Hello everyone, I've got a cummins NTC 350 with a CPL of 021 In a peterbilt 359. Lately it's been pouring out blue smoke at startup, idle, and at normal operating temp. I replaced the injectors and it still smokes know matter the temp or the amount of load on the motor. I recently ran the overhead on it using the inner base circle method within change in amount of smoke it pours out. This cummins has over 800k miles and I've never opened it up to check rings or anything like that. We bought it for a farm truck and it hasnt always smoked this way. Any information would be greatly appreciated. Thank you.
Mid 70s engine ?
Yes sir. '74
That cpl was superseded to cpl160 in 1975 .there are some guys on the site lots closer to you than me .one of them will chime in soon.
Thank you very much.
My first Question is when did it start pouring smoke? Second remove the exhaust head pipe and look inside turbo to see if exhaust compressor wheel is wet with oil.
It started about a month ago. At startup and while warming up. Then just a haze while warm.
Well you are dealing with a fixed injector timed engine with that 855 Cummins and those were the same right up to early Big Cam IV engines after that Cummins went a STC injection timed engine to cut back the smoke on start up. All the small cams and early big cams were smokers. With that said check around the exhaust manifold area were it bolts to heads, sometimes they can run wet running out between the gasket, that will tell you if you have a wet cylinder. the other is use a infrared temp gun and check the manifold for balanced temp at the ports where it meats the heads. Should run 275* after a few minuets. But Remove the head pipe at turbo and check that.
I'll send a couple pics of what I see. Thanks for the information. I appreciate it.
This is fuel from around the heads leaking down the passenger side of the block.
I'll check the turbo next.
So I checked the turbo, its dry. I pulled the exhaust manifold off and this is what i found. The #1 cylinder is wet. The other 5 are dry.
Well either it has broke some rings on #1 cylinder, or you have some liner O-rings leaking coolant that scuffed the piston and bore, or an injector is puddling fuel at a great amount. Next thing I would do is drain the oil and drop the pan, roll the engine over so you can look up and check the piston and liner for scuffing and coolant droplets collecting on the bottom of the liner. While you there you can have someone bar the engine over and check the cam lobes for wear. If you don't have a way to pressurize the radiator to make the liner o-rings leak, just let it set awhile like a few days and check now and then for coolant on bottom of liner or on the steer axle and floor. When those o-rings go bad it won't stop leaking. When you pull the oil drain plug just let a little out first to see if there is coolant in bottom of oil pan. By pulling the pan first you can check several things at once for only the cost of gasket and oil. The fuel that's leaking down the side of the heads is probably the o-rings under the fuel crossovers leaking. Or it,s a mixture of oil also leaking from the rocker box seals on the end of the rocker shafts.
Last week I changed the oil, it was over the full mark and there was fuel in the oil. But I do plan on dropping the pan. Thanks again for your help. I'll keep you posted.
When you set the overheads/adjusted the valves did you set the injectors and valves at the same time on each cylinder? And how many inch lbs on the injector preload adjustment?
No sir. I soun the motor around to Mark A on the accessory drive pulley. Found which cylinder had the valve train that was loose which happened to be valves on #5. Checked them and adjusted injector on cylinder #3 to 6 inch pounds. And followed procedure from B to C and back around to A etc.
Do me a favor and take photo of the cam followers on the left side of the block just below the injection pump, please. Just to make sure we are on the same page.
I can tomorrow. In the mean time I have these pics if it helps....
Its identical to this one.
By that It should be a small cam, but get the photos so we know what we have. That has a date of 10 of 72, by what I can see in that photo. And there were no Big Cams in 72.
From small cam to big cam is the overhead adjusted differently?
As far as clearances go
injector settings are 60 in lbs on that eng.
Ohh alright then.
I'll get a picture tomorrow morning.
The one in your photo above is a big cam, I'm just making sure you didn't set the overheads on a small cam if that could be what you have-to big cam settings. Big Cam CPL's start with the Big Cam I and the first CPL # starts at 205
Actually its even easier than that, look on that engine tag again and see what the timing code is-if it says something around 36 timing code it's a small cam. If the timing code runs from 66 to 70 it's a Big Cam. The photo you posted didn't show the whole tag which should also show the timing code if still readable or Cummins even stamped the code on the tag, sometimes they didn't back then.
So I ran to the shop to check the tag. Apparently some of it's missing. I couldn't find the timing. But I took a couple pics of the followers.
