My friend has a cat d8h 46a32000 he has had the heads fixed and has put new rod and main bearings in it it has a knocking noise that will come and go from time to time sometimes it is loud sometimes barely can hear it I can hear a noise sounds like it is in the oil cooler or starter it dont have any blowby and the oil pressure stays up in the green even at idle it was making this noise before any of the work was done to it
Mack you really need an experienced engine man there to listen to it as you run it u from low idle to high idle and back down. Then as you open it up and load it. Could be many things even a broken crank. Later Bob
I've seen plenty of injectors and fuel injection pump settings cause the kind of knocks you are talking about. I don't see in your post where the fuel system was gone through at all. Bob is making a good suggestion considering how much money has likely been spend so far or could be spend should it be something potentially catastrophic. Good Luck
I am pretty confident the crank isn't broke the oil pan was just off last week they just put the bottom end in it. I know he put a set of aftermarket spray nozzles in it about a year ago and a piece was fixed in the back of injection pump looked like a horseshoe kinda. just sitting still you can go from low to high idle and I don't hear anything that sounds abnormal it burns clean but when you walk the dozer a little ways you can hear it in a way it sounds like a loose rocker arm they have set the valves and everything on the engine
Not up on Cat's innards, but on forklifts (large capacity-30K up) you can get something like you describe due to a loose flywheel or tight flywheel and loose t/converter mount plate bolts.
Giddy mack, does your tractor have a cab with down bars? If you do it could be rubber bush where the down bar bolts to the cab. As you walk it hits and channels the noise down thinking you have a bad knock at the back of the engine.
Could be you have a lifter hanging up... that would explain the intermittent noise. If you think that may be the problem dump some motor honey or an equivalent and see if it goes away .
Check the rear engine mountings and the drive shaft joints on the transmission also the winch drive if fitted, if the heads have been off it is possible to mix up the oil feed pipes to the rocker shaft if the heads are swapped, the oil feed should be to near the fan on the front head, near the flywheel on the back head, to get the full sump off with the engine in frame is a tough game?? did anyone check the small end bushings in the rods as D8's are known for eating them, the piston pins also suffer heavy wear this causes a goodish tap on the over run or speed change point on P/Shifts or when releaseing the main clutch, the exhaust valve guides also wear a good bit causing an extra tinkle for the ear to pick up, the oil pressure should be 30 psi the oil pump is positive dissplacement flow controlled. tctractors
Before one gets too crazy, how many hours on the machine? Then did the do any re-ring or pull pistons? Reason for the questions, if the engine is a high hour it will have considerable piston/cylinder clearance wear, keep that in mind as you perform the next steps: Run the engine at a slightly fast idle, cancel out each injector slowly(Crack the fuel line to each nozzle or on electronic engine with a test light 'short' out the injectors one at a time) any knocking at this point will be the running mate of that cylinder and is probably piston slap. Have seen it mainly of high mile engines that were just slam worn out and no one took into account piston skirt wear. Won't kill it but will be a scary rattle all the while.
The pistons have not been out. The heads were done first about 100 hours ago then this knocking started and the rod and Mains were put in probably have 2 to 5 hours on them. The noise I talked about is coming thru the trans cooler is it possible the torque is coming apart I started it stalled it out in 3rd gear about half throttle then drained the torque got somewhere between 2 to 2.5 gallons I also got part of a metal ring out of the plug looks like a metal sealing ring has small holes in it like oil passages
For what its worth, I have seen 2 older H's break a piston in Half through the wrist pin bore. One failure junked the block when the bent rod went through the side. The operator said "it had a small tap" starting. I would be very suspect of high time pistons.
