Multifuel engine noise

[mobileauto2000]

My truck some times knocks at cold idle, some times it doesn't. Some times the knock at warm idle is faint and not troubling other times it's quite loud. The oil pressure is a steady 58lb Hot or cold at idle will go up to 70 at speed cold but will stay right at 58 hot. The knock is not there cruising or decelerating. It is light and not troubling during acceleration. The knock seems to be loudest on cyl 4. It won't quiet down when cracking any injector lines. But cyl 4 drops the idle more than any other cylinder. The truck had a bad Hydrolic head. i had hoped replacing it would cure the problem as it had 2 dead cylinders. i also replaced cyl 4 injector. it now hits on all 6 at idle. (cyl 4 was not one of the dead ones.) I have heared some trucks on you tube with the same knock but that dose not mean there is nothing wrong.

I would suspect a rod or piston problem but i have never see one that would not always make noise

Do some trucks just knock at low rpms? has any one else had a similar problem.

Also the knock is worse on diesel than WMO but not much.

I just don't want to miss something before i bite the bullet and inspect bearings.

Thanks for any input And please don't tell me to search i already have.
John

 

[wsucougarx]

My '68 has a 1990 rebuilt LDT-465 Continental MF w/5k miles on her. At cold start I seem to hear a small knock of sorts about 1 every second. When she warms up the knock goes away. She was louder during cold start when I ran synthetic Rotella in her. When I changed the oil and put in conventional Rotella-T, the knock was much quieter. I sure hope this is normal. I don't notice any knocks at acceleration or cruising speed. She's been doing this ever since I got her two years ago and have not had any issues.

 

[Floridianson]

Have you tryed to use a broom handel or very large screw driver and try to hear and pin down where the knock is. ( upper or lower end).
Do you think it could be a timming knock as you said it happens on Acceleration?

 

[mobileauto2000]

It dose sounds like a timing knock. It is a deep knock at the top of cyl 4 Sounds lighter but still loud at the pan. But it dose not go away when the injector line is loosened. that is the part that gets me. rod or injector it should change when fuel is removed. I think ill try to recorded the sound and post on You tube. mabe someone will recognize it.

 

[deathrowdave]

Sounds like forged pistons heating up to desired clearences

 

[Floridianson]

So you can get it to knock with out a load? Most fuel /timming knock would seem to be under load as the truck weight or loaded bed/ hill type thing I believe.

 

[mobileauto2000]

I recorded the knock this morning and uploaded it to you tube. Their compression muffled the sound so crank it up and let me know if i'm worried about nothing. I have never heard another Multifuel run. I am concerned becouse the knock is not always there.

[media]http://www.youtube.com/watch?v=qLADXa9Zx8k[/media]

 

[RANDYDIRT]

A rod will knock under load. It almost sounds valve related.

Dirt

 

[MikeON]

My truck sounds the same, and under the same circumstances. It's only at cold idle.

 

[sandcobra164]

Ditto on MikeON's post, I thought that's how a Deuce was supposed to sound cold. I've driven many in the Guard and my personal truck sounds just like that and has been going strong for quite a while now.

 

[Flyingvan911]

I think the deuces tend to knock when cold because the cylinders/pistons are cold and we aren't getting proper/complete combustion. I wait for a minute or so after I get full oil pressure then pull the hand throttle a little to get the cylinders warm.

 

[kipman]

Mine sounds like that, runs great, 4 years now, run it, you will get used to the the truck, they all have their own personality.

 

[JasonS]

A rod will knock under load. It almost sounds valve related.

Dirt

A rod knowck will also get louder as the engine gets warmer. My truck also makes a knock when cold; I have suspected that it was a loose valve.

 

[OPCOM]

mine made a pronounced noise at times and eventually the exhaust manifold gasket blew out.

 

[mobileauto2000]

I want to thank every one for their replies. I spent the afternoon on you tube comparing my videos sound with many other trucks and have come to the same conclusion that it is normal engine noise for a deuce.

I truly apprentice every one that replied

John

 

[Varyag]

Sounds Just like mine. You are right not to get worried.

 

[1983M35A2]

mine 3 sounds the same.

 

[cattlerepairman]

A timely post! I picked mine up from winter storage yesterday. Not having heard her run in a while I kept thinking ''she has a knock'' on the first few minutes of the drive. Once the temp gauge started moving up, the knock was gone.

 

[patracy]

Sounds fine to me, if anything I hear a valve or two that might be loose. But nothing that sounds like it's going to come apart anytime soon.

 

[mobileauto2000]

I am reviving this thread as i am still on the fence as to if this is normal engine noise.

Most reply that their truck sounds like this cold. Mine sounds like this all the time.

I plan to take the truck to the Washington rally in July. Thats several hundred miles.

So i recorded my trip home from work so you can hear it under load and tell me if I am just an old worry wort or not.

http://www.youtube.com/watch?v=duzASAz3IU4