Hey gang,

After letting my disco sit for a while i'm finding all kinds of gremlins. Most have been sorted.

Here's a new one.

When the car warms up, if I rev the engine, while in park. The engine makes a high pitched whistling sound.

If I put the parking break on and put it in Drive or Reverse the sound doesn't occur.

Wondering if anyone else has had this issue. I searched for a vacuum leak and found nada. Used a stethescope and can't pinpoint it either.

I read some threads on LR2s having a PCV valve that goes out and produces a similar sound.

Anyone ever encounter this?

 

Ok so this is now happening even when in park. Went to go get the truck smogged yesterday and just a mile from home this high pitch sound wouldn't go away.

From other posts it can be a slew of things.

- AC Compressor
- Alternator Bearing
- Belt tensioner
- Fan Clutch
- Powersteering

Took a video from off to start, to revving, to off again to see if anyone can point me in the right direction.

Vimeo

When the AC is turned on it just slows the squeal.

Power steering fluid is full and no leaks.

Any and all help appreciated.

 

After watching my own video numerous times it looks like the whine stops as soon as the alternator stops spinning....

Anyone else have this happen before an alternator jumps ship? May go buy one for the hell of it to do an A/B test.

Let me know what you think.

Thanks!
Ian

 

The alternator stops spinning at exactly the same time that the rest of the accessories do. Before buying parts, get one of the cheap stethoscopes from Harbor Freight and start poking around. Those actually work really well when trying to pinpoint the source.

Have you tried running the engine without the belt? That would eliminate all of the accessories and pulleys if the sound remains.

 

Good point on removing the belt, I'll go do that now.

Yes I used a stethoscope and couldn't pinpoint the sound when I had it on the accessories when the engine was running.

I'll report back in a min once I pull the belt off and give it a quick run.

Thanks!

 

Just took a few things apart, and noticed the lower right throttle body bolt was a bit loose. Tightened it all up and the whistle isn't as pronounced, so it was definitely part of the problem.

Sound is coming from the top of the engine when it does happen, so it's none of the accessories, thanks for pulling me back from that ledge.

Hoping to put some miles on the truck tomorrow night to complete the drive cycle for smog and see if anything else comes up.

 

Good deal. Sounds like a vacuum leak to me. It is loudest when the throttle is closed so it's somewhere after the butterfly valve.

You said there was a loose bolt. Did you check the gasket between the TB and the plenum?

 

Gasket was in perfect shape.

I've looked at all the vacuum lines and haven't been able to see/detect a leak

Going to dive back in it a bit more tomorrow.

 

I was thinking the same as @Red5 being a vacuum leak. Do you have SAI? Are the hoses connected to the rear of the intake manifold?
Take a pic of your engine bay and post it up.