Suddenly out of nowhere, I think my TH400 transmission is acting up on my 88 XJ-S.
Once I have driven about 20+ minutes, the transmission seems to make a whining noise above 2000RPM, and the pitch is higher as the RPMs go up. In Neutral, the noise does not happen. It happens in 1st, 2nd or 3rd. It is under load or not under load, as long as rpms are above 2000rpm.
I’ve also noticed, the auxillary fan comes on more often now at idle, it used to rarely come on unless it was a very hot day. (There are transmission cooler lines to radiator, correct?) And when I went to check the transmission dipstick, the fluid level was fine, but the actual dipstick was quite hot and I actually saw ‘steam’ come off of it. Fluid is still nice and pink too.
So I assume somehow, my TH400 is running hot!? I changed ATF about 1 1/2 years ago, with a filter change too. I also put in a street B&M Shift kit 1 1/2 years ago. The transmission is shifting fine, btw. Perfect.
What could be going on? If pump were going out, wouldn’t that cause shifting problems? Wouldn’t a clogged filter show up more when cold? Could it be a failing torque converter generating too much heat?
I guess first thing to do is change ATF and filter and see what happens?