Just as I thought you have a Small Cam not a Big Cam. So pull the rocker covers and jakes if it has them. firing order is 153624-bar the engine over til it comes at A with 1 valves closed, set the injector at 68 inch lbs intakes at .014 and exhaust at .027. Set injector first then set valves. Set valves and injector and valves all on the same cylinder each time. But you might have some injector issues with the fact you set them to big cam specs. So first I would I remove the injectors and replace with rebuilt ones at about $45 bucks each . Plus check the injector push tubes that those are not bent and full of oil by tapping the end straight down on a concrete surface-should sound hollow not a thud. Plus check the valve push tubes to make sure those are not bent also. Torque the rocker boxes to 70 ft lbs and jakes to 65 ftlbs if it has them. Set jakes at .018 lash
Ok, can do. I'll let you know what I find. Thank you.
I was always told with top stop injectors to use the inner base circle method. And what your telling me is to adjust valve and injector on the same cylinder correct?
Below are two photos of the 855 injectors, The one with the exposed actuator/plunger spring is a small cam injector. The other unitized model with no plunger spring showing is a Big Cam Top Stop Injector. Yes on small cam engines like 220, 335 and 350's you set both the valves and injector on each cylinder at the same time. Just run through the firing order stamped on the after cooler, the 153624 firing order will correspond with the A,B,C marks on the accessory drive pulley-plus it will be stamped 1-6 next to the A mark and so on for each letter stamped it will show that cylinder also . You might have to use some sand paper to find those marks on the pulley. Don't feel like the lone ranger for setting the overheads wrong, I guarantee you it's happened thousands of times. Just figure it as a learning experience, we all make mistakes. Plus I'm not the only one on here that knows these old critter Cummins engines guys like RZucker, DMiller, Petepilot, kshansen, Junkyard and funwithfuel just to name a few that can help you. This forum is full of sharp mechanics with a scope of ability from A to Z. It's all free help, and no one on here would ever purposely steer someone wrong. Truck Shop
My injectors are the first image shown. On monday I'll pull it apart, check the Injector push tubes as well as the valve push rods for bends. Replace accordingly and start back with the over head. Back to my previous post with the wet cylinder. Do you think that is from having the Injector set incorrectly or possibly a ring issue or seal failure like you had stated before? I've got plenty of down time on the farm right now to tear it all down and rebuild.. I appreciate all the help. You've given me more helpful knowledge than anything I can find on the internet and trying to find an old cummins manual has been a pain as well. Thanks again.
Well it is a old engine with probably hours and miles on it, but the fact there is a issue with the overhead adjustment that was done and that can screw with the injector plungers and cups. I think at this point it would be worth the gamble to install a set of rebuilt injectors, adjust and retorque the upper end and see how it runs before jumping into major repairs. You don't necessarily have to remove the rocker boxes to remove an injector but it would be wise to blow the dirt off everything all the way down between the heads before you remove rocker boxes. And by a set of rocker box gaskets and a bag of 12 fuel cross over 0-rings and reseal those areas along with the rest of the job. You can also adjust the valve bridges while you have everything off/there also know as crossheads, those set on top of the valve stems. To adjust those loosen the jam nuts and back the lash screws off-using your thumb to push down in the middle of crosshead {with some force} turn the lash screw til it stops. Then turn it 1/8 turn-you will feel it rise upward as you push down-tighten lash screw lock nut. Set all the same. When assembling put a small amount of oil on all threads before torquing, things just go better that way. There are a few tools that will make the job easier and necessary if you have jakes. I will post a photo of what is needed.
Awesome thank you. I'll get er taken apart Monday and see what I find.
Some tools that make the job easy, Dial type inch lb torque meter, extra long 5/8 jake socket if you have jakes and a 3/4 overhead wrench for braking jam nuts loose but not necessary. The step washers on the rocker box studs are getting hard to find so don't lose them, and those are a must between the nut and rocker box and only those. One other thing when installing the 1/2" nuts on the rocker studs that hold the rocker boxes down---do not get a case of butter fingers and drop one down through the push tube cavity. If you do-you will have to remove the oil pan and find it. If a nut falls and nests it's self in the cam followers it can on start up wedge and break the the cam follower or the block. The engine might bar over with the nut in the cam follower but it will get pitched on start up.
Thank you, I do have the 3/4 and the extra deep 5/8 socket. And I'll definitely take my time with the step washers.
I once lost one of the washers down the inside but got lucky. I heard it go all the way down into the pan. after draining the oil, I got it with a flexible magnet. sometimes I get lucky- it helps to make up for the times that luck is against me.
