Idle issue and 442F Tranny noise

[sam1]

When driving my 94 LC to work I have some in town driving, followed by 3 miles at 70mph on the highway. After exiting, my idle drops from 400-600 rpms and is fluctuating not stable. It will continue like this until I stop and let the truck sit awhile. Any ideas?

Also, 1st, 2nd, 3rd in my 442F tranny have some whine, I know this is a heavy duty unit, and I am OK with the noise, just wondering if it is normal or indicative of any issue. Planning to switch to Mobil synthetic ATF to see if it will help. Truck has 108k miles.

 

[sam1]

After some searching it looks like I need to clean the throttle body as a starting point for the idle issue.

Any input on the tranny would be appreciated.

 

[cruiserdan]

What year is it?

 

[sam1]

1994... 12/94 production.

 

[cruiserdan]

OK,


Define the "whine" and where does it seem to be comming from?

 

[sam1]

It is fairly high pitched, kind of a scaled down schoolbus whine that grows louder as the revs grow. 1st and second gear are louder than 3rd, no whine on the highway. Sounds like it is coming from the transmission area.

 

[cruiserdan]

Up through the transfer case lever?

 

[sam1]

I will check at Lunch and let you know - should I feel for excessive vibration from the TC lever, or anything else?

(planning to switch to Mobil 1 in the TC and diffs this weekend as well)

 

[cruiserdan]

Some telegraphing of transmission noise through the transfer case lever is normal in 442 transmission equipped 80's. The transfer lever mounting boss is directly on top of the planetary gearset. You will also feel some vibrations in the lever. This too is normal.

 

[sam1]

Thanks for the info! What you are describing seems spot on. Does this not occur in OD due the the converter lock up?

 

[robbie]

May be I missed something, but I did not hear where the wine increases and decreases in intensity with the sifting of the gears. If this is so then I agree with dan, If not then I would look to the t-case, or front drive line. check for Output play on the t-case, Ujoint looseness, front pinon loosness. These will also casue some whines of different types but usually increase with speed with not drop when shifting of the gears. later robbie