Maybe crazy Idea for the old girl. hehe

[Dajain]

Hi everyone!

   I'll try to explain this as easy and as quickly as I can. I have this 1975 Mack Trucks fire engine that I acquired. I got the old girl for free and she starts right up every time. The truck has less than 36,000 original miles so I highly doubt she is worn out. lol

It has the V-8 turbo diesel with the automatic transmission. When driving it, the transmission doesn't shift out of first but pulls just fine in first.  

First question. I haven't had time to look at it or research, but what could be the problem with the no shift problem on this unit? Bad servo? Anyone have any experience with this? Or is this a sign of a transmission that is shot? What automatic transmissions were available for this configuration? But, at only 36k miles, I would be surprised at that.  

Any experience with this would be appreciated.

Now, my plans for the old girl. Yes, this is where it gets interesting. haha

I haul old steel houseboats for salvage and I am currently using a 1969 Ford N-750 with a gasser 391 Industrial. She is slow but does the job. My thoughts are to strip off the "firetruck" pieces of the truck and suit it with a 5th wheel hitch. She has the air for the brakes so I don't think it would take much to convert to a trailer hauler. The firetruck parts of the unit are shot and many pieces have been removed. Not much use as a firetruck left in her any more. 

Then, the way the cab is set up on this thing, I am picturing building a sleeper birth behind the seats (above the engine) to save the cost of a motel room every time I load a houseboat and haul it.

Here is the critical info:

Date: October 1975

GVWR: 33200

Vehicle Number (V.I.N.): CF79fF(15)-1064

Any decode of the VIN would be awesome too. Did a quick search and haven't had any luck.

But the first step is the transmission. 

Thanks for any replies in advance.

 

 

 

 

[alex g]

Well the price was definitely right. I'm not sure on transmission problems is it a V8 Detroit? 

[Dajain]

On 6/13/2021 at 6:23 PM, alex g said:

Well the price was definitely right. I'm not sure on transmission problems is it a V8 Detroit? 

Yes it is a Turbo Detroit. She purrs like no other I've seen. Only 36k miles, she's not even broke in yet.

"Mack" is stamped in the valve covers. 

Too cool to not use in one way or another.

 

NOTE!!!!  I was wrong.....It is not a Detroit. It is in fact a Mack engine. Just want to avoid any confusion. updated 6/16/21

Edited June 17, 2021 by Dajain

[Dajain]

OK, went out to the old girl, turned on the batteries, hit the start switch and she fired right up. Let her warm up and build air. I like to start from time to time to be on the safe side. 

Decided to take a good look thru all the compartments and look what I found! Someone upstairs apparently loves me. haha

The complete service manual specifically put together for this truck and VIN.

I should have all the Info I need now. 

[Dajain]

So, was I wrong in my presumption??? If so, please feel free to say so.

Is the Mack ENDT-865 built by Detroit? I'm finding that Mack specifically built them and no mention of Detroit doing so when I do the searches.

Hmmm. 

[tjc transport]

yup. the ENDT-865 is a Mack V8 engine, not a Detroit. 

325 HP and 1100 Ft LBs torque. 

[Dajain]

On 6/14/2021 at 2:34 PM, tjc transport said:

yup. the ENDT-865 is a Mack V8 engine, not a Detroit. 

325 HP and 1100 Ft LBs torque. 

Yup, I stand corrected. Not the first time I've been wrong. haha.

 Done a little research on this thing and from I can tell, she is a beast! Read somewhere that it is known for twisting drivelines so she needs a tender foot.

Need to figure out the transmission issue figured out though. I am in my busy season and haven't had a chance to research or tear into her, but hoping someone tells me it's a $75 solenoid. Please, Please Please.. haha

Wait..... Tell me that if it's the truth....Not to make me feel better. hmmm   haha

Edited June 17, 2021 by Dajain

[tjc transport]

it may be something stupid like low fluid level. 

i have seen simple things like that cause supposed intelligent people spend big bucks searching for a repair. 

[Steve L]

Hey Dajain, let me have the V8 and fit a E7 400 with a manual gearbox . . . Driveline problem solved 😝

[Rob]

Lot easier to obtain parts for too.

[Dajain]

If I was to spend that kind of money, I would just buy a rig with a sleeper on it already. 😅

 

[Dajain]

3 hours ago, tjc transport said:

it may be something stupid like low fluid level. 

i have seen simple things like that cause supposed intelligent people spend big bucks searching for a repair. 

