Newly purchased 1998 986 making a "whoop" sound occasionally at startup

[austinporsche]

Hi all,

Just picked up a 1998 986 with 72K miles in Nevada after my 2000 l986 with 103K miles and an LN IMS bearing that I had owned for 3.5 years lost to Tahoe that cut a corner too close.

Test drove and checked out the '98 and all seemed fine: frankly, looks like a museum piece.

Anyhow, after starting and stopping several times and getting it up to operating temperature for a sustained period, it has started to occasionally started to make a momentary what I can only describe as a "whoop" sound that lasts for a second or two at the most. It seems to come from the back of the car/engine compartment, and it sounds to me tike an "air" issues rather than a mechanical one (maybe the oil separator as that seems like a common air intake issue? does the car have an air pump as it sounds a bit like the air pump on my Land Rover D2).

Any idea what this could be?

[dghii]

The car does have an air pump but it should only be active for the first minute or two after starting the car.

[78F350]

Loose spark plug?
https://986forum.com/forums/performance-technical-chat/77965-986-normal-engine-noise.html

[Frodo]

Originally Posted by 78F350

Loose spark plug?
https://986forum.com/forums/performance-technical-chat/77965-986-normal-engine-noise.html

There's two vids in that thread—or at least there's supposed to be. The 2nd one seems to be no longer available. I do some of my own stuff on my car, but I'm certainly no seasoned mechanic, but I don't hear anything much different on the remaining 1st vid than what my car has sounded like for the past 80K miles.

The comment later on about the "chirp" sound is what I experienced with loose plug(s), including the description, by pilot, of hearing it at low revs when blipping the throttle (or briefly on normal acceleration from a standstill). I didn't hear it at all at high revs, and it did go away when I replaced the plugs. (I would have just tightened them, but they were due for replacement.)

[JayG]

Where in Austin are you?

If you need a good indy for service, I can give you an excellent recommendation

[Bill in VA]

https://www.youtube.com/watch?v=MdwZDmZOhKQ

Not exactly sure what Whoop means. Starter going bad has this screech or squeal sound. Just had my 1999 (original owner) 986 starter replaced today.

[seningen]

I"m halfway between Austin and Dripping Springs if you want someone else to give it a listen?

The Starter is a likely candidate at startup -- sounds like a whirl to me -- before the solenoid disengages.

[austinporsche]

Thanks, all.

To the Dripping-Austin guys, I am out on Bee Cave Road.

I am now pretty confident that it is the starter, so going with that replacment.

[austinporsche]

Replaced starter, no more "whoop" (maybe more like a whir like some described, like a cable being pulling out of a winch really quickly, probably a more accurate description of the sound).

Pinion gear retraction spring was clearly weaker on the starter I pulled out than on the new starter.

[austinporsche]

On to the next issue (ambient temp sensor)