Tracking down a driving issue

[secretsubmariner]

I've recently suffered a series of breakdowns. In an effort to avoid rambling on with my usual enthusiasm, I will describe the two most recent breakdowns and what I did to solve the problems. (I have been avoiding posting troubles like this lately, refusing to ask silly questions without properly searching my issue. This time, I don't know WHAT I should be researching to solve my own problems)

1978 Fuel Injected 2.0L

First Breakdown: Driving home from work, less than a mile from home. I took off from a stop light in first gear. The bus revved up and took off fine, but 10 feet in the bus started bucking. Thrust from the engine itself was cutting out. I held in the accelerator pedal and the bus would go, then power would die, then come back, and die out again. *The fuel pump continued to whir the whole time, and the engine never actually died when this happened* I could never get the bus up to a gear past 1st because of the low power output, so I couldn't confirm at that time if this was occurring at other gears or speeds.

I managed to limp it into a neighborhood and got it towed home with AAA.

First Breakdown problem solving: My first inclination was maybe fuel starvation. I swapped out the fuel filter. The old one did not appear to be clogged, but better safe than sorry. It did have a few rust specs in it, but I was able to blow through it with the same pressure and output as the brand new filter. The bus started right up.

Then I took the bus around the square mile, I did 4 laps to really blow through the gears, even using 4th going 50 in a 35. The bus was still doing a bit of a jerk - particularly in second going up a slight hill. This led to my second breakdown.

Second Breakdown: The bus was still doing its little jerky thing, but only ever so slightly when building up speed. I took the bus on a little bit of a longer trip this time, doing a 2 square mile lap. I was headed uphill, doing about 39 in 3rd, and the accelerator pedal falls flat to the floor - no response. I immediatley think the cable snapped. That's it! I thought. The cable has been stretching, not opening the throttle all the way, causing my lack of power and jerkiness. I manage to reach the crest of the hill on momentum only- barely coasting into a neighborhood. I crawl under the bus, the cable is still connected at the pedal. OK. Check the throttle body, the cable is till connected. WTF? The cable had stretched 3, maybe 4 inches. Still TIGHT in the barrel on the throttle body. OK. AAA tow again.

Second Breakdown problem solving: Under the bus, I noticed my clutch sleeve or "bowden tube" is split in 3 fucking places. Replaced with new, made in Germany. I replaced my throttle cable with a brand new cable, made in Germany. (Thanks Bughaus!). After the new sleeve was on, I adjusted my clutch cable a little bit too tight (I had 0 inches of give in the clutch pedal). So I backed the wingnut thing off several turns. It may not have been quite enough- I may need to readjust, I still don't think I have 3/4" of give before resistance at the pedal.

Ok! Awesome! New cables, copious amounts of lube recommended by Robbie in his Office Hours series, and I'm good to go, right?!

Took off in the bus, and it's still doing the same thing!! Uneven power in 1st, I'm clutching in and out and giving it gas as evenly as I can. It bucks and gives power, no power, gives power, no power. Eventually it "catches" and I'm able to get enough speed to clutch up into 2nd. I cannot recreate this 'jerk' in any other gear so far (although before breakdown #1 it was doing it in second as well). The bus starts right up, idles fine, revs fine. I only went around the block this time just in case I breakdown again, so I couldn't REALLY blow it out to see how it behaves in other gears, but I did do a little speeding and got it up into 3rd in my neighborhood. It seems fine after it gets out of first.

Now I'm at the point where I just don't have enough experience driving manuals to even know where to start.

Some more info about the engine, etc.

Rebuilt engine. New cam, new hydraulic lifters, balanced rotating mass, line bored case, new rod bearings, etc. etc. New valves and guides. Reused pistons and crank. New seals all over. Plugged oil galleys all over.

Transmission. Plastic bead thing replaced with steel. Axle port things resealed. New nosecone seals. Full of fresh transmission oil (I don't remember if it was GL 4 or 5, but if that's super important I can report back)

The clutch, pressure plate, and throwout bearing were all almost brand new when I took the engine apart. I decided to reuse them all after a very thorough inspection. (the story of bus was, transmission was rebuilt 5K before it was parked. I don't know exactly what that entails, but these new items make me believe it is at least partially true.

I put about 130 miles on the rebuilt engine before I started having this issue. Mostly short trips, up to 20 miles round trip. The bus prior to breakdown #1 was starting right up and driving relatively smoothly. I was driving it about every other day for several weeks leading up to this.

My shifter itself does have a little bit of a "clunk" under the front floor when shifting into 1 and 2. I have replaced all the shifter components along the shift rod, including the shuttlecock looking things, the bellows, and swapping in new bushings into my original German shifter mount thing that connects to the transmission itself. I've adjusted the shift plate several times and I still haven't found that sweet spot.

