[T3] Lost power when warm?

[Jim Adney]

On 2 Sep 2024 at 17:22, Jeff Palmer wrote:

> 69 notchback, fuel injected, automatic transmission. It sat for 20 years and
> my friend/neighbour/mechanic have been getting things going since last
> spring.

Good description of your car. Where are you located? There may be 
someone more knowledgable close to you.

> It had been running more or less ok this year and we were fixing the little
> things like turn signals, speedometer, etc. About two months ago it started
> losing power when warm. After about ten-fifteen minutes of driving the
> accelerator stopped responding in forward and reverse. About the same time
> the transmission started slipping out of gear. I would be driving along in
> third and it would slip into second. To start it I would have to wiggle the
> gearshift with the ignition in the start position for it to catch the right
> spot and start.

The AT Neutral Start Switch is built into the shift lever. That's a common 
trouble area after all these years. For '69 thru '70, it has to be in N to start. If 
wiggling helps, the switch contact is worn out. I've been meaning to make 
replacements.

> My friend dropped the transmission and cleaned it up (not a full rebuild) and
> after a drive yesterday it starts properly and shifts better than ever. But
> still loses power when warm. 

I wonder what "cleaned it up" means. There's a very small chance that the 
shift cable was not adjusted correctly, or that the lever welded to the inside 
end of the shift shaft (inside the AT) had broken from the shaft, making shifts 
erratic.

So far I don't hear anything that sounds like a tranny problem. More likely an 
FI problem, but it could be caused by a low system voltage. Check the 
battery voltage after warmup and with the engine running at medium RPM. If 
it's below 13.5 V, at the battery, replace the voltage regulator. Check here 
before you try to buy a new VR.

Also, make sure the thermostat is still there, or that, at least the cooling flaps 
are open. If the thermostat is gone and the flaps have been allowed to stay 
closed, or are seized closed, the engine will overheat and lose power. This 
could be fatal.  

> Only other significant problem I can think of right now is an intermittent
> problem with the relay under the dash (fuel pump? Fuel injection?)The fuel
> pump doesn´t always come on when starting unless you give the give the relay
> a tap and it doesn´t turn off after a couple of seconds when starting up.

Those are pretty odd symptoms, ones I haven't heard before, but clearly a 
problem. Check for loose connections, or consider getting a "new" relay. I 
have good used relays.

Also, there is an identical relay under the back seat. Check to make SURE 
the screw attaching it is tight. It needs a good ground for the wire that's also 
under that screw head.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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