2nd Gen Non-Engine/Transmission What is this part's function?

[GAmes]

I have a vacuum pump from a '98 12 valve. This piece was mounted in the inlet hole. I have nothing like this on my '97, never have. It appears to be a check valve, but I thought they were only used on '96s and earlier with vacuum assist brakes.

 

[Missouri Mule]

It does look like check valve.

Check valves were placed at the pump because for some reason oil could be sucked thru the line into components such has the vacuum switch on the transfer case and the selection switch for the ac/heater vents.



The vacuum opperated brake booster had a check valve already on it for 94 to 96 models. There was a recall to add the check valve to the vacuum pump.

 

[GAmes]

Thanks Bill. I did a little teardown analysis and it is a check valve, a little ball and spring affair. The pump on my '97 also has a ball and spring, but they are incorperated into the housing. Bottom line, the housings for the '97 and '98 vacuum pumps are not exactly the same.



As an added note, the ball is also a restriction for suction. If it is stuck open and there is a vacuum hose unattached or leaking, it could lend credence to the vacuum pump causing blowby theory.

 

[DieselDoghouse]

Yep. I have a 12V since 'birth' and it has one of these. I really don't see how a check valve prevents engine oil from percolating into the vacuum peripherals (if that's what folks are saying??) I do see how it would be necessary to smooth dependable vacuum delivery. In fact a while back (several years) I lost my vacuum, several shots of penetrating oil into the check valve to free it if stuck solved the problem. Haven't had a problem since and I do this yearly. Jus' my 2¢...

 

[HEMI®Dart]

Here's the TBS for the "missing" check valve. Dealer worked 10 hours repairing a truck.



D-97-10