[T3] Lost power when warm?

[Jeff Palmer]

Hi Jim. Thanks for all the good info a while back. I ended up parking the car a little earlier than planned as although it was 29C today (in the 80s) we could get a dump of snow in a month. 

Lots to check out in the spring. I think we are on the right track with an electrical problem or thermostat or both. Maybe the voltage regulator. And cleaning up connections for sure. 

If it turns out the thermostat has failed, how do you feel about the ones that are sold now? They are different than original, right?

Thanks
Jeff
Sent from my iPhone

> On Sep 3, 2024, at 11:14 PM, jadney at vwtype3.org wrote:
> 
> Okay, lots of good info here. My responses interleaved below.
> 
>> On 3 Sep 2024 at 22:28, Jeff Palmer wrote:
>> 
>> Hi Jim.  I´m in Winnipeg, Canada, about 700 miles NW of you.  There´s a few
>> VW guys around but the community is smaller every year.
>> 
>> I don´t think it´s a crud in the fuel tank issue.  It was cleaned pretty
>> thoroughly two years ago when we first started working on it.  Also,
>> wouldn´t that cause an issue when cold as well?  Right now it´s only a
>> problem when it´s warm and running for 15-20 minutes.
> 
> Okay, but you might still want to disconnect the input hose from the fuel
> pump and verify that gas literally gushes out, and not just a momentary
> squirt. The filter could be clogged.
> 
>> I don´t think it´s a neutral start switch either - that was corrected when
>> the transmission was adjusted.
> 
> One of the contacts is made from thin brass sheet that can develop a hole
> where it needs to make contact. If you still have to wiggle it that can be a
> problem, but it doesn't have anything to do with your main complaint.
> 
>> The thermostat is still there, but if it fails, doesn´t it fail ´safe´ so
>> that it runs cool rather than too hot?  
> 
> Yes, it's supposed to fail safe, but the steel rod that turns to open and close
> the flaps can seize in the alum fan housing. If that has happened, the cooling
> flaps won't be able to open, even if the thermostat is trying to fail safe.
> 
>> I sent the replied to my mechanic friend but I wasn´t describing the
>> situation accurately.  Here is his summary:
>> 
>> "The car starts and runs fine when cold.   Once the car warms it no longer
>> moves forwards or back.
>> 
>> The car, when warm, will also stall when in gear and stopped. Drive or
>> reverse (with reverse being worse).  It can be shifted into neutral and the
>> Rpm can be brought up again.
>> 
>> It almost seems as if the transmission is bogging down the motor.
> 
> I'm at a loss here. I'm not an AT expert. Right now I'm working on the theory
> that the warm engine is weak. It has enough power to rev when there's no
> load, but not enough to move the car. It's just a working theory, but it's all I
> got.
> 
>> Also, the fuel pump relay is not working properly (under dash) yet when the
>> two reds are connected (on the relay under dash) the fuel pump runs and the
>> car runs normally.
>> 
>> With the fuel pump not shorted across the two reds it may start (sometimes)
>> but quickly run out of gas.
>> 
>> Before, something under the dash (likely a relay) was clicking the entire
>> time the car would run. Now the clicking is gone and the relay must be
>> shorted to put power to pump.
>> 
>> We have NOT tested the fuel pump power supply relay (under back seat behind
>> driver) nor have we tested/confirmed regulator, but everything else in the
>> car is working, lights, turn signals, brake lights, interior lights, and it
>> seems to be charging as the dash telltale for the alternator goes out once
>> engine is started (as normal).
> 
> The clicking relay is an important symptom. It means that either the main
> power relay under the back seat is loose (tighten that screw) or the control
> wire #19, from the FI brain is making intermittent contact, or power to the
> main relay, from the ignition switch, is intermittent.
> 
> Things to check:
> 
> Wiring to both relays, and mounting screw for main power relay.
> 
> Wire #19 connects from the FI harness to the main harness in the front of
> the engine compartment, just to the left of the intake air distributor. Find that
> connection and verify that it's good.
> 
> Make sure the wire from the battery + terminal to the main power relay is
> good.
> 
> Fix this first, as nothing else will work right until you do.
> 
> Then check the battery voltage as I described before. Even if it seems to be
> working, a worn voltage regulator will produce a reduced system voltage and
> this will cause the FI to run rich. A warm engine will not run well on a rich
> mixture.
> 
>> Also, the oil pressure light is NOT functioning (we will test sender
>> eventually)
> 
> Make sure the engine oil is full. With the key ON, touch the sender wire to
> ground. If the light goes on, replace the sender. If not, check the bulb and
> wiring.
> 
>> 2 years ago, the Transmission was leaking, fron the pan and around the
>> Governor, so it was drained, pan and Governor removed, and screen inside was
>> cleaned, pan reinstalled with silicone as no gasket was available, also a
>> number of the bolt holes needed thread inserts (pan bolt holes) as they were
>> stripped.  After a test drive everything seemed ok, but the Governor spring
>> clip and cover came off while driving. Checked and cleaned and put back in
>> place with wire until this year when transmission was removed and Governor
>> shaft seal was removed and new one installed, cover O ring replaced and new
>> spring clip made and installed, no leaks.
>> 
>> This year, the car was coming out od gear, so upon inspection the two bolts
>> that hold the cable in place at the transmission were loose and one was
>> missing, thus the shifter transmission not staying in gear and starting was
>> difficult. This was sorted with a couple of drilled and inserts put in and
>> bracket reattached to transmission body. The shifter was indexed and all
>> gears are in the correct position as is attested by 1 being able to put it
>> in neutral and starting the engine. Drive, 1 and 2 all respond as expected
>> as does reverse."
> 
>> Does that help at all?
> 
> Yes, sounds like you did a lot of good work on the AT, so that should be
> good now. Just for reference, I have good AT pan gaskets and governor
> cover O-rings.
> --
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
> 
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