Strange noise from engine

[dtyler]

Recently I have been hearing a strange intermittent noise from the engine area of our 2008 Ford Expedition. It only occurs when accelerating at speed or going up hill at speed. The sound generated is a loud rattling hissing noise that only stops when I back off on the accelerator. Initially I thought it could be pinging as I was running 86 octane fuel, but I have since switched to 91 octane fuel and the problem has not gone away. I suspect temperature may be a factor as it has been around 100 degrees for several weeks now, but I am not sure. Anyone have experience with a similar problem?

 

[VTfireftr]

I had the same issue.

The dealer dignosed it as an issue with the exhaust manifold. All taken care of by the exteneded warranty.

Good luck.

 

[FordCustSrvc]

Recently I have been hearing a strange intermittent noise from the engine area of our 2008 Ford Expedition. It only occurs when accelerating at speed or going up hill at speed. The sound generated is a loud rattling hissing noise that only stops when I back off on the accelerator...

Hi dtyler.

I recommend you take it in to a Ford dealer for a diagnosis. Let me know how it goes and I'll step in, if necessary.

Ashley

 

[FordandPolaris]

Yeah I had a dust shield on my transmission that would only rattle when in motion. It was missing one of the bolts and so was lose on one side.

If you can get a video of it that would help. Still my money is on an aluminum shield somewhere that has lost a fastener or something.

 

[ndpuckhead]

Does it make the sound right when you start it up as well? It sounds like an exhaust manifold gasket to me. I replaced the passenger side one last year, and now the drivers side is bad as well. The problem is, you will most likely have to replace the manifold since they crack easy, and the bolts are a major pita to get out. Hopefully its still covered under warranty, mine was just out and it cost me over $400 to get it fixed.

 

[dtyler]

Looked at the exhaust line

Took a look at the exhaust this weekend. I could see about 10 of the 16 bolts holding the exhaust manifolds on and none of them appeared to be loose and I didn't see any signs of leaking exhaust. Of course it could be one of the other 6 bolts I could not see. I did not notice anything unusual about the rest of the system. However, I did notice that shortly after I started the motor, water started to drip from an exhaust joint behind the driver's side catalytic converter. I am not sure if that is related or not, but I am thinking that if water can leak out of it, so can the exhaust. Unfortunately the noise only occurs when the engine is hot and running under load, so it is very difficult to locate. I will probably take it to the dealer to get it diagnosed, but as money is tight right now, it may be a while before I can have it done. Thank you everyone for your suggestions and I will post what is found when it is diagnosed and/or fixed.

 

[dtyler]

Found problem

I finally was able to take the truck to the dealership. The problem turned out to be a leaking vacuum line to the left hub actuator for the 4 wheel drive. It turns out that the 4 wheel drive hub is activated by a lack of vacuum, so if the line develops a leak, it will try to activate. The noise I was hearing was the front hub trying to engage at high speed. :O Fortunately the loss of vacuum was not complete and nothing was damaged.

 

[smb78]

Do you know which line was replaced I have the same problem and the dealership cant find it or says they cant recreate the noise, im hoping to fix this before it causes any other damage. If you could put up a pic that would be appreciated.

 

[dtyler]

Unfortunately I don't have any information other than what the dealership told me which I included in my earlier post. By the time I was able to take the truck in the noise was fairly consistent and it wasn't too hard to reproduce.