1974 Jeans Bug - 1000km old engine running very poorly

[kuusj]

Hello,

First of all, English is not my native language, excuse me if something is unclear

A few months back I replaced the worn out 1300cc F-engine in my Tunis Yellow Jeans Bug with a rebuilt 1641cc engine. The first 150-200km's it ran just fine, but then it began 'misfiring' while on a drive. Drove back home, next day everything was fine. A few weeks later the supposed misfiring came back again and went worse as km's went by.

At around 400km's on the engine I went to my mechanic and he checked the timing (which was off a bit), checked the spark plugs (which had the right brownish color), and checked the spark plug cables. Cylinder 3 wire had come loose. We pushed it in and it was so stuck it wouldn't come off again. Problem solved... At least I thought... 50km's went fine, and back was the hesistation when accelerating. Back to mechanic, and he replaced the sparkplug wires because cyl #4 wire was broken in half. I had a year old Bosch set of cables, now he put in 80 Euro Beru sparkplug-cables and new Bosch W8 sparkplugs just to be sure. Sure enough: problem gone. Until another 50km's.

This time we took apart the carburettor and checked jetting, replaced the distributor with a new one, and went ahead and adjusted the valves. Intake valvespring on cyl #2 was broken Took 5 hours to replace that, but sure enough: the engine ran better than ever Only to go on a drive a few days back and completely lose power after 6km's of driving. The engine could hardly keep itself going. Mechanic came to the rescue, we checked timing and that was all over the place while running idle (which was almost impossible in itself because when it finally started it wanted to die without extra throttle). Checked valveprings and they were all fine. When we repaired the valvespring we also did a oil-change. The oil had no metal particles in it.

Driving was near impossible because it would not increase in RPM much if given more throttle and ran like absolute sh*t so we towed it home.

Now we don't know where to search for the problem. I'm getting it towed to his workshop tomorrow and there he is going to run a cable directly from battery to engine to see if something in the electrics is broken. The battery charges fine. Carb gets plenty of fuel, my OEM distributor has both vacuum and centrifugal advance and when the engine was tuned up that worked perfectly. It had very good power when the valvespring was fixed. I'd say around 60-65hp.

Do any of you experts have any clue on what to look for? It's like it doesn't get the electrical power it needs to properly ignite. Coil measured 4 Ohm's. We did a compression/leak test on cyl #2 to check for damage because of that broken spring, compression was perfect. What puzzles us is that the problem went away every time we did something to the engine. I started it today and after 25 seconds of cranking it fired up running extremely poorly so I shut it off.

Engine specs; No expenses spared, most expensive fuelpump etc.
- Linebored AB AS41 case
- New 1641cc AA-pistons
- New EMPI heads
- New OEM crank
- New W100 cam
- New oilcooler/oilpump/distributor/high power Bosch coil/Beru -
plugwires/Bosch sparkplugs
- Completely revised 34PICT carb
- Couple years old Bosch 44A Alternator
- New fuel pump
- New high power Bosch starter

Thanks a lot for your input

[ashman40]

[Xevin]

Expert, I'm not, but I am curious.

What fuel pump did you buy? Brand and Model #. Are you getting 3PSI out of the pump? Your old engine had a Pierburg pump. Is that what you are using?

Also have you checked for clogs and debris in the fuel tank. Also check fuel filter.

Wow! New EMPI heads with a broken valve spring in 600km I hate EMPI. Sorry kussj. What's the torque like currently holding on those heads. Just curious
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Keep on Busin'

[Tim Donahoe]

Ashman may have mentioned the cure: the condenser.

I once had my timing mark going all over the place, and it turned out to be a rather new Bosch condenser which was faulty. When I mentioned this in another thread, others spoke of having problems with new Bosch condensers. I even wrote Bosch in Germany to complain.

These faulty condensers cause erratic impulses, which means this or that spark plug isn't getting spark. The engine will run like shit. Sometimes, you'll get an exhaust backfire, but not always.

Try another condenser and see if this helps.

Tim
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Let's do the Time Warp again!