*I also heard an interesting sound, just ONE time, very very briefly. A high pitched squeal that lasted maybe one second, no more. I was so distracted by the jerking that I don't exactly recall when that squeak happened. It may have also been a suspension squeak or another rattle of some kind. I thought it might be important*


Where can I start to search? Seasoned bus drivers of the samba, what does this sound like to you?
_________________
-Tony
ᏣᎳᎩᎯ ᎠᏰᎵ
1978 Champagne Edition Bus FI
1970 Auto Fastback FI

[jtauxe]

Do you have points in your distributor, and, if so, have you cleaned off any "tits" and regapped them? I have had similar crappy behavior when my points are not set up nicely.
_________________
John
"Travelling in a fried-out Kombi, on a hippie trail, head full of zombie..." - Colin Hay and Ron Strykert
http://vw.tauxe.net
1969 Transporter, 1971 Westfalia, 1976, 1977, 1976, 1977, 1971, 1973, 1977 Westfalias,
1979 Champagne Sunroof, 1974 Westfalia Automatic, 1979 Transporter, 1972 Sportsmobile, 1973 Transporter Wild Westerner, 1974 Westfalia parts bus, 1975 Mexican single cab *FOR SALE*, 1978 Irish 4-door double cab RHD

[ImAddicted]

Is your alternator belt properly tensioned? What is your battery voltage like?
_________________
1979 Transporter (sold)
KC1MUR

[busdaddy]

[SGKent]

[airschooled]

A fuel pressure gauge will tell you a bit about the pump's mojo. (Several FI pumps I've installed this year sounded like mosquitoes right out of the box. One was Bosch.)

Points and timing have to be good, and vacuum leaks sussed out. (Check the torque on your eight intake manifold nuts. 13mm.)

Post a picture of your AFM with the cap removed. I'm curious about track wear.

Measure TS2 for resistance. We want to see above 1,200 ohms when cold, and below 250 ohms when fully warmed up. (Ballpark figures here; the engine can tolerate a LITTLE variance.)

Robbie
_________________
Learn how your vintage VW works. And why it doesn't!
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[Xevin]

Because, it is easy. I’d inspect your fuel lines for any “Kinks” I’ve seen that happen on a buddy’s bus. Coincidentally a Champagne too.
_________________
Keep on Busin'

[aeromech]

Gary once found a sock in the gas tank on a bus brought to him with a similar issue.

Steve, you have a good memory. Yes, I had some kids from Europe come to me with a similar problem in their 1974 bus

Drained the tank and almost burned up the bus because I didn't disconnect the battery

Found this and pulled it out in pieces through the tank outlet

_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
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Capable of leaping tall buildings in a single bound

[secretsubmariner]

[busdaddy]

[airschooled]

The mounts being sold today are Mercedes parts, so you’ll have to modify them a little, or else they just buzz more.

Thread an M6 nut onto one end. Cut 3-4 threads off with a cutoff wheel or fine saw, then remove the nut to “clean up” the threads. The cut end threads into the chassis, the long threads face the pump.

The lazy hack way, is to just leave the M6 nuts on and not cut the threads, letting the bits act like a spacer. (This just leaves more metal-to-metal contact for vibration transfer.)

Thanks for the Office Hours plug see you in season two!
Robbie
_________________
Learn how your vintage VW works. And why it doesn't!
One-on-one tech help for your Volkswagen:
www.airschooled.com

[secretsubmariner]

[Wildthings]

If it sat for 5 months with ethanol laced fuel in the tank, you may well have sticky injectors at this point. You can try adding Tectron to the tank and see if that works. On my '91 Vanagon that sat for several years it was adding a bottle of synthetic motor oil to a full tank of gas that finally got the injectors functioning well. If you don't drain and clean the tank your problem may persist for 5000 thousand miles as the gunk on the bottom of the tank slowly dissolves and passes through the injectors fouling them again.

[secretsubmariner]

[SGKent]

[secretsubmariner]

[airschooled]

Right hand on the wrench, left hand tensions the belt to allow it to grab better. 90% of T4's I see act like this.

Frankly, if it doesn't slip a little towards TDC, I'd be concerned that the belt is too tight, or the engine has low compression. Let it slip a little; the alternator bearings will thank you. (It's not a T1 where you lose cooling, after all.) Either way, a belt slipping on an otherwise good T4 has never in the history of VWs caused a stutter. If the battery can start the car, it can power your ignition system for hours without the alternator.

Make sure you're adjusting your points at the spot in rotation where they are "most open." This is not TDC; you must watch the points while the engine is rotated slowly. Been there, done that, got the t-shirt. :)

The fuel pressure gauge will pay for itself on your Type 3. We can talk about that and voltmeter readings whenever you'd like.

Without a way to set timing, you won't be able to do a complete job of points adjusting, since adjusting the points alters ignition timing. Luckily you have an all stock engine, so you can static time to 5°-7° btdc with the key on, engine off, and you'll be damn close to perfect. I'd recommend that after points adjusting for now.

The Air-Schooled Static Timing Procedure.
1- shifter in neutral, key on.
2- rotate engine from 40°btdc to 10°atdc.
3- somewhere in there, the distributor/coil will make a tiny popping sound. This is your spark firing.
4- turn the distributor until the popping sound occurs at your desired degree.
5- snug distributor, enjoy.

Gotta go make my dual horns louder in time for the weekend protests…
Robbie
_________________
Learn how your vintage VW works. And why it doesn't!
One-on-one tech help for your Volkswagen:
www.airschooled.com

[secretsubmariner]

Ah, so I do need to just put my back into it. LOL I will definitely do the two hand trick tonight.

I do realize the points being most open isn't TDC, foolishly I was trying to use less words to illustrate a point, which wound up being the long way around anyway.

Why use lot word when few word do trick?

I will examine the points when they are "most open", scrub up any titties, and report back.

[SGKent]

you can also stop when it starts to slip, wait 15 - 20 seconds while the compression bleeds off, and then complete the stroke. Never leave the wrench or socket on the pulley even if you get a phone call in the middle of working on it, because you will walk away and forget about it. And who knows what it will hit when you start the engine with it on there.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Wildthings]