85 VW NA 1.6 Diesel won't run above idle at full throttle

[Linc]

Hi to the group,

I've got a problem with my VW diesel I'm hoping someone can help me diagnose.

I bought an old '85 VW NA diesel in California last June.  I bought it planning to rebuild the engine when time/money permitted.  It had been converted to run on veggie oil (conversion needs work, which I plan to do).  Odometer broken, indicated 199,000 miles.  Engine had a small amount of blowby through valve cover opening, but not bad.  Owner had just had oil changed and a new fuel filter put on.  Car ran well on trip home with no overheating (temperature gauge broken but I stopped periodically to check engine and didn't seem hot).  I did have the oil pressure light come on after climbing a long hill at low revs as I started to descend, but it went out again when I revved it, and stayed out as long as car wasn't pushed too hard.  I ran it entirely on diesel fuel, no veggie.  About 1 mile from home  in late evening with cool temperatures, it started bucking and blowing smoke which looked blue but smelled like unburnt diesel.  Made it home (our cars are amazing in this way - they usually wait until we're within walking distance of our house or a good friend's house before they break down) and parked it for the summer.

I finally got a chance to work on it this week.  I drained some water from the water separator under the gas tank, and checked for water at the fuel filter but didn't find any.  I then checked the compression and found that while the readings were low around 300 psi each, but my tester was leaking by slightly, and I'm testing at 7300' altitude.  All four readings were within 30 psi of each other.

I pulled the valve cover and checked valve clearances.  All were within spec except for 3 exhaust valves which were .001 inches too tight, not enough to cause it to run like it does now, I think.

I pulled the injectors and had them pop tested by a good diesel shop.  They said they tested within specified range with good pattern.

I checked the glow plugs.  The bus gets power during the glow cycle, and each plug tested at over 12 amps current when bus removed and jumpered from battery, then dropped to around 11.7 amps towards end of glow cycle.  Based on that, I think they are all OK?

I bought an IP timing dial gauge and checked the IP static timing.  It was retarded a bit, so I advanced it to spec (.95 mm).

I checked the timing belt and the camshaft position when the flywheel indicator read TDC on #1.  Timing belt looked fine - tension good, cam position at TDC right on (cam locking bar fit at rear end of cylinder head).

I put everything back together, (new heat shields on injectors), refilled the IP pump with diesel fuel, bled the lines to #2 and #3 injectors, tightened everything up, charged the battery, and tried starting it again.

It will start, but will just barely run (maybe about 500 rpm?) with throttle wide open, and blows lots of blue-ish looking smoke that smells strongly of incompletely burned diesel.  This is pretty much exactly how it was running when I parked it back in June.  I checked and made sure that IP stop solenoid clicks when power is applied to it, and I made sure that throttle cable is actually pulling throttle in IP wide open.

I'm planning to rebuild this engine anyway, and have the IP rebuilt too, but had hoped to run it for awhile first while I worked the flaws out of the waste veggie system before risking destroying the rebuilt engine and IP with a lousy veggie conversion (I know, there may be no such thing as a good veggie oil conversion for this car).

Sorry for long entry.  My question is - anyone have any ideas why this thing won't run right?  I'm thinking it's the injection pump, so I might go ahead and send that off for a rebuild.  Any advice for best person to send it to for rebuild?  Thanks anyone!

Linc

[Wayland]

Check for air leaks in your fuel system. If it's been converted to VO, chances are there are a number of hoseclamped joints in the fuel system that could be leaking air. In fact, if it were my car, I'd put the fuel supply lines back to stock configuration, at least temporarily until I got the problem worked out. IP rebuilds are costly, so I'd eliminate everything else before sending the pumpout for an overhaul.

[fatmobile]

Clear fuel lines to and from your pump?

[Linc]

Thanks for the ideas.  I'm pretty sure I've got fuel flow  If I disconnect the line between fuel filter and fuel pump inlet, I can pour diesel fuel in there and have it come back out the return, so I don't think the lines are clogged.  I'll try suspending a bottle of fuel (IV drip for a Jetta?) feeding the inlet line to the fuel pump by gravity, to make sure I'm not getting any air.

The car runs consistently bad.  It doesn't start to surge and then stumble, it just barely runs and only if you keep the pedal to the floor, and lots of smoke.  I would think that if the lines were clogged, it wouldn't run at all, and that if there were air in the lines then it either wouldn't run, or it would surge and stumble.  Instead, it runs, but extremely slowly and rough.  I'm thinking that the IP is possibly delivering fuel at the entirely wrong time, or possibly not to all four cylinders, or something like that?

