TheSamba.com :: View topic - Bus is Running again!!!!(No spark, then weak compression???)

Sun Nov 01, 2009 3:20 pm

:(
1973 1700cc with single Weber carb
I finally have figured out my spark woes and bus still wont start. My bus was in dry storage for the last 6 or 7+ years. I have recently been trying to resurrect her. When I got the bus back I put some mystery oil down the cylinders, drained the bad gas, replaced the fuel lines, new points and condensor.
:? Today I checked compression on cylinder 1 and 3 and compression is only about 100 or so. Seems pretty low to me. My tester wont reach 2 and 4 without removing tin. Anyways my guess is that the rings are stiff or stuck from sitting so long. I figure I'll need to pull heads and cylinders and replace or loosen rings. Bus ran great when parked. Any thoughts??

Sun Nov 01, 2009 3:32 pm

adjust valves

Sun Nov 01, 2009 3:35 pm

100 pounds is pretty good for an engine that has not run in a while. Certainly plenty to get it going.

I have resurrected many old engines, the latest was a 1975 Porsche 911 that was out of commission for 10 years.

What exactly did you do to get the ignition working? You may have to retime the engine.

If you have spark pour a little gas down the carburetor and try to start the engine. It should run for a few seconds even if the carb is not working.

If you get a backfire or it won't fire at all there are other problems.

Here is one thing that is specific to VW and Porsche engines, if the spark plugs are fouled or gummed up with oil and unburned gas the engine won't start.

Even if everything is fixed correctly, they will turn over and sort of "chug chug chug" but never actually run.

The cure is to take out the plugs and sandblast them or replace them. I prefer the sandblast treatment, get the engine running, burn off the gook in the cylinders then install the new plugs.

There is a gadget called a "spot blaster" that is perfect for this. It runs off your air compressor. They only cost around $15 bucks and are handy for bodywork too.

If you do sandblast your plugs inspect them carefully under a strong light with a magnifying glass. There are always 1 or 2 grains of sand lodged down inside even after you blow them out with air. Take a sewing needle and pick out the sand then blow clean.

Sun Nov 01, 2009 3:37 pm

100 lbs is not really high, but the main thing is to have all cylinders within 10 lbs of each other. 140, in my opinion would be real good. Try to get her running and drive it slow for the first 1,000 miles or so, then re-run the compression test, you maybe surprised! Be sure to change the oil and filter, and clean the strainer screen. Good luck!

Sun Nov 01, 2009 4:11 pm

Before you put the plugs in spin the engine with the starter to blow out the excess oil.

Sun Nov 01, 2009 4:33 pm

I just pulled the carb off and am going to clean it and see if it is gummed up. put it back on and try and start her again. fingers crossed. I think cleaning the sparks and changing the oil is in order too. If with all that done she still wont start who knows? what next? thanx for the help guys
Even without it running yet its just nice to have her back in the yard. The wife and kids and I poppped the top and had lunch out there today!

Sun Nov 01, 2009 8:14 pm

73vwbussss wrote: I just pulled the carb off and am going to clean it and see if it is gummed up. put it back on and try and start her again. fingers crossed. I think cleaning the sparks and changing the oil is in order too. If with all that done she still wont start who knows? what next? thanx for the help guys
Even without it running yet its just nice to have her back in the yard. The wife and kids and I poppped the top and had lunch out there today!

An engine (any engine) needs three things to run.

1) Spark

2) Gas

3) Compression.

If it has the right amount of gas, a good spark happening at the right time, and decent compression it has to run. It has no choice.

I always start with the spark. Make sure you have a good spark, happening at the right time, in all cylinders, and don't mix up the plug wires. Then, a little gas and it should fire off. If it won't keep running check out the carb. And of course, it should have some compression.

If you did the ignition right, and it has 100 pounds of compression, and the carb is working right, it should run pretty good.

Give it some break in miles. Tune it up and it should be good.

Sun Nov 01, 2009 8:46 pm

As described above, try a "pinch" of gasoline down the carb (or starting fluid). Your compression should be enough to get her going. You have to narrow it down. Try the starting fluid... then you know if the problem is in the fuel system, and you can go from there.

Sun Nov 01, 2009 9:07 pm

100 pounds is fine for a used, cold, not run in years engine. Check it again after 500 miles. Do adjust the valves. If they are off by much then check them again in 100 to 150 miles to see if they are stable.

