Opinions on diesel starting problems? (vw 1.9 AAZ) - Page 3 - PeachParts Mercedes-Benz Forum

katja · #31 11-14-2013, 01:43 AM

Is the AAZ an indirect injection turbodiesel or an early TDI? I was surprised at how much cranking (like 30+ seconds!) it takes when NO glow plugs work on an IDI engine...doing that every day has got to be killing the starter, and I've read something to the effect that all that unburned fuel could dilute the oil and wash down the cylinders, making compression worse but I am not sure if that is true. At the least you sure get one huge cloud of smoke when it finally starts.

And this is a Syncro Golf? I'm not too knowledgeable about VW's newer than the air-cooled generation but I thought the Syncro was a 4WD Vanagon. And I've only seen two diesel Vanagons in my life but I thought they were cool (except very slow). I read about people putting TDIs in them....

fireman1073 · #32 11-14-2013, 09:14 AM

I had a 86 jetta turbo diesel with hard start issues

turns out that a seal on the front of the injection pump was bad allowing the pump to lose prime

a proper fix is of course change the seal on the front of the pump

BUT a simple check valve just before the injection pump works well

Steve

compu_85 · #33 11-14-2013, 09:34 AM

The AAZ is a 1.9 IDI engine. Just like going from the 1.8 gas to the 2.0 gas it is a 1.6 diesel with a taller deck.

Syncro was VW's brand for AWD / 4WD before 1999.

-J

83w126 · #34 11-15-2013, 10:54 AM

Both me and my dad were told not to work on it at all by the person who did most of the work since she got it, and I haven't looked at it much so I don't know for sure, but...

I don't think the flywheel has a timing mark for the diesel on it, so that could certainly be a problem. The crank pulley wobbles a lot, but as far as I know it was put back together properly when the timing belt was done last, so its hopefully not getting any worse right now. I still haven't had the opportunity to take pictures of it at a time when its light enough to see anything, but I will post some this weekend.

compu_85 · #35 11-15-2013, 11:02 AM

If the crank pulley wobbles just stop. Take the belt off and remove the pulley. If the crank is damaged I'd just look for another motor.

-J

83w126 · #36 11-18-2013, 12:49 AM

Quote:

Originally Posted by compu_85

If the crank pulley wobbles just stop. Take the belt off and remove the pulley. If the crank is damaged I'd just look for another motor.

-J

It was like that when she bought it and hasn't really gotten worse since, so it may be ok for a while. It will eventually need to be fixed either witha new crank or a whole new engine. It does start now though, I didn't have any way of testing the glow plugs without taking them out, but I made sure the system was operating properly otherwise, then pulled the glow plugs out and they appeared to all be not working (after cycling the relay 4 or 5 times checking for power in various places the glow plugs were still oily when I took them out). So I put new ones in and it starts right up.

compu_85 · #37 11-18-2013, 01:01 AM

Don't delay checking the crank.

Good to hear new plugs helped it out. Does it have the cold start handle hooked up?

-J

83w126 · #38 11-18-2013, 01:49 AM

You mean something like the old Mercedes diesels have? I don't think so, I don't really know anything about that. I don't really think there is anything I can do about the crank, to the best of my knowledge it is currently installed properly (undamaged pulley, new bolt torqued properly, etc) and doesn't seem to have gotten any worse since the timing belt job was done. The person who did it pretty much told me its fine and its none of my business to worry about it, but who knows. I already told her if it starts to get worse she will need to either rebuild this engine with a TDI crank or look for another one.

compu_85 · #39 11-18-2013, 09:43 AM

Ohhh that's probably a big part of the cold starting problem then. There should be a handle hooked up to the timing advance lever on the IP. You pull it for cold starts:

https://www.youtube.com/watch?v=Lwzpfnxw7jA

Quote:

5.3 Cold Start System

Since the diesel engine relies on the heat of compression to ignite its fuel, it is harder to start in cold weather when the cold engine dissipates heat quickly. To compensate for hard cold starting conditions, the diesel injection pump includes a manually-operated timing advance feature. By means of a cable, pulling the cold start handle-one detent only on 1985 cars, the second detent on 1986 and later cars-advances injection timing by about 5°. The fuel is injected sooner and given more time to burn, offsetting most of the negative effects of a cold engine. The cold start feature affects injection timing up to about 2200 rpm.

-J

barry12345 · #40 11-18-2013, 11:36 AM

Well if they sold it to her with bad glowplugs or did not change them with her starting problem later. You should pretty well know what kind of people you may be dealing with.

It also sounds like they have been at the pulley area as well unfortunately. None of your business about screwed up things is an interesting comment.

May be just some form of personality clash going on here as well. I doubt there is much upside in your situation as well.

83w126 · #41 11-26-2013, 02:15 AM

Well that didn't turn out well. The timing belt slipped while she was on a trip 500 miles from home, so the engine is junk and she is putting over $1200 just into getting it home. I'm not sure exactly what happened, I haven't seen it yet but my dad pulled the belt cover off and it was loose over the cam and injection pump, and the tensioner bearing will no longer turn easily, so there wasn't really much more point in further investigation until after its home.

vstech · #42 11-26-2013, 09:14 AM

Common issue with El cheapo belt change new belt, old tensioner shredded belt... ugh. Don't lose hope the motor may be repaired ...

JB3 · #43 11-26-2013, 09:46 AM

this is like a recurring nightmare thread.

Why does she keep dumping money into this car, and why is she using someone for repairs who sounds like he's doing a poor job?

FYI the crank pulley wobble can just be the pulley itself-

here is what mine looked like-

1986 1.6 diesel Jetta crank pulley wobble - YouTube

Word of warning is ultimately when the car went to a new owner, the pulley itself delaminated and broke into two pieces. Crank was fine, but she had a heck of a time finding a new pulley.

compu_85 · #44 11-26-2013, 10:20 AM

This is why I suggested checking the crank pulley NOW.

The AAZ timing belt is so easy to do properly. The only special tools you need are the camshaft lock and the dial gauge to set the injection pump. A 13mm (IIRC) is the proper size for the injection pump pulley lock pin.

-J

83w126 · #45 11-26-2013, 08:49 PM

I will post what happened when I get a chance to look at it. From what my dad said and the picture she took I think the timing belt tensioner bearing may have failed (even though it was new), but im not sure yet.