Probably bad DMF?

MJGenay

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Gentleman, here's what has been done and what the symptoms are, I'm hoping y'all can help me solidify what this issue may be before I go off half cocked and have a new flywheel put in and the tranny replaced (one bad synchro, one on the way out) in the process.

I have a '91 F250 with a 7.3 IDI (with a Banks turbo installed in February/March I think) and a ZF5. I purchased it in January. Drove it home 700 miles after the purchase; no issues except the one cold start I did (second morning of drive, it was around 30 degrees) had a LITTLE bit of an aggressive rattle that would disappear if I blipped the throttle and completely disappeared as the truck warmed up.

Previous owner claimed to have installed remanufactured IP and injectors within a year of when I bought it. He seemed to have timed it well; when I purchased it he started it up cold in front of me (albeit it was 60 degrees out) but he had been gone the whole day, I arrived before he returned home from work. It gave a puff of black smoke on start then cleaned up immediately and ran well.

At any rate I have had a rattle on cold start that has been progressively getting worse since I purchased it. If the truck is warm, or even kinda warm, the rattle isn't there or it is minimal. If the outside temp is above 60 or so, it is rare for it to have any rattle and it is minimal if it does rattle.

Now we're into the cold weather. I did some work fixing fuel leaks and the glow plug system and now the truck starts reliably in the single digits, however, it rattles like hell.

I've called around and found a shop who will replace the tranny and the DMF with a Luk SMF for $36-3800. Let me be honest here and say that hurts, however, it seems as though I would be close to that myself in parts and special tools if I tried to do it myself.... and didn't screw it up.

I've been through the forum, and all over the internet, and it sounds as though my issue is my DMF although I'm still hoping for a cheaper issue, hopefully one I can fix myself with minimal parts. I pulled the cover off the flywheel and the springs are loose, some looser than others (this was the three or four I could reach). When I say loose they all spin freely, have flat spots worn onto them, and one has almost an inch of back and forth to it, the rest have less than that. What I assume is the pressure plate has about an inch of spin to it.

I'm hoping you gentleman have some insight and experience on this. If it isn't my DMF I would much prefer to put this off as quite frankly this is way out of my budget but I need this truck reliable.

Here is a video of the rattle. I believe the smoke is due to elevation (running rich) and the truck being cold, it clears up when the turbo spools or when the truck is warm. Please ignore the title, at the time I thought it might've been an air in the fuel issue.

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Thank you.
 

BlindAmbition

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I was able to install my transmission and LuK SMF without special tools. Ratchets, tons of extensions, two 6" pieces of all thread to act as guides for the transmission on the bottom bolt holes. All the information on how to do so I gleaned from these forums. These transmissions are fairly easy to remove, I am able to do it solo in fairly terrible conditions at the junkyard using not much more than hand tools and an old tire. Install is different, I used my normal floor jack to lift the transmission in while the rear of the truck was lifted as high as I could get it. I thought the job was going to be quite difficult, but once I did it for the first time it wasn't bad at all, just time consuming.

Black smoke issues I can help on further once I figure mine out, though all reading points to making sure your IP and injector rebuild was done by someone who actually knows what they are doing.
 

MJGenay

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I was able to install my transmission and LuK SMF without special tools. Ratchets, tons of extensions, two 6" pieces of all thread to act as guides for the transmission on the bottom bolt holes. All the information on how to do so I gleaned from these forums. These transmissions are fairly easy to remove, I am able to do it solo in fairly terrible conditions at the junkyard using not much more than hand tools and an old tire. Install is different, I used my normal floor jack to lift the transmission in while the rear of the truck was lifted as high as I could get it. I thought the job was going to be quite difficult, but once I did it for the first time it wasn't bad at all, just time consuming.

Black smoke issues I can help on further once I figure mine out, though all reading points to making sure your IP and injector rebuild was done by someone who actually knows what they are doing.
Thanks. Yeah. I'm debating it... From what I can tell I can probably get a rebuilt transmission from $2200+ plus the Luk kit for under $400. That saves me probably $1000 in labor.

If I was to get cocky and go this route, anyone have a recommendation for a good place to get these?
 

Jesus Freak

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Does the rattle go away when you push the clutch in? If so, I'd say tranny. If it rattles even with the clutch in, I'd say the fuel is turned up too much and the timing is off.
Zf5s are noisy but it should go away with the clutch pedal pushed in.
 

