[T3] Lost power when warm?

[Jeff Palmer]

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.

I don’t think it’s a neutral start switch either - that was corrected when the transmission was adjusted.

The thermostat is still there, but if it fails, doesn’t it fail ’safe’ so that it runs cool rather than too hot?  

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. 

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).

Also, the oil pressure light is NOT functioning (we will test sender eventually)

The thermostat (bellows type) does have a little movement in it, but not enough I fear. It was removed and restored 2 years ago, but I guess it didn't hold 100%. The flaps on all VW's is a fail safe system, I believe, and the engine will take longer to warm up, but will not overheat as the flaps fail into the position of full cooling for the engine, I may be mistaken but beetles and biases work this way, and southerners usually don't bother replacing them as they are like hens teeth. 

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?

Thanks
Jeff

> On Sep 2, 2024, at 5:53 PM, Jim Adney <jadney at vwtype3.org> wrote:
> 
> 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.
> 
> -- 
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
> 
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