Transmission Shifting Test Ques??

[trkosaur]

Hey Guys,
Have a question. I've put about 12k miles on my m1009 and everything has run fine. In the last week or two, it has developed the standard rough/late shift. It wants to shift out of first somewhere between 25-33, but 2nd is still fine.

On my truck, the regulator was already bypassed. So, I changed all the rubber hoses, put a newer, adjustable modulator on the trans and am still playing with it to get things right.

My question is, when I was vac testing the lines I got the same test at the vac pump and at the trans. So I don't think I have any leaks or clogs. However, the vacuum guage bounced furiously between 10-15. Does this bouncing possible indicate that my vac pump may be going bad?? It seems like everything I have read indicates a particular number, whereas mine was more of a "range".

Thanks for any help guys.

 

[Westech]

no the pump is a single diaphragm and will bounce like that..... you should get a higher reading at the pump then the trans.. Vac at the trans should be in the 10-15 Vac at Idle. sounds like the TPS is Shot.

 

[chevyforlife]

have you check your tranny fluid and check for leaks. how many miles are on it total ? cause it might need a tranny flush
another question does the idle sound rough or does it sound different then before this problem started???

 

[Westech]

My question is, when I was vac testing the lines I got the same test at the vac pump and at the trans


there IS your problem!

 

[chevyforlife]

oka check the intake manifold vacuum

 

[Ken_86gt]

oka check the intake manifold vacuum

I am not sure what you are saying. This engine develops vacuum with a vacuum pump. There isn't any real vacuum in a diesels intake manifold like in a gasoline engine.

 

[Westech]

The tps is shot....... Replace this.......

 

[chevyforlife]

I am not sure what you are saying. This engine develops vacuum with a vacuum pump. There isn't any real vacuum in a diesels intake manifold like in a gasoline engine.

yeah i for got about that

 

[trkosaur]

the trans fluid and filter has only 3k miles. since the pan was dropped and filter was changed i have noticed an occasional lag in gears. when i would first start off from my house up a small hill to a stop sign. i would stop and then try to start again and there would be a slight lag for the gear to catch. it only happened at that exact spot though, so i didn't read too much into it. and the trans oil was done by a great old-school mechanic that works on chevys.

i am a bit confused....why would getting the same vac reading at the pump and at the tranny be a bad thing? wouldn't that mean that I am not losing any vac anywhere and the system is functioning normally?

the truck runs great. no idle issues. i did try to run AMS Oil 15w40 with AMS filter. I had less than 2k miles on that oil change, and drained it yesterday. The truck started and ran fine. But its cold where i live and in the morning when i first put the truck in drive or reved it after warming up, you could hear a wine that sounded like it was coming from the back of the motor or trans. the oil didn't feel great to me, so i dropped it and went back to rotella. it made a difference and it i can hear it running better.

i also added the AMS Oil atf fluid into the trans when the oil was changed. now it seems stupid to mix the oils, but i thought i was adding something good to the mix. i am tempted to drain everything and start over with new filter and fluid, but in reality i don't think the fluid is the problem.

 

[trkosaur]

i hear you on the tps. i haven't checked it, but as i mentioned mine was bypassed when i got it. i have around 12k miles on it the way it is and it seems to work fine. so what changed in the last week?

 

[Westech]

you MUST HAVE A TPS !!!!! if it is by passed the trans will think you are idling all the time and shift really really early and the line pressure will be at the lowest point (burn up the trans, soft shifting) you can make it shift "ok" by adjusting the modulator on the trans but the line pressure will be all worng and you will kill that trans! get a TPS and do it right. that IS your problem.

 

[trkosaur]

Update

Thought I would get an update out for anyone else who might be having similar problems.

So, as I mentioned, I got a new modulator (side of trans) w/ adjustable screw. I replaced all of the rubber lines. Since then, I removed the regulator (tps), cleaned it and reinstalled almost all the way up, towards the air cleaner. I also dropped the pan, changed the filter and the oil, cleaned everything I saw and added a drain plug.

When I pulled the pan, I noticed that the mechanic that had previously changed my trans oil had installed the filter wrong. He had placed the spacer for the the filter screw under the filter instead of between the filter and the trans. This caused the filter to sit at an angle and most likely keeping the filter from doing anything at alll. I had noticed that my oil had rapidly become smelly and dark. Luckily I did it myself this time, and hopefully right. Thanks to the manuals and a few conversations here, I knew what to look for.

