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  1. #41
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    did you fix it ?

  2. #42

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    Sure would like to know myself. Having same issue with 1999 K1500 GMC. Transmission fluid is black as oil.
    Son on way to town now to get new radiator, transmission fluid, transmission filter. Have flushed radiator, engine
    and put a new clutch fan on with no result. Loosened the transmission line yesterday and cranked up and pumped
    out the fluid and it was black and thick as burnt oil. Transmission still shifting good. Believe we caught in time.
    "My opinion": Big tires caused transmission to overheat. High mileage on truck when 24" nitto's were put on it. No
    overheating problem prior to that. Now, transmission overheating, circulating too slowly through radiator spreading
    the overheating problem to the adjoining water circulatory system for the engine in the radiator and will not get any
    better until the entire system is purged of old transmission fluid, new filter and fluid to be installed in next few days.
    Will update when complete. BTW--no head gasket problem!!!


    J cat - Do you follow my line of thinking here. This problem persists with GM truck owners of
    the 700r4 transmission when they neglect to change the filter and transmission fluid every
    70000 miles as recommended. I had an '02 Z71 with same issue at about 140,000 miles.
    Didn't mess with it just got rid of it after putting a new fan clutch on it. Although the circulation
    of the transmission fluid and water do not mix, the overheating of one can cause the overheating
    of the other due to the fact that they both use a common cooling radiator. If the water boils,
    the transmission temp. should go up. If the transmission fluid has 150,000 miles on it and has
    never been changed and is black with over-use, the "retention of heat in the fluid" would be
    much longer and more widespread through-out the cooling system" than the "retention of heat
    in water that has coolant in it". Simpler put, Oil/Fluid brought to a boiling point would take
    much longer to cool back down to 190 degrees than water mixed with antifreeze that reaches
    a boiling point and cools back down to 190 degrees. I believe this is the root cause of all this.
    We all have to ask ourselves, when have I had my transmission serviced? What does the fluid
    look like when you pull the dip stick? If it ain't red and has turned brown on the stick, you might
    need to head to the garage SOON!
    Last edited by glenn3564; 09-03-2013 at 03:11 PM.

  3. #43
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    GM very quietly dropped Dexron III. this fluid is now no longer a GM approved fluid. the fluid they found under normal use turns to acid after 20,000 miles. with the trucks , the high heat destroys the fluid much faster than a car.

    this came down back in 2006 . I was lucky that an air craft engineer told me not to use Dexron III back in 1996. so I have had no problems with mobil synthetic transmission fluid . no gray on the dip stick as the defective fluids like dexron III would create.

    with big tires and a heavy foot you will need more fluid replacing and a transmission cooler of a larger size than the OEM. on the 700R4 I do not like this transmission not very reliable. 4L60 with synthetic transmission fluid and a external cooler is a very long lasting transmission.

    anytime the engine has an overheating issue when its all fixed you should replace the transmission fluid.

    normal tranny temp should be 190 deg f. 220 on very hot days. dexron III turns to acid at the 190 deg f ...

    I suspect that ypur transmission is slipping. with the newer vehicles this is monitored and you would feel a harsh up shift . this is because the pressures are increased by the PCM . any slippage will cause tranny temps to rise. another common cause of failures is to tow / haul in over drive / the big D gear.

  4. #44

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    I agree on the 700r4 tranny. I got a 91 Blazer in the back yard now with a broken 700r4. We are taking the truck to the garage
    tomorrow morning to have new radiator installed and transmission filter and fluid changed. Son picked up the Dexron III with
    Mercon I think it said to go back in it. I will send him back to get the green fluid. Transmission is not slipping any at all yet.
    Still shifting exactly where it should, when it should. The tires were bought and put on the truck when my son bought the
    truck about a month ago. Overheating started up about a week ago but due to problems I had with the '02 GMC with same
    transmission that had to be re-built, we jumped right in on the problem and have driven the truck very little. I would suspect
    that the transmission fluid and filter have never been changed.

  5. #45
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    these transmission problems are because in the owners manual GM states the fluid is not requiring change until 100,000 miles . problem is this instruction is made with use , under idea conditions in operation of the vehicle .

    with normal operation , and under typical temperatures found in the operation of the vehicle this fluid is changed every 30-40,000 miles and this is with synthetic or the now approved dexron VI fluids.

    PLOW operators replace the fluid at the end of the snow plow season along with all the other drive train fluids .

    the 700r4 transmission was changed to the 4L60 some time in the early 1990's I think. 2002 should have a 4L60. the other transmission would be the 4L80.

