LDT 465 Knock

[nosajb15af]

Im not new to diesel mechanics, but I am new to the personalities of these trucks. Mine has a loud knock at idle mainly heard from the transmission tunnel close to the firewall. As soon as is give it gas and bring the RPMs to 1200 its dead smooth. No knock under load. Makes the knock cold or warm. Oil pressure is 40psi idle warm, 80psi revved warm. I tried pushing the clutch seeing if its the transmission, but the knock doesnt waver. Should I be concerned? I recently changed the oil and didnt notice any shavings. Next step would be to drop the pan and check bearings, but im trying not to loose 25+ quarts of decent oil. Fuel is at stock position.

Thanks

 

[NDT]

Try the usual, loosen the injector lines one by one and see if the noise goes away. As far as being concerned, knocks never seem to go away on their own and usually have a bad ending. If it were mine I would plastigauge the rods and mains.

 

[Heath_h49008]

Got a mechanic's stethoscope?

They cost $10 at the most for a store bought one, and you can make do with any long prybar pressed to the bone around your ear.

That should at least narrow down the search.

Good luck!

 

[m-35tom]

loose flywheel

 

[nosajb15af]

loose flywheel

Hmm..never even thought of that one...ill have to check it.

 

[swbradley1]

Mine had a knock once...

 

[Heath_h49008]

Mine had a knock once...

Actually yours was what popped to mind from his description, but I wasn't going to torture the man.

 

[nosajb15af]

Haha...what was the final result of your knock?

 

[fuzzytoaster]

Something opened and it wasn't the door. lol!

 

[sandcobra164]

loose flywheel is a possibility. To check for it is a little bit of work. First, remove the bench seat and the center tunnel sheet metal in the cab. Remove the jackshaft between the trans and transfer, undo the bolts holding the trans to the motor, get a 4X4 board and rig it so that you can hook a chain hoist to it. Remove the top plate from the trans which has the shifter attached, secure the trans to your rigging and back it away from the engine and you're good to go. Ensure those flywheel bolts are between 60-70 ft. lbs. When I do it, I apply Loctite Red but that will be met with opinions on this site. I was taught to do that long ago before these trucks were ever thought of being surplussed. I would do it tomorrow if one came in for repairs. I do need to add, if you intend to pull the flywheel, mark where it came off. It will only bolt on in one of 6 positions. 1 bolt hole on the crankshaft is offset about 1/16" of an inch and all 6 won't go back in. If you've ever held a deuce flywheel and tried to line up threads on fine threaded set up, you'd realized that there are some heavy parts on that truck. Before trying to reassemble, get a crank to flywheel bolt and match it up to a longer one to use as a guide. It may take 5 times of "bolting it up" but it's alot easier to see if bolts match when you're not holding the flywheel up to the crank.

 

[m-35tom]

I differ. checking for loose flywheel is not hard at all. put transfer in neutral and trans in 5th. put a bar in driveshaft from underneath and rock it back and forward. or put a socket on the crank with a bar. (lock fuel shutoff in off) it may be fairly obvious. it would be disappointing to pull the trans just to find nothing. another possibility is a broken crank, but it will show up this way as well.

 

[swbradley1]

Haha...what was the final result of your knock?

Post #162

http://www.steelsoldiers.com/showth...in-Deuce-NOT-Crank-Broke&highlight=ventilated



You can read how it started in my first post. She still ran even with all that damage.

 

[nosajb15af]

Well, after a hard day of cleaning the truck, rebuilding the IP, and tracking down the knock..I think I found the knock. I put the Tcase in N, Trans in N, and with a breaker bar/socket I quickly rotated the engine back and forth (with the injectors removed). Smooth and quiet. Then I put the trans into 5th gear, and Tcase in N and did the same....This time not so quiet. The knock was back. So I guess its a transmission drop tomorrow. I hope its just a flywheel bolt, but im happy the engine is almost in the clear.

 

[m-35tom]

what you say tells me it is in the trans. maybe. run the engine with the clutch in and the trans in gear. still got the knock? when you start taking stuff apart without knowing, you give up the chance to diagnose it.

 

[nosajb15af]

When running...clutch in or out...knocks.

 

[sandcobra164]

M35-Tom,
I may have a slower method to diagnosing something but with my experience with these trucks, I think I found the root cause a tad quicker. I will admit that your way would have been much simpler though and I had actually never thought of checking it that way. After reading the OP's last post, I'm pretty sure he'll find a loose flywheel. I would also recommend that he replace all of the flywheel bolts and have the flywheel bolt holes checked to ensure they are still round and not elongated. While in there, I would have the flywheel machined and replace the clutch. I would take these measures as I plan to keep all of my stuff and don't want to do the job a second time if it was possible to take some preventive measures when I did the job the first time.

More directly to M35-Tom,
I'm getting closer to upgrading my transmission and pending funds, I may be able to before the 2014 GA Rally. This year's a bust with the Furlough on DOD civilians but we'll get there when we get there.

 

[nosajb15af]

Just following up. I had 3 flywheel bolts loose. I re torqued all bolts and started the truck with no transmission. Engine sounded great. Thanks for everyones help.