As most of you know the automatic gearbox is somewhat fragile, and frequent oil changes above the recommended service intervals has been suggested many a time.
The reasons for the oil needing to be changed is that the gearbox generates too much heat above the operational temperature of the oil, this reduces the ability of the oil to flow around, lubricate and cool the working parts. Which eventually will cause wear and the expansion of metal parts which is cataclysmic for the box.
After a little investigation it seems the flaw with the automatic box is that the torque converter is prone to slipping during in lock-up which under load can send the oil temps sky high up to 150c.
This slippage occurs even more when the oil is low, or isn't changed regularly...
A solution for this is to upgrade the cooling of the gearbox from the stock to something a little more suitable.
Here is a picture of the stock gearbox cooler.
so there are many different options for fitting additional/alternative ooling.
These are a few examples of other peopel efforts.
GO to Summitracing.com and buy
2 12mm oil line bolts.
Use the existing 4 washers from your cooler bolts.
buy a tranny cooler. I got the BM 14400btu one.
buy 15ft of aeroquip oil line
buy 2 AN6 steel swivel banjo fittings.
I put my cooler in the middle of the grill, in front of the AC condenser. I've noticed the temps now are ~100F+ambient. I cruise around 159F now, instead of 220F. My previous temps saw as high as 280F.
I was tempted to install a fanned cooler in the area under the battery. For my area, I don't see the need now for a fanned cooler. SF,CA.
I would attach a temp regulator if I were to do it again. This is set at 180F, and recirc the fluid until it gets to 180F. This will be my first winter with the cooler. We'll see if there are issues with heating up, but I doubt that, for my area. In the winter, a cheap fix is to cover the cooler with plastic or sheet aluminum to prevent air cooling of the cooler.
I got everything I needed from Summit, which wasn't that much. Cooler kit, hose, 12mm bolts, 2 banjo swivels. When pushing the hose into the fittings, clamp the fittings into a vice and lube the hose and fitting. Then push like you're giving birth.
Good luck. It is an easy puzzle to figure out. Not too many pieces. Take your time and route the lines. The lines CANNOT touch any metal, else they'll chafe and leak. I wrapped my lines in spiral plastic that you get at the electric store for added protection.
For the 2 water lines that went into the old cooler, I cut both lines in 1/2 and used a hose butt adapter to join the two hoses back together. The adapter was from a generic autoparts store hose repair kit for radiators and water lines. It had several butt joints of varying hose sizes.
It would have been nice to just remove 1 hose, and plug the loose end of the other hose in the vacant fitting, but both ends of each hose, was a different size, so you couldn't do that. That is why you cut both hoses in 1/2, and end up with a hose that is the same size on both ends.
I removed the stock tranny cooler and plumbed in a typical air to oil cooler, fastened to the front of the AC condenser. The water lines were joined together, where they once ran into the OE cooler.
I tested the same hill. The hottest the tranny now gets is 230F, instead of 280F+. No more 1st gear issues.
I have read so many things negative about the autobox, which is a shame cause its a dream to drive. If this could actually solve the problems its money well spent.
Any more technical boffins confirm i am not barking up the wrong tree?
There seems to be an issue with where to mount these coolers.
I'm not sure if the winter months in Britain would be cause for concern with this kind of coolers? maybe the device which cuts in and out might be more suitable?
Here a pic form the manual of the original under powered oil cooler
Lots of people suggest mounting the cooler in the same place where the intercooler is mounted on brackets above the engine. This seems like a good idea!
This is a more basic approach jusy routing a vent form the bumper over the sump, although he reports a 5 degree drop
I don't know if the autobox is the same in the late model Vr6 but I've seen one tuned up to 270hp, so I guess it's strong enough, just needing to be spoilt with plenty of oil changes. The audi 20v conversion uses a porsche gearbox with an oilcooler. I've always fancied a Vr6 but the gearbox has put me off.... until now(maybe...)
The guy who has did the conversion with the front rad posts he is apparently looking for a better solution. Which can really only be a bigger cooler. Which then poses the problem where to mount it. One solution would be using similar mounts to intercooler.
