LMTV Allison Stall Test issues

[hike]

I'm asking this trans cooler Question here bc I'm not sure there's another thread on it and it doesn't really fit in the trans ATF write up thread. In the trek of getting this oil pan off, I obviously pulled the trans oil cooler. (Not a fan of the location or mounting layout but such is life). Simple question is do I need to replace these 2 big oil cooler lines going back to the Allison? They're a fabric braid and seem kinda old, one spot feels like a kink is developing. SS routed these right under the engine pan and over the axle. I have no specific objections aside from I just don't like the layout. Last thing I need is to dump the trans oil while going 75 down the highway. I'm think I could have a new set made at the hydraulics shop in town, maybe stainless braid? What is everyone doing , if anything? '04 truck

I have been looking at this as well. Also do not care for the location except that when driving off road we always protect the middle, right? Cheaper and easier things to fix are typically near the edges, expensive difficult to fix things in the middle. Tires over rocks, not avoiding them.

Planning to replace them prior to starting our longer trips. I was not planning on stainless braid. Very interested in other's thoughts, too–

 

[MatthewWBailey]

I have been looking at this as well. Also do not care for the location except that when driving off road we always protect the middle, right? Cheaper and easier things to fix are typically near the edges, expensive difficult to fix things in the middle. Tires over rocks, not avoiding them.

Planning to replace them prior to starting our longer trips. I was not planning on stainless braid. Very interested in other's thoughts, too–

Well at the minimum I'll be changing the way the cooler mounts to the engine. After todays stumblefest trying to get the port side bolt off, I cursed my way into a simple idea. Having to take the compressor off just to remove that bracket is a &$€#%! Bad design, especially when SS used 4 x 1/2"x3" bolts into the block to mount two hose brackets that hold the 1" coolant line that feeds the compressor. With all that the oil cooler is secured by a hose clamp? Someone was doing quicky mods to get these trucks built or something. Anyway, it's obvious the existing oil cooler mount tabs can be modified to bolt up to the 4 holes on the front of the block that are being used for those hose clamps. I also didn't like that they used 4 engine mount bolts to secure the cooler mount tabs. Seems like eyeball Enginerring. Shouldn't the engine mount bolts be dedicated to the engine mount? Rhetorical. I'll fab up that existing cooler mount and post pics of it before reassembling.

All this is just to change the damn oil pump. At least I finally got the oil pan off.

 

[GeneralDisorder]

I just deleted that drivers side upper bolt "fork" from the cooler mount. It's stupid and redundant - that bracket isn't going anywhere with just the three bolts remaining.



To get that bolt loose I had to modify a box wrench and even then it was an absolutely horrible job to get that bolt out and then tighten it back down without the cooler bracket under it.

My A1R mount pictured above shows the newer style cooler mount - no more hose clamps. The cooler bolts down to the hanger bracket. The cooler is rectangular not round like the old style.

 

[MatthewWBailey]

I just deleted that drivers side upper bolt "fork" from the cooler mount. It's stupid and redundant - that bracket isn't going anywhere with just the three bolts remaining.

View attachment 925754

To get that bolt loose I had to modify a box wrench and even then it was an absolutely horrible job to get that bolt out and then tighten it back down without the cooler bracket under it.

My A1R mount pictured above shows the newer style cooler mount - no more hose clamps. The cooler bolts down to the hanger bracket. The cooler is rectangular not round like the old style.

I thought about modifying the 7/8 box wrench I have which is already a shortened one I have for some past project but wasn't sure it would work. So I got an education on the compressor removal. I have to strip most of that side to get to the ECM anyway and might as well replace the water and oil senders.
Does your A1r cooler have studs or use u bolts to attach to that bracket pictured?

 

[GeneralDisorder]

The ECM shouldn't require stripping anything really. You can snake them out - sometimes it helps to move the PS reservoir.

Here's the A1R cooler. It uses bolts and lock nuts to attach it to the hanger.

 

[Ronmar]

Real coolers are round!

 

[MatthewWBailey]

The ECM shouldn't require stripping anything really. You can snake them out - sometimes it helps to move the PS reservoir.

Here's the A1R cooler. It uses bolts and lock nuts to attach it to the hanger.

View attachment 925755

View attachment 925756

Ah, I didn't know the new ones were square.