There are definitely those times were you get lucky like that. Usually if it starts out bad for me, it goes south from there
The real trouble maker is the two 1/2 nuts in the center, gravity really comes into play with those two.
Yeah those can be a pain simply because of the location. Not much room for error on those guys, one little slip and they are gone. I try and run it up the threads then get two fingers underneath of the nut just incase it pops out.
Small Cam, fuel leaking from External head to head tubes, lots of miles, would really be concerned of the fuel in oil as to Injector O-rings gone so will need bearing inspection, get that far and heads will need come off, pan already off, due for Overhaul where will find a lot of bearing wear. At that level you are better on the Small Cam to drag it out do out of frame cam bearings and all. No telling how bad cracking will be in upper liner bore or the sleeves sidewalls as to electrolysis or cavitation erosion. Engine Cam timing is done with the Cam Followers and not a beginners task as well need special tooling.
If I get into it and find lots of issues I'll put another motor in it for now and rebuild the cummins when later in the spring. I have a 3406B I can swap.
How many miles do you run this rig each year? Because if it's real low usage you may as well just repair the top end and run it for now, Unless your really in love with the truck I wouldn't throw too much at a small cam cummins. because when your done that's just what you have is small cam engine. Better off putting the money in a later engine. So I would just replace the injectors for now and see how it performs. I have addressed all other issues in previous replys guys.
We use it everyday to haul with around the farm. But that's within a 50 miles radius.
So what-maybe 7,500 miles a year?
Probably around that. But I need it to run solid and be reliable when I am using it.
Yeah I'll start with the Injectors and the other possible issues first that we discussed
If it does look like it needs more I have used these parts before and have had good luck with them. They offer just about everything. https://www.agkits.com/Cummins-Engine-Rebuild-Kits-855.aspx
Ok great. I'll look into that
also, block deck surface on all those 855's gets worn from the heads squirming. they can be finicky to re-seal. cummins has changed the gasket design a couple times over the years. if you are happy with the cam follower injector timing and only want to reseal the follower assemblies(end plugs or gaskets) we used to just mic the gasket/shim thickness and put the equivalent thickness back in(new shims) and allow for squash(compression) after torqueing of a couple thousandths. if you remove the follower assemblies, you should be able to get a good look at the cam lobes. if the follower assemblies aren't leaking, it may be best to leave them alone if you find the problem elsewhere. i'm not saying this is the right way to do it, but if you don't have the injector timing tools, and are on a tight budget, this will save time and money and it should run well enough for the use you intend
Thank you for the information, I'm digging in to it right now. I'll post what I find. Thanks to everyone for all the insight.
Small Cam engines were notorious for cam degradation. Inspect it closely., Follower rollers were bad for flaking, NT Series Cummins Exhaust push rods are also well renowned for becoming oil filled and deflecting causing engine 'miss' at higher rpm.
I'll check the push rods for oil right now. Thank you.
Easiest way is to remove, then drop a inch or two to concrete, they should 'Ring' and bounce slightly, they don't and just Thud they are oil filled/filling.
I ran Into a few that were full of oil judging by the thud. Also I pulled the injector from #1 cylinder. Found lots of crap in the brass cup..
Conventional Injectors not Top Stops.
So those are conventional?
Basic PT Injectors.
Standard injector for small cam, What you called brass are actually called coppers and seal out the coolant jacket. There is a special cone shaped brush for cleaning the coppers. But I'm going to step back and let others finish this thread. Good luck.
Better stay....you’re the resident expert sir.
I agree, I just throw down what I can remember as my biggest headaches.
Yep just plain old PT injectors none of that new fangled top-stop stuff! Am I showing my age here or what? To be totally honest spent many years working on small cam and other Cummins engines but only ever touched one that had top stops! Company got away from doing our own engine work and also leaned much heavier towards Kittiy Cat for most off-road equipment right around the time Cummins came out with the top stops. Also we used the dial indicator method for setting injectors, seemed to have better luck than the torque method. One point on those push tubes. If you find them full of oil, would expect more than a couple, be careful what you do with the junk ones. At a Cummins factory class I went to many moons ago was told that a guy had decided that tubing would be handy for some homemade tool. Not sure if he used a chop saw or cutting torch but which ever when he was cutting off one end the oil inside flashed and he got burned real bad. So if you decide to cut one use a hand powered hack saw for the first cut then wash out!
Same here, been so many years since I really worked on a small cam or any Cummins I forget how big a hammer to drive those injectors in with!
Made many a center punch with the pushrod off a Cummins injector.
