black dawg
1/2 ton status
what all on that truck needs vacuum? If it is only for a th400, they make a cable operated (like a 700 tv cable) vacuum modulator.
CK5
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Vaccuum pump
- Thread starter cybrfire
- Start date
what all on that truck needs vacuum? If it is only for a th400, they make a cable operated (like a 700 tv cable) vacuum modulator.
Yes they do make cable operated modulator valves,but they too cost 125+ bucks...if the truck has A/C or operable EGR,then you may as well stay with the stock vacuum pump..
black dawg
1/2 ton status
I think the cable deal would be neat then. Could delete the vac pump and vrv and hoses. I have never seen the cable modulator in person before, but I imagine it would outlast a few vac pumps for sure?
I'm gona try and locate one and see whats up. Haven't found a supplier yet. One of the big catalog companies lists a vac pump but can't tell if its in stock, figure i'll call them on Monday and see if they have the cable operated one and check inventory on the factory replacement.
I've had good luck finding used parts on car-part.com Many yards have their inventory online there us-wide. Not sure if the vacuum pump would be listed but worth a shot.
A used pump or pod would be a gamble,the diaphrams rot or tear after sitting idle in a junkyard...if you can get one for 20 bucks or less it might be an option..
Here is one of several cable operated modulators--I think some military trucks had them as factory equipment...saw some surplus ones on a google search at some military surplus site,maybe Boyd's ?..
Here is one of several cable operated modulators--I think some military trucks had them as factory equipment...saw some surplus ones on a google search at some military surplus site,maybe Boyd's ?..
rompinstompinmudmonkey
1/2 ton status
I've got a spare cucv for parts. I'd gladly pull it off, but I have no idea what shape it's in.
I did end up getting one ordered. Took a lot of searching and phone calls.
mfg. that I know of,
Cardone
Dorman
Delphi
I found Summit had a Delphi. Not in stock either but available so 7 days give or take for delivery. Both other brands were out of stock and no expected date for new inventory.
Didn't find a whole lot on the cable actuated one either. I think if the modulator comes with the correct cable, that'd be a super slick way to go. Electric options... Meh, not really what I wanted for this particular truck.
Truck has been laid up long enough now, my kid has lost some interest in it. Kinda sucks I guess, but I get it. He's got other vehicles so its not a necessity. Once its a little more drivable and he gets to using it more it will become more necessary and bring more interest along with that.
mfg. that I know of,
Cardone
Dorman
Delphi
I found Summit had a Delphi. Not in stock either but available so 7 days give or take for delivery. Both other brands were out of stock and no expected date for new inventory.
Didn't find a whole lot on the cable actuated one either. I think if the modulator comes with the correct cable, that'd be a super slick way to go. Electric options... Meh, not really what I wanted for this particular truck.
Truck has been laid up long enough now, my kid has lost some interest in it. Kinda sucks I guess, but I get it. He's got other vehicles so its not a necessity. Once its a little more drivable and he gets to using it more it will become more necessary and bring more interest along with that.
I'm not positive but I think I read a stock 700R4 throttle valve cable is what is used with those cable operated modulators..
Greg Ducato fixed me up with a modified govenor and a spring to put behind the modulator valve,so the TH400 will upshift into the higher gears earlier with little or no vacuum to the modulator..
I drove my truck quite awhile with a dead vacuum pump,the transmission would hang in second gear until you got above 35 or so..you could coax it into third sooner by pulling it down from drive into second ,then back to third...it would also "free wheel" when you coasted if it had not upshifted into third yet...that got annoying in city driving,but it does not seem to have harmed the transmission any..
It now goes into second earlier and firmer,and into third at 25-32 mph ..sometimes it still free wheels in second though,unless I put it in second manually...
I'm not sure the vacuum pump in it now is really producing as much as it should,my gauge just pulsates up and down and only goes up to about 8" of vacuum when I put it on the hose nipple to check it..
Actually with less or no vacuum,the line pressure goes higher,so it wont let clutches slip or burn,it shifts very firm and late..
I think having a vacuum pump that is "good" has the potential to send too much vacuum to the modulator if the vacuum regulator vale (VRV) on the injection pump is faulty or not adjusted right and cause soft early shifts and clutch slippage..I bet more TH400's die from that on diesels than any other cause..
Greg Ducato fixed me up with a modified govenor and a spring to put behind the modulator valve,so the TH400 will upshift into the higher gears earlier with little or no vacuum to the modulator..
I drove my truck quite awhile with a dead vacuum pump,the transmission would hang in second gear until you got above 35 or so..you could coax it into third sooner by pulling it down from drive into second ,then back to third...it would also "free wheel" when you coasted if it had not upshifted into third yet...that got annoying in city driving,but it does not seem to have harmed the transmission any..
It now goes into second earlier and firmer,and into third at 25-32 mph ..sometimes it still free wheels in second though,unless I put it in second manually...
I'm not sure the vacuum pump in it now is really producing as much as it should,my gauge just pulsates up and down and only goes up to about 8" of vacuum when I put it on the hose nipple to check it..
Actually with less or no vacuum,the line pressure goes higher,so it wont let clutches slip or burn,it shifts very firm and late..
I think having a vacuum pump that is "good" has the potential to send too much vacuum to the modulator if the vacuum regulator vale (VRV) on the injection pump is faulty or not adjusted right and cause soft early shifts and clutch slippage..I bet more TH400's die from that on diesels than any other cause..
Totally agree. A faulty vacuum pump probably makes your trans last longer however, with the Detroit in the rear and icy roads the super late shifts make for hazardous driving situations. It's unacceptable around here right now.
Turbo 400's are an easy rebuild and I have 5 of them in storage. Adjusting the VRV is not difficult. Just a trial and error process.
Annoying to say the least in town. It's basically a 1 gear trans right now, constantly revving but then slow back down to make the turn or stop at the intersection.
Turbo 400's are an easy rebuild and I have 5 of them in storage. Adjusting the VRV is not difficult. Just a trial and error process.
Annoying to say the least in town. It's basically a 1 gear trans right now, constantly revving but then slow back down to make the turn or stop at the intersection.
I even considered a manual valve body,but I know I'd get sick of having to shift it 1000 times every 5 miles...but with one of those you can start it off in second or even third gear from a dead stop if desired--that helps a lot to kill wheelspin under icy conditions or off roading,especially if you have 4:56's or other "low" gears..
The VRV valve is another expensive piece that is a hunk of plastic and fragile-- that I'd just assume ditch too...its kind of a hokey setup,the whole "simulated gas engine vacuum" system consisting of the pump,and VRV ...sort of a cobbed setup GM thought up to adapt a TH350 or TH400 to a diesel...the mechanical modulator used on military applications kind of shows they knew it was kind of a crappy setup..
The VRV valve is another expensive piece that is a hunk of plastic and fragile-- that I'd just assume ditch too...its kind of a hokey setup,the whole "simulated gas engine vacuum" system consisting of the pump,and VRV ...sort of a cobbed setup GM thought up to adapt a TH350 or TH400 to a diesel...the mechanical modulator used on military applications kind of shows they knew it was kind of a crappy setup..
Bet that thinned out your wallet quite a bit !..
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I have this situation with my CUCV. It's been sitting since I got it. Now that I've started work on it, it is generating its own interest. I'm even considering using it for DD status when it's back together. Quite a promotion from its duties the last few years.
