Rebuilt transmission already acting up (edit: vac pump actually)

[Cubey]

When in Salt Lake city a couple hours ago, I stopped off for fuel. Then I took some city streets to a city park to walk Lucy.

And it happened: it was upshifting later (than it has been) and when approaching a stop slowly with foot off throttle and brake, it noticeably downshifts. That's exactly how the old transmission behaved when I bought the RV in 2019. The upshifting isn't as late as it was then, but it has the adjustable vacuum modulator, where as th we old one had a factory non-adjustable one when I got it.

Temperatures haven't been crazy (pan usually 180ish, TC output 220ish). Pan does get around 190-200 on steep grades, and TC output higher, but it has been warmer weather (90-95).

What do I do now?

 

[Black dawg]

Sounds like modulator/vrv/ vacuum leak, not internal trans to me.

 

[Cubey]

I guess I should add that I'm only 150 miles from the RV park I'm going to stay at for the next two months. I'll probably just relax today and go there tomorrow since I wanna make one more Walmart stop in the morning.

There's a highly rated transmission shop in the small town there near the RV park, so I might consult him and see what he says. Lots of reviews from travellers passing through having things fixed.

 

[Cubey]

Sounds like modulator/vrv/ vacuum leak, not internal trans to me.

Yeah I was thinking that. Maybe my vacuum pump is starting to get weak.

I guess I'll pull out my hft vac gauge and test it directly. I do have a dedicated gauge for vacuum and it has been showing lower, BUT the thin vinyl tubing got very hot in the engine compartment yesterday, the 1/4" bit at the end, and it was collapsing in on itself so I figured that was why. The reading showed better this morning but maybe the pump is going. It's the lifetime warranty one I bought for the F250 5 years ago, so maybe it's just starting to go.

Richfield (78 miles from here) has an O'Reilly's, so I might be getting that warrantied tomorrow.

 

[Cubey]

Yeah, the pump has lost about 5 PSI.

A good pump, with nothing hooked to it except the gauge, showed 25PSI in 2019:

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Now it's showing right about 20PSI with just the gauge on the pump. Maybe that's enough to screw with the transmission.

And the lifetime warranty is garbage, if you're in a hurry. I have the paper receipt still from 2017. I called the Richfield, UT O'Reilly and I would have to pay $10 freight for a direct replacement (Dorman 904-808) to the store because they don't carry that exact one anymore.

Or I'd have to wait 2 days for a different brand pump (Cardone 64-1006) and pay $37 more, because the Dorman pump I have was $120 in 2017, and the Cardone one without freight is $157, and they make you pay the difference.

I might just buy a spare from Amazon for $80 (gonna get a PO Box while at the RV park) and see about warranting the O'Reilly one this winter, when I have time to hang around waiting for a part to come in.

 

[Big Bart]

Cubey,

Try adjusting your vrv valve. I know you mentioned you have it maxed out likely towards the window. But their is a cap over the top of the vrv valve where the vacuum ports stick out which pops off when you pull it up and away from the valve. Then you actually see the top of the valve. Underneath the head/top, where the vacuum ports are, there is a nut with four indents. You can twist/screw that nut up or down. I can do it with my fingers, but maybe you will need a screw driver to get it started. That nut changes the shift point. Members on this site said toss them they cannot be fixed, but the can be recalibrated with that nut. Be very careful not to break off your vacuum ports messing around with it.

Nick Pisa now makes them, not sure how good they are but food for thought.

You can also adjust to some extent with the modulator, but I find it easier to do with that nut.

As you know these vacuum pumps don’t seem to last but 3-5 years.

 

[Cubey]

Yeah, I'm going to just replace the vacuum pump with an online sourced one for now. It's not getting any worse at the moment according to the in cab vac gauge, so it'll probably last long another 110 miles left to the RV park.

I'm actually just going to go to the Walmart for the night, in the off chance the pump dies today and I have to source one asap from an auto parts store. It's only 38 miles to there. That way the engine will be cold in morning if I have to change it out.

 

[Cubey]

Huh, I can actually just get a refund for the vacuum pump, according to the warranty info. It just says you need the receipt, not the packaging.

"If you need to return a product under warranty, please take it into any O’Reilly Auto Parts location or return it following the process described below. In order to be eligible for service under this Limited Warranty, you MUST return the product along with the original sales receipt to any O’Reilly Auto Parts store, and at our option, we will either replace the product or provide a refund."

I guess I might just return it this fall for a refund, and perhaps buy another online from O'Reilly with a promo code for "ship to
home". They might not like how faded the receipt is, but it's the company's fault for using thermal paper. You can JUST see the writing still for the product info, date, and barcode/number. Might install the O'Reilly one and keep the Amazon one as a spare, actually.

Well in any case, I can get my money back out of it, either by an exchange in store or a refund in store. I'd do better to return it and buy another, since it would reset the warranty. Not sure if a warranty replacement gets a lifetime warranty also or not.

 

[Cubey]

Made it to the RV park. Braking is still ok at least, so that wasn't a problem. I have tried to keep an eye on the vac gauge and I have notice it sway down a bit when the trans downshifts itself when it gets below about 35-40 (when braking) so yeah it's most likely that.

There is an ATV/UTV trail next to the highway, so I can probably just ride the scooter to town on that trail, if I don't wanna drive the RV. Might be able to get UPS/FedEx here, if I post my own sign on the office door on days I'm expecting a delivery. I had to take a spot outside of the back row where UPS/FedEx deliveries are directed to by a sign on the office door, but I'm in the # range where the owner said to go for monthly, so yeah. I doubt the owner would care, as long as I use painter's tape (won't leave sticky behind) and I take the sign down when I don't need it up.