I'm thinking you mean the plunger out of the injector? Or would that be the short rod from rocker arm to the plunger? Just might want to wear eye protection when hitting them believe they are pretty hard steel!
I typed plunger. Didn’t proof read it, evidently my phone liked pushrod better. I’ve actually never had an issue with one making shrapnel.
I still have all the complicated timing tools for those engines. I can’t even remember the last time I even got them out!
I’ve got em too
Thanks Junkyard-But it looks like I'm going to be free spooling some cable here soon, just waiting on the phone to ring with{You ready -trucks 434 and 438 stuck at Walmart Hermiston but first stop at the last exit west bound off ramp in Pendleton truck 460 is in trouble on curve}. It's that time and snowing hard, so if he has a question you guys answer it.
What was always fun was if you had to replace cams or timing gears in a 1710. Used the same tools with the exception that you had to do it twice and if it was off you had to figure out how much it was off and which direction then pull cam and press off the gear(s) and remove the original cam key and then determine which way the new offset key had to face. Then heat the gear up and reinstall it and hope you got it right the first time. Then repeat on the other bank! At least the KT1150/19 engines we had only had one cam. Never worked on a V engine KT.
Always had the old welding mitts in the box for a gear install, even then was a race to get it on before cooled too far or burnt the crap out of my hands, Three Guys!!!! One held cam, I grabbed gear, other swung Dead Blow onto Wood block or a PAR-X socket to set the gear. Wrecker work is NEVER Done, sucks to be you tonight in the slick with the idjits.
Holy buckets. Busy man! Be safe.
Ok everyone, first and foremost thanks for all the helpful tips and knowledge. Its greatly appreciated and needed. I'll get the brush to clean the coppers. I pulled the head off #1 and #2. Found lots of coolant ontop of piston #2. I ordered Injectors today as well as push tubes. What could be causing the coolant on the pistons? I'm assuming there may be more than one with this issue..
Cylinder #1 cylinder #2
Thermostat housing.... definently some sealing issues somewhere...
yes not top stops
time for a set of recon heads and lots of very close inspection
I was kind of assuming as much but I'm glad you gave me clarification.
I also see oil cooler or liner problems . drain the radiator and see how much oil comes out then you have to determine which of the above is bad
No winch out yet. Either the injector copper was leaking, liner leaking around head gasket or the simple fact that when you removed the head coolant dribbled out the water ports and landed on the piston crown. Unless you have the heads PT'ed pressure tested it's only guessing, but more than likely it came out of the head when you removed it. If it's oil in the cooling jackets and T-stat housing more than likely it would be a oil cooler issue. The diesel did a fine job of washing #1 cylinder.
I drained the radiator and the coolant was so discolored Its hard to tell what's in it. At the end of draining it all out, for a good 45 seconds its was completely brown.
I'm taking the heads in tomorrow.
When was the last time the coolant was changed, the fact it was brown means it was mostly water and possibly some oil.
I drained the coolant last year in May. Also did a coolant check in October 2019.
ok that could be fuel in the coolant
The one in the photo is Big Cam III 400, the core engine is a Big Cam II 400 with a 449 CPL #. Stuff is out there . https://eastoregon.craigslist.org/hvo/d/pendleton-cummins/7049766522.html
Yah- if a copper is leaking it can push fuel into the cooling system and coolant into the fuel when setting hot.
I'm definitely going to look around and check out some options.
Swapping Cummins to Cat is problematic, not much aligns from series to series so a great deal of adaptation will have to happen. Swapping from a SC to a BC1 or II is simple, stay away from Lo Flo Cooling engines as not gonna be happy with that outcome either. Agree on the coolant from pulling head, do not see any internal to liner Steaming damage but the potential of fuel in coolant can be cups/coppers too where higher pressure fuel while pulling will enter coolant, may not have coolant pressure to push water back into fuel galleries until engine off.
One less than explanatory note by Cummins, get the Block Clean and dry, get ALL the liquids out of head bolt holes, lube the head bolt threads and under the bolt heads to washers when go to reassemble but while handling the Head gaskets try to avoid hand contact to the sealant inserts or striping as the oils or just basic slop on our hands can disrupt the seal when installed. We were sloppy in the old days with injectors, essentially got the O-rings on them and then displaced the O-rings slightly to remove any roll in them, can either dip in a can of Clean oil to o-ring coverage or use a dribble nozzle and flood each o-ring with oil prior to install in the head. Gently set them into the home then take a Rubber handled hammer Handle end(CLEAN) and rapidly Shove/Pop the injector home. Does not feel right or does not pop down pull it and inspect the O-rings. As to head bolts unless are just replacing ALL have to inspect shanks, any crusty or corroded areas or any detectable hair lines, replace those. Bad areas just above threads and just below head on bolts.
