Farm I work on has a old Cat D8G. Engine seems to be only running on three cylinders. Verified by cracking loose the injector lines at the pump. Also fuel pressure tends to stay in the red. Engine runs somewhat smooth at idle but very heavy greay and black smoke. Third exaughst port from the front has what looks like oil or diesel fuel that had ran out. Engine rpm will pick up on its own and then settle back down. Also consuming a lot of oil now. Don't hear any rod knock. Exhaust starts to "pop" at above idle. Already pulled one injector to find it was bad. What should we check next?
The for sale ad's for a newer machine JUst kidding
My suggestion would be valve clearance if you haven't already. May be an exhaust valve is either too tight or burnt. Check the other three injectors also.
That would be a good point to start! Next would be a compression test if tooling was available. One question I should have asked is this something new?
It's something new. Started rolling out heavy smoke while pushing up a brush pile.
how is your fuel quality? any water in it causing rust inside the injector? when was the fuel & air filter was changed?
What should the valve lash settings be? 15A serial number. Haven't checked the filters yet. Did find two bent push rods and a sticking valve.
Fuel is good. Filters changed last summer. This dozer maybe gets 80 hours of use a year.
That would make me walk funny....
Loosing engine oil out the exaughst. Also now when the engine picjs up rpm there's a distinct "knock" that develops.
Probably time to pull it down and inspect....
My boss is thinking about junking it. Doesn't really have the time to fix it. Has a newer D8H anyway. I do have the opportunity to look it over and decide for my self if I'd like to fix it for my own use.
What size fitting will I need to do a compression test?
The only problem that you have is a bad injector nozzle. Loosen the lines on the injection pump one at a time until you find the cylinder that's missing. You can also use an infrared thermometer to see which cylinder is running cooler than the others. Then move that injector capsule to another cylinder to verify that the miss follows it. That knock that you hear is a classic sign of a bad nozzle(capsule). That oily exhaust will clear up when you work it hard. Those old ones will do it if idled around.
The Acmoc forum is a good place to ask as well. If nothing else should the boss decide to sell it post on there first, hopefully someone will save it from scrap. http://www.acmoc.org/bb/forum.php Sounds like a fuel issue to me.
To test a capsule (injector) the easiest way is to undo injector line from adaptor and clear pipe from over the union area, then squirt a bit of oil into the top of the adaptor and spin over engine on compression, if the oil blows off the top of the adaptor the capsule is a knacker job, this can be done easy on 15A's but with the throttle set in the stop position fuel will leak from the injector lines constantly but not under any pressure. tctractors
Would a fuel issue cause the bent pushrods though?
No not at all, the engine is stuffed, these tractors are fitted with the first issue of the D342 engine (14A-15A Series) Non turbo with in seat starting, its Cylinder head off time. tctractors
Alright. I have a service manual for the dozer. Im also curious where I could get new steering clutch parts if I need them?
I know we Like pictures here. I also am now armed with a video scope and a parts manual.
A few more engine pictures. The black oily stuff is believed to be fuel.
Some undercarriage pictures. I have been punching in part numbers into google to get some prices on possible needed replacement parts. One part I cant find is 8B375. Its a clinder liner. Has it been superseded by 8N5676? Are there valve stem seals?
Yes, 8N5676 supersedes 8B375. If you ever see a Cat part number like 8N375, put zeroes after the second letter to make up four digits (in this instance 8B0375).
Is it possible that the pushrods were bent inside of this engine before this issue came to light? Meaning, if it ran a "little off" before this, then bent push rods could explain the valves not opening completely & those affected valves not following the cams "personality". Then this current issues proving to be a fuel issue, but being clouded / confusing by the bent push rods? I have seen guys reuse parts that they know are no good. This case would not be the first time. However, It is a great idea to remove that cylinders injector & using a bore scope inspect the inside of that cylinder. By doing that, you will be able to tell if there is any damage inside that would call for a more invasion tear down for inspection / repair reasons.
I was able to borrow a bore scope from a neighbor. I think your right msllc. Probably started in the valves first.
I performed this check and found another bad injector. I'd still like to have the whole lot ched out by a shop just to be sure. Also noticed when I cranked the engine over with the compression lever set to "run" it looked like there wasnt much fuel pressure. Flow was good but not much pressure. The pony engine start has been removed and a electric starter put in.
See above.
The fuel capsules are low cost items Non O.E. and work at very low pressure, you can screw the capsule and the adapter onto an injector tester to do a simple test although its a bit messy, I have a Pre Chamber cut down to test the injectors in a more controlled way, due to the low cost of the items they are not often worth the messing with testing unless your Diesel shop is willing to just Pop Test them for a few $$. tctractors
What gasket is 7h9984?
It's a gasket for the push rod compartment. It's been replaced with 7N4407.
General Gear has your steering clutches.
With other parts I may need, is there a easy way to tell online if a part number has been replaced?
Yes, you have to get access to the online Parts Store(SIS) at your local cat dealer. When you order it at a Cat dealer or through the online Parts Store, it will automatically update to the newer part number. In SIS, NPR(Numerical Parts Record) is the source for part number changes through the years. Here is another source for parts lookup: http://www.machinerytrader.com/list/partssearch.aspx?PartNum=7n4407&btnPartSearch=Search&PST=Starts Scroll down to the bottom of that page and plug in your part numbers. Be careful with their alternate part matches as they aren't always reliable. Off Road Equipment in Alcoa TN has new old stock Caterpillar parts too. Go to their website or call them with your part numbers.
