hard shift from 1st to 2nd
Question:
My 99 k1500 sub has started shifting funny. When the engine and tranny are cold, it shifts HARD into 2nd for the first mile or 2. Then everything is fine. Any similar experiences out there? I am afraid to change the fluid because I am afraid that may rush an oncoming rebuild. I have 75,000 on it and had been thinking about doing the fluid change soon but now I feel like I should just wait and see what it is going to do.
Response:
We had the exact same problem with my wife’s ‘95 Blazer with the 4L60E tranny. Turns out it’s a sticky valve in the valve body, which we didn’t learn until we had the valve body rebuilt 3 times (fortunately we had the extended warranty). The problem remained but recently I replaced the fluid, filter and added some top quality additive that helps with sticky valves and it has decreased the 1-2 shift hardness greatly. I don’t understand where you get the idea that by changing your tranny fluid you would hasten any problems. Seems to me that dirty fluid would cause more problems than clean. Try a complete fluid change with a new filter (NOT a fluid flush), and some top quality additive that helps with sticky valves (I used the Greased Lightning brand, but there are others). Literally, it couldn’t hurt. Good luck – Jonathan — Acta Non Verba – Deeds Not Words Lieutenant Jonathan Race, EMS Supervisor Orange County (FL) Fire-Rescue Department
– Hide quoted text — Show quoted text -> My 99 k1500 sub has started shifting funny. When the engine and > tranny are cold, it shifts HARD into 2nd for the first mile or 2. > Then everything is fine. Any similar experiences out there? I am > afraid to change the fluid because I am afraid that may rush an > oncoming rebuild. I have 75,000 on it and had been thinking about > doing the fluid change soon but now I feel like I should just wait and > see what it is going to do.
Response:
Not wanting to rain on your parade; We had a ‘97 GMC Safari that had the same problem, but the hard 1st/2nd shift became a constant. Seems there was an internal leak in the tranny valve body? (I think that’s what he said; this is a coupla years ago) LUCKILY; even though it was a few K out of warranty, they goodwilled the repairs. I think if you do some searching in the archives you’ll find some tech info on Tranny problems with GM vehicles of that era. Chris – Hide quoted text — Show quoted text – > My 99 k1500 sub has started shifting funny. When the engine and > tranny are cold, it shifts HARD into 2nd for the first mile or 2. > Then everything is fine. Any similar experiences out there? I am > afraid to change the fluid because I am afraid that may rush an > oncoming rebuild. I have 75,000 on it and had been thinking about > doing the fluid change soon but now I feel like I should just wait and > see what it is going to do.
Response:
Several tranny shops told me that if the tranny was acting up, a fluid change could hasten the problem. In fact, one told me he would strongly discourage it. He told me of several times he has had someone insist on a fluid change to solve a problem and then they have the vehicle towed back in a few hours later. I may just go ahead and change it and look for the additive. – Hide quoted text — Show quoted text – >We had the exact same problem with my wife’s ‘95 Blazer with the 4L60E >tranny. Turns out it’s a sticky valve in the valve body, which we didn’t >learn until we had the valve body rebuilt 3 times (fortunately we had the >extended warranty). The problem remained but recently I replaced the fluid, >filter and added some top quality additive that helps with sticky valves and >it has decreased the 1-2 shift hardness greatly. >I don’t understand where you get the idea that by changing your tranny fluid >you would hasten any problems. Seems to me that dirty fluid would cause >more problems than clean. Try a complete fluid change with a new filter >(NOT a fluid flush), and some top quality additive that helps with sticky >valves (I used the Greased Lightning brand, but there are others). >Literally, it couldn’t hurt. >Good luck – Jonathan >– >Acta Non Verba – Deeds Not Words >Lieutenant Jonathan Race, EMS Supervisor >Orange County (FL) Fire-Rescue Department > My 99 k1500 sub has started shifting funny. When the engine and > tranny are cold, it shifts HARD into 2nd for the first mile or 2. > Then everything is fine. Any similar experiences out there? I am > afraid to change the fluid because I am afraid that may rush an > oncoming rebuild. I have 75,000 on it and had been thinking about > doing the fluid change soon but now I feel like I should just wait and > see what it is going to do.
