C3 transmission. Taking it in under warranty. Changes gears at high rpms.

I heard this started yesterday. I drove the truck just now and it's hissing repeatedly and throwing white/blue smoke. This is happening only at high rpms. Anyone know what this means?

 

I turned the truck on again and i've been driving for 25miles now. No smoke to be seen, even at high rpms

I would considered the problem fixed yet. Since it happened yesterday and today. But maybe this new info narrows it down a bit

 

This is an IDI diesel truck with a C-3? I didn't know a C-3 could be used. If so, that is good to know.

I don't see any truck that fits this description in your profile unless it's the F150 gas so I am confused. Your 4x4 6.9L shows a manual 4 speed transmission - or is that the F150? You need to at least get these trucks listed properly in a signature to avoid this confusion every time.

If it is a C-6 in an IDI the shift point RPMs are controlled by the VRV on the right side of the injection pump which would need to be properly adjusted. I would assume that a C-3 behind a diesel would be the same.
In a gas truck it is controlled by manifold vacuum as it changes with engine RPM.

Hissing could be a leaking vacuum line that goes to the modulator on the back of transmission which could cause high RPM shifts, or any vacuum line but I don't know if this is the kind of 'hissing' sound that you are describing.

If they installed the transmission and their work installing it is under warranty I would have them look at it. Properly adjusting the VRV should have been part of the job but maybe they didn't include that in the work they did or maybe the person doing the work didn't know about the VRV.

 

I'll update my info.
I'm referring to my 1990 E350 UHaul van.

 

From the factory that would have an E4OD automatic (Electronic 4 speed Over Drive transmission). Those don't have VRVs but have instead an FIPL (Throttle Position Sensor) to control shifting. I don't know how E4ODs with FIPL work exactly as far as controlling the shifting. Some E 350s came with C-6s although it was being phased out. A C-6 was available but I think that was by special order. Some buyers wanted them for their known toughness and endurance. I doubt if U-Haul would have ordered one with a C-6 but they might have, knowing it's proven reliability and since they didn't have to buy the fuel. Those trucks were ordered with just the cab and chassis (includes drive train) and the box part was added on by whoever makes those for U-Haul. It will say on the tag on the box.

The E4OD had some significant problems back then, so possibly yours was replaced with a different transmission if that is not what you have. Now days the E4OD can be rebuilt to be a strong and dependable transmission.
I have still never heard of a C-3 behind an IDI diesel yet. The C-3 was for little cars like Ford Pintos.

In any case I would recommend taking it back to the transmission shop and explain exactly what happened with the shifting at high RPM, the hissing sound and the smoke. They might know right away what caused it.

 

I think it is a c6. It was C something. For some reason I think 3 because either only has 3 gears. I dropped it off. Every day my truck is out, I use budget truck rentals, they cost me $150/day and I get good rates as a "business ". So I pay about a grand when I bring it back in, which will be 2x after it was rebuilt 2 months ago. ****ing a

 

I'd probably advance the timing slightly... Should help with high-RPM smoke.
It's happening because you aren't advanced enough to burn the fuel fully at the high end. At the low end, you've got the light-load-advance making things better.

 

How do I advance timing? And can is this related to the hissing? It's not one, consistent hissing sound, it's a consistent rattlesnake rhythm hissing sound.

Anyone have a picture of the VRV on the injection pump?

I'll check the vacuum line. Turns out the issue with high shifting was because the vacuum line was pinched when I replaced the air filter and put it back on. It shift normal now, but the blue smoke and hissing is getting worse.

 

I have no clue about the hissing. Sounds like a vacuum leak perhaps?

The smoke, though, that's timing. Advance it a dime's width and it will probably go away and have more power.

 

How do I advance it? Never done it before so I don't exactly know what I'm looking for

 

Here's a video I just took of my truck driving by.

 

Not only is it smoking, it's losing power. 45mph max.

 

My brother is saying that he thinks this part might have something to do with it. It makes a buzzing sound when turning the key over when the wait to start light is turned on. A buzzing sound that we did not hear before.

Any thoughts on this piece being related? And what is this part??

 

Here's a video I took of it buzzing. The hose I'm touching feels just like a cellphone vibrating.
Watch "Buzzing sound AND buzzong/rattling feel." on YouTube

 

As you can see, when I touched my phone to it, it vibrated the phone.