Senor PuffPuff Posted May 29, 2013 Report Share Posted May 29, 2013 I recently did my trans fluid and filter change, cleaned the magnets off which has LOTS of "clutch mud" but didn't seem to have any metal shavings in it, put in a new filter and some Mobil 1 Dexron 6, and put it all back together (no flush, just drain). Now, this problem I've been having off and on has seem to really come out. When I stop at a light, sometimes I can feel the transmission switch back into first but it happens after sitting at the light for about 5 seconds completely stopped. Sometimes if I slow to a stop, and then immediately get back on the gas it will hesitate for a second and then SLAM into first gear really hard which makes the entire car jolt forward. It was doing this before, but not nearly as badly. I have no idea what it could be, I've been looking at lots of different forums for answers and it seems like everyone has a suggestion but nobody really knows how to fix it. SO if anyone has had this problem, PLEASE let me know what to do to fix it, because I don't want to have to take it to the trans shop because I know they'll just say "Oh well you need a new transmission". I've also had a problem which seems unrelated but when I'm accelerating to the speed limit, around 35-45mph my car switches into 3rd (or maybe 4th gear), drops to about 1300rpm, and then surges until I reach about 45mph. If it starts surging and I press the gas a bit harder, it changes down a gear and the surging stops. This is another thing I've been looking for a solution to, but nobody seems to have found out how to fix it, and everyone has a different idea of what causes it (everything from a bad MAF sensor to a dirty cat). Thanks in advance for any help! Quote Link to comment Share on other sites More sharing options...
Hairdo12 Posted May 30, 2013 Report Share Posted May 30, 2013 Ah the old rev catch.... Had that happen to me twice and have seen it happen to others. You have ether a sticky valve or a seal isn't sealing correctly in the valve body. When you rev, it builds up enough pressure to make the valve move. The good news is, every time, a bottle of KW Trans-X fixes it every time. I have saved probably 7-8 transmissions from the default "you need a rebuild" answer. It can be had at Walmart or autozone. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted May 30, 2013 Report Share Posted May 30, 2013 assuming you're stopped or at a low enough speed to be in 1st gear, moving the shifter to 1st will bump up line pressure quite a bit on a 4T60.... the 4T65 might have a similar function? Quote Link to comment Share on other sites More sharing options...
Hairdo12 Posted May 30, 2013 Report Share Posted May 30, 2013 In 1, 2 or just plain drive the transmission always work as it should. Symptoms only occurred while selector was in OD. I've seen this mostly on 4t60... No e.. But once on a 4t65e. Not my current car though. Quote Link to comment Share on other sites More sharing options...
LA1 Posted May 30, 2013 Report Share Posted May 30, 2013 It does not sound like the usual symptoms, more than likely it is the PCS, Pressure Control Solenoid, or Force Motor. Do you have A 4T65E trans ? google the model of your trans and PCS. The good news is you can replace the PCS yourself. It is a lot of work but it can be done. go to you tube and search for PCS replacement , and 4T65E ...etc There are or were 3 or 4 videos where people dropped the driver side of their sub frame and replaced all their solenoids on 4t65e, do not know about other models. .... if you do do it get an engine support and the CV Axle will probably be the hardest to remove b/c of the sub frame can not get a good place to insert a pry bar. Quote Link to comment Share on other sites More sharing options...
Senor PuffPuff Posted May 30, 2013 Author Report Share Posted May 30, 2013 What I found out from a GM master mechanic is that it's actually the forward clutch sprag (whatever the **** that is) and he basically said those go on these 4t65's around my mileage (250,000km) so he suggested I rebuild the whole transmission before it goes completely. Normally I wouldn't trust a mechanic but this guy said he's seen it before... The thing is that I only get the slamming in either 3 or D, not 1 and 2 so he seemed pretty certain when I said that that it was the forward clutch sprag. Also, he said when the forward clutch sprag goes it usually doesn't show ANY codes, no matter WHO checks the computer - which I'm having. Probably just going to use this as an excuse to pick up a used 4t65e-HD and I'll just rebuild that on the bench for now.... Saves me having to put the car OOS and find a new ride for a few weeks, anyways. Thanks for your help guys - and if you know anyone with this issue PLEASE let them know what it might be... Otherwise they'll be paying for stuff they don't need! Quote Link to comment Share on other sites More sharing options...
Senor PuffPuff Posted May 30, 2013 Author Report Share Posted May 30, 2013 I was looking at the instructions from GM's website (the part for licensed techs) and it was actually saying that you don't NEED to take off the axle to do the PCS... Which seemed kind of odd to me considering even in their own diagrams they show it removed... Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted May 31, 2013 Report Share Posted May 31, 2013 not convinced this is even the transmission. Quote Link to comment Share on other sites More sharing options...
runt Posted May 31, 2013 Report Share Posted May 31, 2013 If you have the selector in 3 rather than OD does that change anything? The 35-45 things sounds like the torque convertor is locked up. I believe it should lock in 3rd gear above 35mph and in 4th (OD) at 45mph. If the master tech said it needs a new tranny I'd at least try some of the "fix it" fluids that they sell. Quote Link to comment Share on other sites More sharing options...
Senor PuffPuff Posted June 23, 2013 Author Report Share Posted June 23, 2013 I remember trying to see if it would happen in certain gears on the selector, and it would only do it in either 1&2 or 3&D but I forget which it was... And supposedly that is the symptom of the forward sprag clutch. I'm not getting any sort of engine light, but I still haven't brought it in to have trans codes checked. Maybe I should. Quote Link to comment Share on other sites More sharing options...
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