So I’m fairly certain I’ve got some transmission issues going on. I’ve got a 97 f350, manual trans, 4wd, 305k miles. When accelerating in 1st/2nd, even fairly lightly, the truck will lurch and clunk. When decelerating in all gears at lower RPMs the truck will also clunk and lurch. This often happens when depressing the clutch while coasting as well. I experience some resistance putting the truck in gear.

Accelerating in any gear including neutral produces a brief loose change rattling noise. I haven’t greased the spline since owning the truck at 277k, so that could be the source.

I’m also getting a clicking noise that gets faster with increased RPMs, but only when the truck is in gear. It’s also started to happen when moving the shifter towards reverse/5th gear. I’ve managed to get this on video. It sounds a bit like a dead injector, except I’ve just replaced those and it only produces when the truck is in gear.

I’m not experiencing a loss of power or any issues staying in gear, even under load. I just replaced the injectors not 500 miles ago, and I’m babying the truck since I know the tranny is old. Plus I’m separating from active duty in 2 months and will be pulling a trailer with all our stuff from NV to PA, so I need it to last.

Troubleshooting:

Ran a good buzz test on the new injectors just to be safe. I checked oil levels since they are new injectors (180/30) and thought maybe it could be a loud injector. I’m not an expert so I’m trying to eliminate anything that may seem common sense. I’ve checked all pulleys for play and my drive shafts. The middle joint of the rear drive shaft has some side to side play, not sure if that’s normal or not. There is no rotational play in the driveshaft.

 

Do you still have the dual mass flywheel? If so, that’s my bet.

 

I’d assume so. Everything was stock on the truck when I got it besides an aftermarket cassette tape player and billet door handles.

Excuse my ignorance, but is this something I can limp along safely until after my move, or is this more of an urgent repair?

 

it will be fine as is until it decides to not be fine any more.
i have seen a bad DMF last 100,000 miles, and also seen them fall apart leaving the shop after recommending change soon.

 

check your trans oil level ASAP
if it sounded like marbles in an ash can taking off at low RPM, could be clutch or the trans main shaft bearings.
You need to investigate this sooner than later.

After hearing the video, i think trans is low on oil.
5th and R are on the bottom part of case and their bearings get all the debris in the trans.


drive shaft ujoints should have no play and could be your ticking sound
check carrier bearing while there too

 

Drop the inspection cover to tell what flywheel is in there, look from the crank side toward the aft of the truck. If the DMF, I would change immediately if loose.

The Luk kit seems to be a very nice SMF kit with a 13" clutch for about $325.

 

If you do end up changing to a SMF, don’t freak out if you get a new noise. The dual mass masks the gear rollover and with a single you tend to hear it at slow (lugging) speed. There are methods to quiet it down some though. I went with Southbend, it’s been good.

 

Can add a extra quart to quiet it down some

 

Sorry for the delayed response. Got my hands full here, but wanted to give ya’ll an update.

First off thanks for all the great info. I drained just shy of 3 qts from the trans and refilled with 3.5. I also pulled the inspection plate and found a very bad DMF. It also looks like that’s the source of my loose change sound. I’m assuming the springs are the cause of that.

I’ve never touched a transmission before. I actually knew nothing about diesels when I bought this truck. It’s been a fun learning project to keep me out of trouble lol.

That being said, since I‘ve already upgraded to 180/30cc injectors which I believe produce basically the max torque and hp the stock trans can handle, I’m sitting on 305k miles, and need to pull the trans anyway - is it worth strongly considering a stage 2 trans at this point?

 

Glad you are learning. I keep learning more.

DMF has a lot more to it than a SMF



un sure about stage 2, i think the clutch is going to be the weaker item

 

With that much injector, you may want to eyeball South Bend's 425hp clutch kit as I think yours are good to about 375-400. Seems to be a good balance of smoothness without a crazy pedal. I have heard good things about Valair too, they are just west of me outside of Fort Worth. I have the South Bend OFE which is rated to 475hp, it is definitely a grabby guy as expected. Pedal feel is the same as the Luk and I think one side is feramic and the other HD organic. It does like more input power to be smoother, hard to explain really.

I do not know the limit of the Luk clutch assembly I previously recommended, but many guys use it with 160/0s and tow heavy. Also really surprised your DMF is still there with that much injector as they are known to die with stock 90s. My OASIS report for my 96 shows the DMF replaced around 55k! I figure it died again and its PO installed the Luk kit.

Regarding the trans, has it ever been split? Any background on the truck? 300k and it will be a bit tired. You could easily replace third and fourth gear syncros as they are right at the front of the case. Only one bearing to pull (input pocket). Easy to inspect the 5/R slider and the R gear as they are usually borked up from careless drivers.

 

Well, the new injectors haven’t been in for 2 weeks yet, but I have noticed the woodpecker noise getting much louder since then, so I don’t think I have much left on this DMF. I’m not sure what you mean by the transmission being previously split, so I can’t say.

The truck’s history is mostly unknown. I purchased it from a dealership and they were very upfront about it having been neglected the last few years. It was originally purchased by one of the Florida Marlins after winning the World Series in 1997, can’t remember who. It stayed in central Florida its entire life until I got it. Last owners were soy bean farmers.

Everything on the truck was stock when I got it except the stereo and door handles (upgraded to billet). From what I was told they regularly pulled a horse trailer with it. The alternator was the only component that appeared to be recently replaced. I found a single brand new AB code injector (#1 spot) in there amongst 7 other basically dead AA’s when I replaced those.

The bed had a 5’ wide 4’ long hole in it. Windshield was cracked, headlights and tail lights were busted out, instrument cluster didn’t work, injector harness was shot, turbo needed rebuilt (ebpv was stuck, pedestal was leaking, boot was torn, plunger was leaking), truck was full of trash, etc. Shower heads in the fuel tank were gone. At one point they cut the hole in the bed even bigger to access the fuel tanks and left all the broken plastic in there. So I figure they basically did the bare minimum to keep it running and no preventative maintenance.

Seeing as the engine itself was in surprisingly good shape, and the trans has held up at least since I’ve owned it (277k miles), I’ve got to assume it was well taken care of most of its life but neglected by the last owner.