We have a 2000 blazer push button 4x4 with a 4l60e transmission in it that was installed by us earlier this year. We've had some problems that had escalated recently blew the lim gasket due to that lovely dex cool eaten up the gasket when we removed the manifold we could see that the gasket had failed in the same places that almost all other videos and pics i had researched online had failed at and the back two coolant passages were blocked 99% on drivers side 85% passenger side wonder it lasted this long . before we replaced the gaskets we had been having some shifting issues right around 45 55 rpms would get squirrely and it would jump until finally it would shift fine But then my fiance drove it one day in an area with lots of steep inclines and when he was on his way back home he said he went to turn onto the service road and it wouldn't shift into high gear so we thought maybe the TPS we purchased it and where about to change it when but he opened the oil cap to check the fluids first and to our suprise it was full of coolant we had no idea at the time it had gotten very hot while a friend was borrowing it for a driving test. we replaced the gasket plugs wires oil filter transmission fluid and filter solenoids 1,2 2,3 transfer case switch ( due to atf in vacuum lines) still no 4th every other gear is fine help we have no idea where to look next and dont want to spend a ton of money at christmas throwing it at the car also no check engine light and there sorry if that was all over the place this tranny is driving me crazy we did not end up replacing the tps

 

The leaky lower intake manifold gaskets were not the fault of the Dexcool. Lack of proper coolant maintenance is what causes the gaskets to deteriorate. The two rear coolant passages in the heads dead end at the lower intake manifold, (100% blocked). If the cooling system is not flushed often enough, that's usually where the gaskets deteriorate first. Using Felpro MS98002T intake gaskets will help with longevity, but the cooling system still needs to be flushed regularly. Installing green, ethylene glycol coolant will cause ongoing problems with the cooling system, especially with the water pump.

There should be 4 distinct shifts on acelleration. When it shifts* into overdrive, it's not quite as noticeable, it kinda "slides" in, which is normal. Did you replace the 3-2 and TCC, (Torque Converter Clutch) solenoids in the transmission? If the TCC solenoid is not functioning properly, overdrive will not occur.

With no check engine light and no DTC's in the current, or history files, the TPS, (Throttle Position Sensor) is OK, save your money on that one

* not actually a "shift". The torque converter locks up which causes engine RPM to decrease. If you have the GU6 rear axle with 3.42:1 axle ratio, at 70MPH in overdrive, engine RPM should be 2K. If it's above 2K, the converter is not locking up.

 

So I drove the car and it's not just overdrive.When i hit 20 the rpms jump and it wont shift unless i rev it up and let it rev for a sec then it will shift when i get to 45 it wont go into overdrive either. the check engine lights not on wich i just assumed would rule out electrical issues but i'm no mechanic also, the 4x4 is not engaging.I just dont want to put a bunch of money into this when we have one sitting in the garage that could be rebuilt and put back in this time with an external transmission cooler and proper maintenance schedule.Speaking of rebuild what price am i looking at for parts and labor?

 

we replaced the 1-2 2-3 solenoids but there was also a considerable amount of shavings in the pan and atf in the vacuum lines could the particles have clogged up the shift valve possibly

 

What ever is causing the slip at 20mph is probably causing the shavings in the pan. Be best to have a transmission shop check it out. ATF in the vacuum lines is caused by a faulty vacuum switch on the transfer case and or leaky front seal on the transfer case.

 

I know this is an old thread but my 2000 zr2 drove perfect all day yesterday and I put a transmission cooler on this morning and went for a ride and now the transmission will not go into overdrive. it shifts 1-2-3... then it's like it goes into neutral. WTF?