truck makes a new noise

[jam0o0]

so i'm almost done moving into my new rental house. i've been using my truck more than usual. it started making a loud bang, rattle, knocking noise. it's not consistent or rhythmic. but the noise does go faster with RPM. it only makes the noise when i'm accelerating or reving the engine in neutral. the new noise seems to be louder when the engine is cold. but it still does it after pulling an 8k lb trailer 60 miles. i can hear the knocking clearly in the cab when driving. but i can't hear the new noise over all the other noises when reving it from under the hood.

since i've had to use the truck i've been driving it despite the nervous feeling this noise is giving me. and i've noticed that the truck seems to smoke more on start up the last 2 starts. it's blue smoke so i assume it's not cavitation /coolant.

the SCA's are good and have been since this truck got it's second engine. i'm not losing enough oil to see on the dip stick. i'm not losing any coolant. the truck isn't down on power. it still idles beautifully. engine has 160k on it. i think the fuel system is original to the engine. i have no way to check timing, fuel injectors, fuel pressure, cylinder pressure. my pyrometer and boost gauges are in a box somewhere.

help. i'm worried i'm screwing something up driving it and i have a 700 mile trip coming up on memorial day weekend.

 

[Brianedwardss]

Could it be the DMF? (dual mass flywheel?)

 

[mattplumber]

Im gonna say that one of the springs in the dual mass has broken and is rattling around and/or is loose in the clutch. Common problem. Solid flywheel and clutch kit fixes it.

 

[Diesel JD]

Could you post a clip Sam? With a 7.3 you have to be a little concerned that it could be a valve and a piston getting acquainted, in which case you'd hear a backfire through the intake (dog in the intake, barking noise) which could also be bad lifters or a banging noise out the exhaust (above and beyond the usual V8 diesel chatter) what it PROBABLY is is a leaky injector or funky spray pattern. How many miles on the reman engine? It sounded fine when you had it up here. The other problem could be that there is something laying on one of the high pressure injection lines and that usually will cause an audible knock type sound in the cab or under the hood.

 

[jam0o0]

thanks for the ideas everyone. this is all really helpful.

i'll see if my camera mic can get a good recording of the sound. and i'll pull the intake to see if the noise gets worse. i should have a helper this weekend to rev the motor wile i search for where the noise is coming from.

if one of the dual mass springs is loose can i see anything through the inspection plate? i know the truck got a heavy duty clutch of some kind. it's got a way heavier clutch petal than any other 90's ford i've driven.

 

[mattplumber]

Did YOU put/have the "heavy duty" clutch put in? The reason I ask it that i was sold the same bill of goods on a truck once and it turned out to be a busted dmf.........IIRC there are no heavy duty clutches available for these engines that increase pedal effort that much. If the clutch pedal is that stiff then 90% odds the flywheel is on its way out.

 

[jam0o0]

no i didn't put in the clutch. i bought the truck from my old boss. he is an honest guy. i get a call or message from him every few months asking how the truck is working or when he finds some paperwork or old receipts for it. he said he replaced the clutch with a heavy duty model. most likely it's a napa clutch with slightly more clamping force that they only sold 9 years ago.

there is a lot of gear rollover noise around 1500 rpm. i have no idea if it's a dual mass, or solid or something weird like a lucky mod. either way i've been looking for an excuse to pull the trans to see what's in there and grease or replace the throwout bearing.

only annoying thing is i need the truck to bring my tool box (42" roll cabinet) to the garage. hmm maybe i can squeeze a favor out of one of my fellow 4x4 club members.

 

[rhkcommander]

Check the engine mounts... Mine did the same. Crawled under and found P.O used normal nuts and they had punched through the plate

 

[jam0o0]

thanks again for the help guys. this is the first real problem i've had to diagnose on a diesel.

i got to look at the truck this last weekend. the motor mounts look good. but i really need to get a pry bar and check them that way.

the noise with my head under the hood sounds like a 3lb sledge hitting the engine block. i can't tell you if it's coming from the bellhousing or the block it's self. it's definitely not something rattling. i'm really thinking leaky injector now.

the noise is way louder when the engine is cold. and gets quieter and happens less when it's really warmed up. it happens at nearly all rpms under part to nearly full throttle. in neutral or in gear. clutch in or out.

so i'm thinking its fuel system rehab time. can yall check my parts list and let me know if my sources are wrong.

pump - moose pump (mel)
injectors - moose misters (mel)
return line kit - (type 4)
fuel filter - napa gold
low pressure pump? - ?