loud click/pop on startup
 

This morning I went to start the car, engine fired up normally but I started hearing a very loud click-pop-click-pop (every 1 second). Popped the hood, nothing was wrong with the drive belt or anything I could see, sound was coming from the passenger area, towards the front I would say, almost sounded like the ABS but I couldn't say for sure. It stopped after a few seconds. No warnings on the dash, drove fine to work.

Any idea what this could have been? I have never heard anything like this before. The click was similar in sound to the a/c clutch engaging (but not coming from the lower left, and my ac was off because it was only 35F this morning).

I'm about to give up on this car. I haven't had it for even 500 miles, and I'm just so tired already :(

It sounds like something that responds to oil pressure, so look at the VVT's and their solenoids, the timing chain tensioners . It is possible that a tappet cup is sticking as well.

Oh my gosh... don't even tell me that. I'd rather hear that the ABS pump or suspension compressor is going. I've started it in colder weather and not had any issues...

The engine was running smoothly, so not sure. The engine fired and ran for a few seconds before the popping started. Then it stopped popping and all was well. I guess I will see what happens next time I start it up.

What is the 3" round piece on top of the LH valve cover? Is that part of the PCV?

Hi.

I am experiencing a strange noise too after stating the engine when it is very cold and damp weather.
Here is a clip on You Tube;
Have a listen folks and see what you think.

I'm at my Indie dealer on Friday so may have to ask him.

Les.

The clicking noise could be the Evaporative Emissions Canister Purge Valve operating to clear out the canister of petrol fumes back into the engine.

As regards Les's noise, this is definitely a problem !

I am almost positive that's the suspension air compressor...mine did that while I had it sitting outside in 30 degree weather while the garage was being remodeled.

Les's sounds like an old central heating system pipe through joist expanding noise - something on the exhaust rubbing on the chassis.
Not engine related.

It sounds like a belt squealing over a pulley. Check out the belt driven things to see if something is amiss. It also looked like one of the lights on the dash was indicating a problem, look into that as well, it may be related.

Yeah? Is it indicating a pending failure?

It did it again this morning, but not as ominous sounding. More like "click-whoosh, click-whoosh" a couple times then stopped. Where is the control block for the air suspension located?

Anyone know where the emissions air injector pump is? That would be the other thing that I can think of running on cold starts. The evap purge I don't think should occur on a cold start--that system usually only functions once the car is up to temp and in closed loop, and generally that only purges when you're cruising at a steady speed.


Les, I agree with Oldmots, that sonuds like a belt squeak, along with maybe a rumbling idler or tensioner. Hopefully not your SC itself.

Put your ear down by the driver wheel on your next startup, that compressor is right behind the splash shield. I'm leaning toward the piston rubbing on cold, hard seals. When I heard it the first time, the only thing I could think of was, 'if it does that much, some physical damage is likely to occur to whatever is sticking/rubbing, perhaps leading to the overworked, overheated compressor issue down the road. I bought a new compressor seal kit from one of our members, and hoping that new kit will fair better in the colder weather.

The block you refer to is in the boot, under the spare tire next to the air tank/reservoir.

There is a shaft connector inside the supercharger snout that may be failing and the belt is slipping trying to get it turning when cold. I haven't heard about too many problems with them but it has happened before.

Tried it today. It wasn't quite as cold out but the same thing happened to a much lesser extent. I gave the belt a quick squirt of Silicone spray and the noise instantly stopped.
Has to be the belt I reckon.
I also notice that the front and rear heated screens come on automatically when it's cold thus adding extra load on things. It's probably all connected as it never happens when the weather is warmer or the engine is warm, etc.

I have a new Gatorback belt to fit so hopefully that will cure the noise.

Oldmots, the light you refer to was due to me having the door open, so no sweat there!

I will update after fitting the new belt, assuming the weather stays cold that is!

Regards. Les.

Thanks! It's under the driver side fender? I thought I saw it in the passenger side... I wonder if that's the air injector pump over there...

You can get a seal kit for these compressors?

Les, make sure you clean off all the pulleys with brake clean or similar, you don't want silicone on the new belt. It'll either start slipping or deteriorate quickly.

Here's that thread that talks about the seal kit.

https://www.jaguarforums.com/forum/x...pressor-84990/

Wow, how did I miss that one?! Thank you!

That's quite a nice bit of engineering, I will have to order the seal kit! Still making the noise in the morning, but not as much since the weather warmed up to the 40s. Think it is coming from the front left fender, guess that figures! Will add that to my list of warranty items to be fixed...

Your welcome. Preventative maintenance...this is a perfect example.

Didn't make the noise yesterday, but this morning @ 29F it started again. It's definitely from the passenger side front bumper. Not the driver side. Looks like the secondary air injector pump is in there... I guess it's good news that my suspension pump is quiet... not sure if the dealer will replace the knocking pump under warranty if they can't replicate it.

Hi.
Had mine confirmed as the worn belt slipping slightly off then back on to the tensioner pulley.
New belt and all is cured.
Good luck with yours buddy.

Regards. Les.

Okay... so much for that dealership service department.

Left the car there for 4 days, with very specific details on when and how long the car would make this noise. Cold starts < 50F and only for about 30 seconds on first start. Typical, got the "could not replicate customer complaint" response. Of course they "guessed it could be the Secondary Air Injection Valve activating."

I will give them that it's most likely in the AIR system, but this only started a few weeks ago. Does it mean the AIR pump is on its way out? Or just a valve?

This morning first thing I went out and made a recording of the noise:

The OP starts a thread with his noise and someone hijacks the thread with his own noise. now I don't know which is which. Bad form.