How to check Manifold leak? - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

MK XR8 · 01-31-2002, 23:13

I have seen a few replies to posts recommending they check for leaks around the manifold.

I have an XF with a bit of engine running problems (explained a few posts ago) and was told that a vacuum leak might be a good place to start looking, but how exactly do I go about doing this?

01-31-2002, 23:16

One way I have done is spray CRC around the manifold and if the revs change then that's where the leak is.

Aussiblue · 01-31-2002, 23:23

CRC, Carb Cleaner, water dishwashing detergent all work if you spray it around. An unlit butane/propane torch also works particularly where it to a spot that you can't reach with a liguid spray but be prepared for some backfiring into the inlet manifold and remember it can light up. Spray the stuff pipe by pipe and listen for a change to see hwere it's leakinh though if it's a big leak you'll alos see the fluids being sucked in. You can also buy an expensive detector that can sense the frequency that the air being sucked in makes; big $ item though. Sometimes you may also hear it with a mechanics stephoscope or broomhandle used as same.

PS Use a hand spray bottle for the water or detergent etc, Sparey a little in the air inlet (after the filter) 1st to see what the change in revs will sound like.

ebxr8240 · 01-31-2002, 23:26

Quote:

Originally posted by gtho4
One way I have done is spray CRC around the manifold and if the revs change then that's where the leak is.

Yes or a thicker oil.Smoke obviously out tail pipe when doing this
means leak but engine will change usually to better idle for short time ..

MK XR8 · 01-31-2002, 23:35

Thanks guys, I'll go try these ideas out shortly.

MK XR8 · 01-31-2002, 23:54

Just tried spraying around the manifold with soapy water...but no sign of a leak and no change in the revs.

Thanks anyways.

Road Warrior · 02-01-2002, 05:31

When I said vaccum leak I was referring more to those stupid little black hoses that run everywhere to those funny little vacuum switches on the thermostat housing and intake manifold, amongst other places. There is quite a few of them - the little hoses go everywhere, but only a few of them can actually affect the engine's running characteristics if one is disconnected or is connected to the wrong place:crazy1:

It could also be an EGR valve, looks like a little flying saucer and is usually attached to the intake manifold somewhere and has one of those stupid black hoses going to it.

Best bet I reckon is to take it to Dyno Tune or something where the mechanics are reputable and experienced on all makes and models, and might have half a clue.

MK XR8 · 02-01-2002, 06:00

Ahh I see....sorry, my mistake. I'll have another look at those stupid little hoses tomorrow, but I think my best bet would be to take it into a decent mechanic and let them have a look.

Anyone know of any decent mechanics in Canberra?

discokin6 · 02-01-2002, 22:05

Actually, does anyone have any vacuum line diagrams out there for XE and XF EFI systems? I havent been able to find any as such, and the Gregory's isnt much help on this topic..

EXECJIM · 02-01-2002, 22:21

an old trick, be carfull and put some petrol in a cup and dip a paint brush in the cup of petrol and then run the paint brush around the carby base and intake manifold and vacuum hoses.

dont have to have the paint brush soaked in petrol, when the motor responds in revs, that is where the leak will be.

if the motor doesnt respond when you do this, you might have a problem somewhere else??

oh and try to tighten all your manifold bolts anyway, you might find a loose 1

you will find dishwashing liqued or windex work well on leakes that are pressurised such as LPG gas pipes/joins/fittings.

what is the motor doing??