Originally Posted by IGeeky1

While I said I wasn't really here to talk about diagnosing my issue several of you have been kind enough to offer help in that arena so I figure I may as well post my intentions for tomorrow.

Oil does not look so good so I intend on changing and putting in a synth for cleaning as much as anything else. So I think I will try the shell that xj88 is looking at along with a napa gold /wix filter. This jeep will be my wife's and he puts very few miles on a vehicle. I also will use it to tow my 2000 lb boat/trailer. This will be low mileage for us so I figure one change in spring/one in fall will likely be plenty so price of synth not so much and I like the engine cleaning benefits.

As a side note she is having to give up her Wrangler, that I nearly forced upon her 11 years ago, so that I can have a vehicle to tow my boat. Her fee for this is not only the Cherokee but also a motorcycle. I have a great wife!!!!

While changing oil i will remove oil pressure sensor (looks very recently replaced) and check for sludge and such both there and in the pan.

I have already requested one of the oil analysis kits be sent to me and will save at least 4 oz of the middle flow oil as it drains to send in when the kit arrives.

After the oil change if pressure does not return, I will once again remove ops and check with mechanical gauge. If good with mechanical, I will replace with new napa ops. If still bad I will remove oil fill cap and make certain I'm getting some oil flying around up there. If so, let my wife drive and wait for oil analysis to come back.

I've removed the oil cap and peaked in through the valve cover to the cylinder head passenger side and did not see anything odd. I did this with engine cold thinking that would be the best time to see a fluid difference look. I will do again with engine hot.

If I'm missing something or need guidance .... please, type away!

Originally Posted by bigbadon

excellent article on oil pressure http://www.synforce.com.au/node/24

Originally Posted by bigbadon

.......since 10 weight or 40 weight have close to the same viscosity at 210 degrees.......

Originally Posted by IGeeky1

.......And why do I feel like if I were designing I would put a filter prior to the pump instead of after it? Seems like you would want to keep garbage from being sucked into the pump?.....

Originally Posted by djb383

There is a screen/filter designed in ahead of the pump. It prevents the large chunks (gasket material, etc.) from entering the pump.

There's also a screen/filter in the auto tranny.....it's easily changed and comes with a new tranny pan gasket for +/-$30.

Originally Posted by IGeeky1

Is a trans flush a backflush process? I think if it is a backflush process that changing the filter first and then flushing would be better, if not a backflush process, then flush followed by change makes better sense in my mind

Flush then change
Advantage> The filter will be clean
Disadvantage> If it is a backflush, it would flow junk back out of your filter and circulate it to where it may cause harm.

Change then flush
Advantage> Would not have the gunk in the filter be backflushed through the system and would save on some trans oil (minor)
Disadvantage> may end up dirtying a brand new filter prematurely

Anybody know if it is a blackflush process? Does my reasoning hold water?

Originally Posted by salad

...

Another way to change everything out replies on the transmission's own pump. One gent on here disconnected the lines at the cooler, put one end in a catch pan and fed new ATF in the other. No high pressure, no change in direction, etc. Would be super handy if you're confident that there's nothing in the filter worth looking at.

Originally Posted by djb383

Seems like 10 weight and 40 weight are a little farther apart on the chart than "close to the same" at 210 degrees, no?

http://www.bobistheoilguy.com/viscosity-charts/

Originally Posted by djb383

I've never heard of a back flush on a auto tranny.....complete fluid exchange (using the tranny pump), yes.....but not a fluid flow reversal.

Originally Posted by bigbadon

At 32 degrees the range is wide apart but at 210 the range is very narrow. Pull the dipstick on a hot engine and I bet you cannot tell the difference,but compare the two grades at 32 or even a 100 degrees and you will feel a big difference. That is why it is important to chose viscosity based on start-up temperature. Even lucus or stp with its heavy dose of VI (viscosity improver) will shear and lose viscosity rapidly at and above 210.

Originally Posted by IGeeky1

That's awesome! Not for this time but in the future i may just give it a shot. I imagine a two gallon bucket on the receiving side may be required, may get with away with a pint to a gallon on the fill side as long as you were ready to constantly be filling it. I wonder how fast (qt/min) transmission fluid is fed through?

I know when I've had flushes/backflushes done by a service center it has taken them a while. So it is a backflush a service center performs, yes?

Originally Posted by IGeeky1

For the drain and fill method you would need to go through a few gaskets right?

Originally Posted by djb383

I've never heard of a back flush on a auto tranny.....complete fluid exchange (using the tranny pump), yes.....but not a fluid flow reversal.

Originally Posted by IGeeky1

I'm not saying there is one, I simply don't know, I'm asking. I thought when you went to a service station and they keep pumping in trans fluid untill it looks pretty again was a back flush, opposite direction that the fluid normally travels in.