Any suggestions on a hissing TDCi

[dkmobile]

I have a 1.8TDCi Ford Focus (55 plate) - note its not a 1.6TDCi or a 2.0 TDCi, but a 1.8 and it has just developed a loud hissing noise during acceleration above 2000 r.p.m. the noise comes on very suddenly but is only apparent when the car is being accelerated

One of the intercoller burst pipes was found to have split about 3 weeks ago and after it was replaced the fuel consumption & acceleration dramatically improved, but now the hissing noise has returned and its even louder.
I have checked the intercooler and all of the pipes that I can access, but it is proving extremely frustrating as the noise is only heard when its been accelrated.
So, you can't repeat the nosie when applying the same revs stationary.

any suggstions. The car has been regularly serviced and its only done 64K

[Codefaster]

Sounds like identical symptoms to my what happened with my old Mondeo. In my case it was caused by the EGR pipe popping off due to excessive backpressure in the exhaust (which had corroded internally).

I would make a guess that your problem is also EGR related. Someone might be able to provide a picture of what to check here? My Mondeo was was an old V6 so the setup would have been rather different.

I think you have to get the engine under load to generate enough pressure in the exhaust to hear the sound (which is why you can't just hold the RPM at a certain level to observe it).

[andy-xr]

Ah, when I saw the title I was going to say intercooler pipe as I had the same on my Mondeo.

The hissing is air escaping, sounds like a carrier bag rustling? I'd check the intercooler pipe again, mine was the main one and had split down the back of the pipe.

Helpful tip: dont wear gloves when you do it as you cant feel the split. That took me a while to figure out

[focusboy]

lol its that two man operation game again, when i say rev, rev, bu66er thats the hot exhaust,

all joking aside get a mate to rev the car hard stationary while you check for leaks, thats the only way i found my split on a focus 1.8 tdci

garry

[dkmobile]

Thanks for all who replied. The rustling bag is a good comparison, but I would also describe it as sucking air past your teeth (with your mouth open) , but your teeth clenched shut.

The split that someone described was exactly where the first pipe failed, but I have physically taken off the two rubber hoses off which feed the intercooler (?) radiator at the front of the car and checked them both, I have checked the air filter box and the rubber hoses that feed that and the large 3 inch (90 degree) rubber hose which runs past the poly header tank to metal intake (unknown metal box) but they are all fine.

The cooling rad is not punctured as I have taken it off and blown into it (blocking off one end) to see if it leaks.

I could check the EG (?) valve, but could anyone tell me where it is?

I know that this is a two man job and have the assistsnce of Mrs K, but,is blocking the exhaust off likely to load up the car in the same way.

thanks for everyones response so far

[andy-xr]

The two man job is because of the fly by wire throttle, rather than cable that you pull so someone needs to rev the car from the pedal while another is under the bonnet feeling where the air is coming from.

You can do it with a piece of paper held infront or behind the rubber pipe you're checking so you dont end up touching a hot piece of metal. You dont need to go near the exhaust! The paper will be pushed away from the pipework (and there's your leak)

It sounds like a straightforward air leak, just needs finding

Start mid left in the engine bay and work your way down to the intercooler, might help to have the car either on ramps, slightly jacked, or 2 wheels on the kerb, 2 on the road if you need to get underneath

Your other option is to coat the pipes in talc

Edited by andy-xr on Sunday 15th February 07:45