Be sure that the throttle is open when you crank it to check compression, and count the strokes. I usually do 3 then read.

Sun Nov 01, 2009 9:33 pm

Glad to hear that 100 lbs is good for well rested engine. I pulled out an old note book that I had written down a compression test in from back yrs ago when she was running and all four were around 135-140. Anyways a have good strong spark on all four, and descent compression. I hope to get time to take a good look at the carb tomorrow and put that back on...might have to try the starter fluid. Who knows.

Mon Nov 02, 2009 6:10 am

Starter fluid is a good way to make sure you will not have good compression in the future. Throw that stuff away so you will never be tempted to use it.

Mon Nov 02, 2009 3:34 pm

Yeah Ive heard that about starting fluid before and haven't used it yet. Funny thing though my first truck was an 83 Chevy stepside. Thing loved its either. Especially when it was cold. I used it on that truck hundreds of times and never had any problem. The guy I sold the truck to must have had good luck cause I would see it still driving around years afterwards. Anyways back on subject. I cleaned the carb up, really not dirty, and put it back on just before it started getting dark. (4:45 :( ) I tried to get her to run but still sitting idle. I feel like I am getting close though. Turned her over and there were a few backfires and hickups.

If I only changed the points and condensor that shouldn't have screwed up the timing right? As far as I know the distributor hasn't moved? In past though I remember when my timing was off the bus still ran it just ran like crap. Anyways thanks everyone for your help. Any further help/ideas is appreciated. I hope to get some pictures on here soon too.

Mon Nov 02, 2009 8:22 pm

Did you remove the distributor to install the new points and condenser? If you did, are you sure the got the cog on the bottom of the distributor shaft properly aligned with the slot on the distributor drive. If not your timing may be way off and could be causing the backfiring and spitting you are seeing.

Tue Nov 03, 2009 2:30 pm

Hey all thanks so much for all the help. I am sure to hit this sight up again as I go through my restoration. To answer your question I did not remove the distributor. Anyways I discovered that the wire going to the automatic choke was loose. I fixed that and she fired right up. :D :D :D :D :D Not sure if that was it or not. I also put 2 more gallons of gas in the tank. That makes 4. Maybe 2 wasn't enough although I don't think the gas was it. Anyways it seems to be running well. Sounds good anyways. I have discovered that my clutch cable is not disengaging the clutch?? When I went to put it in 1st gear I depressed the clutch but she wouldn't go into gear. Peddle doesn't seem to be doing anything. hopefully it is just the cable. Will check it out closer soon.

Tue Nov 03, 2009 4:47 pm

Will the clutch pedal spring up if the clevis pin is broken? I need to get under there and see whats going on. Now that the bus is running I want to go for a ride, even if only around the yard for now. :D

Wed Nov 04, 2009 8:35 am

Changing the points, or even adjusting them, will change your timing. It sounds like yours is still close enough to run but you should put a timing light on it and check.

Wed Nov 04, 2009 3:11 pm

Thanks Rusty I will put a timing light on it and check. So I adjusted the clutch cable a bit and seams to be shifting fine.

Anyways my new question is about the starter. When I turn the key all I get is a click. When i first got the bus back it was doing this once in awhile. Now it is not turning over at all. If I remember correctly back ten yrs ago it would do this once in awhile too. Anyways my guess is the starter is shot?? Any thoughts on this? is it likely rebuildable or should I start shopping around for a new one??

Wed Nov 04, 2009 4:13 pm

You need to get out the old meter and make sure you are getting 12V (or close to that) to the starter when cranking. Otherwise you are just guessing as to what is wrong.

Wed Nov 04, 2009 8:52 pm

73vwbussss wrote: Thanks Rusty I will put a timing light on it and check. So I adjusted the clutch cable a bit and seams to be shifting fine.

Anyways my new question is about the starter. When I turn the key all I get is a click. When i first got the bus back it was doing this once in awhile. Now it is not turning over at all. If I remember correctly back ten yrs ago it would do this once in awhile too. Anyways my guess is the starter is shot?? Any thoughts on this? is it likely rebuildable or should I start shopping around for a new one??

Before you invest in a new starter check the voltage as Wildthing says. Sometimes all you need to do is clean up the connections where the wires fasten, check for frayed wires, and a good connection on the battery cables.

Wed Nov 04, 2009 9:46 pm

Thanks guys. I'm thinking loose or bad connections too after reading up on this problem. I will take a good look at everything tomorrow.