How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Matt Your Own Question
Matt
Matt, Mechanical Engineer
Category: Jaguar
Satisfied Customers: 21864
Experience:  BEng hons Mech engineering, in auto industry 22 years
12772297
Type Your Jaguar Question Here...
Matt is online now

Jaguar xj6 twin carb with AED. Having just replaced inlet

Resolved Question:

Jaguar xj6 twin carb with AED.
Having just replaced inlet manifold gasket car now runs at about 3000rpm when on choke cfould this be due to AED or other fault?
Submitted: 3 years ago.
Category: Jaguar
Expert:  Matt replied 3 years ago.
Hello

1st thing to check is if the carbs are pulled down evenly and have a good seal
and do the same for the inlet manifold joint

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.
Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.
Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.
Expert:  Matt replied 3 years ago.
hi

do you still need help with this?
Customer: replied 3 years ago.
Sorry for the delay, do you still believe this to be the case bearing in mind it only ran fast while on choke and went back to normal idle when the choke wenr off.
Expert:  Matt replied 3 years ago.
Hello Steve

thanks for the extra information

for it to idle fast then more air than normal must be finding its way in and as the choke will add extra fuel then this will raise the idle speed still higher so yes I do think that there's a vacuum / air leak still
Matt and other Jaguar Specialists are ready to help you