Bump start

Starter went kaput - 2004 PD TDI ...
Could not even rolling bump start a warm engine !!

Question ???
There is ( from what I know ) a sensor that tells the
glow plugs to not flash if the engine is hot .

• Can that sensor be overridden to be turned off
there by flashing the plugs to a warm engine,
there by making it less difficult to rolling bump-start
a warm TDI ??

• I suspect it would have started if I could have flashed the plugs.

As it was, I was in a busy spot and bumping it was very unsafe - tried 5 times in second gear - almost got it - but then the area I was in just got too busy to try it anymore.
Had to flat bed it to the shop - NEW Starter ! ... that's all it was .
Works fine now ... I'm just thinking in academic terms now after the fact ... if there was a better way to have gotten it running ??

2nd gear? did you try 1st gear? bump start mine all the time from a rolling stop when i stall it. Reverse is actually the best gear to bump it in. its as low or sometimes lower than 1st. you want high gear rotation and dump it as fast as possible. On cold days its impossible for me to bump it though. been a while since then.
Just get an OE starter, not a reman, duralast or any other crap POS and you wont have this issue again or when you do it wont be worth what mods you would to to try and make it easier. glow plugs are not going to make it much easier at all. either its warm enough or its not.

You could've just went and bought a starter and install it right there. At least that's how I do it.

1 - call someone to pick you up
2 - go buy a starter
3 - install starter
4 - drive off
5 - if you didn't know it was the starter, smack yourself in the face
6 - learn to troubleshoot

Opposing view...

Bump starting in 3rd gear works far better. 1st or 2nd has less leverage to flip the engine over.

AndyBees said:

Opposing view...

Bump starting in 3rd gear works far better. 1st or 2nd has less leverage to flip the engine over.

Click to expand...

This always seemed the better gear to me too.

I vote for bump starting in 3rd it seems to work better when I have had to bump start the car. hell I bump started my 2006 jetta in the dead of winter in Wyoming stone cold because the starter decided to chew up the flywheel......

Like I said at the outset of this thread ...
This question is academic at this point ...
as the car now has a new bosch starter
and since the 1st starter racked up 320'000 kms of starts,
I suspect this one will last a long time as well ...

Specifically to the smart ass with his list of things to do -
bruth-a, I've been driving VW diesels as far back as my 1980 rabbit !!
of which I had to often start with a steak knife ( cross wiring the leads )
( nice wooden handle to not get a shock ) ...

of which - 'leads' back to the original jist of the question,
which was to do with the glow plugs . . .

In those days - ( the 80's ) I think you could still flash the plugs on a warm engine -
as that old Rabbit would bump start with little to no roll
in 2nd gear, or 1st, of which, that flash of the plugs,
I think could have made bump starting easier with that extra 'umph' to aid combustion ...
but now a thermostat sends a signal
to not flash the plugs if the engine is hot ... so the question was :

Is there perhaps a fuse or a simple way to disengage the thermostat,
thereby flashing the plugs on warm engine in a 2004 TDI ?
Thereby in theory making it that much less of an effort to gain combustion and bump start the car ?

P.S. Next time - I'll try 3rd ! - thanks !
I was stuck in a busy mall parking lot ...
cars - people - cars - people - weekend -
As it was - each try at bump start involved laying on the horn !!
and screaming " Get out-a-the way !!! we're try to bump it !!! "
Had to flat bed it out a there ....
just too dangerous and congested with people traffic at the time.

yea you can override the temp sensor for the gp's on the car just install a toggle switch that bypasses the relay.... easy fix...... if you need to use the gp's when the car is warm though you have bigger problems

Not being a wise guy here, I'm serious. Describe your bump procedure.

Many years ago I had a jeep with a bad ring gear on the flywheel. I could bump start it any pretty much any gear. I just used whichever gear corresponded best to the rolling speed and direction I could achieve. It obviously didn't have as much compression to overcome as a tdi. The main thing was to remember to have the ignition in the on position.

well ill never know, my 3rd gear has been dead for any thousands of miles. dont have the money right now or the foreseeable near future for a trans swap or repair.

While it doesn't cycle the glow plugs manually, it will make them stay on as long as possible. Disconnect the coolant temp sensor...

As JDSwan87 stated, the Sensor is the Coolant Temperature Sensor (CTS) in the coolant flange on the end of the head. It is a two in one.. Gauge and ECU. If you disconnect the sensor plug, the ECU defaults to -40c. I suspect that will cause the ECU to trip the GPs as well as increase fueling. VCDS will show Engine Temp at -40c with the CTS unplugged.

As the OP, my first VW Diesel was a new 1980 Rabbit with the 1.5 engine. The OE GP Relay was notorious to give up the ghost. So, I installed a Push Button switch below the dash (very heavy duty) to provide direct current to the GPs without the use of a Relay.

