transmission fluid leak


57cruiser
05-27-2010, 12:52 PM
1999 Suburban, 1500, 2 wheel dr. recently developed a fluid leak when parked on incline. Does not leak when on level ground. replaced rear tranny seal, still leaks. no groove on yoke. no evidence of wetness on tunnel or excess fluid around the rear of tranny. pretty much dry and clean. drove the car on 200 mile trip yesterday. parked in driveway on incline. checked to see if there was any leakage, none found. checked under the car every 30 minutes, nothing. last time I checked, 5 hrs later, saw a drop or two of red fluid on U-joint, pressed on rear seal to see if it was full of fluid, nothing. No obvious fluid leakage. Is there fluid build up inside the yoke so that if there was a hairline crack I would get seepage. any thoughts?

j cAT
05-27-2010, 02:19 PM
1999 Suburban, 1500, 2 wheel dr. recently developed a fluid leak when parked on incline. Does not leak when on level ground. replaced rear tranny seal, still leaks. no groove on yoke. no evidence of wetness on tunnel or excess fluid around the rear of tranny. pretty much dry and clean. drove the car on 200 mile trip yesterday. parked in driveway on incline. checked to see if there was any leakage, none found. checked under the car every 30 minutes, nothing. last time I checked, 5 hrs later, saw a drop or two of red fluid on U-joint, pressed on rear seal to see if it was full of fluid, nothing. No obvious fluid leakage. Is there fluid build up inside the yoke so that if there was a hairline crack I would get seepage. any thoughts?

the use of some manufacturer seals may not work ..try another seal manufacurer..

when installing clean the metal seal/tranny where it sets in the bore , then coat this metal with a small amount of sealer , install seal .

inspect yoke suface for ridges and wear..

if the bushings are worn this too can cause some leakage as well as clunking fwd/rev....

what tranny fluid do you use ...old dexron III causes seal damage.. seal conditioners with fluid replacement helps restore seals that have hardened or shrunk..

57cruiser
05-27-2010, 02:24 PM
this leak just started all at once. no initial drip or whatever, one day the driveway was clean and next , red fluid on the driveway. U-joints were replaced within the last six months. The yoke is good, no groove, also clean. only leaks when on incline for several hours. no fluid build up in the rubber seal, is the fluid inside the yoke that could leak out from a hairline crack?

j cAT
05-27-2010, 04:10 PM
this leak just started all at once. no initial drip or whatever, one day the driveway was clean and next , red fluid on the driveway. U-joints were replaced within the last six months. The yoke is good, no groove, also clean. only leaks when on incline for several hours. no fluid build up in the rubber seal, is the fluid inside the yoke that could leak out from a hairline crack?

normally this is how it goes...one day some oil on drive way ...

most do not do under vehicle inspections daily...

the U joints where replaced ! this would mean this seal was disturbed so after a period of time the leak began..this is normal...

do as I suggested ..try another manufacturers seal...

and all the other stuff..

how big is the driveway spot? 1inch or 6inches or more..

the yoke will have fluid around it ..the bushing is lubed by the fluid..

so what fluid do you use ? dexron III ? how often do you service the fluid/filter ?

you think the yoke is hollow ? tranny fluid on the U joint is the seal.

57cruiser
05-27-2010, 04:21 PM
U-joints were replaced 10-21-09 so it has been awhile, should not have an effect on seal I'm guessing. I use Dextron III, transmission fluid was emptied and replaced on 5-20-09. yoke was dry last evening until about 5 hrs after I parked it. I park in the same space at work every day. there is not even a spot the size of a dime there. in my driveway this morning there was an area approx 4 inches wide x 24 inches long. some of the length is due to the incline of my driveway which is in the area of 30 degrees. I am assuming there is fluid inside the yoke where it runs down the splines of the output shaft. I am wondering if I have a crack in the yoke where the fluid can seep out after a period. it apparently does not come out when driving as the drive shaft tunnel is not wet or coated with fluid. tail shaft of tranny is dry as is the front part of the drive shaft.

j cAT
05-27-2010, 09:01 PM
U-joints were replaced 10-21-09 so it has been awhile, should not have an effect on seal I'm guessing. I use Dextron III, transmission fluid was emptied and replaced on 5-20-09. yoke was dry last evening until about 5 hrs after I parked it. I park in the same space at work every day. there is not even a spot the size of a dime there. in my driveway this morning there was an area approx 4 inches wide x 24 inches long. some of the length is due to the incline of my driveway which is in the area of 30 degrees. I am assuming there is fluid inside the yoke where it runs down the splines of the output shaft. I am wondering if I have a crack in the yoke where the fluid can seep out after a period. it apparently does not come out when driving as the drive shaft tunnel is not wet or coated with fluid. tail shaft of tranny is dry as is the front part of the drive shaft.

the use of dexron III was stoped by GM in 2006..this was because of too many tranny failures with this transmission...It apears that the fluid breaks down very soon and then the acid takes over and causes the failures..the replacement fluid is dexronVI..THIS IS A NEW BLENDED FLUID...

when you buy this dexron III today it does not have a spec or GM application Number on it...probably made in china..