Richard O'Brien

[Cusser]

[wcfvw69]

I'm also curious about which 'new' distributor you installed. Most of them now are all Chinese made and are poor quality. Sticky pivot plates, quickly blowing vacuum canisters, etc.. You can check this new distributor with a timing light. Fire it up and rev the engine. The timing light should show you if the timing is advancing on the pulley.
You could also install a hand vacuum gauge on the vacuum canister (if it has one). Pump it up and stop. Does the vacuum can hold the vacuum or leak down? If it holds, take the distributor cap off the distributor. Pump the vacuum gauge. Do you see the vacuum can rotate the breaker plate?

I recently installed a NOS condenser in one of my bugs. After finishing the tune up, the engine had a low grade miss under acceleration and load. The hotter the engine got the worse the hesitation got. It idled perfectly.

I changed the NOS condenser to a known good used one. It fixed the hesitation and the car ran fine again.
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Decades of VW and VW parts restoration experience.
The Samba member since 2004.

**Now rebuilding throttle bodies for VW's and Porsche's**
**Restored German Bosch distributors for sale or I can restore yours**
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**Restored Porsche fuel pumps or I can restore yours**
**Restored Porsche distributors or I can restore yours**

[kuusj]

[wcfvw69]

Is this a fuel injected engine or carb? If carb, it sounds like you possibly have a spark plug wire crossed in the distributor cap.
_________________
Contact me at [email protected]
Follow me on instagram @sparxwerksllc

Decades of VW and VW parts restoration experience.
The Samba member since 2004.

**Now rebuilding throttle bodies for VW's and Porsche's**
**Restored German Bosch distributors for sale or I can restore yours**
**Restored German Pierburg fuel pumps for sale or I can restore yours**
**Restored Porsche fuel pumps or I can restore yours**
**Restored Porsche distributors or I can restore yours**

[kuusj]

[bluebus86]

Id find another mechanic. sounds like your mechanic is simply replacing parts for no reason, why was the distributor replaced? did this mechanic build your motor too? why was the spring broken? were the motor parts properly put togther? what was the compression ratio set too? the builder should know this, unless the builder simp,y slapped the parts togther, look out.

the distribuator needs to match to the carburator at least.

old style pumps are rebuildable, new diaphram and they dont leak anymore, so save the old one. when a new pump is installed, the fuel,pressure MUST be checked and adjusted as need to 3 to 5 psi.

your mechanic found a defect in the broke spring metal? Im not buying that one, what did he say, the metal crystallized at the break? not,likely, what was this defect he found?

sound like you were sold a poorly made motor, and have a clueless part swapping mechanic who will help you empty your wallet. evidently not a full time mechanic if he runs a parts store.

what a mess
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Help Prevent VW Engine Fires, see this link.....Engine safety wire information

Stop introducing dirt into your oil when adjusting valves ... https://www.thesamba.com/vw/forum/viewtopic.php?t=683022

[sb001]

kuudj, would it be possible to post a few photos of your engine bay? With the list of symptoms you described being so varied, I doubt anyone could accurately diagnose whatever is going on (it sounds like about 4 different issues.) But I have often found it helpful when there are pictures to look at to determine a possible cause/ solution.
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I'm the humblest guy on this board.

1969 autostick sedan, family owned since new
1600 SP engine
Solex 30 PICT 3 carburetor
Bosch 113905205AE autostick distributor

[mukluk]

The symptoms do sound most like a problematic condenser.
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1960 Ragtop w/Semaphores "Inga"

[kuusj]

[kuusj]

Edit: *oops* I thought I was editing my last post...

Here is an album with full resolution pictures: https://imgur.com/a/T8uYH
The car has been picked up by the mechanic an hour ago, I mentioned the condensor but he seemed convinced there was nothing wrong with that thing (It says "Olympic" on top of it btw) because the points were not burned severely. I'm no expert so all knowledge I have is either from reading forums/watching video's, I'm sorry if I get technical stuff mixed up. Tried to convince him but he insisted that the thing could not be faulty, but he said he does know that bad condensors can cause various problems As long as I don't have to pay for his working hours (50$ an hour) he can try everything he wants I guess...

