Spent hours and hours last night scrolling through the tranny forum, and this forum.

Learned alot more about C6's, and how to check for a bad VRV.

Disconnect the vacuum line going to the modulator, and if you find oil in there, the VRV is done.


Ok, so clearly my vacuum modulator is gone, when I took the line off of it, a table spoon of oil drained out the modulator it's self and abit more out the line....



Now, my question is witch I couldn't find an answer to, would the bad modulator could have caused my C6 to overheat and burn the oil like it did?

And oil must have gotten so hot, it started leaking around the dipstick tube.

But it only lost about a quart of fluid.




Now other than badly needing a flush, it starts off in 2nd gear sometimes, i've learned a sticky Governor can cause that, and usually what causes a sticky governor is caused by dirty fluid, so, so far all my problems are all related together.


Any thoughts on the busted modulator causing all this crap?

 

I can only see the oil getting burnt if you kept starting out in second for a while. The fluid would get hot pretty quick, especially with weight of the vehicle. Starting in second is almost like slipping a clutch in a manual and you know how hot those get if you slip em a bit.

It's not uncommon for a vacuum regulator to go out but it's not a regular part to change either. Generally when the regulator goes junk it leaks, shifts get funky. The engine may wind way up and slam into the next gear or it could shift early and act like a slipping clutch, sliding into the next gear with the rpm jumping up as it slides into the gear.

I wonder if there was an air lock someplace. You went on a trip, installed a trans cooler before leaving and now have burnt fluid and a junk vacuum regulator. Perhaps the flow was restricted by an air lock or some other thing that restricted the flow and burned the fluid, the heat split the diaphragm in the regulator which has a few years on it

 

John, i think you have things confused. a bad VRV will make the trans shift late, or not shift at all until you let off the throttle.
a bad MODULATOR VALVE will leak oil into the line and cause the problems you are describing.

the VRV is mounted on the injector pump.


the modulator valve is mounted to the back of the trans.

 

Yes yes sorry about that, I am talking about the vacuum modulator!

 

I installed my tranny cooler on it during my Florida trip! Witch was 2 months ago....

I did 6000 miles on it! Not a problem. This happened on my very last trip of the season, this past labor day long weekend. And I always check all oils before leaving home for everytrip, oil was still nice clean/red when I left. 875 miles and 3 days later come home with this crap!




But I did notice about 4 hours from home, it was shifting kind of late from 1st.... the engine would rev almost to the governor before shifting, but shifting to 3rd was normal.


I will more than lately rebuilt the trans. seing how I travel very far with this thing, and now that it's overheated that bad. Fine it still seems to operate well even though, but just to be sure. It's not like it's very hard or expensive to rebuilt a C6 anyways.

I just wanna determine the cause of failure, as this is bugging me like you wouldn't believe. And it might be a useful thread to someone in the future, and you other C6 guys out there can learn a lesson on this! After 25 years of good service, might be a good idea to replace that damn vacuum modulator even if it's still good! So this doesn't happen to you!!!


And from now on, I'm gonna carry a spare modulator in my F150, and in the camper!

 

if you are going to do the rebuild yourself, take a close look at everything.

it cost me $1500 to have my C6 done, because the planetary gear assembly was warped and that caused the housing to crack.
the trans worked fine. i wanted it gone over before putting it in the truck though.
the guy that did it said i would only have gotten a few thousand easy miles or a few hundred hard miles out of it before it died.

 

Well john if you need a C6 that needs a band and some other small stuff in it when you rebuild it, I got the C6 from the 86 that is yours if you need it. I will say this, If your Vaccum Modulator is gone you got very lucky getting home. My buddy Jared lost his on his 81 with a I-6 w/C6 and he only got 40 miles and the tranny just didnt shift anymore...

 

Well, dropped the pan today, no UFO's, just a good amount of metal shavings on the magnetite I installed in the pan earlier this year.

Cleaned everything, new filter, re-fill. Run through the gears 4 times, P R N D 2 1 - 1 2 D N R P etc.

Disconnect the cooler line coming from my aux cooler - back to trans. fire up the engine, hardly anything coming out...

Tryed the line coming straight from the trans, see if it wasn't one of the coolers clogged, nope, hardly anything coming out of that one.


So, pump is DEAD.


I'll search around here for the next week or 2 if U-Haul still has some C6's. If not, I'll drive it to winter storage (8 miles) and leave it there for winter, and during winter, see if I find something, if not, next spring, drive it back home, and drop and rebuilt this transmission.


Gonna be real easy dropping this trans anyways, I have full easy access to all bell housing bolts

 

I'll call the guy that had a bunch of u-hauls near me.....if you don't find anything this fall, I 'might' park my dually between now and spring, if I do, the C6 in it should have about 15-20K on it since it was rebuilt if all the info was right when I got it. I'm thinking of doing a dually conversion on the one F350 that's here to replace mine, complete with another flatbed/dump on it, to give me 4wd, and a fresher body. If I do that, everything here will be 4wd, and not much sense keeping the old 2wd C6 around for parts!

 

I've been through the uhaultruckparts.com and no more C6's left there.

I went through all 28 pages of U Haul stuff on their ebay section. No more C6's!


I did find on kijiji a 1990 E350 ex. Fire rescue van, 7.3 Diesel. It is a 1990 so good chance of being a E4OD, but since it's a fire van, might have been ordered with a C6. I have to call the guy sometime. Hes asking 950$ for the whole thing running! If C6, I'll pull the trans, and keep the rest of the body as storage.


If that ain't a C6, let me know what you do with yours, and I can take a road trip to go get it when time comes.

 

There's a chance the guy here has one still, he was going to check tomorrow morning and let me know.

Mine may also be coming available this winter sometime, looking under the dually today, and discovered the cross member at the back of the cab is rotting out, I wondered why my cab seemed to be creaking a little more lately. I guess 8 years, (the time I've had it), 160K kilometres (total over 320K now) and hundreds of tons of stuff moved on it takes it's toll. Also had a close look at the frame of the truck I'm thinking of replacing it with, it has a typical 'scale' on it, but looks really solid if that gets cleaned up. All the sheet metal on that truck needs to come off, so that will create a good opportunity for it to happen.

 

I have a nice trans for you john, a great E4OD.

 

Well if I don't find anything around here, looks like I'll be making a road trip to Peterborough this winter


And snapon, if I even wanted to consider having OverDrive in this pig, I'd go through the trouble of a finding and installing a 4x4 ZF5 before E4OD

 

Actually, the shifter would sit too far back so you cant swap a zf in.

 

Shifters are bendable


And it wouldn't sit that far back actually, this ain't no 1970's Dodge Tradesman van. lol