Allison MD 3066

[crane operator]

Have a allison md3066 behind a cummins ISL 330. Its in a 2002 link belt 8640 truck crane.

One of the guys called me that the transmission temp was up in it. I didn't think the gauge even worked because I've never seen it up. It has a large aux. transmission cooler, mounted just in front of the rear tandems, with a hydraulic drive cooling fan.

Turns out- he hyd. cooling fan isn't working. The hyd. motor is bad, none available from link belt. I've got a aftermarket electric radiator fan from oriellys cobbled up and mounted, but I'm concerned that there's actually something also wrong in the transmission itself, to be generating all the heat.

It was running around 200-250 with no the fan not working on the cooler. It actually got warm enough to turn the warning light on at about 260, and burped some atf out the top. When it was that warm- it wouldn't shift into the highest gear. Oil looks good on the dipstick and doesn't smell burnt. Takes it about 20 minutes of driving to get to that higher temps.

So- is the fan not moving air past the cooler enough to cause the temps to be 50 degrees warmer than they should be? Or do I have something going bad in the trans?

I'm planning on getting the 12v aftermarket fan running, and giving a little test run up the shop hill, see what the temps do. And then I want to drop the oil in the trans and cooler and do a debris check to see if there's any clutches laying in the pan.

Any words of wisdom?

 

[Vetech63]

Is there a manufacturers tag on your old fan motor?

 

[cfherrman]

Do not go above 250 for any reason unless you want a new trans.

Most likely the 12v fan won't be enough, that's why there was a hydraulic on there. If you still have cooling problems I highly recommend either a hyd fan or going to a coolant based cooler.

 

[crane operator]

 

[crane operator]

My parker man hasn't got back to me, but that's not unusual with them.

And we've already crossed the rubicon on 250 degrees. Its been there already.

 

[Vetech63]

There should be an aftermarket replacement for that. Call Flint hydraulics in Memphis and give them that Parker #

 

[heymccall]

This site says 1 available, but no price.
https://www.lifcohydraulics.com/Pro...ry&dep2=Gear&dep3=Aluminum&dep4=PGP511 Series

But, that ain't an "all or nothing" motor. Has the supply been tested for pressure/ volume?

 

[crane operator]

The fan motor has a solenoid/ block controlled by the temp switch. Oil makes a loop through the less resistance of the solenoid loop, when it hits temp, it closes the upper loop, forcing the oil through the motor (I think)

I capped off the solenoid loop, so oil was only going in and out of the motor, and it would only spin slow- increase throttle also made no difference on fan speed. I pressure checked the line and a brief 10 sec run showed 1000psi. I think this runs off the power steering pump, and I've got good steer pressure also. I'd think if I've got flow issues it would show in the power steering and I wouldn't have pressure. But I don't have a flowmeter.

 

[crane operator]

Thanks for the parts links guys, I'm mostly just worried I have something going on in the trans, vs. just having a cooling fan issue.

 

[crane operator]

And it would be nice if a fan fixes it. This band aid isn't going to fix it.

 

[crane operator]

 

[Vetech63]

Yeah that electric fan is worthless compared yo a hydraulic drive fan

 

[crane operator]

Here's a picture of the hyd. system. I basically closed off the loop that ran up to the solenoid when I was testing it.

 

[Knepptune]

Do you have hyd schematics. 1000psi seems pretty low.

That fan looks suspiciously like the carrier hyd cooler fan of a grove tms.

 

[crane operator]

I didn't rev it up or anything on the pressure test, because I don't know where the relief would be or what it would be set at. I just basically fired it up and shut it back down while someone else watched the gauge to see if it was making pressure.

 

[crane operator]

Electric aftermarket cobbled up fan passed a check ride yesterday, seems we dodged a bullet and the transmission shifts fine.

Hydraulic motor has heavy wear in the housing. Found a parker one that has "maybe" availability, but going to simply rebuild the old one with hopefully available parts.

Electric fan moves a surprising amount of air, kept temps around 150-180, got to 200 on a long big hill. So we are going with that until the hyd. one is rebuilt.

Going to need a fan also- it didn't survive removing from the motor, but I think I've got a source for that.

Thanks for the help guys.

 

[cfherrman]

Typically rebuilding a hyd pump or motor is almost the same cost as a new one.

I wonder if you can replace the whole cooler with a double electric fan model, do you have the room?

 

[crane operator]

New parker motor was over $1,500 if and when available. Around $500 to rebuild.

 

[92U 3406]

I think your main source of heat in an Alison would be the torque converter. If its unlocked the little bit of normal slippage will make a lot of heat, especially in stop & go driving conditions.

 

[Birken Vogt]

They make lots of heat in slow speed, high power, converter unlocked situations. And very little heat in converter locked situations. They do have a fairly good reserve of oil to get hot before the temperature starts really getting out of hand. If you do not spend too much time maneuvering with high power, I would guess that 2 healthy electric fans would be adequate. Idling in drive is another good heat generator but the heat builds up slow in that situation.

Another consideration on this crane is, does the transmission carry load and/or generate heat when the crane is in operation?