Hey guys,

I have a 97 with a manual transmission. 2 weeks or so ago the clutch seemed to be slipping. The weird part about it was that I didn't smell any burning clutch, (and never have in this truck), and when I drove it back home from work it seemed perfectly fine. Did not slip once.

Basically I only drive this truck ever now and then when I have to. Its been cold here lately (between 25-40 or so, the morning in question it was probably right around 32). On my way to work, probably about 4 minutes into the drive on the freeway, it seems like my clutch was slipping. My RPMs would go up but I wasnt going faster. I would let off the gas a little and it would catch, or if I stepped on the gas a bit it would catch. Basically, it only seemed to slip when I kept the same RPMs.

That seemed weird to me - its been a while since I have burnt up a clutch, but I want to say that it always slipped worse when you stepped on the gas. The morning in question it actually stopped the clutch from slipping. Beyond that I could also hear a distinct "scratching" sound. It reminded me of when a dust shield is scraping against your rim. Or if you grabbed a butter lid and started spinning it at a consistant speed on loose gravel. Like I said, its been a while since I've burnt a clutch up, but I'm pretty sure I have never heard that sound when a clutch goes.

When I exited the freeway it seemed a lot worse.

At lunch time I wanted to check it out again to re-evaluate whether or not I shoudl try to make it home on the freeway or call AAA. I drove to the liquor store and to my amazement it did not slip. I drove it around the block a few times and even TRIED to make it slip by bogging it down. Seemed perfectly fine. I decided to drive it home and, again, it worked fine on the way home.

After about 1.5hrs of fighting the view/fill port on the transmission I finally was able to check my fluid. It seems full but definitely needs replacing. Am going to do that and then test drive it around again.

Questions:
A) Does this experience sound like a clutch going out, or something else?
B) What else could it be/what else should I look/listen for on my next test drive?
C) What does a clutch run for these trucks if you DIY, what does it cost to have a shop do it? (Ball park figures obviously)
D) How hard it to change out these clutches? How hard to drop the tranny/install the tranny (and have a shop do the install)?

I have dropped trannys before, dont think i've ever actually done the clutch, but its been a while. If someone has a link to a write up I would be forever grateful.

Cliffs:
A) Suspected clutch slipping - only when kept at same RPM, slowing down or speeding up would stop the slipping
B) No smell
C) Heard a scratching sound - seemed like a rotating round object with slight friction
D) Semi cold weather
E) Clutch worked perfectly fine later in the day - no issues.

Sorry for the novel and any help is appreciated.

 

Throw out bearing could have been hanging up and not letting the clutch fully engage or the slave cylinder not fully disengaging. The noise sounds like the clutch fork riding on the bearing slightly.

 

Thanks for the possible diagnosis. What is the proper way to check these possibilities, or would I be better off taking it in at this point?

 

It could be the whole set up; clutch disk, bearing, DMF if orginal. You will need to convert to a single mass setup if you conclude your clutch is the problem. Valair is most reputable on this site and really good to work with.

 

Does doesn't have any weird shakes at any time. I have experienced the cam positioning sensor going out, if that is what you were referring to (though I don't necessarily see how that would be related?).

I guess the main reason I'm not pulling the trigger on the clutch having gone out is because of the fact that there was no burning smell, the scraping sound and it worked perfectly fine just 8 hours later. It almost seemed as if it was the cold weather causing the issue, though I don't really see how that could be. Its been a couple weeks, but even if it was our coldest night of the winter so far it wouldve been like a low of 17* and the sun is well up by the time I leave for work at 7:45am. I mean, I'm not in Alaska where parts could literally freeze up.

Come to think about it, the last couple times I started my truck early in the morning it started rougher than normal and had some hiccups for about 20 seconds then starts idleing just fine. I guess I could consider this a weird shaking sensation? Like I said though, it ran perfectly fine after 5-10 minutes of idling, and what I experienced is not what I would call abnormal for a diesel.

 

Remove the inspection cover and try to turn the flywheel. If it turns a few degrees back and forth, the dual mass flywheel is on its way out. The DMF sux anyway, so if you're still on it, this would be an opportune time to clean house. While you're at it, look at the front of that inspection cover. If it has a "flange" jutting forward, grind or cut it off; it's been known to "saw" through the oil pan.

No surprise about the no-smell. The only time I've smelled clutch burning is on launch when towing 10K with stock power and 3.55s. I've had clutches wear just about down to nothing on several cars over the years, and even when they slip like crazy, they don't smell.

 

I just put a tuner on my truck, and it slips exactly like you said. There is no smell or anything, and a very metallic scraping noise. I am quite certain it is the DMF. I have a new clutch/SMF on the way.

I pulled the inspection cover, and it turned about 1.5 inches. I'm not driving the truck anymore until the clutch is changed....don't want the DMF coming apart and taking out the transmission.

 

Here is a couple of pics of my DMF and shows what happened to to it. The clutch disc was still good and no slipping, It did shake the engine, more at idle and smoothed out a little at higher RPM's. Not being familiar with the DMF it was misdiagnosed as a engine miss.





When I took the inspection cover off I found a couple of ball bearings and other metal in the inspection cover, one bearing was broke in half.