Allison Transmission

Paulie G · February 8, 2008

So I was down to the parts store to pick up a bunch of Mobile 1 ATF to do a fluid change using the Hoots method. Well the parts guy had been talking to a local GM mechanic that opened his own shop that warned me not to do it unless I wanted to bring it to him to have the Trans re-built.

he claimed that the Trans is very sensitive to being run dry and He has rebuilt plenty of them because of people using this method. Now I'm at a stand still. Having never done this method before I certainly don't want to risk anything.

I asked how they did it and they said they have a machine (which I hear bad things about) He said they don't use and solution, they just cycle oil through, drop the pan, then change the filters and fill up. This is for $100 plus the filters using dex 3. It would cost a little more for dex 6.

Maybe I should just do a pan drain and spin on filter using dex 6.

I'm bummed out and confused.

Paulie G · February 8, 2008

I should clarify that he was not trying to get my business. I contacted him after the parts guy told me. They are a busy shop and at no time did he push for my business.

Killerbee · February 8, 2008

True, you need to not run it dry. But that is not a challenge with simple care, using 1st grade math. Just don't pull out more than you put in.

Paulie G · February 8, 2008

True, you need to not run it dry. But that is not a challenge with simple care, using 1st grade math. Just don't pull out more than you put in.

But how low is to low.

Are you saying over fill it and run the over fill amount out.

Or are you saying fill it to normal level and then run some out? How much before it gets too low and you stop and refill?

RonJ · February 8, 2008

True, you need to not run it dry. But that is not a challenge with simple care, using 1st grade math. Just don't pull out more than you put in.

But how low is to low.

Are you saying over fill it and run the over fill amount out.

Or are you saying fill it to normal level and then run some out? How much before it gets too low and you stop and refill?

Its not worth the risk to me.

dewfpo · February 9, 2008

I've done this on many vehicles and never pumped out more than 2 qts at a time. No problems ever. Even on a tranny that had over 100K miles on the original fluid. The sump has a reserve in it. If you pump out 2 qts at a time, the tranny will never see air.

Read the HOOT instructions and follow them to a T. Hundreds of folks have done this method and not had a problem.

DEWFPO

lpetersonjr · February 11, 2008

So I was down to the parts store to pick up a bunch of Mobile 1 ATF to do a fluid change using the Hoots method. Well the parts guy had been talking to a local GM mechanic that opened his own shop that warned me not to do it unless I wanted to bring it to him to have the Trans re-built.

he claimed that the Trans is very sensitive to being run dry and He has rebuilt plenty of them because of people using this method. Now I'm at a stand still. Having never done this method before I certainly don't want to risk anything.

I asked how they did it and they said they have a machine (which I hear bad things about) He said they don't use and solution, they just cycle oil through, drop the pan, then change the filters and fill up. This is for $100 plus the filters using dex 3. It would cost a little more for dex 6.

Maybe I should just do a pan drain and spin on filter using dex 6.

I'm bummed out and confused.

Paulie G, I'd really like to know what have you read about machine flushes that make you wary. The reason I'm asking is I have a flush machine and do a lot of flushes with it and haven't had a problem. It hooks up to the battery and has two fluid containers, one for new fluid and one for old fluid. It has an internal pump that is activated by the old fluid coming into the machine and causes the new fluid to be added to the trans at the same rate as it's being pumped out. I prefer to add an extra quart or two more than called for on Total Fill just to be sure everything gets changed. I also run the gear shift through the gears several times just to make sure new fluid is pumped throughout the valve body. Another good feature of this machine process is since the fluid is withdrawn and added through the cooler lines I can check fill level anytime because I'm not dumping trans fluid down the fill tube. When the New fluid level in the machine gets to within 1 quart it automatically pauses the pumping process so I can add or drain fluid to get the correct level. Then I reconnect the cooler lines and test drive and recheck.

If I change the suction filter I drop the fluid from the pan, measure it, and after changing the filter I add the same amount of inexpensive new fluid back into the pan just to be sure I don't run anything dry. Then I hook the machine up and finish the process.

Hopefully this will give you a little better idea on what to look for in finding someone to flush your trans. You might ask the individual you mentioned earlier if this is similar to the process he uses.

I hope this helps. Please feel free to ask any questions you might have.

Lynn

Paulie G · February 11, 2008

Lynn,

There is a lot of reading on Trans flushes. I don't know a lot about it but reading I've done I think is mostly to avoid the power flushes that run solution through the Trans.

That same day I just picked up a spin on filter and Got some dex 6. Drained the pan and changed the filter. The GM dealer made it sound OK to mix the Dex 6 with the 3. It was a piece of cake.

The old oil looked good but it was a bit low. Not quite a quart. The trans seems a bit more quiet and more smooth but that's probably all in my head.

Is there a way to see what fluid is in it being I'm not the original owner. Got it with 40,000 on it and at 67,000 now. I know the differential fluid was not the factory fill.

Anyways,

Have a nice day