TheSamba.com :: View topic

Mon Mar 24, 2003 1:45 pm

Ok,
I started a thread a lttle while ago about pulling my gas tank because it seemed as if my fuel filters were getting clogged. Well after some consideration, i feel that i should ask you guys if that is the wise thing to do. Here is my situation in detail:
1972 Westy, type 2, dual solex.

What is happening is my bus is falling on its face when i want to give it gas under load. At idle in nuetral i can rev it till the cows go home. If i feather the gas it almost seems like it is running well. Then all of a sudden after about a mile of driving it starts to cut out all together. I stop and look at my filters and they are practically dry, even though about 20 minutes ago at idle they were full no problems. The reason why i felt it was my tank is because the filter closest to the main line has a rusty tint to the paper, and the other filter away from the main line does not have any color change. I see no chunks or particles though. I know this is long winded but i want to be as specific as possible.

Here is what i have done:

This weekend i checked for vaccum leaks with soapy water, i found a couple bad hoses and replaced them.

The previous owner disconnected the vaccum tube that connected the two carbs. i reconnected that.

I recently did a valve job which i feel was 75% successful.

Plugs look a little rich, so i leaned the carbs. a little.

The compression is low two 110 psi and two at 80 psi. The vehicle had sit fot one year though and this was befor i adjusted the valves.

PLEASE HELP, I NEED DIRECTION!!

Mon Mar 24, 2003 2:16 pm

There's an old saying that you can't make a silk purse from a sows ear. If you have 110 in two cylinders and 80 in two cylinders then you are wasting your time trying to fine tune this engine. If the engine sat for a while there may be a chance a couple of valves are just sticky and you can get the bus to limp around enough until the valves free up and seal better. You may also have your valves adjusted too tight meaning you don't have enough gap and/or you may also have a sticky distributor that isn't advancing properly. However, the fact of the matter is you will never get the gremlins worked out at these compression levels. You need compression and you need vacuum. Especially on these dual Solexs. Sorry to be the bearer of bad news, but it sounds like you need to remove the heads to get a better idea of what the problem is. Good luck.

Mon Mar 24, 2003 2:21 pm

By the way, what did you mean when you said you did a valve job? I assumed you meant you adjusted them. If you actually removed the heads and rebuilt them then your rings must be really shot, valves are too tight, or you didn't lap the valves enough when you reinstalled them.

Mon Mar 24, 2003 2:36 pm

Sorry, valve adjustment.
So taking off the heads will allow me to
check my valves and see if they are sticking??
Also, why am i having this weird fuel filter phenomenon, full and then bone dry??

Mon Mar 24, 2003 3:27 pm

do you have an electric or mechanical fuel pump? if electrical I had a problem with too high fuel pressure on my 69. it would idle forever. under a load it would die let it sit ten minutes or so would work for about two blocks. I went to mechanical fuel pump no problems since. fuel psi should be 1.5-3 psi Check your carb specific. could also be valves with the comp differences

Mon Mar 24, 2003 3:39 pm

mechanical fuel pump.
I bought a new one but have not
had a chance to change it, that is my next
challenge. The socket head cap screws
seem almost impossible to get to.

Mon Mar 24, 2003 10:18 pm

After removing the heads you can remove the valves and check the condition of the seats, guides, and valves. You can also check for cracks in the head or blow-by in the rings or bad cylinder to head mating contact. I don't know what to tell you about the empty fuel filter. I always assumed the float had shut off the flow to the bowl and this is what caused the filter to go dry. I really don't know, but I also know it isn't anything unusual. Sometimes it has gas and sometimes it doesn't. Your fuel pump may be bad, but your biggest problem is the low compression of 80 PSI in two of your cylinders. Nothing is going to make the compression problem go away or make your enging run well unless you address the compression problem. There is still a chance you adjusted your valves too tight when you did the adjustment so double check your work there and do another check. If the next compression check shows the same compression then you may as well remove the engine and cylinder heads and investigate the problem further.

Tue Mar 25, 2003 9:06 am

Thanks gokayaking,
I am ordering new valve adjustment screws
today so i can get full adjustment. Two of my adjustment screws are at the end of the adjustment. What would be the lowest acceptable compression for a cylinder?? Also, is it best to check on a cold engine or a warm engine?? How many starter revs. should i do for proper measurement?? I have done compression testing before on Fords, but never on VW's so i was wondering if there was a trick.

Tue Mar 25, 2003 2:14 pm

There are different opinions so I don't want to offend anybody that does it differently, but this is what I do. Warm the engine up to operating temp, but not so hot your burn yourself on every thing you touch. Idle it for 5-10 minutes which should be enough. Remove all the plugs and disconnect the coil. Use a screw on type compression gauge to check each cylinder and write down the results. Then squirt or use a straw to inject a couple tablespoons full of oil into each spark plug hole and check compression of each cylinder again. Maximum compression should be reached within about 5-7 rotations of the crank. If the compression goes up by 10-15 lbs on any cylinder after adding oil then your rings are worn. If it doesn't change then your heads need a valve job and probably new guides. DO NOT try to replace the spark plugs until the engine is stone cold in a couple of hours. Replacing plugs on a hot engine is how people strip out the plug threads. Anything lower than 85 is just not acceptable, but in reality I would consider fixing anything under 110. You shouldn't have more than about 25 lbs difference between the lowest to highest cylinder either. This can cause the bearings and case wear much like driving high speeds with a tire out of balance. If compression changes by less than 5-10 lbs after adding the oil then your rings are OK and you should just remove the heads and send them to a machine shop for a valve job and possibly new guides. This shouldn't cost more than $75 per head and probably less. Good luck.

Tue Mar 25, 2003 2:29 pm

Gokayaking you are a wealth of information.
Much gratitude.
I will try this ASAP.
CHEERS
PINNER

Wed Mar 26, 2003 1:32 pm

Well??? What happened?

(tapping foot impatiently)

Wed Mar 26, 2003 1:53 pm

Sorry, I am out of town
until this weekend so i wont be able to give
a progress report till Monday.
I will give details though, you can
bet on that.