65 Riv - vacuum trunk release

[moran75]

Hi all

 

I need help with my attempts to diagnose / understand my trunk release issue - that’s assuming I’m correct in believing it should work with engine off...

 

 

So...all vacuum lines and switch in glove compartment set up as per manual.

 

But trunk release only works when engine running.

 

Engine off - when vacuum pump attached to reservoir vacuum line from t-junction in engine bay , vacuum is held and truck can be released from glove compartment.

 

Im thinking all is good then from that line all the way to the trunk release?...

 

So if reservoir evidently does it’s job when engine is running, and also holds vacuum when engine off, why doesn’t it work after shutting down engine?...

 

thanks in advance

 

kev

 

 

 

 

[Seafoam65]

You are apparently missing the vacuum check valve at the intake manifold. without a working vacuum check valve in the system, all the vacuum bleeds into the intake manifold the moment you shut off the engine. The reservoir is of no use without a working check valve in the system.

[moran75]

29 minutes ago, Seafoam65 said:

You are apparently missing the vacuum check valve at the intake manifold. without a working vacuum check valve in the system, all the vacuum bleeds into the intake manifold the moment you shut off the engine. The reservoir is of no use without a working check valve in the system.

 

aha...great - may be a stupid question but what does a vacuum check valve look like? My vacuum line at the manifold connects to a cube like connector as illustrated in the manual..not obvious what im missing? Or maybe that cube link thingy is the valve but it isn't working properly?...

 

Many thanks

 

Kevin

[Seafoam65]

They have two nipples on them, one on each end of the part. Usually they are round in shape........and have one nipple going to the intake vacuum hose and one on the opposite side of the valve going to the hose for the trunk release. Inside them is a check

valve which allows vacuum to flow in one direction only. They usually were made of plastic, but I have seen metal ones on older cars. On some GM cars

the valve is located right next to the vacuum reservoir, on others it is located right at the intake manifold vacuum nipple.........It will definitely be in one of those two places. I'm not sure what they did on

the 65 riviera as my car doesn't have that option. The same kind of check valve was used on the A/C controls vacuum feed hose

so that when you accelerate the engine and vacuum drops to zero, the A/C doesn't blow out the defroster.

Edited May 15, 2020 by Seafoam65 (see edit history)

[48Super]

On the '65 Riviera the vacuum check valve is built into the vacuum reservoir tank and they do go bad. I had the exact same problem with trunk release on my car and I added a separate check valve in the supply line from the manifold to the tank. The system will now hold vacuum for months. You should be able to pick up an inexpensive vacuum check valve at any local auto parts store. 

[moran75]

59 minutes ago, 48Super said:

On the '65 Riviera the vacuum check valve is built into the vacuum reservoir tank and they do go bad. I had the exact same problem with trunk release on my car and I added a separate check valve in the supply line from the manifold to the tank. The system will now hold vacuum for months. You should be able to pick up an inexpensive vacuum check valve at any local auto parts store. 

Thanks chaps...and if I had searched the forum first I would have seen yr post ..there’s a moral there somewhere 😀