1982 Rabbit Turbodiesel - unusual starting problem

stuebben

Member
Joined
Dec 7, 2003
Location
San Antonio, TX
TDI
Passat 1996 white
I'm hoping someone can provide insight into an unusual starting problem my 1982 Rabbit Pickup has had for the last two years. It has a 1.6L turbodiesel engine from a 1991 Jetta.

The truck has no difficulty with cold starts. However, if the engine is at operating temperature, it will turn over but will not fire. When that happens, I have to "push start" it the old-fashioned way (turn the ignition on, push to 5 mph, and drop it into 1st gear).

I have replaced the air filter, fuel filter, fuel shutoff solenoid and glow plugs, but that didn't help. Unable to make any progress, I took the truck to a local garage to be repaired. They've had it for over three months and can't figure out what is wrong either. What am I missing?
 

compu_85

Gadget Guy
Joined
Sep 29, 2003
Location
Springfield VA
TDI
... None :S
Are you sure the starter is doing OK? Is the cranking speed high enough when warm?

I believe the starter used on the 01M automatics works fine on the 020 manual transmission :)

-J
 

stuebben

Member
Joined
Dec 7, 2003
Location
San Antonio, TX
TDI
Passat 1996 white
I have not checked the compression hot. If the truck had a compression hot problem, wouldn't that also make push starts impossible?
 

compu_85

Gadget Guy
Joined
Sep 29, 2003
Location
Springfield VA
TDI
... None :S
There isn't much to one of these engines. Are you sure the fuel pump isn't leaking? The fuel cutoff solenoid gets constant power with the key on?

-J
 

stuebben

Member
Joined
Dec 7, 2003
Location
San Antonio, TX
TDI
Passat 1996 white
Compu_85: The fuel cutoff solenoid gets constant power.

Antsrcool: I think you're on to something. I'm kicking myself for not thinking of this earlier -- it does have a very old starter. Plus, your solution has the advantage of being a (relatively) easy and economical fix. I'll discuss this with the garage tomorrow.

THANKS TO ALL!
 

vwconejo

Well-known member
Joined
Nov 5, 2009
Location
Texas
TDI
B4 and couple or Rabbits
Has timing been verified? If your timing is off and you have an older starter it will not want to start. If you need help let me know what shop its at and I can stop by.
 

primerisgood

Well-known member
Joined
Jan 27, 2005
Location
Sudbury, Ontario
TDI
1992 Jetta TD with 1984 Rabbit TD engine, 2nd '92 original engine, '90 Jetta TD GL
Possible you are not getting full voltage to starter when hot? I have replaced positive connection cable to starter on ALL of my TD's eventually, due to corrosion inside cable at one end or the other. Most recently had a hard/no start caused by corrosion inside lower connector (onto solenoid), not visible externally.
Alternatively, perhaps you are sucking air into your fuel line between filter and tank, do you have a transparent area in fuel line where you can see fuel/bubbles? Perhaps when sits enough 'solid' fuel runs downhill into filter/pump to allow start, at which point 'suck' of the pump overcomes air leak? You could try starting engine from small container held above level of engine.
3rdternatively, have you tried manually triggering glow plugs (by-passing coolant temp sensor circuit) when engine is hot to see if you can start that way?
Finally, I have also had the lead to the fuel solenoid break inside the sheathing adjacent to the solenoid connector, resulting in an intermittent engine shut-off condition.
In my experience, these engines want to start, want to run. I have started, and run at highway speeds, with broken rings, holed injector lines, kerosene/gasoline fuel (alternative was generally a mid-winter (late night?) stranding). Currently a '90 TD is my daily ride.
[I'm switching to Hercules Avalanche studded tires for my next northern Ontario winter - they rule on my wife's Aveo this year.]
 

v8volvo

Veteran Member
Joined
Aug 1, 2004
Location
WA
TDI
2001 Jetta
Issue present immediately when trying to restart after shutting down or only if it sits for a few minutes? How many miles on the motor and what's the history?

Hard restart after a short sit when warm is pretty common to see on one of these as they age. Bet all the times it is easy to start are the times when you can hear the GP relay click on (even if only briefly), and the times it doesn't want to are when there is no GP action? And furthermore, I'll wager that if you reach under the hood and pull the GP thermo signal wire off the sender in the back of the head, then glow for a second or three, it fires right up?

IDI motors need glow plugs more of the time than DI setups even under the best of conditions (i.e. compression to new specs, cranking speed correct, timing and valve clearance all OK), and as the motor ages or is affected by other factors over time (e.g. weak starter, battery, batt cables/terminals, ground connections etc) and begins to need glow to start more of the time, the programming logic of the glow controller slowly becomes inappropriate. IOW, when cold it glows and starts easily, warm just after running it's hot enough to start easy without glow, but when partially warm it falls through the cracks to some extent, where it's not cold enough to trigger the glow system, but not warm enough to start without glow. Easy start when cold but hard when warm suggests not an air ingress problem, rather an issue having to do with in-cylinder conditions (in which cranking speed does play a large role).

Marginal starter would be a good first step. If it cranks same speed cold and warm that does not guarantee starter OK, when the glow plugs are on it will start even while barely cranking at all.... On a couple I have had adjusting incorrect valve lash be the cure but a '91 should be hydraulic so not likely in your case unless someone put on a different head at some point. Cam and pump timing matter to some extent though presumably you have ensured that those are OK if it has ever had a belt while in your care.

Once all else is exhausted it comes down to compression, on a couple where they were just getting tired enough to have this issue but otherwise still ran OK and the owners preferred to continue to limp along with them for awhile rather than overhauling, I've had success temporarily adding a low-ohm resistor in the GP relay temp sender circuit, this has the effect of slightly shifting the controller's temp vs glow logic so that the temp threshold for turning the plugs on is lowered. Effective provisional cure, and leaves the option of driving it like that or doing repairs in the future, without burning up the starter in the meantime...
 

stuebben

Member
Joined
Dec 7, 2003
Location
San Antonio, TX
TDI
Passat 1996 white
Problem solved! As suggested by Antsrcool and v8volvo, I replaced the starter about three weeks ago. Was reluctant to declare success before placing the truck back in regular service, but I think we can now say this problem is fixed. With the block cold (and glow plugs on), it will fire almost immediately. With the block warm, it will crank for up to 5 seconds, but ends up firing every time. The battery cables and ground connection are original 1982 vintage, so they will be the next to be replaced.

I have not (yet) tried triggering the glow plugs (when hot) to see if that will decrease the warm start time -- but may after finishing work on two Passat TDIs. Thanks again to all.
 
Top