Re: 1.6 NA maximum injection pump timing advance questions (tochtli83)

Where are the injection lines leaking? If it's close to the pump, you might try loosening and tightening the check valves on the pump... or perhaps replace the copper washers behind them. Sometimes the return line nipples will crack on the injectors, causing the fuel to leak as if one of the rubber hoses is split. As far as too much pressure, that isn't possible. The injectors are supposed to 'break' at 130 Bar, so the pump can't really overpressure the system. Too much pressure would just cause more fuel to be injected. I have successfully set the timing to 1.05mm without any detrimental effects. And yes, 390 psi is way too low, as Bentley says 400 is the bare minimum. How long since the last valve adjustment? Valve recession will cause clearances to close and valves to leak. Adjust the valves and recheck the pressures...and check your cam timing. If the cam is retarded then compression pressures will drop.

 

Re: 1.6 NA maximum injection pump timing advance questions (BUGMAN7)

Yeah, I do need to check the valves, but need to buy a micrometer first to measure the shims (the etched markings on the bottom of the shims are never readable). I don't think that the valves have been adjusted in about 30-50k. I've owned the car for 30k and have not adjusted them yet, so that may explain the low compression. It does not look like the head gasket is blown (no loss of coolant, blow-by is minimal and compression is fairly even across all cylinders). Mileage is low and because blow-by is low, I doubt that the rings are bad. So, my only options are mal-adjusted valves and/or the valves are not seating properly due to carbon build-up.
But to be honest, I don't know what that would have to do with the choke lever not working, unless it all depends on compression. Even though the compression is low, it's still within/near the lower limits of compression. If the car runs (albeit rough) on startup, it should be able to improve with advanced timing. I might add, that the lever DID work for a few months after I bought the car 3 years ago, but has since stopped working.
Thanks for the info on the timing. How has the advanced timing affected your fuel comsumption and performance?

 

Re: 1.6 NA maximum injection pump timing advance questions (tochtli83)

Your compression is not too bad, I have heard of guys with much less and still running. You can read about them over at a VW Diesel Forum. Compression will really give you trouble when trying to start it in the winter.
If the temperatures are warm enough, you should not notice much of a difference with the cold start level in or out. I do hear more clatter with the cold start level out than in when the engine is warm. If it is 30F or below, it should miss a little with the cold start level in, and smooth out when out.


Modified by dieselsnowmobile at 4:09 PM 4-6-2007

 

Re: 1.6 NA maximum injection pump timing advance questions (tochtli83)

If you are continually leaking at your return lines, you may have a restriction in the return path back to the tank which is causing the pressure in the return side of the fuel system to be too high. You can check this by removing the fuel tank cap and then using compressed air to blow into the return line back to the tank to make sure that it is clear.
As for your cold start timing setting, your measured values sound identical to my '81, as far as how much farther advanced it goes with the cold start control pulled out (I accidently set timing with this pulled out the first time, d'op).
I have my timing set at 0.96mm IIRC now, and I get good power and economy (about 47mpg). The best thing to do is to try a setting for a week and note power, starting, and economy to determine what works best for you. Too far advanced and you'll see worse MPG figures and no additional power. Same with too far retarded, when I set mine the first time with the lever pulled out I think I was getting less than 40mpg.
I have a friend with four VW diesels (two caddies, two sedans) and on one of his he notices the same as you--that the cold start seems to have no effect whatsoever on how it idles when cold. On mine, it runs like crap when cold for the first few minutes if I don't have the control pulled out. Above a certain RPM the cold start has no effect anyways.

 

Re: 1.6 NA maximum injection pump timing advance questions (tochtli83)

Low power and no change in idle sound when the cold start advance is pulled out... The pump's advance mechanism is not working. Normally as the engine revs up and the pump turns faster, the feed pump will raise the pressure inside the pump and cause the advance piston to move, thus advancing the timing. The cold start lever advances the timing by using a cam that presses against the advance piston. If for some reason the piston has been damaged, or the pin that connects the piston to the cam plate has slipped or is damaged, you won't get any timing advance as the engine speeds up... thus the "no power" syndrome. In any case, to fix the advance piston and/or linkage, the pump must be disassembled, removing all the components from the distributer head, down to the cam roller carrier. Only then can you get to the linkage pin that connects the advance piston to the cam roller carrier. This pin must be removed to install or remove the advance piston.
My advice? get a used injection pump.

 

Re: 1.6 NA maximum injection pump timing advance questions (TurboDieselTech)

Quote, originally posted by TurboDieselTech »

Low power and no change in idle sound when the cold start advance is pulled out... The pump's advance mechanism is not working. Normally as the engine revs up and the pump turns faster, the feed pump will raise the pressure inside the pump and cause the advance piston to move, thus advancing the timing. The cold start lever advances the timing by using a cam that presses against the advance piston. If for some reason the piston has been damaged, or the pin that connects the piston to the cam plate has slipped or is damaged, you won't get any timing advance as the engine speeds up... thus the "no power" syndrome. In any case, to fix the advance piston and/or linkage, the pump must be disassembled, removing all the components from the distributer head, down to the cam roller carrier. Only then can you get to the linkage pin that connects the advance piston to the cam roller carrier. This pin must be removed to install or remove the advance piston. My advice? get a used injection pump.

