macattack

i think your correct mack4ever. spoke to a service man at parker today and he said the same thing. oh well never removed one i guess it will be a learning experience.

thanks guys

thanks. it is electric operated. dont know if the pressure switch has anything to do with it. i also replaced the solenoid approx 1 year ago. (the little elec valve that allows tran fluid to the pto to engage i guess?)

this is on my other truck. its on a international with a 5 speed allison auto. last friday i could here a clinging sound with the pto disengaged. what seems to be happening is my pto is not disengaging fully.

does anybody know if there is something else that could cause the pto not to fully disengage.

what does the pressure switch on the pto do? its got 2 little slip on connectors and is threaded into te pto.

just want to make sure there is nothing else to check before i pull the pto.

thanks

check www.truckcomponentsonline.com they have diagrams . it will show you your model and whats inside. washers, adjust collars etc...

hope this helps.

nah just gonna heat up the rubbers. may as well have a steak or two also/

thanks guys. time to fire up the bbq.

gonna replace the rubber bump stops that sit above the top plate on the front springs. this is on an mr 688s truck. one rubber looks a little weak.

any tips on doing this? doesnt really look like too tough of a job.

thanks

replace the sending unit. testing the unit by bypassing it will turn on your warning lite. that is what it should do. try a new sending unit.

yes thanks. as soon as the parts arrive.

thanks guys. a rare failure indeed! well it was the last thing i could check external wise and i lucked out. when it went down it was the strangest thing. no hints or strange noises but when i look back it did seem to shift from 1st to drive rather quickly. anyways so far so good. ordered 2 of these valves today got to keep one in the cab.

85.00 dollars each.

update. no tranny needed!!! did the mod test. basically bypassed the mod valve by plugging the air line and the mod valve. truck went into reverse and did not die in drive. i did not realize that an air operated foot controller would have a pneumatic mod valve.

all my backups.alram,camera came back. gonna order two of those pneumatic modulator valves and keep one in the cab.

maybe some others with air operated foot throttles had the same issues and got taken to buy a new tranny. check those pneumatic mod valves if your tranny is acting up. phew i came very close to buying a trans.

dam drink is gonna taste fine.

thanks guys.

thanks. buddy.

thanks for replying!!

yes non electrical. checked the linkage all is good there. gonna check my mod valve. the truck has an air operated throttle control and just found out the modulator valve is a pneumatic type. mech told me to plug the hose end and plug the mod valve. start truck and see what happens. hopefully the valve. also the trans fluid is clean no smell at all.

relays did nothing. off to the tranny store. got a couple quotes. approx 8500.00 for a reman. holy sheeeeeaaaaaat.

yah she is a tough one. i replaced the 2 relays and it didnt help. i took off the linkage to make sure everything was good and it all checked out. i even shifted it by hand at the trans and still nothing.

one mechanic told me the torque converter is locked up, i guess a nice way of saying shes F*cked.

anyone have a ht740rs for sale?

got either a trans problem or electrical issue. this is what happens. when i put my truck in drive the truck dies. i also have no reverse. no backup lites, alrm, camera etc....

when sitting idling there seems to be a slight misfire, when the misfire happens my reverse lites, camera etc... flash momentarily and the driveshaft looks like it wants to turn.

i found 1 of the 5 circuit breakers were tripped. i reset it and tried again, but still nothing. i found 2 relays one for neutral the other for reverse, as soon as the part store opens i am gonna try replacing those relays and see what happens. i replaced the filters and cleaned the breather. oil looks great and there are no funny noises.

i also found a silver box under the dash that looks like either a voltage reg or ign module?. would anybody have an idea of what is going on?

thanks

gonna try replacing the reverse and neutral relays. i found 1 of the 5 circuit breakers tripped. i reset it and now gonna replace the relays as soon as the part store opens. hope that is the problem.

any help?

does anybody know if a 96 mack e7 300 engine would have a cam timing sensor? engine does not have a computer? if so where would it be located?

truck has a bosch fuel pump.

thanks

thanks, truck was only out for about 10 minutes before she started acting up. this has a cable shift and that part seems to be fine. but this is what i found out today. truck is a 96(my avatar) it does not have a computer.

i started the truck and let it idle for a few minutes. i just replaced the trans filters and topped up the fluid. truck is idling nice i then put it in drive and the truck dies instantly. i restart the truck and now about every 10 seconds or so a slight misfire happens. when there is this misfire my backup lites and camera flash on for a millisecond and my driveshaft wants to turn. does anybody know if the mack e7 300 engine would have a cam timing sensor or if my fuel inj pump is acting up. when it does misfire it only does for a very short time and then idles fine. 10sec later misfire then fine. i am thinking maybe a sensor or fuel inj pump and thats why it shuts off when i put it in drive. still no reverse though. dam i think this is gonna piss off santa.

did you get this fixed?

had this happen to me this morning in -30Celsisus. my 96 mr688s garbage truck had no reverse. picked my bin and selected reverse and nothing. put it in drive and the truck dies just like i pulled the red engine shutoff?. when i go to reverse all my backup lites.camera,alarm does not work.

possible a short somewhere. but where do i look.

do you think the nsbu switch?

also when there is a misfire the driveshaft looks like it wants to turn?????

the trans is an allison ht740rs automatic. would there be a relay or circuit breaker somewhere giving me trouble.

thanks in advance.

i will try to get some pics later today.

I would suspect the front tires..

did the front balance on my floats and fixed my problem. had beads added and was told it will take a few miles for the bag to seperate and spill the beads. but for now its definately helped my problem.

thanks everybody.

sorry for misleading you about the spacers and longer studs. that post never came out sounding like it should. but actually it has the proper offsets installed. i was not sure what they were called so i just stated spacers. i did have the fronts off for the brake work and kingpins. mechanic said that its all fine. gonna throw some beads in my front floats and see what happens.

sorry for the bad post.

thanks for all the responses. i am going to tackle this problem this week. i will post what i find.