M-52 tractor engine knocking sound

[5 ton monster]

Hello everyone, Maybe someone can shed some light on this subject for me. I recently purchased a 1972 M-52 bobbed 4x4 tractor with the LDS-465-A-1 turbo engine with only 800 miles on the truck and engine since a military rebuild. When I picked the truck up I noticed a knocking noise from the engine and was told it was the normal sound. Now that I have 1,500 miles on the truck the knocking seems much louder. At idle it is quiet, but as soon as you put load on the engine or start to drive the knocking is very noticable. Is a knocking sound normal or do you think there is a problem ?

 

[avengeusa]

uh oh, that aint a good sign...... is anyone near you more familiar with the engine in your truck?

i am sure a ss member may be close to you

 

[panzerwillie]

If you are not familiar with DIESEL engines may be dificult to to tell noices, there could be many things making noices , have you check the oil for any metal shavings or maybe take a oil filter out and and look for any metal particles, also if it has a bad injector coild make it knock but it should blow a lot of black smoke, if you rev the engine in neutral can you hear it, i live in miami , probably will be going to virginia next week to pick up a military MEP=005A maybe on the way back can stop and listen to it if you have not figuere out by then

 

[5 ton monster]

Hi Panzerwillie, Thank you, You're right about not knowing much about diesel trucks and engines, This is my 1st, The oil and filters where replaced when I bought the truck and was told everything was good, I've checked the oil several times and the level remains and looks fine on the dip stick other than the typical black. When you rev the engine out of gear there is no knock, only under load... Although there is black smoke while idleling and tons durring acceleration through the gears and seems to go away once at desired speed, I'm surprised the law hasn't said anything there is so much smoke.

 

[panzerwillie]

Ok so no particles on the be oil dipstick is good, as cheap as those filters are may be good to take one out and look at it good maybe run a magnet and see what you get, my smokes pretty good under acelaration but it depends how hard i'm on the throttle, do you have any pictures you can post, does it have super singles, that makes the engine work more so you need more pedal effort to gain speed , but i think you mention is a bob style so probably has one less axle, this engines fuel hard between 1500 rpm and 2100 rpm or so defenectly will put a lot of smoke out of the stak, however it should clear if its getting full boot or at least my does....

 

[G-Force]

Loosen each injector line as it is idling and see if you get a double knocking sound out of the cylinder.
If so then that is probably the cylinder with the rod knock.
Personally, I really don't think you have a rod knock. It sounds like you're overfueling.

 

[5 ton monster]

Thank you G-Force, A coment was made to me by the seller that this truck seemed to have more power than normal and that someone must have turned up the fuel injection pump which might have to do with what you're talking about being over fueled. Is there an easy way to turn back the fuel injection pump that they where talking about ?

 

[digitaldust]

I dont know what its worth but i have a deuce that does not smoke but makes that knock wile under a load i'm told its normal. I have not had my truck get any louder its been 200 mile if city driving thru all the gears. but check the oil filters and the pan maybe USE a very clean pail

 

[5 ton monster]

I was just told the military by-passed the fuel compensator valve when they redid the engine to get more power. Do you think this could be the cause for the knocking sound I'm hearing. Since it smokes so much could it be getting over fueled and causing the knock ?

 

[panzerwillie]

Does it still have the fuel air heater in the discharge tube of the turbo for cold weather make sure the switch is off and is not leaking that would make it smoke and knock because is delivering fuel before injection time kind like pinging on a gas engine..

 

[5 ton monster]

Hello everyone, I wanted to thank everyone for their input to my knocking noise question that I had posted yesterday. Pete from John Winslow sales was so concerned about my happiness with my new truck that he contacted Big Case from New Smyrna Beach on his own to have him drive clear out to my home to test drive and listen to the noise I was hearing. Like a new parent with their new child I was over conserned about what turned out to be a normal sound for the motor I have and gave me a clean bill of health. Big Case who considers his Duce with super singles huge was also disapointed to see his wasn't the biggest anymore which made me the proud father/owner of my 5 ton monster M-52. You guys are the best.....

 

[digitaldust]

man, thats not my truck but i'm Sooo relieved for you.
keep that 5 ton trucking

 

[M543A2]

All of our engines are turned up, with no resulting knocks or other problems when they are driven with good sense. The turned up fuel is NOT the problem. We have one engine that if we do not run the flame pre-heat regularly, it gets air in the lines and one cylinder wants to make a knock sound. It clears up when the air is removed by running the pre-heat. We always look askance at the plastic return and other fuel lines because they seem prone to not staying tight, allowing air to enter and leaks to happen. We think it would be a good idea to replace them with copper and steel where appropriate, but we never got one of those "round tuits" for the job.
We had one truck we drove about 300 miles home that had a knock sound in it, and the oil gauge fluctuated at idle. The sound went away at high RPM and the oil gauge steadied. We noticed the sound at idle went away when we pressed the clutch pedal. After some evaluation, we found the crank was broken. We find this is not unusual--an engine will run with a crank broken. The usual cause of the break is out of control harmonic vibrations caused by a bad front pulley dampener. If someone heats the front pulley too hot to install it, it damages the rubber in the dampener portion of the pulley. You will see frayed rubber in the seam line. We found the crank was broken by prying the front pulley in and out and watching the corresponding action of the flywheel.
Regards Marti

 

[roger-wilco-66]

Interesting post, Marti! Thanks!

Mark

 

[5 ton monster]

That's funny that you mention the leaky fuel lines and a corresponding cylinder knock, I drove the truck home with the fuel injector return line spraying from a melted spot in the hose and didn't notice till I got home, I was showing off the new truck to a heavy equitment friend and he spotted the leak while watching the motor run. It would only spray when you gave it gas then let off then it would spray. I complained about the knock and he told me about a dozer he took all apart due to a knock and found nothing wrong and finaly figured out it was air in the lines causing the problem and when he bled the lines it ran like a sewing machine. Do you think there an easy way to bleed my lines to easily get rid of the knocking noise ?

 

[ida34]

Since you got a clear bill of health from the experts then you should be good but I suggest getting an oil analysis once in a while to make sure the engine is healthy.

 

[Big CASE]

Hey Monster , I just got back from a 1800 mile trip to John's and to see the CMVPA guys , doing a pick up of a M105. Thanks for the cool post . Iam glad I could come out and check your motor.
I hope too see you in town with it , I am now off to TX for some more OD Green thing .
we will have to meet up when i get back . till then have fun driving that little 5 ton ...
some day you will get a BIG M35A2