Although the harder you cool these things the harder they will to warm up so a control device might actually be the best way to go. so it can cut in and out.
There seems to be an issue with where to mount these coolers.
I'm not sure if the winter months in Britain would be cause for concern with this kind of coolers? maybe the device which cuts in and out might be more suitable?
I agree Jim, think that a controlled temperature would be better for the auto fluid but it would need to be adjustable when to turn the fan on. Where did you find this one?.
I have it on good authority that nearly ALL of the American Rialta motorhomes, with the vw Eurovan base have removed the factory cooling system in favour of an after market that sets in font of the radiator.
The so called cooler on top on the gearbox actually uses coolant from the engine which is already warm, so when the engine is hot as well as the gearbox its meltdown.
There are many on the rialta forums who change their oil every 10k... Also talk of synthetic oils which can cope better with the high temperatures.
I know i am posting to myself here, but hopefully it will help some others in the long term.
The problem with the radiator with no fan assistance is that the gearbox tends to overheat when it is on steep climb when it has to shift down, and is usually travelling slowly at this point hence there is no airflow over the cooler so the temperature still climb to high.
In addition to the additional cooling lots of people seem to add an oil temperature gauge/sensor, this would definitely be needed if you were adding a fan controlled unit.
As i see you can either have it inline where you will mount the additional tubing for the coller or make a sensor for the sump, like the following.
Some very useful info here JimT:. You are the autobox guru.
Having just bought an auto caravelle,I'm very interested in fitting this mod. Those Sonnax fittings look to be ideal,couldn't find a price on their website though Keep the info coming as I'm definitley going to fit a cooler.
Cheers, Alan.
That's interesting you mention that German engineering is better, because after they added the lock-up torque convector in 1994 the unit was manufactured in Mexico...
And it was the lock-up convector that has been blamed in the past for the high-temperatures
I would love to hear if anyone has had any problems with the pre 94 automatic gearbox?
I love all your info on Auto-Boxes, it's all very useful. T:
A while back I was having problems with my Auto-box.
After a fluid change the van ran great, but it was only a matter of a few months before it started playing up.
I had suspicions that the ATF was getting too hot and degrading too quickly. So, I rigged up the VAG-COM and went out for a drive to monitor the Auto-Box temp. I was a tad shocked when I discovered that it took no time at all to get the fluid up to 120C (250F) and went as high as 140C (280F)!!! Ok, I reckon the temperature sensor might be a bit dodgy, but the readings were still a cause for concern.
So, I did a bit of trawling on the web and came across a few suggestions:
Fit an oil cooler.
Use a synthetic ATF.
Adjust the torque converter solenoid by winding it in an extra 1/4-1/3 of a turn. (This apparently compensates for wear, reducing the amount of fluid being cut-up in the torque converter, keeping the fluid cooler.)
Out of these 3 I went for the Synthetic ATF.
(Fitting an oil cooler was a bit of an expense and I was a bit nervous about adjusting the torque converter solenoid.)
Anyway, I changed to Amsoil Synthetic ATF.
According to their website it's suitable for the T4 and it handles temperature far better than non-synthetic fluids.
That was about two years ago (15,000 miles) and the van has ran fine. I must admit that the van was not as smooth as with the genuine VW fluid, but it wasn't bad. If anything it seemed a bit more positive.
I still think that the cooler has to be worth a go, so when I get funds released from the missus I'll definitely give it a go. Think I'll leave off the fan and shut off valve though.
I'd also love to do the full Sonnax solenoid mod that you had a thread on while back, just not sure that I'll ever get round to it.
Those temps are crazy! The Sensor for the oil temp through the Vagcom is located in the torque converter itself, so gives a very good readout on not only the oil temperature but the actual compenent temperature.
You could hook up the relay is you were a bit of a boffin on this sensor, but that kind of wizardry would cost time and money.
There is a unit called the "scangaugeII" which is a great gadget for hooking up and getting all sorts of codes etc, including oil sensors, not bad money either Price: 158 €
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