M35a3 screeching noise

[Jeffval]

I've got a 1982 model m35a3 that was upgraded in 1993. It has 6000 miles on it and is in excellent shape. I took it to a lube shop to have all the fluids changed. They filled the transmission with oil from the top fill tube inside the cab. They did not use a pump from the bottom. When I got home I noticed oil dripping onto the ground. I checked the transmission dip stick and it had blown out. It was completely full with oil. I drained 2 gallons and it was black in color. I told the shop that they must've not got out all the old oil from the torque converter and the new oil is contaminated. So they drained everything again and filled it from the top again. I got 1 mile down the road a it made a terrible screeching noise when it hit 3rd gear. I checked the transmission oil and it was full. When I got back on the interstate it bogged down and wouldn't shift. I pulled over for a minute then took off manually shifting from 1st, 2nd, 3rd, and Drive and got up to speed. Then I pulled over 5 miles later on a level surface and checked the transmission oil again and the oil wasn't registering on the dip stick. I added 2 1/2 quarts of oil. It started operating as it should but when it hit 3 gear it made that loud screeching noise again. The noise doesn't happen all the time but every do often. And the truck just doesn't have the power it had before they changed the oil. I don't know if the problem is with the transmission or torque converter or both. What could the problem be the problem? The shop manager said those trucks make those noises under high RPMs and is not taking any blame. They told me to take it to a diesel mechanic. I can't find anybody who is willing to look at it here in Butte Montana. I need some answers because the lube shop owner is going to call me tomorrow. Thank you so much.

 

[Elk1111]

You should probably post this in the Deuce section for a faster reply…

 

[gringeltaube]

You should probably post this in the Deuce section for a faster reply…

Moved.

 

[glcaines]

It sounds like the guy simply dumped oil into the transmission without using the dipstick. Have you read the TMs for the M35A3? You check the transmission fluid level with the engine running, not stopped. Hopefully, the transmission isn't damaged. What kind of oil did they put in the transmission? I would have recommended getting rid of the motor oil and switching to Dexron 3. The Allison 1545 transmission in the M35A3 trucks work much better and smoother with Dexron 3. Never use any Dexron fluids with a higher number than Dexron 3 as damage to o-rings and seals will occur. I switched over by repeatedly draining and filling with several miles driven between cycles, including some reversing. The shop manager is full of BS. The M35A3s don't make screeching noises except perhaps if you have a loose or worn v-belt or something else is damaged. Is the lock-up torque converter still locking up and unlocking correctly? Do you have an Allison transmission mechanic near you? If the lube shop has damaged your transmission, you need to document everything because repairs to that transmission are very expensive.

 

[Jeffval]

It sounds like the guy simply dumped oil into the transmission without using the dipstick. Have you read the TMs for the M35A3? You check the transmission fluid level with the engine running, not stopped. Hopefully, the transmission isn't damaged. What kind of oil did they put in the transmission? I would have recommended getting rid of the motor oil and switching to Dexron 3. The Allison 1545 transmission in the M35A3 trucks work much better and smoother with Dexron 3. Never use any Dexron fluids with a higher number than Dexron 3 as damage to o-rings and seals will occur. I switched over by repeatedly draining and filling with several miles driven between cycles, including some reversing. The shop manager is full of BS. The M35A3s don't make screeching noises except perhaps if you have a loose or worn v-belt or something else is damaged. Is the lock-up torque converter still locking up and unlocking correctly? Do you have an Allison transmission mechanic near you? If the lube shop has damaged your transmission, you need to document everything because repairs to that transmission are very expensive.

Hi. Thanks for your reply. The guy drained the transmission and the torque converter. He used 15w 40 oil and poured it in the dip stick tube. He brought it up to operating temperature and went through all the gears including reverse several times. I have read some of the TMs. I have 2 manuels. What kind of oil did they put in the transmission? The shop manager is full of BS for sure as he shoulve measured the amount of oil coming out and pumped the same amount back in.

Where is the v-belt located? The noise sounded like it was coming from behind the drivers seat, not in the middle where the transmission is located.

I dont know what you mean about if the torque converter is still locking up or unlocking correctly?

I have not had a total loss of acceleration since I drove it yesterday on the interstate which is when I had to manually shift through the gears to get ut up to speed and when i added 2 1/2 more courts of oil.

I drove it 20 miles today on the interstate at full speed and through steep hills on a gravel road. Everything sounds normal but it did make that noise 4 times when I went up hill. However it doesn't seem as quick to accelerate as it did prior to bringing it to the lube shop. And it stalled one time when I went down hill, but it started right up again.
The oil still doesn't look brand new and is contaminated from the old oil even though it has been drained and refilled two times. I did relieve a big airbubble from the valve on the radiator when it was over filled by 2 gallons. The manuel said 15 quarts but the plate near the glove box says 10 quarts. But after the second refill I still had to add 2 1/2 quarts. I added the extra 2 1/2 quarts when I tried entered the interstate and it wouldn't get up to speed.

