Grumpy idle noise in gear

[Montana Pirate]

Just recently got this truck and have been un-hackifying the whole thing (previous owners had some interesting solutions to problems) it's a 94 powerstroke body with a NA 7.3 from a 91 f250. main thing I'm trying to figure out right now is the very odd grinding/whirring noise I get when I put it in gear and let it idle down the road. the sound goes away entirely if you give it some pedal. . . not sure if its just starving for fuel... or why it makes that noise. seems to have plenty of power when you do give it the beans just kind of grumpy in idle.

any input would be very appreciated! thanks in advance.

 

[IDIBRONCO]

Most likely, it's what's called gear rollover noise. Someone probably put a solid (single mass) flywheel on it. They came with dual mass flywheels that didn't make the noise. I don't believe that there's any new dual mass flywheels made anymore. Some people say to add .5-1 extra quart of ATF to the transmission to lessen the noise. I'm so used to mine making that noise that it sounds normal to me. The only thing that it hurts is that it gets on people's nerves.

 

[WrenchWhore]

I'm assuming it's a manual. If so, i'd guess gear rollover noise like @IDIBRONCO said. Always helps to post a video of the noise just to be sure.

 

[The_Josh_Bear]

If you have a Zf-5 and it's gear rollover noise, some overfill the trans as said, but I just turned up the idle to 800-ish RPM. I just turned it up till the noise stopped. A little higher idle doesn't bother me any since I almost never sit in traffic or leave the engine running for no reason.

 

[WrenchWhore]

@The_Josh_Bear Speaking of that. Has anyone overfilled there T19's the same way to get rid of rollover noise?

 

[IDIBRONCO]

I haven't heard of rollover noise being an issue in the T19s. It may be, but I just haven't heard about it.

 

[franklin2]

Raising the idle speed calmed mine down a lot also. But it's still there, especially when it's cold outside. And I noticed also, the amount of noise depends on how smooth your engine runs. These engines vary in the noise they make and how smooth they idle, probably depending on the age of the injection system and how its timed.

You will learn to live with it.

 

[Old Goat]

@The_Josh_Bear Speaking of that. Has anyone overfilled there T19's the same way to get rid of rollover noise?

Never had any roll over noise on my T-19 trans.
Bought it with 192K now 361K, runs smooth.
Maybe you have a bad bearing or???


Goat

 

[Montana Pirate]

wow! lots of responses that I didn't see until just now. yes the truck is a Manual ZF5 it seemed to do it quite a bit when I first got the truck. but after putting about 2500 miles on the thing and slowly fixing a lot of things on the truck it seems to be getting better? (or maybe I'm just tuning it out now because I'm used to it) next time I go to take off in the truck I'll try to remember to take a video... then try and figure out how to upload it here.

 

[Jesus Freak]

If you got rollover noise, and it sounds like you do, there should be ATF in the ZF-5. But some "hackifiers" have put 90wt gear oil in them to shut them up.......but that won't go well. So for piece of mind make sure your ZF-5 has a high quality automatic transmission fluid in it! And get used to funny looks if you're easing around a parking lot.....rrrrrreeeerrrrr....rrrrrreeeerrrrrrrrrrrr........rrrrrrreeeerrrrrrrrr.........lol...

 

[Nero]

Its not a bug, its a feature.

Some people will overfill them a half quart or so and have reported it helps with noise. It doesnt bother me at all.

 

[IDIBRONCO]

It doesnt bother me at all.

Same here.

 

[KansasIDI]

Typically rollover noise doesn’t bother me, it hasn’t in my other trucks. But in my 91 service truck, it’s REALLY loud, compared to any other ZF5 I’ve been around. It had a ZF5 with a bad 5th gear, that put out about the normal noise level. Then I put this one in. It shifts beautifully, nothing seems to be wrong with it, but it’s much louder than most ZF5s. Definitely louder than the engine, even chatters a bit going down the road until about 2300 RPM in 4th or 5th, then it smooths out some.

 

[The_Josh_Bear]

So I've never gotten a clear answer-- does gear rollover noise do any damage or is just annoying?

 

[KansasIDI]

annoying

I think that’s all. I’ve never heard that it causes damage, it is just the way that engine vibrations transfer through the aluminum case of the transmission, with a single mass flywheel that doesn’t dampen said vibrations.

I’ve done some poking around, right now I’m running 4 quarts of Synthetic Valvoline ATF, next time I change engine oil I think I’ll throw 5 quarts of Valvoline Synchromesh in. See if that makes a difference.

On my 86, I put CAT transmission fluid in the ZF5 I put in it, that transmission wasn’t healthy and eventually it literally exploded (shrapnel through the floor) but it never had any gear rollover noise.

CAT TF is a slightly thicker ATF without the red dye for all practical purposes, I doubt that it was the demise of that ZF5, I think it’s preliminarily poor condition and my lead right foot, and the all too common occurrence of me treating that poor old truck like a drift car, are what killed the transmission.