    - - - Updated - - -

    Quote Originally Posted by glenn3564 View Post

    tomorrow morning to have new radiator installed and transmission filter and fluid changed.

    Son picked up the Dexron III with Mercon I think it said to go back in it. I will send him back to get the green fluid. Transmission is not slipping any at all yet.
    the transmission fluid your son purchased is no longer licensed by GM . It is not an approved fluid. this fluid is damaging to the transmission. you can use it to flush out the transmission then install the synthetic/ dexron VI fluid.

    the green fluid your stating is the coolant I would assume. with a 1991 vehicle it should be the new green colored antifreeze which is a safer environmental fluid. this fluid should NOT be confused with DEXCOOL GM approved fluid these,,, two are not compatible and mixing is damaging.

  6. #46

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    Update. Went to garage yesterday to take the fluid for transmission and filter.
    Spoke with garage owner/mechanic. The green fluid will be used after he again
    flushes the engine and heater core. New radiator will be installed. I was surprised
    that he was already aware of the problems with the GM Dexcool fluid. The one we
    had just put back in it (to no avail) has the GM Trademark, Dexool-M. All that's coming
    out and he is to pick up the green fluid that he knows is the correct fluid for the engine.
    After transmission fluid and filter change, radiator replacement, and correct fluid installed,
    he said he guaranteed that it would cool even at an idle in traffic with a/c on. When he
    gets through with my sons' 99, he is going to take my 09 Silverado in with 69,000 mi. and
    change fluid, filter, flush and replace with green fluid. May be through with '99 today. Will
    give it about a week in service to see if all turns out well and advise you. Bottom line is
    both the antifreeze gelling and old transmission fluid contributed with overheating. Also,
    he has driven the truck and done a pressure test. No transmission damage and no head
    gasket damage. Will let you know after a few days in this 90 degree weather to see if
    all worked as should.
    Thanks
    Glenn

  7. #47
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    with your coolant issues and the use of DEXCOOL GM approved coolant. this product must be used in vehicles that were manufactured with this product. the coolant system requires this along with distilled water to properly cool the engine down.

    with the 1991 vehicle that was with NON DEXCOOL and should be kept that way. any newer vehicle I would not recommend any non dexcool to be used.

    the issues with DEXCOOL is very simple . owners/mechanics/lube jockeys they contaminate the coolant system when they add NON dexcool and tap water. these fluids will cause the growth of organisms to create a gel type mess. then the overheating/loss of heater operation.

    having used DEXCOOL since 1996 and still operating this vehicle along with others newer I have not had any DEXCOOL issues.

    I ALSO MIGHT ADD THAT NO ONE WORKS ON MY VEHICLES BUT ME!

  8. #48

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    J cat, Got 1999 z71 with overheating issues back yesterday morning after another engine and heater core flush, replaced
    with brand new radiator, flushed and replaced transmission fluid with new fluid and changed filter. Mechanic runs shop about
    4 miles from my house. Country boy with city education that came home to his dad and took over the business after
    extensive education on more modern "computerized" vehicles. He drove the truck before and after service. No transmission
    problems of slippage or otherwise. Overheating priority issue "at that time". After thorough flush of transmission, fluid was
    at point of causing problems. Basically, bottom line on his 1999 was this. (Remember,he just bought it a month ago).
    The transmission had never been changed or filter. Fluid thickened reducing ability to circulate properly sending overheated
    transmission fluid to radiator where it could not cool but also added to the in-ability of the radiator to take care of the
    engine water coolant. Next problem, engine coolant gelling due to a mix of red and green fluids. Result, slow circulation of
    engine coolant also. Remedy: FlusHed entire system of engine and transmission coolant. Replace radiator (not taking chance
    on old one due to past history of abuse). Replaced engine coolant with the new green coolant that is now recommended
    for his vehicle. Replaced transmission filter and fluid with correct new fluid. PROBLEM SOLVED. IN BEACH TRAFFIC
    YESTERDAY AND ENGINE TEMP. NEVER GOT OVER 190 WITH A/C RUNNING WIDE OPEN. HOPE THIS WILL HELP SOMEONE
    ELSE AS IT COST ME A VERY GOOD CONDITION 2002 Z71. SENDING MY 09 SILERADO IN FIRST OF NEXT WEEK FOR SAME
    WORK BEFORE RADIATOR GETS CLOGGED.
    Last edited by glenn3564; 09-06-2013 at 09:42 AM. Reason: WORD MISPELLED