So the 1st fill was 2 gallons too full and I relieved a big air bubble. The 2nd fill had 2 1/2 quarts too little with no air bubble. The noise didn't start until after the 2nd fill. And it seems like I have a decline in acceleration with an occasional screeching noise when it hits 3rd gear.

I would have had them switch out the 15w 40 to Dexron 3 because i read a thread about it 2 days ago. But it said all the old 15w40 has to be drained because it's not compatible with 15w40. And since they did such a crappy job of removing all the old oil on the first fill, I thought just use 15w40 and I will have a professional transmission shop switch to Dexron 3 on the next oil change.

I don't know if there is a Allison transmission shop near me, but I will check.
I really appreciate your response and willingness to help. Jeffval

 

[rustystud]

Hate to say it but you might have clutch damage. That screeching sound is a lack of fluid and the clutch trying to engage. That is also why your performance is bad. The clutch packs are slipping.
There are not many transmission shops left that can work on a AT1540/AT540 transmission. Even though they are very similar to TH400's . Even back when I learned to rebuild them in the early 1980's they were going obsolete.

 

[glcaines]

When you drive the truck you should be able to easily and distinctly tell when the transmission shifts to 2nd, 3rd, and 4th and when the torque converter locks up, assuming you still have a 1545 transmission and it wasn't changed out for a 545. You should also be able to tell when the transmission downshifts to 1st when you come to a stop. Mine lagged downshifting to 1st when stopped and was a jarring thud when it did, and was harsh shifting up when I still had the motor oil in the transmission. With the Dexron 3, it immediately and smoothly downshifts to 1st when stopped and shifts up through the gears very smoothly. Now it's just like driving my F250 pickup.

 

[Jeffval]

Hello. Thank you for your reply. When it had 2 1/2 quarts too little and when I tried to get up to speed while getting on the interstate it struggled it was lacking in power through 1st and second gear then it wouldn't go any faster and made a "Wooooing" noise. Then I walked it up to speed through 1st, 2nd, 3rd and Drive. It hasn't made that sound since. The "Screeching" noise happens for 1 split second and it sounds like it's coming from behind me, not in the center where the transmission is located. I dont know what that could be? Maybe the transfer case? Anyway, I ordered a new exterior, interior transmission filter and gasket for the transmission. They should be here in 4-5 days. I found a local transmission shop to drop the pan and check out the inside of the transmission. So we will see. Thanks so much. Jeffval

 

[rustystud]

Hello. Thank you for your reply. When it had 2 1/2 quarts too little and when I tried to get up to speed while getting on the interstate it struggled it was lacking in power through 1st and second gear then it wouldn't go any faster and made a "Wooooing" noise. Then I walked it up to speed through 1st, 2nd, 3rd and Drive. It hasn't made that sound since. The "Screeching" noise happens for 1 split second and it sounds like it's coming from behind me, not in the center where the transmission is located. I dont know what that could be? Maybe the transfer case? Anyway, I ordered a new exterior, interior transmission filter and gasket for the transmission. They should be here in 4-5 days. I found a local transmission shop to drop the pan and check out the inside of the transmission. So we will see. Thanks so much. Jeffval

Here's hoping they don't find anything bad !

 

[glcaines]

If they don't find anything bad, now would be a good time to switch to Dexron 3. I purchased 5 gallons of Dexron 3 equivalent from NAPA under the NAPA brand, which I was told is the same as Valvoline Dexron 3. The repeated drain, fill and drive technique worked great for me, but did take some time.

 

[Jeffval]

If they don't find anything bad, now would be a good time to switch to Dexron 3. I purchased 5 gallons of Dexron 3 equivalent from NAPA under the NAPA brand, which I was told is the same as Valvoline Dexron 3. The repeated drain, fill and drive technique worked great for me, but did take some time.

 

[Jeffval]

Hi. Thanks for your reply. Yes I plan on using Dexron this time. After reading the manuels, I see where the shop failed. They just went forward and reverse and through the gears. In the manual it says to put the parking brake on and Rev to 1500 rpms for one minute once the temp is up to 160 and then run through the gears. So I have my truck on a level surface and have the tires blocked and I'm going to that procedure in the morning. Someone also to me those trucks tend to make a screeching noise when making a tight turn? The screeching noise did happen on a few turns. Is that correct? Thanks

 

[rustystud]

Hi. Thanks for your reply. Yes I plan on using Dexron this time. After reading the manuels, I see where the shop failed. They just went forward and reverse and through the gears. In the manual it says to put the parking brake on and Rev to 1500 rpms for one minute once the temp is up to 160 and then run through the gears. So I have my truck on a level surface and have the tires blocked and I'm going to that procedure in the morning. Someone also to me those trucks tend to make a screeching noise when making a tight turn? The screeching noise did happen on a few turns. Is that correct? Thanks

Any vehicle that has power steering can make a screeching noise when turned to the knuckle stops. The over-pressure valve is relieving pressure and it makes a squealing sound. That being said your truck does not have a standard power steering system . It has an air powered "steering assist" drag link system.

