Engine Diagnostics

I did the compression check -- first, I took the #1 plug out (with all others still in -- does that make a difference?

I think it does. Every procedure I have says to "remove all of the spark plugs from the engine" before doing a compression check. It makes for a lower load on the starter, and the engine will spin faster so you'll get a fractionally more accurate reading (less time for any leakage on each stroke).

Should the compression test be done on a cold or warm engine?

A cold engine will usually give a higher reading -- and of course you want to find the 'worst case' situation -- not the best case.

I decided to do the oil test, so I poured a little oil down in the #1 cylinder. Got a reading of 120 (110 before). So, a little bit of a difference.

Most likely the rings are worn. And since none of the readings are up in the 120-130 zone, they are probably ALL worn to some extent -- it's just showing up more on one side of the engine than the other.

One more thing. This is the kicker. I took the plug out, after realizing it wouldn't tighten, and noticed pieces of the cylinder head on the block in the threads of the spark plug. I really did it this time! I think I just ruined my entire engine.

What a shame -- sure indicates a stripped thread. But it CAN be fixed with a helicoil, any competent workshop can drill out the head hole (which SHOULD be out of the car so they can clean out the metal filings properly), and screw in the helicoil, which gives you a new thread.

I do not understand how I could have gotten readings over 20 psi apart, doing the exact same procedure, when the only difference is that the lower reading was with all plugs out, and the higher with all plugs in (with the exception of the one being tested).

But was the engine temp the same in both cases?

I think I am going to have to call Houston (Victorville -- Desert Autohaus in Victorville, California) and have them beam me a new engine.

Sounds like this plan is getting longer legs, since the stripped thread is just one more thing to add expense to the old engine anyway.

One thing to note (VERY CAREFULLY PLEASE). If the new engine comes with NEW heads rather than reconditioned ones, they will have the long-thread plugs in them -- the newer heads are all made to suit the 3/4" length rather than the older 1/2" length (NGK plugs are B5HS for short reach, and B5ES for long reach, for example). If the heads are reconditioned old ones, it could be either. Make sure you ask when you get the engine, because you MUST use the correct length plug. Using the long plug in the "short plug" heads risks the outer electrode touching a piston. And using the short plugs in the long-hole heads means the spark is not inside the cylinder, but inside the plug hole, and this leads to uneven firing, and more susceptibility to detonation.

Also ask about the compression ratio for the replacement engine. It should be kept to around 7 or 7:2 to 1 to enable you to use any fuel from 87 "pump octane" up. Any higher than 7:2 (7 is preferable in hotter climates), and you will need to use the higher octane gasoline.

We picked up a '74 SB for nearly nothing in a tow lot. When we give it gas and try to slip into first gear from idle, it does not want to go. It's as if it slips out of gear very gently as the clutch is let out, and then has died a couple of times if the clutch is left out and the accelerator pedal is continually pressed. Sometimes in that situation it jerks a bit, and will sputter and finally "catch" a little and go forward enough to put into second, where it does the same thing. It does the same in second, but does not do it in third or fourth.

When we try giving LOTS of gas when accelerating into first or second, it backfires and jerks, but will go a little better. It will move forward if I ride halfway between clutch out and in and the gas pedal. I had to resort to that to get it home tonight.

It seems to idle fine -- if we take it out of gear it idles smoothly. (Like when we go down hills -- engines idles just fine).

Probably not really enough to go on, but it sounds like either a carburettor/distributor problem, or a gearbox problem.

If it's going into gear, staying in gear, and changing OK, then it's probably NOT the gearbox. Popping out of gear, crunchy changes and sloppy gear stick are the most common gearbox problems.

You said that the engine idles OK but when you try to apply power it sputters and resists -- THAT sounds like a fuel/ignition problem.

A blocked main jet perhaps (runs on the idle jet OK but fails when you try to accelerate on to the main jet), blocked accelerator pump (which helps spin the engine up), or maybe the advance section of the carburetor has failed (is it a 009 or vacuum distributor?) and it's got no advance as you rev the engine.

If you have a timing light this one is easy to check. Paint the timing notch with a blob of white-out etc so it's easy to see, put the timing light on and start the engine. Pull on the throttle arm to rev it whilst watching the notch in the timing light - with a 009 it should start to move to the left (advance) smoothly as you accelerate the engine past about 1200 rpm (very fast idle). With a vacuum distributor - the timing mark should JUMP to the left as you blip the throttle.

Carburetor type and distributor type might help me work it out.

Oh - and could it be the clutch itself - slipping or not engaging properly? Are there any noises/vibration when you use the clutch?

And binding brakes -- could that be a problem? Does the car roll OK if you push it (gearstick in neutral).

I just bought a 1974 orange Super Beetle... It was running perfect, then it started to lose power. (I thought fouled spark plug).

As it lost power was the engine still running smoothly, or was it getting a hesitation of stutter (trying to eliminate plugs and fuel here)?

I checked the back and it looked like oil was coming from the fuel pump onto the fan belt. It was very hard to start, like a real low battery (bought brand new one - wasn't that). Then it wouldn't start at all.

So is it cranking at normal speed, or slow-cranking? If slow-cranking (with a good battery and the ignition lights still dimming as it's cranking), the starter might be on the way out.

Or not cranking but you hear a clicking as the starter solenoid moves (starter kaput - rebuild); or not clicking at all and the ignition lights stay full bright (solenoid not pulling in - starter kaput).

We tried push starting, rocking it, etc. We thought the engine might have seized, but it still will turn over in reverse.

So you can turn the crankshaft anti-clockwise (viewed from the back) but not clockwise?

That's really weird. Nothing stuck down behind the crankshaft pulley is there?

What happens when you push the car forward and try to bump start it in say 2nd - does the engine turn over or does it lock the back wheels when you let out the clutch and the engine stays motionless?

We are totally at a loss as to what could be making it want to seize. There was plenty of fuel, oil.

Not too much oil I hope. The VW crankcase uses 2.5 litres (2.2 US quarts) of oil. Overfilling can cause an excess of oil behind the pistons (since they lie on their sides just above the sump), and too much oil sloshing about there can cause problems with oil being forced out of the sump (but not usually causing overheating). I mention this because you said some oil seems to have been forced up out of the fuel pump area. Was the fuel pump replaced at all? there are several types of fuel pumps, the older type (pre-'71) have a longer push rod inside them which would make it difficult/impossible to screw down the pump properly- - any possibility a wrong pump/rod has been fitted?

Could it have gotten overheated?

Nothing definite there, but a few things worth checking.

It does sound as though the engine has been overheated. It might turn over OK once it has fully cooled, but the cause needs to be found. If it has been overheated, it might have suffered internal damage too (sure hope not!)

1. Anything obvious like a rag caught in the cooling fan inlet? Occasionally the thick tarpaper sound insulation on the firewall just in front of the engine can come loose and will easily cover the fan inlet.
2. Timing too retarded - unlikely to get hot enough to sieze it, but it's possible.
3. Brakes binding? Feels like a loss of power. Easy to test - the car can't be pushed (gearshift in neutral and hand brake off of course :-)
4. The oil on the fan belt has caused it to slip so much the cooling fan isn't cooling?
5. You said it's had work done on it recently? Distributor put back in the right way? (it goes only one way but can be forced 180 degrees out).
6. Cam shaft removed from crankcase? If it's out a cog or two that will affect both valve timing and ignition timing - could easily cause overheating?