  9. #49
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    Quote Originally Posted by glenn3564 View Post
    J cat, Got 1999 z71 with overheating issues back yesterday morning after another engine and heater core flush, replaced
    with brand new radiator, flushed and replaced transmission fluid with new fluid and changed filter. Mechanic runs shop about
    4 miles from my house. Country boy with city education that came home to his dad and took over the business after
    extensive education on more modern "computerized" vehicles. He drove the truck before and after service. No transmission
    problems of slippage or otherwise. Overheating priority issue "at that time". After thorough flush of transmission, fluid was
    at point of causing problems. Basically, bottom line on his 1999 was this. (Remember,he just bought it a month ago).
    The transmission had never been changed or filter. Fluid thickened reducing ability to circulate properly sending overheated
    transmission fluid to radiator where it could not cool but also added to the in-ability of the radiator to take care of the
    engine water coolant. Next problem, engine coolant gelling due to a mix of red and green fluids. Result, slow circulation of
    engine coolant also. Remedy: FlusHed entire system of engine and transmission coolant. Replace radiator (not taking chance
    on old one due to past history of abuse). Replaced engine coolant with the new green coolant that is now recommended
    for his vehicle. Replaced transmission filter and fluid with correct new fluid. PROBLEM SOLVED. IN BEACH TRAFFIC
    YESTERDAY AND ENGINE TEMP. NEVER GOT OVER 190 WITH A/C RUNNING WIDE OPEN. HOPE THIS WILL HELP SOMEONE
    ELSE AS IT COST ME A VERY GOOD CONDITION 2002 Z71. SENDING MY 09 SILERADO IN FIRST OF NEXT WEEK FOR SAME
    WORK BEFORE RADIATOR GETS CLOGGED.
    these 1999 and newer use dexcool. this is the GM recommended coolant. using other coolants is not recommended by GM.

    the mechanic who stated that non dexcool antifreeze is the recommended coolant is very wrong in the 1999 vehicle.

    I hope no one does what you had the mechanic do with the coolant choice.

  10. #50

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    I poured out an almost full gallon of GM Dexcool-M yesterday. I'm fixin to have it dumped out of my 09. If Dexcool-M is so good then why did his truck still run hot within 4 miles of home after a complete purge of the system and re-fill of Dexcool M by GM when he left here with a cold engine. Why now does it cool properly and has been doing so now for 3 days with no issues? My 02 did the same thing and I would have still owned it today if I knew then what I know now. After all, it had only 66,000 miles on it. I could give a rat's a-- what GM recommends. I use what works. Where you are at 85% it probably is 85%. Here 85 carries a humidity level of 90+% percent with a heat index of 103%. Maby that's the difference, I don't know. All I know is what I see with my own eyes. That radiator was full of Jelly when he got back as we purged it again to see what came out. When we drove it to the shop, we did so with nothing but water in the engine and radiator and it ran cool. As a matter of fact, my brother in-law is having the same problem with his 04 and he has owned it since it was brand new. Nothing ever used in it but Dexcool and he went to the trouble about 6 months ago to put twin electric fans on his. Didn't help at all. Now drives with heater on in this hot weather. He now sees the results of the 1999 with 236.000 miles ( I thought it had only 150,000) and just as soon as he gets a long weekend off, his is going to the same shop. I am a member of a campground/horse ride park and have many friends who are diehard fans of GM products that pull horse trailers with sleeping quarters in the front. There are 13 of them. Only 1 has a F250 diesel that is having no issues with cooling. All of the others are having a running hot problem and they are pulling only 40 miles one way with windows down. Can't run a/c. 3 of the 12 GM owners have traded 2012's for the new 2014's and are already having same problem. The only one's that are not having problems with their GMC or Chevy truck whether it be a 1500 or 2500 series are those that went to Palmetto Chevrolet where they bought their trucks in Conway and the service manager on his own decision purged all of them of GM Dexcool and put in a green old type fluid. That's where I got the idea of changing the 1999. Before I did so, I did some digging for about 2 weeks on the subject of Dexcool and regular antifreeze If you run a separate "stand alone" transmission cooler, Dexcool will work. But in cases where the standard radiator containing both the engine coolant and transmission cooler the owners were having overheating problems. As far as others following my decisions to FIX a problem, that's their choice. It worked for me and several of my friends that pull 8 horse capacity trailers with living quarters and that's the bottom line.
    Last edited by glenn3564; 09-07-2013 at 07:43 AM. Reason: spelling

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