First M35A3

[YOUNG GUN]

Let me know of any rally's relatively close by, I would definitely be interested in attending.
Also, if anyone is interested in trading parts/services/help let me know; I have a full machine and fabrication shop in Portland with a 5 ton overhead crane.
I love working on this stuff.

 

[autigers35a3]

I was told today to clean all the coolers and radiator with Simply Green and a strong hose.
Spray with product like Simply Green degreaser and spray from back of coolers and raditor.
Flushing dirt etc. out to the front and not back into cooler/radiator. Do this with engine off.
Good luck..

 

[YOUNG GUN]

That makes sense to me, I'll add that to my list.
Thanks for the advise.

 

[autigers35a3]

Also there is a vent on top of the trans you need to check.
I saw it posted here somewhere how to do it.
Check search.

 

[YOUNG GUN]

That makes sense to me, I'll add that to my list.
Thanks for the advise.

 

[YOUNG GUN]

Oops, sorry for the double post...How did that happen???
Anyways, I read about that in the Allison transmission manual, and have that on the list as well.
Thanks again.

 

[BadMastard]

Welcome to the party! Here's two cents. Did your transmission temp go up with your engine coolant temp? I think the valve that operates the fan is connected to the engine coolant. You will definitely hear the fan "engage" at temp, since it sounds like a jet engine. It "spins" all the time, but that's just free wheeling.

What color is your trans fluid? If it's oil, and it's pure and clean, good! Good idea to switch to dex iii or transsynd, but NOT ANYTHING ELSE!. A lot of other fluids will eat your seals. That would be bad.

Filter change, great idea. Clean trans cooler- good idea. Check gauge? Good idea. Check radiator for oil? Good idea. If you are leaking fluid out, it may end up there. Less fluid=higher temp.

Let's see. Did I miss anything? Oh ya, we'd LOVE to use your machine shop for stuff! We have been dying for someone in the PNW to make centers for rims, etc, etc. So, welcome!

 

[YOUNG GUN]

Coolant is clean but going to replace anyways for piece of mind.
Transmission fluid is clean and full of 15W40 (that's what came in it) but I'm still going to change both filters and put fresh fluid in (may switch to the other fluid later.
I have definitely NOT heard the fan engage and can't remember how hot it got that day;what temp should it turn on at?
Definetly doing all the other stuff.
All of my gauges seem to work properly, however a few backlights are out; can I replace the backlights, or do I have to buy new gauges?

Thanks for all the help.

 

[AceHigh]

I was off post airing up the tires in the hot sun when I picked up mine. The fan came on while I was working on a front tire- scared the stuffing out of me! It is loud.

 

[Bolkbich]

my a3 was running 250-275 trans temp . so i changed to dex 3. it runs alittle cooler around town. as soon as you start working the truck harder it goes right up to 250- 275. i think part of the problem is that the trans cooler depends on the engine fan to get serious air flow. my engine runs so cool ive only heard the fan come on once for a minute. so basically the trans cooler has no forced air flow and runs hot im going to put an aux cooler with its own fan on the truck. i think that would tak care of it.

 

[Ferroequinologist]

Welcome to the site! Nice looking A3!

The fan clutch is operated by a temp controlled air valve on the engine. If that is sticking, it won't open and provide air pressure to engage the clutch. A simple way to check it would be take it off (since you said you were going to flush the radiator anyway) and put it in a pot of boiling water, just like you would test a thermostat. put some short lengths of hose on it before you dunk it, so you can blow through it while it is in the boiling water. You can put a thermometer in the water, and as it heats up blow through it at every 5-10 degrees or so starting at 160. If it doesn't open up until the water is at a rolling boil, it maybe bad. If you can get air though it, you most likely have a bad fan clutch.

The lights are easy fixes, just unscrew the two round plastic covers on the gauge panel. The bulbs are behind those.

 

[BadMastard]

I'm thinking more and more your transmission fluid is warmed up going into the engine radiator and cooled off in the trans radiator. In any event, since it's no where near warm here, my trans routinely runs in the 125 range. pulling 8k trailer, up to 250, never more and I'm running 15/40.

If your shifting is good, and your truck is moving well, I might think it's relatively ok with occasional jaunts in to the hot range.

Napa can order you lights for the dash. there aren't any lights IN the gauge, it takes light off the dash bulbs through the front side of the gauge. I carry a book light with me for mine, makes them hella easier to read.

 

[YOUNG GUN]

Shifting seems pretty good for a big truck.
Just drove it the 34 miles to work this morning, 25% at highway speed, and 75% at slower stop and go speed, about an hour drive total; Engine temp ran about 160, and transmission never went over 160.
I'm doing new trans fluid and both filters this weekend, flushing coolant system, cleaning exterior of of radiator and auxilary cooler, also straitening out some bent fins on the auxilary cooler I found, I imagine that could have been part of the overheating issue.

Thanks again for all the help everyone, I really appreciate it.

 

[YOUNG GUN]

I changed the transmission oil and both internal and external filters.
Attempted to find the transmission breather with no luck, I assume you must take off the shifting tower and floor plate, maybe next weekend for that project and the coolant flush. I did however find a disconnected 1/4" black plastic hose on top of the tranny with a fitting on the end; it leads to the back of the cab and runs up with several others to just below the back window; are these breather lines???

Anayways, I drove it to work this morning (about 45 mins) and immedietly pulled into the shop and checked teperatures with my infared thermometer; All the temperatures taken are the hottest I could find on each given part.

Transmission Cab Guage Temp Reads: 200F
Infared Thermometer Readings:
-Transmission Oil Pan: 135F
-Transmission Aux. Cooler: 150F
-Transmission External Filter: 165F

Engine Cab Gauge Temp Reads: 170F
Infared Thermometer Readings:
Engine Oil Pan: 170F
Radiator (inside closest to engine): 175F
Coolant Overflow Tank(bottom side): 175F


It seems that my Transmission Temp Gauge is not working properly, and everything is actually running good temps.
Did I check these Temperatures at the best places possible?

Any input will be greatly appreciated.

 

[Floridianson]

Never done the slow mudding thing in my A3 but those temps were not that high in my thinking. Just a smart thing to do while mudding slow with not much air realy moving watch the gage. Stop and run Idle up some till she cools down some. What were the outside temps the day you were playing?
Once again these trucks were cargo haulers and you would think they were on some what good ground and allways moving at least 20 mph??????

 

[YOUNG GUN]

The day in question was only about 60F
Based on the troubleshooting that i've done, I think my trans temp gauge is bad, or I suppose the sending unit could be bad as well.
If you look back to my last post, I believe this indicates one of the two being bad, however I'm not entirely sure I was taking my temp readings from the correct/ideal locations.

 

[BadMastard]

You're probably right in your gauge or sender being off a bit. Those are indeed breather tubes, for things like the air brake, trans, etc. If your filter temp is solid at 200, that's probably your best indicator of your trans temp since it SHOULD be from the hottest part of the tranny.

If I had an IR temp gauge, I'd throw my numbers at you, but alas, I do not. Maybe one of my local boys does, and I'll run numbers on my a3 if they do.

 

[YOUNG GUN]

I think the gauge is off (hopefully not the sending unit).
If the external tranny filter is a good indicator, I don't think I have anything to worry about @ 165F.
Would that dissconnected breather line go to the tranny?
It is laying right on top of it, so I would think so.
If you end up using an IR thermometer let me know what temps you get.

Thanks for the help, it's greatly appreciated!