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Mon Jul 02, 2012 8:33 pm

my 66 vw bug 1300cc is doing some weird things. First, it seems like going up and hill and definitely down a hill its shakes really bad. like its choking for fuel or something. Put a new fuel pump on btw. It broke down the other day and just stopped completely. I coasted to the side and finally got it cranked again. White smoke is coming out of the oil fill. what would cause that? back pressure? how do it fix it.? thanks

Mon Jul 02, 2012 8:54 pm

White smoke is usually caused by bad rings. The oil gets into the combustion chamber and is burned causing the white smoke.

Mon Jul 02, 2012 8:56 pm

Coming out of the oil fill? You mean piston rings?

Mon Jul 02, 2012 9:32 pm

bmorrow wrote: my 66 vw bug 1300cc is doing some weird things. First, it seems like going up and hill and definitely down a hill its shakes really bad. like its choking for fuel or something. Put a new fuel pump on btw. It broke down the other day and just stopped completely. I coasted to the side and finally got it cranked again. White smoke is coming out of the oil fill. what would cause that? back pressure? how do it fix it.? thanks

White smoke coming out of the breather is blowby gasses ( water,oil, fuel, sulfuric acid mixture).
Smoke coming from the tailpipe; White = coolent leak into the combustion chamber ( not applicable to air cooled engines ) Black = rich mixture. Bluish = burning oil, steady blue smoke are rings, a cloud of blue smoke on deceleration is usually worn valve guides.

Mon Jul 02, 2012 9:34 pm

All me inexpirenced, (and with motors I admit I am) but I thought it was blue=running rich white=burning water and black=oil...?

Mon Jul 02, 2012 9:39 pm

"White smoke coming out of the breather is blowby gasses ( water,oil, fuel, sulfuric acid mixture).
Smoke coming from the tailpipe; White = coolent leak into the combustion chamber ( not applicable to air cooled engines ) Black = rich mixture. Bluish = burning oil, steady blue smoke are rings, a cloud of blue smoke on deceleration is usually worn valve guides."
Ok I had the black and blue mixed up

Tue Jul 03, 2012 9:47 am

I think it could be a bad piston ring. But if it were wouldn't it foul a plug?

Tue Jul 03, 2012 1:34 pm

bmorrow wrote: I think it could be a bad piston ring. But if it were wouldn't it foul a plug?

Not necessarily, I've seen engines with worn rings not foul up a spark to the point of no spark. In the early stages of oil burning some manufacturers even recommend a hotter plug. Why don't you pull the plugs and read their condition, and while they are out do a compression test, while they are still out do a leak down test. That would be the way of pursuit of the facts for me.

D.

Tue Jul 03, 2012 3:46 pm

Quote: Why don't you pull the plugs and read their condition, and while they are out do a compression test, while they are still out do a leak down test.

Verily, verily, Helfen, thou hast said the thing which must be said.

Selah. 2x.

Thu Jul 05, 2012 8:24 am

I put new bosch plugs in about a week ago so they are good. the compression was 90, 90, 100, 105

Thu Jul 05, 2012 9:06 am

(Edited.)

Ok, I stand corrected, and defer to the below.

Thu Jul 05, 2012 10:09 am

I wouldn't tear it apart just yet! There are just too many variables that haven't been addressed.

First, the white smoke from the breather could be normal. If the car is used often for short trips, more moisture and other bad things build up in the oil. If you now get it up to temp or a little on the hot side, that stuff starts to burn off and you will get vapor out of the filler that looks like smoke.

Second, your compression numbers aren't that bad. The main question is did you have the throttle propped open during your test? If not you can get a lot of different numbers that may not be a real reflection of whats going on.

Third, a spark plug check. This is a bit of an issue with a VW. Aluminum heads NEED to be cold before you start unscrewing plugs or else you run a big risk of removing the threads with the plug.

Simply unscrewing a plug to see if it is clean or fouled, isn't going to tell you much. You have a carb which has a very wide variety of mixtures based on a lot of different things while it is running. If anything on your carb is just a little out of adjustment for the current weather conditions, or you let it load up a bit before you pull the plugs, you may get a bad plug reading.

And plug readings will change sometimes depending on if you are on the low speed circuit or the high speed circuit of the carb.

Start with the simple stuff. Go back to your shaking issue. Have you checked in the gas tank to see if it's clean? It's easy to do, jack up or park so the gas tank filler neck is on the low side and look in the tank with a flash light. Water will look like little gellatin globs on the bottom of the tank. Crud just looks like crud.

If you have a fuel filter in line, change it. Often times they fill from the inside out, so you never see the crap that is in them. They can get clogged but still look clean.

If you have the early style fuel pump with the center screw in the top, pull the top off and check to make sure the screen is clean. (you said you replaced the pump, so this may not apply to you)

Pull the top off the carb and remove the emulsion tube. Clean it. A little piece of crud in the tube can really cause some strange running conditions.

Check your point gap. If it's closed up things start running poorly.

Check the timing. Again if it has changed, things don;t run the way they should.

Check your plug wires. If they have been on the car for 40 years there is a real possibility you have spark jumping to ground which is also creating bad running conditions. Wait until dark and start it up then look in the engine compartment carefully and follow the plug wires looking for sparks jumping.

If your coil is dirty on top, in the right atmospheric conditions, the crud on there and moisture in the air can make a nice pathway for your spark to go to ground and not to your plugs. Usually cleaning it or giving it a shot of WD-40 will help to eliminate this issue.

Check these things and make sure the simple stuff is all good before you throw in the towell and tear apart an engine that may not need tearing into just yet.

Fri Jul 06, 2012 3:46 pm

bmorrow wrote: I put new bosch plugs in about a week ago so they are good. the compression was 90, 90, 100, 105

Compression test should be done with the engine warmed up, all plugs out, throttle opened wide. This is the ONLY time I take plugs out of a VW engine when it is warm. I would much rather take them out cold because of the thread issue as already mentioned. On stock 1200's you cannot have a cylinder pressure variation of 20 psi of each other. For 1300, 1500, 1600 no more than a 14 psi difference.
So here's the spec. rub from VW;
Engine compression ratio's with 6.0:1 should read 85-107 psi. With 6.6:1 should read 100-114 psi. With 7.1:1 should read 100-128 psi. With 7.3:1 should read 107-135 psi. With 7.5:1 should read 114-142 psi. With 7.7:1 should read 135-156 psi.

Maximum wear perimeters; Engines with compression 6.0:1, 6.6:1 and 7.1:1 compression ratio should have a minimum compression of 65 psi and all within 20 psi of each other.
1300, 1500 engine should have no more than 14 psi difference in compression and are as follows; with 7.3:1 compression no less than 85 psi. Engines with 7.5:1 compression no less than 100 psi. For engines with 7.7:1 compression should be no less than 114 psi.
To be honest I just thought the author of the thread wanted to know " What would cause white smoke"?