That was where I was going to start when I get the time to look at it. haha

Short example:

I have a "74 International 2010 dump truck I picked up for $600. It was a old hwy dept truck and has the hydraulic tank on the passenger side. They said the truck was no good because it wouldn't lift and dump anymore even though the Hyd. tank is full. The hyd. lift is a separate system than the hyd tank which was for the plow lift and spreader. Filled the lift cylinder with fluid and it's been going fine ever since. Moral of the story, makes sure the fluids are full before the tools come out. 🤣 

And yes, for the $600, I did get the snow plow with it too, if anyone was wondering. haha

Edited June 17, 2021 by Dajain

[Vladislav]

Speaking the automatic transmission I would suggest two possible matters of the issue. Worth to point out I have never dealt with hydromechanical units on big trucks. But rebuilt them on Mercedes cars of 70's and 80's years. The principles seem the same. The transmission has hydraulic "brains" - multi-valve hydraulic control unit which directs oil pressure to some shift cylinder or another which makes gear change. There are two main parameters the tranny figures out when to shift (or not to shift) - vehicle speed and the throttle pedal position. The logic is simple. More speed and reasonable or low gas - upshift. Low speed with plenty of gas (load) - stay in gear or lower it. Higher speed - upshift. High speed and full gas - downshift for maximum acceleration - "kick down". Ok, the tranny knows both those parameters by some way. The speed usually measures inside the transmission buy special valve connected to the output shaft. You should be an automatic transmission rebuilder to get to it to check or fix if needed. Gas measure provides much more simple usually by a linkage or a cable which connects vehicle's throttle linkage and something sticking out the transmission. Usually a small lever or so. You just observe the tranny for something that connects it with the gas control and operates together with it. The important for the matter point is if the throttle is settled for "full gas" for the transmission (jammed or wrong set linkage) the tranny would suggest it as a full load. And it wouldn't upshift staying in the 1st gear. A variation of the issue could be if the tranny is equipped with special "kick down" control. In cars there usually is an electric switch put below the throttle pedal. So when you press the pedal full way down the switch connects its contacts and supplys electric power to a solenoid in the tranny. The latter opens or closes certain oil passage in the control module (the "brains") and orders the tranny to downshift. Usually if the spoken switch gets short connected (jammed) the tranny starts from 1st gear and continues driving in it no matter how fast you try to go. My suggestion is a big truck or a bus may have a dash switch or a knob for hand operated kick-down so you should watch for anything like that in your rig.

All written above could be count as "simple reasons". If you found nothing of those another matter could be the brains - hydraulic control unit. It's quite complicated assembly mounted inside the transmission and can be accessed with the lower (oil) pan removed. You need a rebuilder to check it out of another unit to swap in in a hope for correct operation. In some cases no upshifting can be determined by incorrect operation of the speed valve. Usually hydro-mechanic tranny has a few plugs at the outside to connect a check oil line and pressure gauge. It allows to control the main operational pressure (no vehicle move if it's fail) and that "speed" or the output shaft spinning pressure (every control signal in those trannys is a pressure since it's hydraulic not electric). I have such checks done using just a common pressure gauge and a hose with a fitting suitable for the tranny connectin. But I had a repair manual for the particular unit I dealt with. 

All in all you have good chances with finding the "simple" reasons and if no my next step would be a search for an old automatic tranny specialist. My guess is a car tech could also find the issue if at least has any interest in doing that.

Vlad

Edited June 21, 2021 by Vladislav

[tjc transport]

very good  point Vlad. when i got my 79 F350 the guy said "it would not upshift and needed a trans" 

it only had 21,000 miles on it. no way a 2 year old truck with 21k miles needs a trans. 

i took it for a ride, paid him his asking price, and drove a block away. 

popped the hood and smacked the downshift lever real hard to get it off full throttle. 

easy throttle for the 20 mile ride home and it shifted fine. the next day, i was looking it over and found a tree limb wedged in between the trans and the downshift rod. at full throttle it would jam the rod and keep it in downshift position. 

234,000 miles later and it still shifts perfectly. 

 

[Dajain]

I think it's ironically funny that you talk about a dash switch, or something of the sorts Vlad. I have wondered if this firetruck has some kind of over ride or "safety" associated with the PTO transfer case for the water pump to keep the pump from over speeding. 

Should be interesting when I finally get the chance to work on it. There seems that there may be a few factors I need to look at.

When I work on it, the first thing will be getting rid of the transfer case and have a driveline built. That should eliminate any Safety that would be needed to protect the pump. There are electrical wires going to it, so it's a definite possibility

 

[Vladislav]

Good points. Another idea is to put a thread in the Firetrucks section of the site with a question of something like CF automatic tranny issue. Plenty of former or actual firefighters pay attention to that particular forum and if there's any special switch put by means of pump operation or so the answer would be right on a surface.