GMC K1500 - Transmission Noise

[sbebenelli]

I have a GMC K1500 5.7. When the transmission is in 1st gear it makes a grinding noise, as soon as it shifts the noise goes away. The transmission works perfectly. This same noise is also present in reverse. No codes present. Truthfully the noise almost seems like it's more under the hood than under the truck where the transmission is.

The customer wants us to install a transmission but I want to make sure this is needed.

[steven kiser]

I've had front diffs cause noises like that.

[sbebenelli]

The front diff makes a noise only in 1st or reverse? How does that happen do you know?

[steven kiser]

Do you get the noise when it's on a lift? I've seen noises seem to disappear at higher speeds. The mention of it seeming to be more under the hood made me think of the diff. What year is it and is it automatic 4wd.

[JBUTITTA]

Not a trans guy but sounds like a cracked reverse reaction drum (sunshell). HTH Jerry

[sbebenelli]

Do you get the noise when it's on a lift? I've seen noises seem to disappear at higher speeds. The mention of it seeming to be more under the hood made me think of the diff. What year is it and is it automatic 4wd.

I have no idea how I forgot to put the year. It's a 1994 and it is not automatic 4wd. I'm going to get it in today to have a better look at it. All I have done is test drove it. We where to busy yesterday to get it in.

[sbebenelli]

Got a better look at it. The noise seemed more up front than it really was. Pulled the pan and it had metal laying in it. Ordered a remanufactured transmission.

[steven kiser]

Has the radiator been replaced? May be a good time considering even if a small amount got through the filter it may return to damage the new transmission. Most of the trucks i see already have the added cooler but on the ones that don't i suggest installing an oem along with lines.

At one time i considered that over selling but i got stung once so i started adding it in. I filtered out the crud when i flushed the trans cooler in the radiator on a truck and was amazed with the amount of metal. I used a "pig" mat and a couple of cans of brake clean (to cut it) and after the fluids absorbed into the mat there was enough metal to cover the head of my pocket magnet.

Hope everything isn't salt corroded like it would be in the North East. On G.M. trucks this old i always take a good look at the fuel and brake lines. They're so much easier to replace when there is all that room with the transmission and transfer case out.

[brianp87]

lots of debris

[sbebenelli]

lots of debris

Yes and amazingly it worked perfect other than the noise in 1st and reverse