IDIBRONCO

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Does the rattle go away when you push the clutch in?
This doesn't matter at this point. The only thing that matters here is the fact that the springs in the flywheel are loose. That means that the flywheel is bad. I didn't mention it in his other thread because I got the feeling that he was tired of hearing me say it and I was hoping that someone else would point it out. No one did. Once the springs get loose, they no longer hold the two parts of the flywheel where they are supposed to be. The parts can move back and forth almost at will. That causes the rattle. That also causes the vibration in the engine.
The lesson here is: if the springs are bad, the flywheel is bad.
 

ROCK HARVEY

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From what you said it’s 100% certain that you need a new flywheel. The LuK 07225 kit is $316 on rockauto right now. I would’t spend a dime on your transmission until you see how it sounds with a new flywheel. It’s not a hard job, I did it in my driveway without any specialized tools.
 

ROCK HARVEY

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Your truck looks like it sits about as tall as mine does, and I was able to remove and reinstall my zf5 without jacking up the truck. I modified my floor jack to act like a transmission jack, using a piece of plywood reinforced with 14 gauge sheet metal in the bottom. I made it so I could bolt my transmission to the plywood and easily maneuver it. I took the trans and transfer case out together, but if I did it again I would remove and reinstall them separately. I strongly suggest you do what blindambition said and get some extra long 1/2” bolts or threaded rods to act as guides for the re-install. The whole thing can be done in a Saturday. Here’s my jack setup:
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ROCK HARVEY

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I also want to add that the zf5 is pretty straightforward to rebuild, there was a very thorough walkthrough on YouTube that I watched, and the zf-5 tech manual is available online for free and has step-by-step instructions.
 

IDIBRONCO

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Next thread - how long can I drive on a bad DMF?
That was already covered in the last thread.
I would’t spend a dime on your transmission until you see how it sounds with a new flywheel.
I seem to recall that he said that he has bad synchronizers.
I took the trans and transfer case out together, but if I did it again I would remove and reinstall them separately.
For sure. The transfer case isn't that heavy and can easily be bench pressed into and out of place. You can get a helper if needed. I've used a floor jack many times for R&R on a transmission.
 

MJGenay

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Thanks for the help guys. I understand I may be annoying some of you and I respect that it isn't your job to help me although I do appreciate the advice and knowledge.

Naturally, even though I'm getting the vibe it might annoy some of y'all, I'm going to throw a wrench in the works. We've established my flywheel is bad. I'm going to take a risk and keep driving on it for a little bit and do some more research into rebuilding this ZF5 so hopefully I can do both at once.

This evening I ran an experiment. I turned the truck on and just took off driving. I could still hear an occasional rattle although it was hard to notice over the sound of the engine. Additionally, while driving this rattle seemed to be associated with a drop in power. Guess this ******* still has fuel issues. I'm going to give the ATF in the filter a go tonight if I have time.
 

MJGenay

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This doesn't matter at this point. The only thing that matters here is the fact that the springs in the flywheel are loose. That means that the flywheel is bad. I didn't mention it in his other thread because I got the feeling that he was tired of hearing me say it and I was hoping that someone else would point it out. No one did. Once the springs get loose, they no longer hold the two parts of the flywheel where they are supposed to be. The parts can move back and forth almost at will. That causes the rattle. That also causes the vibration in the engine.
The lesson here is: if the springs are bad, the flywheel is bad.
I wasn't tired of hearing it, I wasn't clear as to what actually classified as to a bad flywheel. Thank you for clarifying. I appreciate your and everyone else's insight. I am not a mechanic nor have I ever been, I swing hammers.
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I like those and will make a set.
I also want to add that the zf5 is pretty straightforward to rebuild, there was a very thorough walkthrough on YouTube that I watched, and the zf-5 tech manual is available online for free and has step-by-step instructions.
I have looked at a few guides and jumped around in a few videos. Generally, I figure I can pull it off as long as I don't screw something up.
 

WrenchWhore

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Man, how did I never think of that for reinstallation? Dowel's for the win! Sometimes it would just fall back together and others would take an hour of wiggling with some of the bolts started before it slid in.
 

Nero

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Just throwing out my two cents too, when I was in Arizona, my dmf started going out, and it would rattle when I had taken it out of gear and slowed down at a light or something. As soon as I blipped the accelerator, the rattle would stop. So I wouldn't say the cold is the culprit per say, cause mine was rattling on 100°f+ days.
I second just wanting to replace the clutch first before rebuilding the trans, you may find a good donor too.
 

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