on and timed the injectors. the local diesel guru told me to just remember "too young (1,5 timing mark A) too old (3,6 timing mark B) just right (2,4 timing mark c)" and that never to use TDC for the timing procedure on the injectors. critical dimensions include the injector tip protrusion, proper inch lbs of torque on the injectors and as always proper head torquing sequence. that don't mean that it is overly complicated, it's mostly just different for a few of use who are not used to top stop injectors.

Since you have the heads off, I'd have them pressure checked to be safe, start with that, it will tell you which heads need work done if any, and then go from there. If you have the coppers put in, it wouldn't be much more to have the injectors seated properly as well. I'd be happy to help you if you need on timing the injectors, just let me know.
 

DW818

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New surprise under every bolt...I'm tracking down the injector cups and finding a good machine shop for the pressure test...That's a great analogy for the timing...and thanks again for the help Doug...I have spent many a restless night studying Will Wagner's #8 thread on injection and valve timing and reading all of the tech manuals for correct torque specs and correct torquing order for the heads...even made myself a poster to hang on the inside if the hood for the " day of torquing"...have a nice inch pound torque wrench for the injector torque procedure...I'm tryin to cover all bases so that the everything will go back together as it should. I even picked up the engine barring tool for the ole cummins to make rolling her over easy. I do have another question for ya...might sound stupid but where do u find the timing marks and pointer on the accessorie drive?...I should be getting the original non top stop injectors as well this week...Thanks again for the help.
 

grunex125

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The timing marks are on the accessory drive, you should see four marks there, many times the marks are covered over with heavy olive drab paint so you may need to take some steel wool or some chemical paint remover to remove the heavy paint, please don't use a electric grinder with a wire brush as you may scrub out your marks. Your marks will be visible on the outside rim of the pulley as well as the front side of the pulley. Your pointer will be right on the timing cover near the accessory drive pulley. To aid in identifying the marks, (in case they are not real evident with stamping or letters) look to the outside of the pulley, three of them should be approximately 120 degrees apart and one will seem to be only 50 to 60 degrees ahead of the next one. To identify the right marks, the mark that is about 60 degrees ahead of the next mark is TDC, you will not use TDC for setting the valves and injectors!!the second mark is (A) the third is (B) and the fourth is (C) (A) corresponds with cylinders 1 and 5, (B) corresponds with cylinders 3 and 6, (C) corresponds with 2 and 4. Bar your engine over until you align with(A), either cylinder one or five will be slack, adjust the cylinder that is slack and move to (B) either cylinder 3 or 6 will be ready to adjust and then move to (C) adjust and move to (A) again and repeat for the last three cylinders. You will also see that the cummins manual says to set the injectors to 72 inch lbs (hot or cold I'm not sure anymore) the guy that walked me through this said to set them at 65-68. you be the judge, but from my experience in the woods and needing HP I'm glad that the second time around we set them to 65. (second time around we set my turbo 350 to 65lbs) starts real easy, plenty of lugging power, and not that much difference in fuel consumption that I could notice. On long hauls and over the road you may prefer better fuel economy, but since mine is being used for logging I need to pull out of some of the most gawd awful places you can imagine and need the HP.

I probably should have mentioned this before, but since this thread is being read by others with the same headaches it should be said to use the proper torque method shown with the cylinder head gasket instructions, and always pull the cylinders down in increments between 75 and 100 lb increments IE: start with a torque setting of around 100 ft/lbs. and move up in 75 ft/lb increments to ensure even pressure is applied.

Hope this takes some of the worry out of what you are about to do, I know once you do it the first time it will seem as easy as a walk in the park.
 
