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Car Forum / Mercedes-Benz Cars / October 2005

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massive vacuum leak???

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dbb1porter@netscape.net - 13 Oct 2005 22:04 GMT
Hi all,

Trying to pin down a vacuum leak on an 82 380 SEL and could use some
help. Using the Miti-vac, I can see most of the system holds vacuum
pretty well. I pulled the 4 way tee off the Intake Manifold and pulled
20 hg and it held pretty good...a very sloooowww leak, but not enough I
would think that makes the car undrivable.

However, when I tested the big black line off the charcoal canister
going to the Throttle Valve Housing I couldn't get a reading. Went to
manual mode (mouth) and was able to push and pull air throught it
pretty easily and could hear the air whistling in the air guide
housing. Did the same thing on the line from the distributor to the
Throttle Vavle housing (white/red line) and got the same result...no
vacuum or pressure response but could hear the air moving in the
housing. Should these two lines normally be able to hold vacuum? Could
the Throttle Vavle Switch be a culprit?
taxman - 13 Oct 2005 23:09 GMT
Did the same thing on the line from the distributor to the
| Throttle Vavle housing (white/red line) and got the same result...no
| vacuum or pressure response but could hear the air moving in the
| housing.

the vacuum advance connection on the engine is just before the throttle
valve and after the cis airflow meter. Its not going to hold vacuum. If
you're sucking the other direction, i.e. the vacuum advance diaphragm, then
it should be able to hold vacuum, and if it isn't, replace it.
dbb1porter@netscape.net - 13 Oct 2005 23:33 GMT
thanks for the input...tried the other direction, and the adv diaphragm
did hold vacuum. But atleast I know I can move on to the next item.

When the car is idling, I get a real bouncy reading of 5-10in Hg. The
jitterry reading my be from worn valve guides (or other), but the
reading is still really low.  The engine bogs down when I give it gas,
but when I pull the throttle and push on the air plate the engine revs
just fine. I read somewhere that this is because there isn't enough
vacuum to pull down on the plate. I'll test the injector seals again
with carb cleaner but any other ideas?
Karl - 14 Oct 2005 01:34 GMT
What is your timing set at????

> thanks for the input...tried the other direction, and the adv diaphragm
> did hold vacuum. But atleast I know I can move on to the next item.
[quoted text clipped - 6 lines]
> vacuum to pull down on the plate. I'll test the injector seals again
> with carb cleaner but any other ideas?
Peter W Peternouschek - 14 Oct 2005 05:28 GMT
You should also check the valve timing. it may have jumped a cog. I had
similar low vacuum symptoms on another car sometime back.
Peter
> thanks for the input...tried the other direction, and the adv diaphragm
> did hold vacuum. But atleast I know I can move on to the next item.
[quoted text clipped - 6 lines]
> vacuum to pull down on the plate. I'll test the injector seals again
> with carb cleaner but any other ideas?
 
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