Post corrected for accurate information.

 

[HDN]

The stock air assist on my truck doesn't squeal when I hit the stops, but YMMV.

For those unfamiliar, I have audio of my truck that includes multiple gear shifts with a 1545 running 15W-40. There's some whining consistent with automatic transmissions of all kinds. Start at 2:30 to hear it. It still sounds this way.

The truck is run between 30 and 45 mph throughout the recording.

As for screeching on tight turns, my truck doesn't do that. Instead it makes a big CLUNK sound.

 

[gringeltaube]

............. your truck does not have a standard power steering system . It has a powered "steering assist" drag link system. It's possible I suppose to cause so much back pressure that the hydraulic pump starts to squeal but I never heard of it.
........

Really? What does a hydraulic pump do in an air-assisted system?

 

[HDN]

Really? What does a hydraulic pump do in an air-assisted system?

To be fair folks here have adapted the 5-ton hydraulic power steering to the deuce. I wouldn't have expected air-assisted from the factory instead of hydraulic but AM General seemed to think it was a good idea for the ESP.

 

[Jeffval]

It sounds like the guy simply dumped oil into the transmission without using the dipstick. Have you read the TMs for the M35A3? You check the transmission fluid level with the engine running, not stopped. Hopefully, the transmission isn't damaged. What kind of oil did they put in the transmission? I would have recommended getting rid of the motor oil and switching to Dexron 3. The Allison 1545 transmission in the M35A3 trucks work much better and smoother with Dexron 3. Never use any Dexron fluids with a higher number than Dexron 3 as damage to o-rings and seals will occur. I switched over by repeatedly draining and filling with several miles driven between cycles, including some reversing. The shop manager is full of BS. The M35A3s don't make screeching noises except perhaps if you have a loose or worn v-belt or something else is damaged. Is the lock-up torque converter still locking up and unlocking correctly? Do you have an Allison transmission mechanic near you? If the lube shop has damaged your transmission, you need to document everything because repairs to that transmission are very expensive.

 

[Jeffval]

Really? What does a hydraulic pump do in an air-assisted system?

I've got some good news. I followed the TM instructions. I brought the truck up to operating temperature then held the gas pedal at 1500 rpms for one minute. Then with the emergency brake and tires blocked I put it in drive and reverse then neutral. Then I checked the dip stick and it indicated empty when there was already 12 1/2 quarts in the transmission. I repeated the procedure and filled until it was full. It took 6 more quarts until full. Then I checked the air filter and there was about 300 dead hornets in there. Then I took off the stack and there were 5 nests that clogged the intake port holes. I clean the filter with pressurized air. Then I took it out fir a drive, and Wow, what a difference in power and no screeching noise at all. It's running totally awesome now. Sounds like a jet. I'm going to have the transmission flushed and the oil switched out with Dexron 3. Thank you so much for all your help and insite. I feel totally relieved.

 

[Jeffval]

Any vehicle that has power steering can make a screeching noise when turned to the knuckle stops. The over-pressure valve is relieving pressure and it makes a squealing sound. That being said your truck does not have a standard power steering system . It has a powered "steering assist" drag link system. It's possible I suppose to cause so much back pressure that the hydraulic pump starts to squeal but I never heard of it.
I'm pretty sure your hearing the transmission pump or clutches making this noise.

I've got some good news. I followed the TM instructions. I brought the truck up to operating temperature then held the gas pedal at 1500 rpms for one minute. Then with the emergency brake and tires blocked I put it in drive and reverse then neutral. Then I checked the dip stick and it indicated empty when there was already 12 1/2 quarts in the transmission. I repeated the procedure and filled until it was full. It took 6 more quarts until full. Then I checked the air filter and there was about 300 dead hornets in there. Then I took off the stack and there were 5 nests that clogged the intake port holes. I clean the filter with pressurized air. Then I took it out fir a drive, and Wow, what a difference in power and no screeching noise at all. It's running totally awesome now. Sounds like a jet. I'm going to have the transmission flushed and the oil switched out with Dexron 3. Thank you so much for all your help and insite. I feel totally relieved.

 

[rustystud]

I've got some good news. I followed the TM instructions. I brought the truck up to operating temperature then held the gas pedal at 1500 rpms for one minute. Then with the emergency brake and tires blocked I put it in drive and reverse then neutral. Then I checked the dip stick and it indicated empty when there was already 12 1/2 quarts in the transmission. I repeated the procedure and filled until it was full. It took 6 more quarts until full. Then I checked the air filter and there was about 300 dead hornets in there. Then I took off the stack and there were 5 nests that clogged the intake port holes. I clean the filter with pressurized air. Then I took it out fir a drive, and Wow, what a difference in power and no screeching noise at all. It's running totally awesome now. Sounds like a jet. I'm going to have the transmission flushed and the oil switched out with Dexron 3. Thank you so much for all your help and insite. I feel totally relieved.

Good to hear all is well !