I'll post some small versions of the pictures below with some comments:

It is currently filthy and greasy from working on it, but there are no oil leaks anywhere. I'm still using the ugly 1300F oil-bath air-cleaner. Other reused parts are the alternator-stand and the alternator itself (which is a 50A btw, I said 44A previously).

The best image I could take of the numbers on the distributor. I guess it's a 050 then? The VW and Audi stamps suggest it's not from China I suppose. It also looks like there is a Bosch logo between the 050 and Audi logo. Edit: lol, so after some searching it looks like a 050 is pretty 'rare', and not stock, but a genuine German Bosch part. Parts stores I looked up have a specific condensor for this distributor, and I'm pretty sure I don't have that one on my car...

This is the fuel pump. Like I said, we checked if the thing pumped good fuel and it does, the fuel 'chamber' of the carb was 3/4's filled which from what I've read is perfect.

Underside. I'm still using the 1300F stock exhaust because I'm not sure what aftermarket exhaust I want, yet. And again, it's dirty

[Cusser]

Easy to check, run the engine at night, see if you can tell if any sparks are jumping to engine metal. I can't tell by the coil in your photo, wire looks spliced with butt connector there. And #2 spark wire looks like it's touching hot intake manifold.
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1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297

[sb001]

Two questions:

1. From your photo it appears the positive "+" terminal on your ignition coil is on the right side (viewing from back of car) and the negative "-" terminal is on the left. I just want to make sure that the green condenser wire coming off your distributor is indeed connected to the LEFT (negative "-") terminal--kind of hard to see where it goes once it wraps around the distributor.

2. it looks like you are using an autostick intake manifold, it has that largish angled port coming off the neck of the manifold with a short hose attached. Can you please verify that that hose is blocked off with a bolt or some such object? If that hose is open or not sealed off completely it will cause a significant vacuum leak.
_________________
I'm the humblest guy on this board.

1969 autostick sedan, family owned since new
1600 SP engine
Solex 30 PICT 3 carburetor
Bosch 113905205AE autostick distributor

[bluebus86]

1...I see that apparently the electric choke is not hooked up, no wire visible on its terminal. that is one problem, if it is missing. The choke terminal should be connected to the ignition terminal on the spark coil, terminal 15 on the coil. the other small terminal on the spark coil is number 1, it should have the wire that goes to the condensor (capacitor) attached to it. both the number 15 and 1 should be printed on the coil, often molded into the bottom cover, make sure the corrct wires are hooked up there, not mixed up. (may use a mirror to see the two numbers on bottom of the coil, molded into the plastic)

the igintion wire from the key switch goes to number 15, along with the electric choke wire and the antirun on valve (the antirun on valve is in on the left side of carb, with the red sheathed ended black wire on it make sure it is on 15 terminal on coil, the wire from the key switch should also be black, it too should be on the 15 terminal so there should be three wires connected the 15 terminal, the one from the key switch, one to the antirun on valve, and on to the choke, and all should be black.
on the # 1 terminal of coil there should be one green wire to the condensor, and one grey/Green wire that goes to the diagnostic plug, althlugh the motor will run just fine without the grey/Green wire.

2...There is apparently a wire from the spark coil, orange in color draped over the left side heater hose, pinched on the hose clamp, bad place for that wire, if the clamp cuts thru the wire. route it better, also no orange wire is supposed to be there, what is it for, do you have a tachometer installed? If you have a tachometer added, that might explain its presence.


Anyway, check out the wires, confirm what you have.

OR

Take another photo and post, make it a bit more close up of the coil, and remove the dizzie cap to get it out of the way so we can see the connections on the coil better.


Keep Buggin!
_________________
Help Prevent VW Engine Fires, see this link.....Engine safety wire information

Stop introducing dirt into your oil when adjusting valves ... https://www.thesamba.com/vw/forum/viewtopic.php?t=683022

[Cusser]

[bluebus86]

[kuusj]