My truck is still shifting a bit late, but after studying the manual, I noticed that for my elevation, 6300 ft., the trans needs around 17 or 18 in. of vacuum to shift properly. I think I am only getting around 15. So, I will eventually change the vacuum when I can afford a new one, or just move to a lower elevation. Ha.

Thanks for all of the input guys. Since I have a drain plug now, I plan to change the oil every few thousand miles or so to help keep things running smoothly.

thanks
Chance

 

[4bogginchevys]

you could change the oil again in 3000 miles for piece of mind but after that 15000 would be very early, I know from experience you CAN over change tranny fluid and reduce the life of it drastically. good luck

 

[walkergun200]

were do i get one i

The tps is shot....... Replace this.......

were can i get one and how much? thanks for your help this is one great sit.

send answer to walkergun2004@yahoo.com or here and again thanks

 

[lindyp38]

yes..id like to know..where i can get a TPS......

THANKS

 

[ralbelt]

Member Doghead has some for sale, includes a home made adjustment guage block and instruction sheet.

 

[allrevup]

Westeck is probably right.

But for ALL is worth...Today I fix a problem that I had had this past week with eratic shifting; not wanting to hold high gear and downshifting during normal easy asseleration or at at higher speeds, 30-50 MPH.

The square Rubber hose connector on the side of the TPS, look OK, but had dry rotted and had small cracks (26 years old rubber part). I just did away with it & connected the hosses directly to the TPS (very tight but possitive fit) I, also replace the hose adapter at the output of the vacuum pump, it looks like a "T" with a cap "OFF" on one side. Wile at it replace the rubber hose going from the hard steel line to the transmition modulator, as is most expose to the elements and all the chemicals gunk from the engine bay. Total= about 30 min. , $3.16 for 4' of 7/64" Goodyear vacuum tube & $2.99 for vacuum connectors at Autozone.

If you are having a hard time locating a TPS, There is a tread with clear photos, somewhere under "CUCV transsmision", showing how to take it apart, clean a maybe refurbish it.

 

[tm america]

You have one of two or three things happening.Either you need to turn the screw on the modulator out 3 or 4 turns or the governor is sticking,One other thing is the kick down soloniod could be not seating if it doesnt seat and hold pressure it will shift late like you are in passing gear. You have plenty of vacum adjust the modulator first if you see a change adjust it till you get the shift timing and feel right.If no change pull the governor and hold it with the gear pointed to the sky squeeze the weight together and make sure the valve moves freely. If it does put a new kick down soloniod in there.

 

[1984M1009]

I just changed my injection pump and saw the connection on the side of the tps was cracked I did the same thing sliding the hoses directly over and now the tranny shifts great

Westeck is probably right.

But for ALL is worth...Today I fix a problem that I had had this past week with eratic shifting; not wanting to hold high gear and downshifting during normal easy asseleration or at at higher speeds, 30-50 MPH.

The square Rubber hose connector on the side of the TPS, look OK, but had dry rotted and had small cracks (26 years old rubber part). I just did away with it & connected the hosses directly to the TPS (very tight but possitive fit) I, also replace the hose adapter at the output of the vacuum pump, it looks like a "T" with a cap "OFF" on one side. Wile at it replace the rubber hose going from the hard steel line to the transmition modulator, as is most expose to the elements and all the chemicals gunk from the engine bay. Total= about 30 min. , $3.16 for 4' of 7/64" Goodyear vacuum tube & $2.99 for vacuum connectors at Autozone.

If you are having a hard time locating a TPS, There is a tread with clear photos, somewhere under "CUCV transsmision", showing how to take it apart, clean a maybe refurbish it.

 

[motormayhem]

i hear you on the tps. i haven't checked it, but as i mentioned mine was bypassed when i got it. i have around 12k miles on it the way it is and it seems to work fine. so what changed in the last week?

You dont want that bypassed. The truck will always think it is running at low load and cause early shifts and make the transmission burn clutches faster. You want it to shift later and build up more line pressure when it is under a load. First thing to do it buy a TPS and hook it up and get the readings the TM says at the transmission. Then troubleshoot from there. DONT LEAVE IT BYPASSED.


EDIT: Didn't see the 2nd page...looks like someone already covered this.