Going to drop pan and change filter and fluid. Getting enough fluid to change again some miles later for partial flush. Thinking of doing TransGo ZF5HP-24 pressure regulator valve upgrade when there. It's only $37 on Rock Auto.
118k miles on Jag. Don't think ever had any transmission service. Transmission works fine, no hard shifts. Question is - any idea of how often failures are related to old pressure regulator, 1 in 10 or 1 in 100?

 

Why gamble? Removal of the valve body is easy.

 

+1, ...you mean the trans works fine now, like RJ said...why gamble, your already there. Watch a YouTube video or 2 on it to be sure...I recommend Gary Ferraro.

 

Had recent trans service done at my trusted shop. Shop made a valid point about DIY trans flush. Dropping the pan doesn't drain the torque converter, so it's actually NOT a flush. They "power flush" to get the fluid out of the torque converter that holds about 1/2 the total volume.

 

Agreed. The mechanic I trust has the flush machine, but it does not have hookups for the Jag. Don't want to go to mechanic I don't trust. Afraid get some new hire who will screw it up. My plan is to drop pan, replace filter, put in TransGo, fill and drive for a bit. Then do another drain and fill. That should result in 75% new fluid. If fluid still looks nasty, maybe one more time. My research has Vavoline Maxlife ATF MV as compatible. On Amazon for $18 per gallon so multiple drain and fills not overly expensive.

 

TransGo valve installed. Very simple and easy. Have a C-clamp to hold cover when opening cover over valves. Fluid (118K miles assumed) came out black, but didn't smell burnt. Magnets covered in metal paste. I say paste because could not feesl any grit when rubbed between fingers.

 

You DON'T want to do a flush!! Shops do it because it's way easier then dropping the pan, replacing the gasket and filter and cleaning the muck off the magnet. It's much higher profit because all they do is disconnect one line and start pumping.

We also need to remember these cars have a thermostat in the cooling lines that does not open until the fluid comes up in temperature. You can't do that with a flushing machine. So your not getting a flush like you think you are. Just drop the pan and do it right. You are smart to do the drop and drain more than once to change a higher percent of the fluid out.

Depending on the fluid condition I have done a drop and drain as many as 4 times until I was happy with what the fluid looked like. After the first drain and filter replacement I just drain and refill which is much faster.
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I've done many flushes to bmw s with same 5hp gearbox with filter change of course and none of them had thermostate in the cooling flow. I think i've done to one xk8 too. Not even 8hp have thermostate. I can not say for every 5hp derivates.

 

Make sure you know if your car has the valve or not.

Here is the thermostatic valve as shown in the F-Type factory shop manual.



The manual does say that both systems were produced. So you might have the valve or not.
Does the transmission shop know and understand this variation?

Here is a good article showing the 8 speed ZF thermostatic valve.
8 Speed ZF Thermostatic Valve
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On the X308 platform, excluding the coolant thermostat of course, the only other thermostat on the drivetrain that I’m aware of is an engine oil cooler. The engine oil thermostat lives inside the upper oil pan or “bed plate”.