When bump starting, the higher gear usage provides better leverage in the opposite direction (wheels>axles>diff>gear>engine) to rotate the engine. At a very slow roll (especially on flat ground), 1st or 2nd gear tend to just stop the car, while 3rd or 4th gear will more likely turn the engine over............ < that's the difference (yeah, and don't forget to turn-on the ignition).

My drive-way at the main highway is down hill. When I stop to check snail mail box (in my ALH Vanagon), I usually cut the engine off. When I get back in the Van, I just bump start it down the drive-way in 2nd gear, never fails and is always smooth.

KLXD said:

Not being a wise guy here, I'm serious. Describe your bump procedure.

Click to expand...

Haven't bump started in years but here is one way NOT to bump start. A guy posted here that he turned on the key, put the car in 2nd coasted BACKWARDS down the hill, popped the clutch and then posted here wanting to know how to pull the head.

HI,

I've not had to try to bump start yet but how many mph do you have to be rolling to pop it to life in 3rd?

Thanks
Andrew

Kinda depends. 5 MPH might do it if your on a hill that keeps the car moving. IMHO, 2nd is probably a better choice.

And actually, 1st gear will spin the motor the fastest, but unless you are on dry pavement usually the drive wheels will just lock up when you let out the clutch. Also, 1st bleeds off the car momentum quicker so you need the hill to be steeper than if you were in 2nd or 3rd.

2nd is the best gear for me. You need a pretty good amount of ground speed to spin the engine fast enough in 3rd. 1st gear seems crazy. That would be a pretty rough jolt to dump the clutch in first.

AndyBees said:

As JDSwan87 stated, the Sensor is the Coolant Temperature Sensor (CTS) in the coolant flange on the end of the head. It is a two in one.. Gauge and ECU. If you disconnect the sensor plug, the ECU defaults to -40c. I suspect that will cause the ECU to trip the GPs as well as increase fueling. VCDS will show Engine Temp at -40c with the CTS unplugged.

As the OP, my first VW Diesel was a new 1980 Rabbit with the 1.5 engine. The OE GP Relay was notorious to give up the ghost. So, I installed a Push Button switch below the dash (very heavy duty) to provide direct current to the GPs without the use of a Relay.

When bump starting, the higher gear usage provides better leverage in the opposite direction (wheels>axles>diff>gear>engine) to rotate the engine. At a very slow roll (especially on flat ground), 1st or 2nd gear tend to just stop the car, while 3rd or 4th gear will more likely turn the engine over............ < that's the difference (yeah, and don't forget to turn-on the ignition).

My drive-way at the main highway is down hill. When I stop to check snail mail box (in my ALH Vanagon), I usually cut the engine off. When I get back in the Van, I just bump start it down the drive-way in 2nd gear, never fails and is always smooth.

Click to expand...

---------------

Thanks !!! Great tips in here for everyone - What you described is what I was thinking would have helped.

---------------

KLXD said:

Not being a wise guy here, I'm serious. Describe your bump procedure.

Click to expand...

Thanks - I hear ya - I know how it's done - key over in running position / roll / pop clutch in gear / - I suspect the issue was over coming high compression / gear selection / and lack of room in a busy spot .
I think I'll try 3rd gear some time just for ****s and giggles to see how that goes.

A few summers past on a pretty flat road I pushed my car by myself fast enough to start using 3rd. Not on the first try thou.
Cheers?

I've bump started my 03 ALH more times than I can count and in every gear, but the OP's car is a PD engine so that may be a different story.

I've bump started the PD in my 03 TT a couple times so I don't believe that it's a PD vs VE thing, but it may be a software thing as mine is far from stock.

I bump started the TT on a flat parking lot alone one day - 1st gear is the one to use in that scenario.

My opinion is that you want to be in the gear closest to the road speed and direction that you're traveling at. 99.9% of the time that will be 1st gear for forward and reverse for reverse. During my maximum MPG days, I would frequently bump start after coasting down hills, flats, etc and that's where you want to have a good match between engine speed and road speed otherwise it's a bit hard on things like motor mounts, driveline, etc.

It does take some "touch" though to get all the potential energy from the vehicle into the engine when engaging the clutch, but then depressing the clutch again as the engine fires to avoid stalling it - Especially if you're not in 1st gear.

HOOPER65 said:

Thanks - I hear ya - I know how it's done - key over in running position / roll / pop clutch in gear / - I suspect the issue was over coming high compression / gear selection / and lack of room in a busy spot .
I think I'll try 3rd gear some time just for ****s and giggles to see how that goes.

Click to expand...

There's the problem: "pop clutch in gear".

Try popping the clutch and immediately push it back down so the engine can keep running instead of lurching to a stop.