Response:
You know, if I was in the business of rebuilding and repairing transmissions and had a slight streak of opportunism in me (not saying they all do, but there are some out there), that just might be the thing I would tell a customer who didn’t know better. Heck, your tranny is only 3 yrs old, the fluid can’t be that dirty where clean fluid would wash away whatever grit was sealing some leaks. Just from my personal experience, however, I do recommend a full fluid change with new filter every year or 18 months, depending on usage. If new fluid wrecked a tranny after only a few hours I would think you would have a case against the tranny shop and the fluid manufacturer. I can also guarantee you that there is no fluid out there on the market that states unequivocally on the label "DO NOT change your tranny fluid if you are having transmission problems". If something happened to that poor schmoe so quickly, then I would hazard a guess that the shop either severely underfilled it or used the wrong type fluid, maybe even deliberately. Always remember to check your levels yourself after someone else services your vehicle. Cheers – Jonathan — Acta Non Verba – Deeds Not Words Lieutenant Jonathan Race, EMS Supervisor Orange County (FL) Fire-Rescue Department
– Hide quoted text — Show quoted text -> Several tranny shops told me that if the tranny was acting up, a fluid > change could hasten the problem. In fact, one told me he would > strongly discourage it. He told me of several times he has had > someone insist on a fluid change to solve a problem and then they have > the vehicle towed back in a few hours later. I may just go ahead and > change it and look for the additive.
Response:
This is an infamous problem with 4L60E transmissions. I’ve had it happen to two of mine -both ‘97 vintage. Question: Are you getting a service engine soon light? Or has it thrown any codes. If you’re having the same problem I did then you’ll get a P1870 code. The code means "internal slippage" or something to that effect. The hard shift is caused by the PCM commanding maximuim line pressure for the shifts in order to accomplish the without burning up the clutch packs. The hard shift is actually a good thing. The cause, however, needs to be corrected. Usually, it can be traced back to the TCC Valve in the valve body. GM changed out their indestructable cast iron valve body in ‘93 for an aluminum one. The TCC valve can wear the bore in this softer material, allowing fluid to get past, which lessens pressure in the circuit that applys the torque converter lock-up. The slippage can also be caused by another TCC valve in the circuit. That one is called the TCC apply valve and it’s housed in the body of the pump. Sometimes it does not seal completely in it’s bore. In the vast majority of the cases, it’s the TCC valve in the valve body causing the problem. The fix is to 1.) replace the valve body at great cost (if out of warranty) or, 2.) Ream and resleeve the TCC bore & replace with a new valve from Sonnax. Sonnax also makes a TCC apply valve with a teflon seal that can be inserted in the bore which is located in the side of the pump. The TCC apply valve is accessable with one of the solonoids removed from in front of the valve body. The Sonnax TCC Valve runs about $60, and the reamer goes for about $75. I think the TCC apply valve costs around $25. The job can be done without dropping the tranny in about 2 hours by a backyard mechanic -less if you have a pro do the job. There’s a lot of good technical reference material at Sonnax’s web site. Go to www.sonnax.com for more info.
– Hide quoted text — Show quoted text -> My 99 k1500 sub has started shifting funny. When the engine and > tranny are cold, it shifts HARD into 2nd for the first mile or 2. > Then everything is fine. Any similar experiences out there? I am > afraid to change the fluid because I am afraid that may rush an > oncoming rebuild. I have 75,000 on it and had been thinking about > doing the fluid change soon but now I feel like I should just wait and > see what it is going to do.
Response:
Don’t take it back the THAT shop. If the tranny has a problem, it needs to be fixed. Changing fluid does not hasten problems. Changing fluids improperly may create a problem that was not there in the first place. I would ask him to explain why and how and see if his butt hole puckers up. HH
– Hide quoted text — Show quoted text -> Several tranny shops told me that if the tranny was acting up, a fluid > change could hasten the problem. In fact, one told me he would > strongly discourage it. He told me of several times he has had > someone insist on a fluid change to solve a problem and then they have > the vehicle towed back in a few hours later. I may just go ahead and > change it and look for the additive. >We had the exact same problem with my wife’s ‘95 Blazer with the 4L60E >tranny. Turns out it’s a sticky valve in the valve body, which we didn’t >learn until we had the valve body rebuilt 3 times (fortunately we had the >extended warranty). The problem remained but recently I replaced the fluid, >filter and added some top quality additive that helps with sticky valves and >it has decreased the 1-2 shift hardness greatly. >I don’t understand where you get the idea that by changing your tranny fluid >you would hasten any problems. Seems to me that dirty fluid would cause >more problems than clean. Try a complete fluid change with a new filter >(NOT a fluid flush), and some top quality additive that helps with sticky >valves (I used the Greased Lightning brand, but there are others). >Literally, it couldn’t hurt. >Good luck – Jonathan >– >Acta Non Verba – Deeds Not Words >Lieutenant Jonathan Race, EMS Supervisor >Orange County (FL) Fire-Rescue Department >> My 99 k1500 sub has started shifting funny. When the engine and >> tranny are cold, it shifts HARD into 2nd for the first mile or 2. >> Then everything is fine. Any similar experiences out there? I am >> afraid to change the fluid because I am afraid that may rush an >> oncoming rebuild. I have 75,000 on it and had been thinking about >> doing the fluid change soon but now I feel like I should just wait and >> see what it is going to do.