 

[Cubey]

Cubey,

Try adjusting your vrv valve. I know you mentioned you have it maxed out likely towards the window. But their is a cap over the top of the vrv valve where the vacuum ports stick out which pops off when you pull it up and away from the valve. Then you actually see the top of the valve. Underneath the head/top, where the vacuum ports are, there is a nut with four indents. You can twist/screw that nut up or down. I can do it with my fingers, but maybe you will need a screw driver to get it started. That nut changes the shift point. Members on this site said toss them they cannot be fixed, but the can be recalibrated with that nut. Be very careful not to break off your vacuum ports messing around with it.

Nick Pisa now makes them, not sure how good they are but food for thought.

You can also adjust to some extent with the modulator, but I find it easier to do with that nut.

As you know these vacuum pumps don’t seem to last but 3-5 years.

Yeah it's fully towards the window by the look of it. I haven't messed with it in forever. Pic I just took:

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And the brand new vacuum pump is only putting out about the same as the old, 5 year old pump of the same exact brand and model number (Dorman 904-808). The build quality has slipped in 5 years by the look of the two. The new one is gonna go back to Amazon. Not gonna pay $75 for a new pump that's no better than a 5 year old pump, which I can get replaced for free later on at an O'Reilly. That means putting back the old pump, but oh well. No telling if the O'Reilly supply of the same exact pumps as Amazon sells will be any better, but I'll risk it.

 

[Vegasfro]

Love these old Diesel Motorhomes. Been searching for one to buy but they must be rare cause never see any for sale

 

[Cubey]

Love these old Diesel Motorhomes. Been searching for one to buy but they must be rare cause never see any for sale

Do a saved search Craisglist for the RV category, keyword Ford, and with diesel as the fuel type. Then anytime someone lists a Ford with diesel fuel set in the options in the RV category, you'll get an email alert. You might get a lot of pickup truck ad alerts but you never know. Oh and have the price set to whatever max you wanna pay, to weed out any stupidly expensive things.

 

[Cubey]

The transmission is still acting up, even with the new vac pump, which is showing good pressure. (25 on the gauge in the cab)

Still late shifts into 2nd and 3rd and can feel it down shifting around 25-35 when slowing down with or without braking.

Now what do I check? Bad modulator? It should be new from the rebuild.

And will it hurt it to keep driving it with it doing that? One time (long drive) today I left off the throttle and it up shifted a bit harshly. Temperatures are doing ok still.

I have the trailer dropped right now and going through a very hot area in AZ in the mountain area south of Page, the trans pan got a bit over 195. (200 maybe?) The engine got a bit toasty too in that area, hanging around 230. I pulled over once. Was kind of a waste since I was about to start going down, but I didn't know that due to the curve and rock walls ahead. Having it in park and giving it small amount of throttle helped it cool down faster. Threw on the heater full blast too and then took off after a couple minutes, cooled down to 220 and stayed down after that. Admittedly that as a slow, steep grade and it as probably 95 out. Oh, and I think I was bucking a head wind too.

I'm on my way to Tucson to most likely buy a very light weight car (you'll have to wait to see, if I get it) and I think I might go a longer route to go back to UT, flat towing the car. US-89 is pretty rough in places to go through when towing when it's 95 degrees. Unless I can plan my return trip so that I go through that really bad section in the early morning (after sun up) when it's about 75-80 degrees out. But I think I'd rather spend the extra $65 in fuel and go a longer way, by way of US-93 from Phoenix up to Vegas, then hop on i15 and go up that way. $65 is cheaper than a blown engine or transmission from trying to tow on US-89 in 95 degree heat. There's so few good places to pull over along 89. At least on 93 and 15, it has huge wide shoulders for emergency stops. And people can always pass me, so I don't have the stress of a line of cars stuck behind me, so I can keep my foot out of it a bit better. Plus, I think it's mostly less extreme climbs that route, except one section between Vegas and St George on 15. Problem with the 93 route is it'll be about 10-12 degrees hotter around Vegas than the 89 route through Page.

 

[Cubey]

Well I finally figured out why the trans suddenly started acting up last year... and probably why that first vac pump I put didn't last... the transmission shop that got $2000 from me decided to save 2 or 3 inches of new 3/16" hose and put a piece too short, making it pull off of the vacuum modulator on the transmission since it was under tension.

The vac pumps have been sucking in raw air/dirt. I don't have a longer piece of 3/16" hose, so I just carefully bent the hard line that the hose connects to so it won't be under so much tension. I'll get a longer piece of hose soon so it won't have any tension.

It's insane how skinflint a transmission shop can be over a few inches of rubber hose when doing a $2000 rebuild.

I finally found it because I went under to try to adjust the vacuum modulator a bit, since it was annoying how it was up/down shifting,. I kept putting off checking it because I didn't expect the hose to be totally disconnected. Note to self: don't do that anymore. It's not too bad to crawl under to check it, just a bit dirty.
.
Totally unrelated to the trans job but I haven't checked my differential in about 3 years and it was about 1qt low (almost 4qts capacity in a Dana 70) so I really need to do more frequent checks on that stuff. I topped it off with 80w90 since it's what I had in front of me. The rest is 75w140 or something like that. It could stand to be changed again soon anyway. Maybe next fall/winter.

 

[Cant Write]

$2000 on a C6 rebuild.....CRAZY!! I hope it lasts 2 lifetimes. Course they prolly pulled it.

Glad you found the culprit!! Get yer GV installed yet?