M1009 basket case vacuum system

[HelluvaEngineer]

I posted about a year and a half ago about the botched TH400 rebuild job I got at a local shop. It lasted about 900 miles until recently when it started revving high, slipping, and the fluid was burned. It's now at what seems to be a much better local shop, and the shop owner has been keeping in touch with me on progress and asking questions about parts specific to the M1009.

The transmission is rebuilt and back in the car, but they are trying to debug the vacuum system because it's skipping shifts and is generally all over the place. Thankfully, they seem to want to get it right. They said someone bypassed the vac regulator altogether and they figured that out, but they say the pump is jumping between 20 and 5 inches at idle. So they asked me to order some replacement parts.

Unfortunately, I found out that both parts are now basically unavailable. I told them I can get the vacuum puck on the pump, but the shop owner is concerned the teeth on the pump may be worn and it's bouncing around on the cam.

Does anyone have any recommendations for locating parts or alternate solutions? At this point we're also considering installing a Lokar manual shifter, but I'd prefer to keep it original Any thoughts? Thanks in advance.

Edit: if we go manual they are recommending a new manual valve body, I believe. The note about the Lokar shifter above is irrelevant.

 

[adf5565]

I posted about a year and a half ago about the botched TH400 rebuild job I got at a local shop. It lasted about 900 miles until recently when it started revving high, slipping, and the fluid was burned. It's now at what seems to be a much better local shop, and the shop owner has been keeping in touch with me on progress and asking questions about parts specific to the M1009.

The transmission is rebuilt and back in the car, but they are trying to debug the vacuum system because it's skipping shifts and is generally all over the place. Thankfully, they seem to want to get it right. They said someone bypassed the vac regulator altogether and they figured that out, but they say the pump is jumping between 20 and 5 inches at idle. So they asked me to order some replacement parts.

Unfortunately, I found out that both parts are now basically unavailable. I told them I can get the vacuum puck on the pump, but the shop owner is concerned the teeth on the pump may be worn and it's bouncing around on the cam.

Does anyone have any recommendations for locating parts or alternate solutions? At this point we're also considering installing a Lokar manual shifter, but I'd prefer to keep it original Any thoughts? Thanks in advance.

Edit: if we go manual they are recommending a new manual valve body, I believe. The note about the Lokar shifter above is irrelevant.

Can you have them pull the pump to confirm the teeth are bad? On eBay there are both used full vacuum pump systems (distributor drive and all) as well as just the pump head (brand new). It’s easy to pull out the drive from the motor and check.

 

[WWRD99]

I posted about a year and a half ago about the botched TH400 rebuild job I got at a local shop. It lasted about 900 miles until recently when it started revving high, slipping, and the fluid was burned. It's now at what seems to be a much better local shop, and the shop owner has been keeping in touch with me on progress and asking questions about parts specific to the M1009.

The transmission is rebuilt and back in the car, but they are trying to debug the vacuum system because it's skipping shifts and is generally all over the place. Thankfully, they seem to want to get it right. They said someone bypassed the vac regulator altogether and they figured that out, but they say the pump is jumping between 20 and 5 inches at idle. So they asked me to order some replacement parts.

Unfortunately, I found out that both parts are now basically unavailable. I told them I can get the vacuum puck on the pump, but the shop owner is concerned the teeth on the pump may be worn and it's bouncing around on the cam.

Does anyone have any recommendations for locating parts or alternate solutions? At this point we're also considering installing a Lokar manual shifter, but I'd prefer to keep it original Any thoughts? Thanks in advance.

Edit: if we go manual they are recommending a new manual valve body, I believe. The note about the Lokar shifter above is irrelevant.

So your vacuum goes from negative 20 to negative 5 hg? Bouncing? Where are they checking for vacuum at? The vacuum system is extremely basic on these...do they have the vacuum lines hooked up right on the throttle valve? Have them swap it around and see if they're on the wrong connections. If it is bouncing that much it screams leak...unless it is the diaphram inside which is technically a leak!! I can see the trans going nuts shifting without a solid vacuum referance.

 

[87cr250r]

The TH400 transmission I'll always shift on the governor if you drive it fast enough regardless of what the vacuum signal is doing. Verify the transmission hits all gears at full throttle (not too exciting with a 6.2). If it doesn't you need to be looking at the transmission, if it does then you can look at vacuum. A weak vacuum system will always shift eventually but smack your head on the back window when it does.

 

[HelluvaEngineer]

So your vacuum goes from negative 20 to negative 5 hg? Bouncing? Where are they checking for vacuum at? The vacuum system is extremely basic on these...do they have the vacuum lines hooked up right on the throttle valve? Have them swap it around and see if they're on the wrong connections. If it is bouncing that much it screams leak...unless it is the diaphram inside which is technically a leak!! I can see the trans going nuts shifting without a solid vacuum referance.

The owner told me they were testing just at the pump to isolate it. He said they figured out the lines and I sent them a diagram from the TM. I'll call today and see if they are willing to swap out the puck.

 

[WWRD99]

The owner told me they were testing just at the pump to isolate it. He said they figured out the lines and I sent them a diagram from the TM. I'll call today and see if they are willing to swap out the puck.

Yes that's where they should test it. Just curious about the actual reading of vacuum, meaning it's bouncing up and down or steady vacuum at 20hg? Changing the puck is easy and I doubt the gear is worn that bad...can pop it out to check though.

 

[HelluvaEngineer]

Yes that's where they should test it. Just curious about the actual reading of vacuum, meaning it's bouncing up and down or steady vacuum at 20hg? Changing the puck is easy and I doubt the gear is worn that bad...can pop it out to check though.

He said it's bouncing high/low at idle. He said it could be due to a rough idle of the diesel, but I'm with you, I don't see a reason to NOT replace that diaphragm.

 

[WWRD99]

He said it's bouncing high/low at idle. He said it could be due to a rough idle of the diesel, but I'm with you, I don't see a reason to NOT replace that diaphragm.

Bouncing that much at idle is typically the diaphragm...the engine would basically have to be shutting off to get that low of a number...there are pods on ebay and other sites for a click over 130$. Might want to send the tech the guide on how to set the vacuum valve on the throttle...once you get that set it shifts nice.

 

[HelluvaEngineer]

Bouncing that much at idle is typically the diaphragm...the engine would basically have to be shutting off to get that low of a number...there are pods on ebay and other sites for a click over 130$. Might want to send the tech the guide on how to set the vacuum valve on the throttle...once you get that set it shifts nice.

Thanks, I did send him those notes and I will probably order a puck to have on hand when I start having problems again.

To close out this post (for now), they determined the regulator was doing a good job of evening out what vacuum there is and they put a low vacuum modulator on the trans, which it likely needed anyway. It seems to be picking much better shift points that ever before, but I don't have a basis of comparison. I think I'll check it at the transmission periodically and change out the diaphragm at some point.

Thanks to everyone for the advice.