bw35 smoke out of filler tube??

stroprock · Post by **stroprock** » Tue Sep 18, 2012 8:35 pm

What would cause smoke to come out of a bw35 dipstick? It seems to do it most in reverse and drive. It also slips in reverse unless you play with the revs, but it does shift through all the three speeds fine. Could it be simply incorrect fluid level or kickdown adjustment, or is it likely to be something serious??

harvey · Post by **harvey** » Tue Sep 18, 2012 9:10 pm

Check the fluid level and set it correctly, and do the same with the kickdown cable, then see if you've still got the problem. Do things one at a time starting with the simple things first. I can't say I've ever seen smoke coming from the dipstick, but if that's the case then something's getting far too hot. If you've filled with DEXRON fluid that overheats the box and introduces slip, but not to those sorts of levels. Are you sure it's smoke and not steam? Has anything been done to the box recently?

DaveEFI · Post by **DaveEFI** » Tue Sep 18, 2012 9:48 pm

Once the box starts slipping, it's toast. Even more so if it's smoking. Time for an overhaul. Was the control cable wrongly adjusted? If too 'slack', this causes low line pressure and clutch slip. Obvious symptoms are changing up at lower than correct speeds and no kick-down.

stroprock · Post by **stroprock** » Thu Sep 20, 2012 8:50 pm

But would a kickdown cable being too slack cause it to smoke whilst stood still at idle??

DaveEFI · Post by **DaveEFI** » Thu Sep 20, 2012 10:02 pm

stroprock wrote:But would a kickdown cable being too slack cause it to smoke whilst stood still at idle??

No - it causes the clutches to slip and burn out. That produces the smoke.

stroprock · Post by **stroprock** » Fri Sep 21, 2012 5:34 pm

DaveEFI wrote:
stroprock wrote:But would a kickdown cable being too slack cause it to smoke whilst stood still at idle??
No - it causes the clutches to slip and burn out. That produces the smoke.

But at idle, not moving??

harvey · Post by **harvey** » Fri Sep 21, 2012 5:47 pm

stroprock wrote: But at idle, not moving??

If the fluid level is correct, and so is the kickdown cable adjustment, and it still slips in reverse you could check the rear band adjustment, but if it still slips after that the only way you're going to know what's going on is to have a look inside, initially by dropping the sump, but most probably by removing the box. Once you do that you should also find the reason why there's smoke coming out of the dipstick tube.

harvey · Post by **harvey** » Fri Sep 21, 2012 7:00 pm

stroprock wrote:
Thanks harvey. Would this smoke be a sign of low or high fluid level?

I don't think the smoke would be caused by either. I've had those boxes with the fluid levels all over the place and I've never had smoke coming out of the dipstick tube.

You never did reply when I asked what had been done to it recently.

DaveEFI · Post by **DaveEFI** » Fri Sep 21, 2012 7:07 pm

Smoke is caused by something overheating. So not good news. I've never actually come across this in an auto, but in general very few faults in them can be cured with the box in place. And this certainly doesn't like one which could.

stroprock · Post by **stroprock** » Fri Sep 21, 2012 7:43 pm

harvey wrote:
If the fluid level is correct, and so is the kickdown cable adjustment, and it still slips in reverse you could check the rear band adjustment, but if it still slips after that the only way you're going to know what's going on is to have a look inside, initially by dropping the sump, but most probably by removing the box. Once you do that you should also find the reason why there's smoke coming out of the dipstick tube.

Thanks harvey. Would this smoke be a sign of low or high fluid level?

stroprock · Post by **stroprock** » Fri Sep 21, 2012 9:28 pm

harvey wrote:
stroprock wrote:
Thanks harvey. Would this smoke be a sign of low or high fluid level?
I don't think the smoke would be caused by either. I've had those boxes with the fluid levels all over the place and I've never had smoke coming out of the dipstick tube.

You never did reply when I asked what had been done to it recently.

Sorry, the box has recently had the front pump o ring, front oil seal and front pump gasket changed, but that's it (since I've owned it anyway)

harvey · Post by **harvey** » Fri Sep 21, 2012 9:33 pm

If that's the case, and it wasn't doing it before that was done, I'd say that the box has gone back together without any end float on the input shaft, and so as that turns, because of that lack of clearance, it's generating heat where the input shaft is rubbing against the thrust washer.

stroprock · Post by **stroprock** » Sat Sep 22, 2012 10:15 am

harvey wrote:If that's the case, and it wasn't doing it before that was done, I'd say that the box has gone back together without any end float on the input shaft, and so as that turns, because of that lack of clearance, it's generating heat where the input shaft is rubbing against the thrust washer.

VERY interesting. I only checked the end float with my hand when I put it together, and it felt the same. How should you adjust end float in the input shaft?
Which thrust washer, is it in any of these diagrams:
http://www.automaticchoice.com/Catalogue/bw35.pdf

harvey · Post by **harvey** » Sat Sep 22, 2012 8:07 pm

If you had some end float then that won't be a problem, so won't be causing the smoke, but if you had none then it could well be.