VWDiesel.net The IDI, TDI, and mTDI source.
Engine Specific Info and Questions => IDI Engine => Topic started by: hamman on October 21, 2019, 10:43:59 am
-
Total admission of inattentiveness, stupidity, etc. here, but have a question.
In the process of resealing the pump, I somehow was able to install the timing belt 180 degrees off. Cranked it up - low and behold it ran. Not very well, and with a LOT of white smoke. Tore it apart this morning, put the cam back into the right spot with timing and it runs as well as it did before. No apparent damage. I am guessing that there was no interference as the crank would put the pistons in the same place twice every cam rotation. The bottom end is in really good shape and I'm guessing it's got very good compression even though I've never measured it (only 80,000) miles. But, why did it even run?
Car is an '84 rabbit 1.6na
-
They will run 180° out. This is well known. Why did it run? Consider what is actually happening when the fuel is injected 180° out. Normal sequence is that fuel is injected at the end of the compression stroke and the beginning of the power stroke. With it 180° out, the fuel is injected at the beginning of the intake stroke and is pulled into the cylinder along with the air. At the end of the intake stroke, the intake valve closes, the piston rises and compresses the fuel/air mixture until it is hot enough to burst into flames. The timing of that combustion event is not controlled, so there is a lot of inefficiency, smoke, poor power, etc... but it will run.
-
Thanks! That makes sense and the explanation is exactly what I was looking for.