Year of filter change

[the caveman]

Which year did VW change to the fuel filters with the return valve. I don't remember if it was 87, 88? I'm pretty sure 85 and 86 had the simple fuel in/out with the bleeder on top.

[Baron VonZeppelin]

I'm pretty sure it was 88.
i KNOW 89 had the thermo T deal for sure.
I keep 4 of them serviced.
If its critical - you might could check applications on AhausAZ.

I've been converting them all back to 85-87 style.
Tested 3 of those plastic thermo T's by putting them in the freezer for a while then bench testing them. And none have worked so far. Will probably be testing #4 soon.

Supposed to divert fuel from pump back into filter - until warmed up. If they worked, i'd leave them in place.

[the caveman]

It's because when i've done VO conversions, i delete it so VO doesn't return to the dedicated diesel filter and gel up when cold, letting the engine start but then stall 3 minutes down the road. I know which filters to get [the older simple in/out] but need to tell someone who is buying my truck which ones to buy in the future.