I had the copper tubes leak fuel into the coolant years back on my big cam 1. exchange recon heads from cummins were cheap. if you change liners, check to see if they are already .010" oversize before you order. there are some older engines that may have had the counterbores cut oversize. the .010" oversize liners were available from cummins and also the aftermarket. these engines were notorious for liner cavitation. had one with a pinhole about 1/2 way down the cyl wall. before I disturb the injector settings, I make a line with a sharpie horizontally across all the adjustment screw heads and after adjustment I can tell if the adjustment has changed by a large amount on one or more cylinders. this can help to indicate a possible follower/cam problem if the adjustment has changed significantly. this only works if the heads or rocker boxes have not been disturbed.
Thank you for the information on engine swaps. I've already removed one head. The head bolts were nasty. I figure itll be best to replace all of them. For now I may look into a donor cummins with fertilizing right around the corner here in the willamette valley and get the small cam fixed up and sell it.
Anymore and has been for several years is to machine counter bores for .020X.040 liners and if a person is going to have the block machined they may as well have the bottom liner bores cut also for lower press fit. It will end the liner head gasket issues associated with the early blocks going all the way back. After the Big Cam IV's came the NT88 series 855 and that's when Cummins went to lower press fit liners and all engines after. None of those had counter bore/liner issues like Big Cam IV's and down. The problem is Cummins also built Recon blocks with counter bore repair sleeves, the counter bore was cut then the repair sleeve installed, then the adjacent counter bore was cut and it cut a moon into the repair sleeve just installed then the second repair sleeve was installed. What you had when done was a block with weak counter bores because there was no real block material left- one counter bore repair sleeve cut into the other, Cummins came up with this idea because Cummins was short on blocks and they got so short on rebuildable blocks that some of the Cummins Recon 855's came with new block and crank. If a block has repair sleeves removing the old liners can also pull up the repair sleeves and if that happens it's show over. Problem is you never know when you buy a old Big Cam if it has the repair sleeves or not. Two winch outs.
Its always somethin thats for sure... here in the valley we have snow and ice, I imagine its getting horrible anywhere about 500ft.
What of the third turd TS, just a friendly tug and gone? More of the mindless ones I presume!
He was able to move after using a set of singles, ramps were not sanded.
Did he put them on by himself? Funny story about chains today: I was getting fuel at Pac Pride in George and a Milky Way tanker was pulling out of the fuel island dragging a chain off his rack (JUST IN FRONT OF THE DRIVERS) so I yelled at him... He flipped me off and kept going. Have a nice day sir.
I thought you were not saying anything else? Thanks for stepping back in. Some folks don't know any better. Had some repair sleeves pull out of one. Cleaned everything up like new money. Put them back in with red locktite. Had bolts and stuff presetup to hold them down. Measured them the next day. All was good and never had a problem. If the cam and crank are good 20/40's and and inframe. We used to put them on the road. Cummins used to come out and cut blocks. It is hard to find that service anymore.
yep he put them on.
Because I was expecting to have to leave and might be gone for hours . So you guys could do the replying. The problem with the repair sleeve is the meat is cut out of the block where the counter bores are over cut and one sleeve is cut into the other, many a block will have a crack directly below the intersection of the two repair sleeves. When that happens she's a done deal. Had Cummins way back when added some extra material/changed the bore spacing the NTC would have been a greater engine than it was.
Worked at Continental Engine Rebuilding div of Gelco for a year, the automatic was to cut the upper bores on ANY Cummins that crossed the door, install sleeves and then overhaul with a .010/.010 crank polished cams. Never liked the way they worked there but money was OK. Had a few guys whined how I ran an overhead but they always dyno'd on the money(they had to run it AGAIN after dyno test).
truck shop- you're right about the .020-.040 liners. my memory let me down again. I found 3 part numbers for liners. 3055099(standard upper press fit liner/lower press fit liner) 3065405( 20/40 oversize lower press fit-pilot dia is .040 larger, flange dia is .020 larger and the flange is .020 thicker) 3046325( .020 oversize upper press fit- the flange is .020 larger dia and the flange is .010 thicker than standard). I guess that's where I got the .010 from and those were the liners I used in my last inframe about 17 yrs ago. they may not be available any more. at the time I had to special order them