Well so far every evening this week I have been soaking down the manifold studs with PB Blaster in the hopes that the nuts holding the lock plates on will back off without much fuss. Hoping to remove the front cylinder head this weekend and see whats going on. A few more questions... What does the cylinder head weigh? What size are the nuts on the cylinder head studs? Biggest socket I currently own is a 3/4. In the picture.. what is the part with the four bolts and what looks like a solid bar between the cylinder heads? Are there valve stem seals? Would it be worth replacing them while the head is off?
You better plan on tooling up. and don't forget a good torque wrench and a manual for your engine. Lots of books for them on ebay.
The square 4 bolt piece between the heads is for a starting engine cooling tube. yours must be converted to direct start so it is blocked off, the heads are heavy not sure what they weigh but probably close to 200 and they can be a sob to get off the studs if it's been a long time since removed. Socket sizes are 1&5/16 and 15/16 if I remember correctly, You will need 3/4 drive set. Good luck it can be an expensive can of worms.
I got around to removing the head yesterday. The carnage is as follows. Looks like the intake valve on the #3 cylinder dropped and then the head of the exhaust valve broke off and is wedged in the exhaust valve opening sideways. The piston appears to be in one piece but beat to hell. The head is still on the engine but blocked up with 2x4s right now. The push rods for the #3 cylinder are longer then the push rods for cylinders #1, #2. The bottom ends of the longer push rods are flat but the tops are machined the same. They are longer by about 3". Are they original? I'll try to get pictures this evening. If the longer push rods are not original the dozer has run this way for at least 4 years.
Think this head is toast? This is the cylinder head off the Caterpillar D815A 2nd picture is the piston. The push rods for the affected cylinder are longer then the rest. Not sure why. Parts book only shows one part number for the rods. The lifters look hollowed out compared to the others too. I'll post the pictures and try to get over during daylight and get better pictures.
Oh dear... those corners are dog eared....
Should I even bother having a machine shop look the head over? I feel like it's probably a giant door stop at this point. I think I have two options. #1 Buy a complete remanufactured head #2 Buy a good used head with good guides and seats and swap over the remaining valves from this head. Purchase a new intake and exhaust valve and new springs. Cost will probably be the same though. I think maybe a spring broke and that's how this happened.
A comparison of the different lifters.
Those are just 2 different styles of lifters, I have seen both but normally not mixed. I would not worry about that part.
It's simply an indication that someone has been in there before IMHO.
Would that be an indication that the somebody who has been in it before had low standards? I don't think you have anything to lose by having a machine shop look at the head. They can see what's happened pretty quick, might not even have to take it out of your vehicle. You might try a couple of machine shops if there's a variety around, some have different standards than others, you're looking for the highest standards that will take you
I'm not worried about the lifters too much. Though I'd like to find two more long pushrods to replace these bent ones.
I think I have my plan of action figured out. Going to replace the cylinder head and piston. Also replace valve springs on other head. New rings on pistons. What gaskets are included in 6H5701?
Part number. Qty. Desc. 0T0225 0001 GASKET 1A6879 0001 GASKET 1S4390 0002 GASKET-CYL HEAD 2A0615 0006 GASKET-MANIFOLD 2F4594 0001 GASKET 4F5607 0006 SEAL-O-RING 4H7380 0001 GASKET 4H8522 0001 GASKET-COVER 5B3718 0006 SEAL-O RING 5H1122 0001 GASKET 5H2537 0005 GASKET 6B7021 0006 SEAL-O RING 6F1069 0006 SEAL AS-VALVE 6F7301 0001 GASKET 6H2007 0004 GASKET 6H9990 0002 GASKET-MANIFOLD 6L7813 0024 SEAL-FERRULE 6L7814 0002 SEAL-DIRECTOR 7N4407 0002 GASKET-ROD COMP 7N9352 0002 GASKET 8F2691 0001 SEAL-O-RING 8M7154 0002 GASKET-BASE
Thanks for that. I was wondering if there were enough gaskets in the group to cover both cylinder heads. I saw this set of gaskets on eBay for around $150.
Have cat check on a classic head might be your cheapest way to go
Would 8n5760 be the correct part number for a set of rings?
I've emailed the local Yancy Cat dealer about a classic cylinder head. Waiting to hear back. So with the $5000 purchase price....how far into this thing is too far? For now I'd like to stay under $7500 invested total.
Went out today and checked the oil filters for metal bits. No shiny or gritty stuff in the filters so I will continue on with the project and will buy this old D8. Head gasket set showed up yesterday. I was expecting it to include gaskets for the manifolds but it doesn't. Kind of bummed about that. Emaild the eBay seller. Still want to take the cylinder head to have it looked over by a machine shop. Just haven't had time during g the week. Also picked up a operation and maintenance manual on eBay for the 14a and 15a d8s. This one doesn't seem to cover wet deck models though.
a neighbor had a 14a when I was young and worked for my dad some, this was in the late 60's. he charged 16 dollars/hr. that was a great tractor. best of luck.
Pulled the oil filters. Thought to check them for metal pieces before going any further and they are clean. I'm assuming there are piston and valve bits down in the oil pan though.
Thought I'd also post a overall picture of the D8
if I lived there I would help you work on that old girl..
Wet deck 14a about the best there is. I have about 15k in mine. Still needs another couple grand.
Haven't updated my project. I have a new head I bought from Iron Peddlers. Complete and outright. Decided to re-sleave the block while I'm in there. I'd get all new Pistons but my budget is just about gone.