[DMCForum] Re: Vacuum questions

["content22207" <brobertson@xxxxxxxxxxxx>]

Check valve is actually located between a Tee in that line (other side
goes to the brake booster) and the barb on passenger intake rail. Has
to be otherwise you'd lose vacuum to the brake booster at throttle.
Fairly easy to trace -- they're the only 3/8" hoses in the engine
compartment I believe. 

You probably have a leak in the lines themselves, or one of the
accessories/diaphragms, rather than a leaking check valve. Pull it out
and connect a hand vacuum pump (if possible a model with an integral
gauge) in its place. If the front system won't hold vacuum, you've got
a leak. Look at the pic in #5939's DML photo album to see what a leak
in mine did to diver side plugs to/from SEDOC last year -- ouch!.

Charcoal canister has two vacuum lines. One from under the U pipes is
the purge signal. Is ported (yay!). Activates a diaphragm on top of
the canister that allows a second line to the cold start tube to suck
gasoline vapors into the engine. Third line isn't vacuum -- is the
source from the gas tank.

CPR vacuum system is an abomination. More of that 1970's Rube Goldberg
engineering. Depends on a thermal vacuum switch in the coolant
distribution pipe, a delay valve, and complicated CPR itself to work
properly. European CPR's don't do any of that -- their enrichment is a
simple 1/4" line connected directly to full manifold vacuum. Sucks a
plate closed, and that's it. My recommendation is to throw it away and
replace the CPR with a European model. Stock manifold connection is a
3/16" barb on the driver intake rail. 

Bill Robertson
#5939

>--- In DMCForum@xxxxxxxxxxxxxxx, "Dave Stragand" <dave.stragand@xxxx>
wrote:
> I'll answer the first part.
>  
> Standing at the rear of the car looking forward -- look at the left
pontoon.
> There is a single grommet going through the pontoon itself with a rubber
> hose coming out of it.  It is inline in that hose.
> 
> -----Original Message-----
> From: cruznmd [mailto:racuti1@xxxx] 
> Sent: Tuesday, August 10, 2004 8:23 AM
> To: DMCForum@xxxxxxxxxxxxxxx
> Subject: [DMCForum] Vacuum questions
> 
> 
> Where -exactly- is the check valve that maintains vacuum for the A/C 
> duct flapper?
> 
> When I firewall the throttle, I lose so much vacuum the flapper 
> shuts, cutting off my airflow. Also, no matter what position the 
> flapper is in when I shut the car off, vacuum leaks and the flap 
> falls to the shut position.
> 
> Also, please remind me of the operation of the thermal 3-port vacuum 
> switch in the coolant distribution pipe:
> 
> 1. Describe the different modes of operation @ different temps.
> 2. 1 line goes to the vacuum advance solenoid.
> 3. 1 line goes to the intake nipple for a vacuum source.
> 4. 1 line goes ????
> 
> How does the charcoal evaporative cannister fit into all this?
> 
> Thanks,
> Rich A.
> 
> 
> 
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