AndyBees said:

As JDSwan87 stated, the Sensor is the Coolant Temperature Sensor (CTS) in the coolant flange on the end of the head. It is a two in one.. Gauge and ECU. If you disconnect the sensor plug, the ECU defaults to -40c. I suspect that will cause the ECU to trip the GPs as well as increase fueling. VCDS will show Engine Temp at -40c with the CTS unplugged.

As the OP, my first VW Diesel was a new 1980 Rabbit with the 1.5 engine. The OE GP Relay was notorious to give up the ghost. So, I installed a Push Button switch below the dash (very heavy duty) to provide direct current to the GPs without the use of a Relay.

When bump starting, the higher gear usage provides better leverage in the opposite direction (wheels>axles>diff>gear>engine) to rotate the engine. At a very slow roll (especially on flat ground), 1st or 2nd gear tend to just stop the car, while 3rd or 4th gear will more likely turn the engine over............ < that's the difference (yeah, and don't forget to turn-on the ignition).

My drive-way at the main highway is down hill. When I stop to check snail mail box (in my ALH Vanagon), I usually cut the engine off. When I get back in the Van, I just bump start it down the drive-way in 2nd gear, never fails and is always smooth.

Click to expand...

-------------------

Do you mean this plug ? ( image link )

http://pics.tdiclub.com/data/uploads//51875/IMG_8808.JPG

HOOPER65 said:

-------------------

Do you mean this plug ? ( image link )

http://pics.tdiclub.com/data/uploads//51875/IMG_8808.JPG

Click to expand...

no, this one......

http://www.myturbodiesel.com/images/a4/TB_head_rem/temp-sensor.jpg

unplug the wire harness at the green arrow

maxmoo said:

no, this one......

http://www.myturbodiesel.com/images/a4/TB_head_rem/temp-sensor.jpg

unplug the wire harness at the green arrow

Click to expand...

I cant seem to view that in here ...
but I sure am curious to see it ??

Can you post the image in the picture gallery here on TDI CLUB
and paste the link ??

Thanks - looking forward to seeing that

HOOPER65 said:

I cant seem to view that in here ...
but I sure am curious to see it ??

Can you post the image in the picture gallery here on TDI CLUB
and paste the link ??

Thanks - looking forward to seeing that

Click to expand...

I still haven't mastered the picture gallery thing....but if you click on this page ...
http://www.myturbodiesel.com/wiki/t...ature-sensor-removal-replacement-mk4-vw-audi/
....it should be the top photo.

maxmoo said:

I still haven't mastered the picture gallery thing....but if you click on this page ...
http://www.myturbodiesel.com/wiki/t...ature-sensor-removal-replacement-mk4-vw-audi/
....it should be the top photo.

Click to expand...

-----

Thank you - I'll try to locate that to get a real visual.
So it looks like an electrical connection
with some push clips to release it ?

So then - to sum up - in theory ( as this is academic at this point ) -
do you feel that unplugging that sensor on a warm engine,
would flash the plugs and make bump starting the car much less difficult,
where the forced compression of diesel fuel could more easily ignite
in a piston environment that includes red hot glow plugs ??

HOOPER65 said:

-----

Thank you - I'll try to locate that to get a real visual.
So it looks like an electrical connection
with some push clips to release it ?
yes

So then - to sum up - in theory ( as this is academic at this point ) -
do you feel that unplugging that sensor on a warm engine,
would flash the plugs and make bump starting the car much less difficult,
where the forced compression of diesel fuel could more easily ignite
in a piston environment that includes red hot glow plugs ??

Click to expand...

I wouldn't say "much less difficult" on a warm engine but, it will start somewhat quicker/easier if the glow plugs are on longer.....especially on a cooler engine.

As previously stated, unplugging the CTS results in the ECU having a reading that defaults to minus 40c. The use of Vag Com Diagnostic System (VCDS) verifies this ....... thus no Theory. This will cause the GPs to glow as well as an increase fueling.

Bump/roll/kick starting is just a means to rotate the engine fast enough (at least at the rate of 250 RPMs) to create compression sufficient enough to ignite the fuel upon injection. Obviously, the ignition needs to be in the ON position for at least three reasons 1). so you can guide the vehicle, 2). so the fuel shut-off/on solenoid is ON. and, 3). so the GPs will glow if necessary (with the CTS unplugged, they will glow).

maxmoo said:

I wouldn't say "much less difficult" on a warm engine but, it will start somewhat quicker/easier if the glow plugs are on longer.....especially on a cooler engine.

Click to expand...

Thanks - a useful & educational conversation.
Under different circumstances in a less congested parking lot
or with a hill available, I'm sure the car would have stared.
Where I was stuck, I think flashing the plugs
would have helped obtain combustion.
All good info should I run into this again, or can assist others.