The Disco is having a weird noise in cold start lately. I will try to explain as close as possible. If you watch the clip (The sound is most apparent during 0:33 into the video) Besides the exhaust note, pay attention closely to a bogging/popping sound.

You can hear a bogging sound. If anyone has ridden a 2 cycle scooter, it sounds like when you're try to give it more throttle and it bogs down.

It only happens when the vehicle sits over night in cold start. After about a minute the sounds dies off. I hope this is not catastrophic. It sounds very loud and scary.

http://www.youtube.com/watch?v=dsTTLwzFHfw

 

It sounds 100% perfect and normal when you first start it.

Then once you hit :22 seconds into the video all hell breaks loose.

Check your belts.
See if they are worn.

If the belts look good.

Check your drive shaft.

 

Any fault codes, any white smoke, adding any coolant?

 

RealRitzcracker, thanks for the response. The belt seems to be in good shape, no apparent cracks or wear. The drive shaft is good too, no play.

Mike, thanks for the response. There are no fault codes, no white smoke, and no coolant leak or adding coolant.

Can this just be the rusted flange connecting the catalytic converters to the mufflers? But it seams the sound is most heard through the engine bay.

 

It is exactly the same every morning?

 

Yes, Spike.

 

Then I would say that it is your SAI pump, remove the air filter to it and clean it, if that does not help then look for a broken SAI pipe or a missing bolt for the SAI pump.

 

how long has this been like that? it starts normal until about :22 but that doesn't sound like SAI pump howling. Check your entire exhaust system and your O2 Sensors. Let us know what you find, but do the SAI pump filter clean any way.

https://landroverforums.com/forum/sh...t=23245&page=3

 

Also, check the SAI pump it'self. The body held together by aluminum rivets, which tend to wear out and pop loose, producing far amount of noise while in operation. A simple test: right after cold start-up in the morning, to grab the left side of the pump (the larger diameter section) with both hands and press firmly together. If this pump portion is loose, it will immediately reduce the produced noise. The next step will be to remove the pump and replace the broken rivets.

 

Doesn't the secondary air pump turn off at 96 seconds and 30 seconds depending on startup temp? Seems like his noise starts at 30 seconds so wouldn't this rule out the pump? Just thinking out loud here.