Definitive answers? Re: Awful performance of my 85 VW Diesel

[the vegenator]

I'm at the point with my 'daily driver' 85 VW Jetta (1.6 NA) that I'm ready to take it to the nearest pro VW Diesel mechanic - better yet, to Jack's! - for some definitive answers and professional help. I've done everything I can - given my limited technical know-how - to get this car running smoothly at 44 mpg, to no avail. This post is my last ditch effort to see if anyone here knows what the heck could be wrong with my car! After this, West Union, Ohio may very well be the next place I go to remedy this problem.

I've had this car since 2004 (bought it on eBay - previously someone's "project" car!) and it has never run right, compared to my other 85 diesel jetta (rip) which never experienced the same problems. For example:

- only gets 30 miles per gallon (on the highway even!)
- idles rough after startup no matter the outside temp. I have to keep it revved up in order for it to stay alive until I get going!
- loud metallic pinging/ringing noise from under the hood (pulley bearings?)
- smells strongly of exhaust inside car (people hate riding in it!)

Before I bought this car, the previous owner claimed he had rebuilt the engine under the "supervision" of a "professional diesel mechanic." The engine looked shiny and new enough but all the problems with the car and all the other shoddy work he did putting everything back together makes me question how "professional" of a rebuild job this engine had! Add to that the fact that he bragged about having run straight veggie in the main tank and veggie oil mixed with GAS makes me really wonder what this car had to endure! With that said, here's what I've done to try and get this car running right (based on suggestions and advice from fellow VW diesel-heads):

- replaced send and return fuel lines (including cylinder-to-cylinder return lines and plug), installed stock diesel filter, dropped, drained, and cleaned the tank, installed stock fuel/water separator (previously missing)
- had injectors rebuilt and reinstalled
- replaced injection pump with new, slightly different off-the-shelf pump
- adjusted IP timing
- adjusted fuel/air mixture
- adjusted valve lash
- tested engine compression - results 'normal'

At this point I'm at a loss, and I'm willing to do whatever it takes to get this thing running smooth and efficiently. If you've got any ideas please send them my way! Otherwise, to West Union Ohio I go!

[MizPahPAH]

AAAAHHHHH.... I am not crazy I have a 86 jetta n/a and have / had some of the same symptoms. Rough Idle, lifter noise, marbles / at idle / midrange, greyish smoke on acceleration only seen at night in others headlights. mine gets 47mpg though. did you check acuracey of your odometer?

are you backing out the full load screw to get better mileage or to get rid of smoke, Maybe someone / PO put in the wrong tranny?

does your pump have the cold start Idle bar on the engine side of the pump? Mine has the cold start lever bar and I was trying to adjust Idle with the fule lever adjust screw instead of the Idle screw. doh!!

I have been driving with the fuel tank cap off and on and I think I am seeing a diffrence in performance Idle and smoke

[82vdub]

You say you've checked the IP timing, but have you verified that the cam position to crank position is as it should be? If your loud noises can't be solved by retarding the IP timing (no matter what the gauge says), then assuming the valvetrain is good, I'm thinking the valves could be kissing the pistons. If the PO used too thin a head gasket, this could cause the piston to be kissing the head/valves too. If you have not tried rotating the engine by hand with a wrench on the crank, you may want to try this and see if you can feel a hard spot, as a piston gets to the top and maybe hits something.

As for fuel mileage, not sure on this one. Brakes dragging, bad wheel bearings, swapped transmission with a final drive that runs the engine faster, poor fuel, poor injectors, overall engine timing. Not sure on that. The engine always running rough is probably a key symptom of what could be up causing the poor fuel mileage, and/or engine noise. How's the engine for power? If it's running rough, it may only be running on 3 cylinders, or partially the 4th cylinder.

[Fatmobile]

Ever try turning the injection pump with the engine running?

[T-BONE]

Remove an injector and seat check for carbon buildup under the seat in the precombustion chamber. may have some buildup after burning alternate fuels. I had this problem with a 1.5 pickup while experimenting with using burned engine oil as fuel in summer it was great but in colder months it wouldnt start so I thinned it with avgas that i could get from work avgas still has some lead in it and the lead built up under the injector seats untill the hole underneath was about the size of a toothpick tip resulting in very poor performance PO may have used some alternate fuel that was conducive to carbon buildup.

[the vegenator]

I'm revisiting this post from four months back, since I've had some time to investigate some of the things folks were suggesting.

Right when I was about to seriously confront all the issues with my IP/engine, I was confronted with the fact that the whole front end (steering/suspension/etc) was shot. Ended up spending $500+ on parts to replace front and rear wheel bearings, CV axles, ball joints, control arm bushings, inner and outer tie rod ends, strut bearings, rear struts, and rear wheel cylinders... definitely a learning experience. Plus my car rides like a dream now!