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DW818

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Just got back from taking my heads to get pressure tested at a local machine shop the specializes in engine building...Owner is only charging me 50.00 a head to check them. Took a look at the accessory drive pulley and started finding the marks.They had a layer of grime on them that made them hard to view. Located the pointer under the power steering pulley I believe, and is part of the gear cover casting like you said...Good info thanks. I will take your advice about the injector torque settings to start and i totally agree with the graduated "step" torquing procedure for doing the heads as well. I will follow the instructions that came with my factory cummins gasket kit for torque specs. I'll keep you updated on my progress. I did'nt really expect to have to do this type of repair right of the bat but I'm in it to win it now and the 818 will run again... Thanks for all the information and tips you have provided me with so far.
 

grunex125

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yeah I didn't expect to have to tear mine apart either, but ......well anything man made is gonna break down I guess. recently at the local fire department auction I saw an 800 series truck that had been repowered with a Mack engine..... looked like it fit in there alright, but air cleaner and etc had to be moved to the passenger side fender, they then routed the exhaust a bit differently, but all in all it fit well. Only thing with it was that they could have done a cleaner installation instead of cobbling the external parts to fit.
 

DW818

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Yes very true...if its mechanical it can break or wear out...I'm a maintenance technician in a die cast foundry...I see machines run at full capacity for many hours with out breaks and needless to say there are failures every now and again...I don't mind wrenching and this gives me a good lesson on an old cummins engine...Your conversion with the 350 cummins sounds really cool...how hard was it to convert?...Thanks again.
 

grunex125

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wasn't too bad to convert, you'll have to switch the oil pans, get a new/longer sump suction hose, (you need to use the fittings originally on the 250 oil suction hose if you want to clear the 6by6 front drive knuckel) next cap off the front port in the switched 250 oil pan, and then switch bell housings, put a new bump in the hood to allow for the higher cross tube and radiator line. the worst was the conversion of the fan to the center mount position, and relocate the expansion tank somewhere of your choosing, Heater core for me came out permanently and will be relocated inside the cab under the bench seat or something like that. for the fan mount I simply took the spindle from the original fan and machined a block to match the bolt pattern on the timing cover and drilled and bored a new hole and pressed the spindle into about a 1.5" solid block of steel and bolted it to the front center section of the timing cover. The alternator was switched to the left side of the engine and now runs off the accessory drive. I had the alternator tested and it indeed does put out full amperage even at half the rpms of the crank pulley so I'm good there. The front cross member has to come out and I used a heavy piece of channel about 12" wide to set the radiator and the front mount on. Once the new front cross member was in I welded supports to the cross member and bolted to the original holes in the frame. I guess thats it in a nut shell. lol:grd: funny thing is........ I'd do it again on another 800 series truck if I had the oprotunity, but for now I'm happy with my first attempt and happy that it works as well as it does. If I were to make some suggestions to anyone doing this, I'd say take the time to make a good fiberglass bump for your hood and use that instead of making one from sheet metal like I did. ( I used what I had available at the time) I still have the five speed , but I noticed with the extra 100 HP the rpm drop is nowhere near what it was when making the jump from 3-4 and then up from 4-5 I can take hills with a load of logs on in 5th gear pulling about 45-50 mph, but I don't do that too much as I don't want to tear the driveline apart. usually I drop to 4th and let it ride usually about 35- 40 or so.
loved every minute of the repower though........it was a challenge I couldn't resist lol
 

DW818

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Update: All three heads passed the pressure test and all my injector cups were good to go...Just got my shop manual yesterday and my injectors will be here on friday...Almost have all the parts to put her back together...I tracked down a spin on oil filter setup and a coolant filter setup that doses in sca into the system...What would be the best place to plumb the sca filter into the system?? Thanks
 

DW818

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I would just like to say thanks for all your help...Over my Xmas break i got the ole cummins running again! she came back to life without to much effort honestly...flushed the coolant system real good...new coolant and added coolant filtration...Got the oil changed and added a spin oil filter conversion...new fuel filter and shes ready to go! Thanks you again.
 

simp5782

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I will add to this for those with any future issues since pics weren't added. Top stop vs non top stop. 20180819_085219.jpg

I will add that Will verified that you can mix top stops and non top stops even though you are not suppose to. You have to use the plunger for the specific injectors. They do use different locking retainers between injectors. Non top stops have a retainer with a washer. Top stop do not have the washer.

Sent from my SM-G965U using Tapatalk
 
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