I might as well strip a few things over there. The bottom of the starter was wet and I don't know why. Something's leaking. Could be the PS hose(s). With the compressor off I can see why @ckouba said the HEUI pre filter wouldn't fit. It's tight back there

 

[MatthewWBailey]

I'm asking this trans cooler Question here bc I'm not sure there's another thread on it and it doesn't really fit in the trans ATF write up thread. In the trek of getting this oil pan off, I obviously pulled the trans oil cooler. (Not a fan of the location or mounting layout but such is life). Simple question is do I need to replace these 2 big oil cooler lines going back to the Allison? They're a fabric braid and seem kinda old, one spot feels like a kink is developing. SS routed these right under the engine pan and over the axle. I have no specific objections aside from I just don't like the layout. Last thing I need is to dump the trans oil while going 75 down the highway. I'm think I could have a new set made at the hydraulics shop in town, maybe stainless braid? What is everyone doing , if anything? '04 truck

General Allison follow up question. What is the line pressure at the trans oil cooler? I'm sure it's probably in the manual as there's a test port there next to the aux starter switch. But I'm interested in the max since I'm replacing hoses. Shop says they're using 2k psi hose.

also, these JIC fittings on the cooler lines are using o rings on the JIC face. Never seen that. 1 is missing of course. After a rough disassembly, the fittings look pretty nasty inside...

I'm replacing the 4 boss fittings just bc they look terrible. I had to cut one off bc it was rusted and seized to the hose JIC.

 

[GeneralDisorder]

In general automatic transmission fluid line pressure doesn't get over about 300 psi. If it does you have a problem - the shop pressure gauge used for testing line pressure and clutch pressure only goes to 300 psi. Cooler line pressure tends to be lower than clutch line pressure - but in very cold weather the cooler pressure could be fairly high. Anything that can handle ATF and 300+ psi should be adequate.

 

[coachgeo]

General Allison follow up question. What is the line pressure at the trans oil cooler? I'm sure it's probably in the manual as there's a test port there next to the aux starter switch. But I'm interested in the max since I'm replacing hoses. Shop says they're using 2k psi hose.

also, these JIC fittings on the cooler lines are using o rings on the JIC face. Never seen that. 1 is missing of course. After a rough disassembly, the fittings look pretty nasty inside...

I'm replacing the 4 boss fittings just bc they look terrible. I had to cut one off bc it was rusted and seized to the hose JIC.
View attachment 926045View attachment 926046View attachment 926047View attachment 926048View attachment 926049

just saw today fittings with the O-ring. appears the flare part is JIC ORB (O-Ring Boss) and the straight side with O-Ring is SAE o ring boss. supposedly they are for more unforgiving environments

 

[GeneralDisorder]

Typical military. Over-built. Often in surprising ways. JIC ORB with viton o-rings - that's straight up hydraulic system shenanigans capable of thousands of PSI being used for a transmission cooler - if this was a school bus that would be hose over a barbed fitting with a chinese clamp.

 

[MatthewWBailey]

I just deleted that drivers side upper bolt "fork" from the cooler mount. It's stupid and redundant - that bracket isn't going anywhere with just the three bolts remaining.

View attachment 925754

To get that bolt loose I had to modify a box wrench and even then it was an absolutely horrible job to get that bolt out and then tighten it back down without the cooler bracket under it.

My A1R mount pictured above shows the newer style cooler mount - no more hose clamps. The cooler bolts down to the hanger bracket. The cooler is rectangular not round like the old style.

I finished the mod to the oil cooler mount. I wasn't a fan of the engine mount being used to attach those forks. Seemed hokey. The 4 bolts on the front of the block work well for this and now the engine mount bolts are unfettered. Suits my OCD. Plus the port side high bolt no longer needs access and can be buried by the compressor as it was originally. A days cutting and welding.

4 pieces of A500..


Tacked up showing the old forked bracket stubs


Trimmed and welded


End product


Clearance from engine mount bolts


Final

 

[Ronmar]

Looks like you could hang a snowplow off of it

Is that blue line running across the front of the engine the makeup line from the expansion tank?

 

[GeneralDisorder]

Looks like you could hang a snowplow off of it

Is that blue line running across the front of the engine the makeup line from the expansion tank?

Yes - in the C7 trucks they changed that to stainless tubing for most of the run.

 

[MatthewWBailey]

Looks like you could hang a snowplow off of it

Is that blue line running across the front of the engine the makeup line from the expansion tank?

Lol Hey I was trying not to go overboard. Had 1/4 plate that seemed good. Probably only needs 12 guage sheet metal. I'm glad SS put 3-1/2" long 12mm bolts (4 of them) into the block for the hose clamps that were there. Good extra strength!

Yes. It goes to a 90 then splices to the line back to the tank up high.