84 rabbit wont start need help diagonising?

82rabbitofob · Post by **82rabbitofob** » Wed Dec 16, 2009 9:08 pm

hey guys. i have an 84 manual non turbo diesel rabbit and i have had no problems with the car for 4 months. Then about two weeks ago i was driving normally on saturday and drove it on and off all day. Nothing seemed broken or out of place when i shut down that night but in the morning it would not start. The car cranks over quite fast. but it doesnt even sound like its trying to fire. (no "starting" sounds just the cranking sound.) The week it went out was not especially cold so im not convinced this is the problem but i have no idea what it could be.
I have tired it with the cold start in and out and no difference.
Please HELP

bscutt · Post by **bscutt** » Wed Dec 16, 2009 9:52 pm

Check for a broken timing belt although unless everything lined up perfectly I'd expect you to be hitting valves with pistons if that were the case. Sounds likee no compression if it's cranking faster than usual.

You could also have jumped timing by one notch and the valves might not hit but timing would be off enough to prevent it from starting

vwkook · Post by **vwkook** » Wed Dec 16, 2009 10:05 pm

Check the glow plug fuse on the firewall behind the master cylinder. My money is on this.

TonyB · Post by **TonyB** » Wed Dec 16, 2009 10:42 pm

It could be that the fuel stop solenoid on the injection pump has failed or has no voltage. If you remove the wire from the solenoid and then touch it to the solenoid with the ignition switch on, you should hear it click.

82rabbitofob · Post by **82rabbitofob** » Wed Dec 16, 2009 11:12 pm

can i get a picture of where the fuel solanoid is and the fuse location. I will check these and the belt in the morning.

Thanks

82vdub · Post by **82vdub** » Wed Dec 16, 2009 11:46 pm

I'm also going for the glow plugs or the fuel solenoid. When trying to get an engine to fire that's had an injection pump replaced and there's no fuel in the injector lines, I've found that the engine seems to crank over much faster than normal. This leads me to suspect the fuel solenoid, but the glow plug fuse check (and voltage check at the glow plugs) is a task that takes 30 seconds.

The fuel solenoid is on the high pressure side of the injector pump, on the top. Trace the hard metal lines from the injectors back to the injector pump, and the fuel solenoid will be on the top of the pump where the lines screw in.

The large flat fuse should be on the firewall. Trace the big fat wire leading from the glow plugs to fuse on the firewall. If you trace the wire, you're not going to miss the box it's in.

82rabbitofob · Post by **82rabbitofob** » Thu Dec 17, 2009 10:52 am

i checked the solanoid and the fuse. The fuse and wires are good for the glow plugs and the light on he dash does still stay on for a couple seconds so i am pretty sure the glow plugs work. The solanoid i found. It was above the driver side where the hard lines screw in. It had one black wire on it and i unscrewed it and then turned the key to the on position and touched it listening for a click and i heard one. I also checked the voltage to the solinoid and it has 12.03V.

What should i look for now. I have little knowledgeon troubleshooting diesels. All i know is there is no spark.

Could the timing be off somehow?

82vdub · Post by **82vdub** » Thu Dec 17, 2009 11:04 am

Ok, you probably need to go back to basics. You have voltage at the fuel solenoid, but do you have voltage there when the key is turned to the start position? Others have had issues with their fuel solenoid not having power when the key is in the start position, but only when it's in the on position. This is a tough situation to verify yourself. Verify that you have voltage at the fuel solenoid when the key is in the start position.

Also, do you have fuel coming out at the injectors? Just because you have voltage at the fuel solenoid doesn't mean it's operating. Crack an injector line loose at the injector (just a little), crank over the engine and then go look to see if you have fuel leaking there. If not, the fuel solenoid may be bad, or your fuel siphoned back from the injector pump (IP) to the tank. Check your fuel system for getting fuel to the IP too. When's the last time the fuel filter was changed? If you never changed it in the 4 months you've owned the car, you should change the filter.

You also checked for voltage at the glow plugs, but are the glow plugs themselves shot? The light on the dash only tells you the glow plug relay is working, not that the glow plugs are actually good or you've got power to them. You need to test for glow plugs that are within spec and actually glowing. If you've got a block heater plug on your car, plugging this in for a couple hours (3-4 will definately work) will allow the car to start without operating glow plugs. This could be an easy way to test for operational glow plugs.

