Check Valves: What's the difference?

[Gunter]

893-906-093-M14 Check Valve, (M12 X 1.5 - M12 X 1.5) 911 (1980-83)
Brand: Bosch [Photo] [Photo]

$25.00

944-608-951-01-M14 Check Valve, (M12 X 1.5 - M12 X 1.5) 911 (1984-89)
Brand: Bosch [Photo] [Photo]

$17.75

They both have the same threads; what's different?
Unfortunately, the photo for the '80-'83 valve is not available for comparison.
What's inside a check valve?
How does it prevent back-flow?

[GH85Carrera]

$7.25

[3.2 CAB]

It would appear that the numbers between the two parts are not correct.
893 906 093--- check valve M12x1.5-M12x1.5 ------80-83
944 608 951 00 -- check valve M10x1.0-M12x1.5----84-89
I believe the part description at Pelican is in error. I obtained the dimensions from my Porsche Parts Books. apparently the check valve on the 84-89yr models have 2 different sized threaded ends, while the 80-83yr models use a check valve that has the same size threads on both ends. Hope this helps!! Tony.

[MBEngineering]

HI Gunter
have a look hear , it may be of some use???

Where's my fuel check valve? (Long...)

and is this any good??



regards mike

[Gunter]

Yes, very good Mike and 3.2 CAB:
Here is what I have:
A brand new Pierburg pump 7.21659.02 came as a spare with the 1980 SC.
It is rated for 6.5 bar and has an internal check valve confirmed by a very helpful distributor:

http://www.ruddies.business.t-online.de/elkraft.htm

This pump has the correct seperate nipple M10 x 1.0-M12 x 1.5 mm screwed into the pump for the banjo fitting.
This nipple looks exactly like the ones in your pictures.
It doesn't have a check valve but, the center hole goes right through.
Because the end of the nipple is open means the gas would just come out there unless it was plugged. (I could take some pictures if necessary)

Correction: Just noticed that a cap nut seals the end once the banjo fitting is installed..........ah so........

[MBEngineering]

HI Gunter
do you have a "banjo" fitting on the end of your fuel pipe to fit on the nipple fitting?? if so you should have a "cap nut" to seal it off!!, if not the fuel pipe has a screw on fitting and a taper fit to seal??

regards mike

[Gunter]

Yes, that's it Mike: Banjo fitting with Cap Nut.
While looking at the parts drawing on PP I noticed the cap nut, then it became clear.
Before seeing the drawing, I envisioned a regular nut with seals on each side but kept wondering how the center-hole is sealed.
Then your reply confirmed the issue.

The pump that's in there now works fine but I don't know how old it is and I am considering just replacing it with this new Pierburg pump which has the right configuration.

Just don't want to get stuck in the middle of nowhere one day with the old pump going kaput.

[MBEngineering]

HI Gunter
would you just check the size of the banjo on the car, as there is 2 sizes and when fitting the check valve to a pump (as the photo of the check valves) the car banjo could be a small one and not fit, the re-placement valve is only the large one, and the banjo has to be changed also.

regards mike