My '89 XJS runs good… Just had the hood louvered and after it’s been running for about four to five minutes all of a sudden I can hear this sound of rushing air near the front of the engine…Filters are tight and sealed… All hoses are connected… What gives… Thanks, Victor
Perhaps this sound is coming from the electric auxiliary cooling fan?
Paul
There are some hidden vacuum lines. …look harder
IIRC the air pump dumps to the atmosphere after the engine warms up… but I never heard mine hiss…
No actually pump dumps air into right air filter box. That’s why you don’t heat it.
It might be a sign of air in the coolant circuit. Have you taken my advise and installed a flushing tee at the highest point in the heater hose? Have you modified the banjo bolt at the top right end of the radiator to open up the passages?
Paul, Aux. fan is not running as engine is not yet at full temp.
Bob, Air pump is connected to right side air filter box…
I will continue to look. It all seems to be coming from the front of the engine… Quite loud… A lot of air… But runs very well…
Ah right, thanks! The AP seems to have fallen off of my car so it’s been
awhile…
Victor,
I think we will need some more help from you about the location of this
hissing noise near the front of your engine in order to figure out what is
making it.
Get about a 2-3 foot length of hose, hold one end near one of your ears
while you move the other end around the front of the running engine, and
try to see if you can pinpoint the source of the noise. Using the hose
this way allows you hear the noise without having to get your head close to
any moving parts. Of course you will have to keep the hose and the hand
that is holding the hose away from moving parts as well. I have used this
method before to pinpoint the location of engine bay noises when they were
vague or in hard to reach locations. . Good luck and write back with your
results.
BTW, have you checked that your coolant level is properly topped off? This
requires bleeding the air from the bleeder banjo bolts at the top of the
radiator by raising the front of the car and adding coolant between
heat/cool cycles to make sure all the air has been bled from the system.
It is not enough to just check the coolant level by removing the caps when
the engine is cool. Air can be trapped elsewhere that will need the
bleeding procedure to remove. I suppose that trapped air inside your
cooling system could cause a noise as the engine warms up and the air gets
compressed and moved around inside the engine past the thermostats and
other small orifices inside the engine.
Paul
I have found the hissing problem… There is a one way check valve that sucks air into the intake manifolds… It connects to a hose that exits the engine bay just behind the left headlight cavity… This in turn pulls outside air into the engine… Once connected the hissing went totally away…Thanks to all who helped me… This is a great group… Victor Gardino, Arvada Colorado…
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WTH? I don’t think there’s supposed to be anything that fits that description on the Jaguar V12. You might be looking at the purge line from the carbon canister, but that would either go to the PCV plumbing or to the throttle body, not to the intake manifold.
Could be fan roar. …isolate every thing. …turn off ac…some people. Spray carb cleaner around vac hoses and if engine speeds up…there it is
Found problem… I twas a disconnected hose with check valve that runs to intake manifolds and exits just behind left headlight box to the outside of engine bay… All is quiet now…
scrimbo https://forums.jag-lovers.com/u/scrimbo
January 30
Could be fan roar. …isolate every thing. …turn off ac…some people. Spray carb cleaner around vac hoses and if engine speeds up…there it is
Hello, fellow Coloradan!
Where are you wiggs ???
