VWDiesel.net The IDI, TDI, and mTDI source.

General Information => Troubleshooting => Topic started by: wolf_walker on February 21, 2010, 12:25:15 am

Title: What else wears in the pump advance mechanism?
Post by: wolf_walker on February 21, 2010, 12:25:15 am

Low pressure = low advance.  Gotcha.
Mechanical wear on the advance slider? 
They are shimmed to control max advance I believe, yes?

Title: Re: What else wears in the pump advance mechanism?
Post by: 745 turbogreasel on February 28, 2010, 05:12:14 pm

roller axles erode the pump housing.

Title: Re: What else wears in the pump advance mechanism?
Post by: vanbcguy on March 01, 2010, 10:49:32 pm

The vane pump itself wears, that's probably one of the biggest sources of pressure drop.  It gets all the junk in the fuel to it first, scores up the inside and then.....

Title: Re: What else wears in the pump advance mechanism?
Post by: fatmobile on March 02, 2010, 07:36:17 pm

I have a pump with decent internal pressure but still has no timing advance.
 There is a little hole in the piston that lets pressureised fuel into the end of the piston so it can push it to the other side.
 I think that tiny hole gets plugged, so the piston doesn't move.

Title: Re: What else wears in the pump advance mechanism?
Post by: wolf_walker on March 02, 2010, 09:43:11 pm

My pet theory on my funny running, slower than ought to be less MPG than ought to be pickup is the 300+K miles pump that sat for three years and has visible surface rust inside is not advancing dynamically as it should.  I haven't talked myself into coughing up for a
real on-engine timing tester, but my ear and gut think it's advanced too far initially then runs out of advance as RPM demands more.
I think I'm just going to buy a rebuilt pump and quit screwing with it.  Eventually.