If you do not have a Bentley manual and are going to work on this car yourself, spend the $50 on the manual as this will save you hours of frustration and could save you lots of money in the process.

82rabbitofob · Post by **82rabbitofob** » Thu Dec 17, 2009 2:19 pm

i have cracked the injectors and then tried to start the engine and then come bak and seen diesel around the injector. Does this mean that the injectors work?

I will check the voltage in the on position when my father gets home.
(note that this car is my little brothers and it was given to him by my grandfather. Brother just turned 16 and he loves the car. I am jeleous, i had to buy my 240 volvo wagon, but he deserves it.)

I will get that bently book. i have one but it is for gas engines so it doesnt really help.

What should i check in the fuel system and how do i go about checking it.
I am guessing IP stands for injection pump. Right?

I will definately change the fuel filter
Thanks for all the help.
STEVE

82vdub · Post by **82vdub** » Thu Dec 17, 2009 2:32 pm

If you have fuel coming out at the injectors when you crank the engine over, then you have fuel in the IP and the fuel solenoid is working. I'd probably go on to the glow plugs from there and verify those. The Bentley manual covers gas and diesels, so if you have a repair book that covers just gas, it's not a "Bentley" manual. Haynes and Chilton manuals are not Bentley manuals, and I would not waste my money one one of those for a VW. Get a real Bentley manual.

82rabbitofob · Post by **82rabbitofob** » Thu Dec 17, 2009 2:43 pm

i just checked the voltage at the solanoid in the cranking position and it drops to 9.5V

I also checked the glowplugs and i got a really confusing reading. I checked conuinuity from the last glow plug to the fuse and it was good then checked the continuity from fuse to battery terminal and both terminals shows continuity with no key in the ignition. I am so confused?
This makes no since.

Can you explain?

steve

Vincent Waldon · Post by **Vincent Waldon** » Thu Dec 17, 2009 5:30 pm

Continuity is actually not very helpful diagnostically here because all of the glow plugs are in parallel, and depending on a bunch of variables you may see phantom continuity backwards thru various parts of the ignition key circuitry.

Probably a better approach is to check for voltage at the glow plug buss bar initially, with the key turned to "on". (note that the yellow light on the dash has nothing to do with the glow plugs getting voltage unfortunately).

If you do have voltage then you'll need to remove the glow plug buss bar and test each plug individually. If you don't have voltage you work your way backwards thru the system... fuse, relay, etc.

Further details/pictures on one approach to all of this here:

http://vincewaldon.com/index.php?option ... &Itemid=28

82vdub · Post by **82vdub** » Thu Dec 17, 2009 7:16 pm

A glow plug is just a resistor that's primary purpose is to give off heat. So, if you try to find real continuity of a circuit, you have to remove all the items that will give false readings or put other influence on the circuit you are trying to analyze.

tawney · Post by **tawney** » Fri Dec 18, 2009 9:57 pm

You might want to look at the "Sticky" topic: Glow Plug Re-Wiring. It's above all the other topics in the index to this forum. You'll get some useful ideas there about how to make the glow plugs easier to test.

viewtopic.php?t=5293

Either way, if you disconnect the glow plugs from the copper bar and check each for continuity individually, you'll probably find most of them burnt out; either that, or your glow plug relay isn't working. I've had temporary success with the relay by opening it up and cleaning the contacts. You could check it with a test light attached to the copper glow plug bar; as stated before, the glow plug light in the dash is not an indicator of if/when the glow plugs are getting current.

rabbit_man · Post by **rabbit_man** » Sat Dec 19, 2009 4:14 am

82vdub wrote:The Bentley manual covers gas and diesels, so if you have a repair book that covers just gas, it's not a "Bentley" manual. Haynes and Chilton manuals are not Bentley manuals, and I would not waste my money one one of those for a VW. Get a real Bentley manual.

I must say that is only partly correct.

The mk2 jetta/golf/etc bentley combines the gas and diesel engines.

For the mk1 jetta/golf/etc they do separate them into diesel specific or gasser specific, I have both.

82rabbitofob, does it smoke while cranking?