With the new front and rear wheel bearings and the new rear wheel cylinders, I can cross a few more potential performance issues off the list.

Anywho.... I've been doing a lot of highway driving the past few weeks - I'm still only getting around 26 mpg city and 32 mpg highway (at 70mph). Power is not great. Avg top speed is 73 (75-80 with a strong tailwind, 85 mph topspeed downhill with a tail wind!). Up hill is slooow. My other 85 1.6na jetta performed so much better than this one.

Idle is still rough and rumbly, especially on startup, but even when engine is hot after driving for a few hours. Possibly sounds like it's missing on one of the cylinders? All four cylinders got compression readings of 400 to 425. If one of the cylinders isn't firing correctly, wouldn't the compression test show it?

I handturned the crank bolt and didn't hear or feel anything out of the ordinary. A few VW mechanics in Louisville listened to the loud marble-in-pan sound I mentioned and thought it was coming from some pulley bearings - possibly ac. Without taking the V belts off and running the engine it's hard to know for sure though.

I checked for accuracy of my odometer against GPS, there's a small discrepancy, but such that it shows I'm getting worse mileage than I thought. Good to know.

My transmission code is stamped with ACH. I doubt anything in the transmission or final drive was modified by previous owners.

My IP has electric/automatic cold start - the pull lever doesn't work with this one. I haven't adjusted the mixture screw in a while ... I was afraid I would further compromise my already low power for better fuel economy. That should be my next step though.. I haven't hand-turned the pump either - I'm absolutely intimidated by the thought of messing with timing, but want to overcome this! I had the timing checked and set by the local VW mechanic 10,000 miles/3 years ago.

-- oh yeah, it's important to emphasize that all these issues were present when I bought the car, with it's original IP. I drove the car for 10,000 miles, thought the replaced the IP with what it has now, and I've probably put 15,000 miles tops since then.

And regarding carbon buildup... when I pulled the injectors to have them rebuilt, I didn't notice anything strange when I peered inside. Granted, I was more curious about the glow plugs working right, and never felt around for buildup.

Should I keep messing around with timing, fuel mixture, etc? Or am I dealing with something greater than I can imagine? Any suggestions on what should be my next move?

[MizPahPAH]

See If I am reading this right

You checked compression 400 to 425 accross the board

changed IP to diffrent one
Cold start advance cable is not hooked up

Injectors have been rebuilt = pop pressure =
timing has been adjusted to = ?

How is smoke? white = unburt fuel

Things that come to mind if pop pressure of injectors is within spec and timing is set to spec with cold start lever on pump pushed towards front of engine "twords pulleys" and you are getting bad Marbles and rough Idle sounds like advanced IP timing.. Are you sure the TDC mark on the flywheel is actually TDC.

Have you checked Internal IP pressure
Any air in the fuel lines
Fuel filter / water seperator /sump screen in the tank

[the vegenator]

You checked compression 400 to 425 accross the board

changed IP to diffrent one
Cold start advance cable is not hooked up

Injectors have been rebuilt = pop pressure =
timing has been adjusted to = ?

How is smoke? white = unburt fuel

- yep, compression tested at shop. those were the readings they gave me.

- IP is different, with no place to hook up a cold start advance cable.

- Diesel Injections rebuilt the injectors - I haven't dealt with timing since before I removed the injectors.

- There is white smoke. I suspect excess fuel ($$) is being sent out the tailpipe.

Things that come to mind if pop pressure of injectors is within spec and timing is set to spec with cold start lever on pump pushed towards front of engine "twords pulleys" and you are getting bad Marbles and rough Idle sounds like advanced IP timing.. Are you sure the TDC mark on the flywheel is actually TDC.

Have you checked Internal IP pressure
Any air in the fuel lines
Fuel filter / water seperator /sump screen in the tank

- I can only assume that pop pressure is within spec.

- I had ruled out timing issues because the old IP was retimed when I purchased the car to fix the problem, then the new pump timing was set, then readjusted a few years later (all by other VW mechanics). Timing however, might be something I need to learn to tackle myself.

- Should find TDC mark and make sure it is TDC.

- IP pressure is something I'm very curious about. I've read that it increase fuel efficiency by 20%!? Is this something that I could tackle myself?

- As far as air in fuel lines, I don't have a clear line installed. That's an easy fix though...

Looks I have a full plate of things to check and double check now. The problem with this car has always been the fact that other different mechanics in different states have done one thing or another.

There's never been a holistic tune-up approach.

Time to buy some new tools and hole myself up with nothing but the car, a garage, and this forum.