[SolarSteve]

Its not so much as the lines being plugged but if any fuel line connection isletting just a little bit of air into the line, you will be replacing fuel with air and not allowing the engine to reach full rpms.

Get 2 pieces of clear hose.  Splice 1 in the fuel line just before the fuel filter and one just before the IP and get it running.  Then look at the 2 clear pieces.  If you see ANY bubbles, air is getting into the fuel lines.  If you see bubbles in the piece before the filter, the air leak is between that piece and the fuel tank.  If no bubbles in the 1st but bubbles in the second, the leak is between the filter and the IP.

[Linc]

Thanks for the suggestion Solar Steve.

Yesterday, I had a mechanic friend over.  We ran the car yesterday with a setup like you described, feeding diesel to the injection pump through a short line hooked up to a bottle suspended above.  There were no air bubbles in either line (before or after the IP).  The car still wouldn't get above a slow, rough, smoke blowing idle with the throttle held wide open.  Let up on the throttle and it dies.  My friend didn't know what to make of that, and neither do I.  I'm planning to take the IP off and send it off for a rebuild (the seals were leaking on it anyway).

[fatmobile]

Does it have an "OUT" bolt in the banjo on top of the pump?
 Kinda sounds like timing is 180 out.
 Maybe the control coller is froze to the plunger shaft.

[Linc]

Yup, it has an "out" bolt on the banjo at the top of the pump.  My mechanic friend thought it sounded like the timing was out too, but the timing is dead on now.  With #1 cylinder at TDC (using indicator on flywheel and checking to see that valve lobes on #1 are up), the camshaft lock bar fits in, and the injection pump gear lock pin goes in (and the injection pump gear notch lines up with notch on the IP mounting flange).  I also checked the IP pump static timing with dial gauge and found it was a little retarded, so advanced it to specs, with no change in the performance.

I just took the IP out, and plan to mail it off for a rebuild.  I was thinking of mailing it to VWDieselParts.  Anyone had experience with them good or bad for IP rebuilds?

[theman53]

for the money I would just send it to Giles. I think VWdiesel parts is Jack and does a good job, but not like Giles. I spoke to Jack and I think he just sends his out to a bosch rebuilder, but you would have to ask him as I didn't go that route.
For what it is worth don't go to dieselvw.com for your pump. I had an NA done and it wasn't good.

[superbro]

Hears a shot in the dark. I had the same trouble with my
83. You had said you drove it home how much of the tank
did you use? Some one had done a geto veg cov in mine
so when it ran it ran fine but after a bit it would do the
same thing as yours. So I did every thing you just said
the last thing I cecked was the gas tank it was part full
of veg so when it hit the slop it wouldn't run but to the
floor. So I don't know maby not.

[745 turbogreasel]

Fixed a gasser with this problem yesterday.
It would die at idle, and only rev to ~1700.

then I cut off the exhaust, runs great now.

[Linc]

Thanks for the additional help.  Jack has them rebuilt by Kelch Repair Service.  I did some internet research and Wendell Kelch seems to have a good reputation, and being unemployed right now, I'll just have to hope that Kelch can do for $425 what Giles might charge close to $800 for.

I drove the car about 1000 miles from California before it died.  I think I was on my third tank of diesel, so I don't think there could have been any veg oil left in the diesel.  It didn't look or smell like it had any veg oil in it, but now you've got me wondering.  That's one thing I didn't try (running the motor off a batch of freshly bought diesel).  Well, if it still runs the same when I get the IP back, that will be my next step.

Restricted exhaust?  Wow, that's another possibility I hadn't considered at all.  No catalytic converters to clog up on these cars I think, but there's another thing to check after I get the IP back.  I'll post the results to this thread in a month or so, assuming it's not too cold here in Colorado for me to get the rebuilt IP back into the car and test it.

I had better luck this week with the gas engined Toyota V6 that I just rebuilt (top end) in our 1993 former UHaul moving truck (going to have to move in order to find work).  Found the valves were so far out of adjustment that three intakes weren't even closing.  Re-lapped them, re-shimmed to specs, put it back together with new head gaskets, and it runs like a top (well, OK, it runs like a top now, AFTER I first found a huge oil leak, tore it back apart and pushed the left front camshaft seal back in that I didn't get seated right...)

[theman53]

Another possibility is the last batch of diesel you put in. My dad has a Sprinter and was taking it to a show. When he filled up no problems, but after about 100 miles the thing started running rough. End of the story is that the service station put gas in the diesel hole and it didn't do well. He has the receipt for the fuel and it is clearly marked diesel, but doesn't help him now. It did about the same thing that yours did. At the very least you could drain it and see.

Kelch will NOT do what Giles does. You will have a good pump, but not a performance pump.