So seven years after my adventure with the speedo drive gear, during which time the car has sat, I finally get a well deserved kick in the butt and a lot of help from my Dad to get the 86 Jetta back on the road. Thanks Dad. We did manage to fish the speedo gear out of the trans after pulling trans from car and much frustration and profanity. Needed new flange seals and pushrod bushing and seal anyway, so there's that. Everything all back together, doesn't drool oil everywhere after new valve cover gasket, new timing belt, starts and idles beautifully.
Only problem is a complete lack of power. Won't rev above about 2600 rpm even unloaded, and won't make it up our admittedly quite steep hill even in first at WOT. Fuel filter is grunged up, of course, two new ones and a vacuum gauge on order, and I'll probably be bypassing the water separator because it's likely allowing air into the supply line somehow. Gave up trying to solve that set of problems and tried running from a quart jug of clean diesel, still have the same problem. We've made sure there's no air in the supply line, and plumbed a boost gauge in to the line from the intake manifold to the LDA, which shows no real boost. There might be 1-1.5psi, hard to tell because the gauge is temporarily zip tied to the hood and vibrates a bit. Absolutely no smoke at idle, with a bit of grey smoke at 2400 rpm at WOT, enough that you can see it in the rearview mirror but not a lot.
Yes we double checked that we aren't pulling a vacuum in the quart bottle, having done that before with outboard motors and felt really stupid about it. No the car didn't want to rev any higher going back down the hill in second at WOT, which was a little odd. Our best guess currently is that the wastegate may be stuck open or the valve seat may be seriously pitted, so we'll be pulling stuff apart to check that tomorrow. Garrett T3 turbo, and if anyone has any hints on how to get in to the wastegate actuator we'd be really grateful. Not really sure where to go from here without doing more high effort troubleshooting like pulling injectors and testing, etc. Hoping someone with a bit more experience on these engines has a brilliant idea, or at least some idea of what might be wrong.
Thanks in advance, and thank you all for the fantastic information available, it's been invaluable getting to this point in the project.