While running and knock is present, crack fuel lines listen for change in knock or if the knock quits all together then when you find the cylinder that has the knock shut engine down, swap fuel nozzles with another cylinder start and crack those fuel lines one at a time if knock goes to the other cylinder you have a bad nozzle your hearing a fuel knock and they can sound really bad. I sometimes also use a bar or something and do the old ear test hold to each cylinder maybe on the exhaust manifold and give her a listen, you can also obtain a good feel for engine change listening to exhaust from far back while someone else cracks lines, Mike
Hopefully you don't have a valve seat coming apart, means you say the head have recently been redone. Also this is not something you want to make a habbit of but I've also ran engine wide open while listening and have someone shut it off immediately to see if noise can pin pointed if it were to be mechanical knock, just a thought, Mike
It would not be the common thing in the U.K. to have heads off + sumps down without pulling pistons and liners??? a D342 block would be rare to scrap after a rod has fired out the side of it, this hole punching is repaired upto 3 times on engines I have worked on (D8 342's) when this happens some damage is found at the cylinder liner bottom location but it is still repairable, the cracked piston is not the cause of the rod flying its the result of this drama, over speed is often the starting point of things letting fly, anyhow it would seem the fault now stems from the transmission with air noise found around the cooler, best thing would be a photo of the part/s found? the engine oil pump does have a PRV that is set to 90 psi for cold starting protection, but this style of oil control is not used in general running, the pump is flow control. tctractors p.s. piston slap and engine condition on D342's is easy to check by blow-by, remove the oil filler cap and try to top up engine oil with the engine set at low idle, if you are wearing the oil after trying this task the motor needs new innards, or at least pulling to bits.
Lol
Yair . . . Regardless of any issues with the engine I wouldn't be running it until the source of the above bit is found . . . blokes on here could identify it from a high definition picture. It sort of sounds like a clutch pack seal ring but I don't know now if I am thinking Cat or Allis . . . but it shouldn't be in the convertor, best I shut my trap before I get in trouble. Cheers.
I agreee with the previous posters. If a metal part fell out of the converter you have a definite problem there. Fix that before moving on to the engine (if necessary). As Tony says the fact the noise appears to be coming from the transmission cooler could mean the noise and the errant lump of metal from the converter are somehow related. What we need is a photo of the piece that fell out with the oil.
This was my thought, a bad nozzle can sound terrible. Also you can cut an oil filter apart to check for metal. We had some early H's where the thrust main was not dowelled and would turn enough to close the oil passage to the next rod forward( #3) the result was not pretty.
Good tip I use when cutting a oil filter open for inspection, cut out a section of the filter and place it in a vice sqeeze all the oil out, I had filter look clean until you do this and you'll be amazed what it shows , I especially do this when troubleshooting hydrostatic transmission, Mike
Might want to check trans filter.
pto bearings can give you a fair fright when cutting open engine oil filters.Bear that in mind if you open one up and assume it's crank bearings.It might not be.Seems to me that the time has come to get the right man on the job to look at it in a methodical fashion. P,S,i had a d8 once that used to knap abit around the top on the over run.Had the pump turned down abit and it worked fine for a few more thousand hours.Don't think the experienced fitters will go down that road though......I am just a cowboy
he removed the torque converter and took it took a shop that has excellent reputation of fixing them. does anyone know how much end play the crankshaft should have they moved the flywheel in and out some.
Have to wait for some one with more experience than me to give you an exact number, but I would think if you know that the crank is moving back and forth, you've got too much play! Andrew
.035 Max Bob
Wow! I realize that is Max, but 0.035" is quite a bit. Learn something new every day! Andrew
Thanks I am going to get a dial indicator and check it
My SIS doesn't show spec's for the D8 engine but checked a 3408/3412 just for fun. Spec's on those engines are: With new thrust plates- 0.004 to 0.024 inch With used thrust plates- 0.035 inch So It sounds like Cat is hung-up on those spec's!
Have a older mechanic coming tomorrow to check it and see just seems a lot to me wana be safe since so much money is and has been spent should be a good machine when it's finished though
checked it yesterday has 0.26
0.026
For 46A D342 Vehicular engine crankshaft end play. New spec 0.012-0.024" Maximum permissible 0.035"
Looks like I'm okay on that end I talked with the guy I took the torque had some bad bearing n the back of it and planetary gears wear worn he said end play in the crank didn't cause the problems the torque has so I hope to get it back in and that fixes the problem
Mack, while the casing is out I would drop in the hole and check your engine mounting bolts on the frame also the nuts/studs onto the back housing. tctractors
You got that right TC.... check those bolts, I've learned that lesson the hard way.