Is this the same scenario even IF the lever appears to advance the timing. As I noted earlier, the lever appears to advance the timing (cam?) when pulled out. I inserted a dial indicator into the pump and pulled the lever. It seems to advance the timing. I'm sorry if this is a goofball question: I'm just not too terriblly familiar with the inner workings of the pump.
Anyway, it sounds like the problem is in my pump (as i surmised). I've been living with it so far. The car runs great when warmed up, and consistently gets about 42-47 MPG, depending on the season and how I drive (usually with a lead foot). It seems kinda odd that the pump would need a rebuild (or replace) after only 169K, but the car is 20+ years old.
On a similar note, I spoke yesterday to a guy from whom I bought a 1982 Rabbit D shell. We got to talking about the timing etc. He told me that on his Rabbit, he advanced his pump timing one tooth with the pump set at .95 mm. He claims amazing power and good economy (over 40 MPG). All this from a car with over 700,000 miles! Yeah, I crapped myself when I heard that. Here's the kicker: it's the original motor. It's never been rebuilt.

I think that the 1-tooth advance was the situation I remembered on the Rabbit D I bought about 10 years ago. That car accelerated like a gasser, and I think that my dad claimed it was advanced a tooth.
Anyhoo, thanks all for the advice. I may try a different pump on my car to see what happens (I've got a couple of spares).

 

Re: 1.6 NA maximum injection pump timing advance questions (tochtli83)

1)
I just built my 1.6na and got it running. I'm being nice to my motor for the 1000 mile break in which sucks to do.
As for that cold start lever- unless it's a TD you aren't going to hear the pitch change in idle.
I was driving my BF's TD for a long time and when ever I pulled the timing advance I would instantly hear the change.
Now I drive my NA and I do not hear the change but I know it works because the car won't start in the cold ass morning unless I have it pulled out! I also have driven my co workers Jetta with the 1.6na in it, and same thing- no auditory change I could detect.
2)
Is it the hard lines leaking? Do you have the little metal bracket things that hold the hard lines in place? I believe there are three of them. If that is the case get at least the top two on!
I was driving my car on the freeway and I head something like a bolt drop off my Rabbit. Being a MKi driver if it drops off and the cluster reads fine I keep going.

For the next three days I had a diesel leak somewhere in the engine area. I thought it was my pump- then I thought it was because I ran bio (which didn't make sense because everything is new) then I noticed my hard line clip on injectors 1/2 was missing. I threw it back on and no more diesel leak.
I dunno what to tell you about your lack of power. But set your pump timing to factory spec- which you have already done. Consider doing the govnah' mod

and play with the fuel screw.
Doing those things should wake up your sleepy and tired diesel.
GL

 

Re: 1.6 NA maximum injection pump timing advance questions (tochtli83)

Quote, originally posted by tochtli83 »

On a similar note, I spoke yesterday to a guy from whom I bought a 1982 Rabbit D shell. We got to talking about the timing etc. He told me that on his Rabbit, he advanced his pump timing one tooth with the pump set at .95 mm. He claims amazing power and good economy (over 40 MPG).

Over 40? That's not news. Most diesel Rabbits get over 40. Mine does and it's driven 100% in traffic. I'd probably get closer to 50 on the highway.
The one-tooth-advanced things sounds fishy to me. There are some real gearheads on vwdiesel.net and vwdieselparts.com, and I can guarantee you that there is a point of diminishing returns on advanced timing, and that point is about 1.05mm which is well before one-tooth-advanced. The only way that much timing makes sense is if he has messed with the injectors or something.
The Cold Start doesn't really do much for the sound of my idle (N/A). But it does make the car easier to start (or at least, with less smoke) and it does run smoother for the 10-15 seconds I leave it out. If I push it in too soon and try to drive it, I get surging and bucking. So you can't really tell that it's working just by the sound of the idle unless you have your static timing significantly retarded or advanced.

 

Re: 1.6 NA maximum injection pump timing advance questions (tylernt)

Yeah I don't know what to make of the whole tooth advance thing either...too advanced and the engine will work against itself.

 

Re: 1.6 NA maximum injection pump timing advance questions (tochtli83)

You might take the advance cover opposite to the lever cover and check the sealing o-ring. Sometimes these swell up and obstruct the fuel bleed passage. If that passage is obstructed, the advance piston won't be able to move very far.

 

Re: 1.6 NA maximum injection pump timing advance questions (TurboDieselTech)

Thanks. I'll check that out.