[82vdub]

White smoke is typically unburned (or poorly burned) diesel fuel. This is either low compression (which according to the numbers you don't have low compression) or retarded timing. Too rich fueling is black smoke. I'd try advancing your IP a little and see what that does for you. This is a very easy procedure. Don't forget to relax your injection lines after you move the position of the IP. That's a key item to not forget.

[the vegenator]

Well, it's been a nearly a year since this thread died out, but I've still slowly but surely been trudging away at my big old mystery problem. Since I'm back home for the holidays and have some extra time on my hands, I figured I'd give a quick little update on my progress...

The biggest issues that I have been trying to work past have been low fuel economy (25-32 mpg - according to gas pump to GPS equation) and hard startup/rough idle.

Here's what I've done in the past year:

Eliminated ringing noise: This was easy. Turns out a thin metal washer that runs next to the idler pulley was sitting loose, waking up the neighborhood whenever I drove by. The noise is no more.

New Fuel Lines: New 5/16" steel lines for supply, with rubber line from steel to tank. Opened up in-tank fuel sender and checked for blockage. Checked out fine. Eliminated stock water separator (and any potential vacuum leaks). New fuel filter, and clear lines running to injection pump (with rubber lines in between clear vinyl and hose clamp). Since I'm running veg occasionally, I set up the system with a return loop instead of return-to-tank system. The fuel lines still seem to tank on a bit of air. Tiny bubbles at times, but also larger air bubbles. Since the hose clamps are tight, I can't seem to think of where the air is coming from.

Pimped out Glow Plugs: Following the instructions on this forum and Vincent's site, I wired up the solenoid/fuse panel with four new duraterms from the local VW parts shop. System seems to be working just fine (indicator light shows voltage), BUT I didn't pull the injectors to do a visual inspection. (Number 4 injector was stuck solidly in place and I didn't want to risk damaging the head/threads).

The extent of my starting issues is such that I can't start it on a cold morning and expect it to stay on without leaving it at high rev for about 20 seconds (when I let it go to rough idle). If I had my block heater plugged in, then it will start and idle relatively smooth - even if small bubbles are in the lines. WHAT!?

Seems like the new lines are likely helping a bit, but bubbles are still there. New glow plug system isn't really giving me desired results. Block heater plugged in makes for a sweet and easy start.

But I'm still getting 30mpg or less. And that's what's killing me the most.

[79 300sd]

I have an 85 Golf NA with an ACH trans. Been running it for the past three years and have only been able to get 33mpg at best also. Power has always been very low when going up hill. It was pretty normal to drop to 55mph uphill on the interstate.

I have tried two known good used sets of injectors (pop tested them before installation), checked and adjusted pump pressure, changed spring and shims for more advance, confirmed advance was working properly with a timing light, set the timing to spec and also tried other settings in search of more power, adjusted the max fuel screw, did the governer mod.

That engine died last week on my way to work. Started tapping and lost power very quickly. Within a quarter of a mile it died and locked up. I can turn it by the crank bolt about a 1/4 turn. I'll see if it is even worth rebuilding at a later time.

I'm in the process of installing a 1.5 taken out of an 80 rabbit I had sitting behind the shop. I'm also installing a t3 turbo from a mercedes 300sd and fabricating a 2.5" downpipe. I'm hoping that I'll have more power and mileage now. It has been so very frustrating having low power and mileage for so long.

David

[coke]

The 1.5s are notorious for cracking blocks, and adding a turbo on to it is really pushing it as the 1.5s were never designed with turbochargers. I'd use cylinder head studs if I were you.

[the vegenator]

David - you get any results after fiddling and modding? Just a busted engine? I'm curious if you ever got any power or economy back before it bit the dust. There's nothing like a finicky, persistent problem that can ruin a VW diesel experience.

I can zip around town with ease, but it is a pain losing power up hills on the interstate. My other identical jetta could accelerate up long inclines, whereas this one is in the slow lane at 50-55 mph.

This is the second injection pump that this car has seen since I bought it. The lack of power and fuel efficiency were a problem with the old pump. The replacement pump was put on in 2006 - a 108A I believe (electronic cold start) - which is what's on it now. I've fixed a lot of other problems since I bought the car, but the same problems I've been griping about never changed from one pump to another.

Two bad pumps? Something that could get fixed with a new (remanufactured) pump? $500 is a lot to drop at once, though...

[82vdub]

vegenator, your air in your supply line is probably coming from your loop return fuel line. The IP sturs things up and the air is probably coming from that. It's normally not a problem as it goes back to the tank, but since you short circuited the loop, it's putting it back in your fuel line.

[TylerDurden]

Anything less than 40mpg in a sedan seems pretty lame.

Since all other variables seem to have been covered, I would verify TDC with a probe in #1 cylinder, then verify/mark the flywheel. Recheck valve and IP timing at that point.