I would say that your leak is too big and should be repaired..

It is possible that there is a crack ,,take it out and inspect it..there are crack revealing sprays that will show cracks in metal..

if it is damaged some how NOW ,,then go to scrap yard for replacement..

57cruiser
05-28-2010, 09:57 AM
my son-in-law has a auto repair shop. However, he specializes in Lexus/Toyota and GM is foreign to him when it comes to specifics. However, he is the one who flushed the transmission and replaced the filter. He said he uses Valvoline tranny fluid, he thought it was gen. V, not sure. Last night w added dye to the transmission fluid, going to drive a day or so and then pull the drive shaft and black light the yoke. He suspects a cracked weld or defect in yoke area. Could have happened when the U-joint was replaced last year. that's where we are headed. I sure appreciate your interest and suggestions. I'll post results toward the end of the weekend.

j cAT
05-28-2010, 01:48 PM
my son-in-law has a auto repair shop. However, he specializes in Lexus/Toyota and GM is foreign to him when it comes to specifics. However, he is the one who flushed the transmission and replaced the filter. He said he uses Valvoline tranny fluid, he thought it was gen. V, not sure. Last night w added dye to the transmission fluid, going to drive a day or so and then pull the drive shaft and black light the yoke. He suspects a cracked weld or defect in yoke area. Could have happened when the U-joint was replaced last year. that's where we are headed. I sure appreciate your interest and suggestions. I'll post results toward the end of the weekend.

when some replace these U joints they do beat up the area quite a bit...I have done many and if you take the time the use of some heat and penetrating oil does make U joint replacement much less difficult..

I also tape up the shaft and always install with the marks made prior to disassembly so as to not throw off the balancing of the drive shafts...


I have been using mobil1 synthetic since 1998..thats when I found out that the dexron III was not good for these transmissions by my friend who was a GM service tech ...the new fluid does work much better than dexron III...

transman618
05-28-2010, 02:53 PM
What you need to do now is pull that tail housing, remove the seal. Behind that seal is a bushing which the yoke slides into. Replace the bushing then install another new seal. Re-install the tail housing and ride. Remember this: Bushing and seal=cheap, cooked transmission due to loss of fluid= too much to talk about.


transman

57cruiser
06-01-2010, 10:11 AM
I found the problem. Put dye in the tranny fluid, drove for a day. got under the car with a UV light. at the bottom of the yoke, between the U joint saddle, there is a hole machined or drilled, can't tell in the center of the yoke. Fluid is leaking out the hole, down the U joint saddle to the joint and dripping off. Had an old time mechanic tell me there is a seal in the yoke to keep the fluid from doing that, Chevy dealer says there is no seal. The solution was to remove the drive shaft, cock the yoke at an angle, clean the area around the hole very good and filled it with an RTV type material. So far so good.

j cAT
06-01-2010, 10:20 AM
I found the problem. Put dye in the tranny fluid, drove for a day. got under the car with a UV light. at the bottom of the yoke, between the U joint saddle, there is a hole machined or drilled, can't tell in the center of the yoke. Fluid is leaking out the hole, down the U joint saddle to the joint and dripping off. Had an old time mechanic tell me there is a seal in the yoke to keep the fluid from doing that, Chevy dealer says there is no seal. The solution was to remove the drive shaft, cock the yoke at an angle, clean the area around the hole very good and filled it with an RTV type material. So far so good.


If you used RTV sealant this will over time break down and possibly leak..best use an epoxy material..this epoxy is also used to repair transmission case leaks...

I thought I heard about this problem once before..hole in the center of the yoke..

57cruiser
06-01-2010, 10:25 AM
Actually RTV was wrong choice of word. My son-in-law used a high dollar product that he uses at his Lexus shop. It looked like black RTV to me so that is what I said. sounds like the leak out that hole is a fluke but not many folks, including Chevy dealer, has dealt with it. I appreciate your help along the way. thank you

Add your comment to this topic!