XJS ( X27 ) 1975 - 1996 3.6 4.0 5.3 6.0

White Exhaust from Dex III?

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Old 11-09-2017, 08:18 PM
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Default White Exhaust from Dex III?

Newbie here. I seem to have a power steering fluid leak, so recently added Dex III. Immediately thereafter, the car started emitting quite a bit of white smoke, primarily out of both pipes but sometimes one more than other. Did I screw up by adding Dex III instead of I or II? Will it cause any harm?
Thanks for any input here.
 
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Old 11-09-2017, 08:25 PM
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That should be fine. Dexron III is backwards compatible with I and II. Are you sure you filled the power steering reservoir? Or is the car just cold and you're starting it in cold weather? Is it really smoke, or just water vapour as cars do emit in cold weather?
 
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Old 11-09-2017, 08:25 PM
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You probably have a fluid leak and it's blowing back onto the hot exhaust pipes. As it burns off you get the white smoke. The p/s hoses are close to the exhaust.

Dex III if fine for the p/s system, no worries

Cheers
DD
 
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Old 11-09-2017, 08:38 PM
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Thanks for your replies. I do seem to have some fluid leaks and I think the P/S is a culprit, so it's possible that's happening.
Yes, I'm sure I'm filling the correct reservoir - had some folks verify for me before I did it.
The "smoke" does seem to be smoke (thought no noticeable odor) and does seem to dissipate after a few minutes of idle, but not totally. I'm starting it in 40s and 50s, not sure if that's cold enough for vapor?
Thanks for the Dex III confirmation.
 
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Old 11-09-2017, 08:44 PM
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Yes, that's cold enough.

If the fluid is hitting the exhaust, as I speculated, it would have a burning oil smell; you could hardly miss it.

Water vapor seems a good explanation

Cheers
DD
 
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Old 11-09-2017, 08:45 PM
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Perfect - thanks, @Doug. Appreciate your help.
 
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Old 11-09-2017, 09:09 PM
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For some reason the V12 seems more prone to showing water vapour as visible exhaust in cooler weather than other cars. No idea why. Especially noticeable in winter.
 
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Old 11-09-2017, 09:34 PM
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Thanks @Jagboi64. Interesting and good to know.
 
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Old 11-09-2017, 10:46 PM
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Are you sure it's not ATF being injested via a defective gearbox modulator?
 
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Old 11-10-2017, 12:48 AM
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For ATF to come out of the tailpipes (!) it would need to get into the exhaust system. The PAS has some hoses that go around the B bank exhaust downpipe but that is it. No way it can get into the exhaust. It would also need to be burned. So basically be in the engine. There is no direct connection between the car's ATF and the combustion chamber. The only way that would happen would be a combination of many nasty things... Tranny cooler leaking into radiator. Head gasket dead. Leaking water-ATF mix into the combustion chamber... Or as baxtor has said being suchen into the engine but then it would only be on one side (A bank).

So it is obvious, unless you really do have 2 failed headgaskets and a failed radiator with tranny cooler, only water vapour coming out of the tailpipes.

ATF would only burn under the bonnet/hoody but not out the rear
 
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Old 11-10-2017, 08:27 AM
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Originally Posted by Daim

ATF would only burn under the bonnet/hoody but not out the rear

Apparently you never been driving behind a car with a significant ATF leak !

If the ATF (or any other fluid) is burning on hot exhaust pipes while the car is stationary the smoke will naturally rise upward. If the car is in motion, though, the smoke is swept along under the car and exits behind the car. The driver, looking in the rear view mirror, would simply see smoke and likely not be able to determine if it actually coming from the tail pipes.

Of course it takes a fair bit of fluid to produce enough smoke to be noticeable while driving....but a badly leaking power steering hose or transmission cooler hose would certainly do the trick !

Cheers
DD
 
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Old 11-10-2017, 08:27 AM
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I always found it pleasant to see the white condensate bubbling out the two pipes of my lump on cold morning. And, at times, a smoke ring!!!!


Now, it is a pain. Flunked SMOG! Smokey exhaust on the "snap throttle" test!!. Fixed partly. Dirty air cleaner. Interrupted by really bad cold. I'm on "limited duty".


Hold a clean sheet of pipe paper into the "smoke". Examine by smell, color and touch. I thinki t is merely vapor.


Carl
 
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Old 11-10-2017, 08:19 PM
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The interesting thing is this never happened UNTIL immediately adding that Dex III. That's why I worried I used the wrong Dex. I'm certain I added it to the correct place, someone here verified a pic beforehand. So why would this suddenly happen, seemingly related to adding the fluid? (It was bone dry before I added.)
 
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Old 11-10-2017, 08:20 PM
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Unless that day mother nature just happened to hit the right temperature outside and it is indeed vapor.
 
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Old 11-10-2017, 08:36 PM
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Originally Posted by Grandpa'sXJS
The interesting thing is this never happened UNTIL immediately adding that Dex III. That's why I worried I used the wrong Dex. I'm certain I added it to the correct place, someone here verified a pic beforehand. So why would this suddenly happen, seemingly related to adding the fluid? (It was bone dry before I added.)
Weird things happen. We could speculate forever

Whatever the root cause is/was, it isn't because you used Dex III versus some other variant. I've had several Jags and have used Dex III, Dex VI, Dexron/Mercon, and Type F in my power steering with no difficulties and no smoking.

Since you haven't noticed a burning odor the most likely explanation is harmless exhaust vapor....often seen in cold weather but can also occur at other times if condensation has developed in the exhaust system.

Monitor the situation (and fluid level!) for new developments

Cheers
DD
 

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