Hi guys!

Unfortunately I'm back. I've done a search, and nothing fits my situation so I'm asking for diagnostic help.

Symptom 1:
In the last four or five days of driving, after 15 to 30 minutes I get a loud, high pitched squeal at certain points when under load, and again when I shut the engine off. It doesn't do it at idle. This squeal is LOUD. At first I thought it was belts, but had someone turn the car on and off with my head under the hood: there's a LOUD squeal when the engine is shut off, and for all the world it sounds like pressure escaping. It appears to be coming from the passenger side, near the fire wall. It isn't belts, because the belts stop spinning as the sound is still going for a half second or more.

Symptom 2:
The ABS light came on after driving for about 20 minutes the other day, and has stayed on.

Symptom 3:
If I turn the key to "ON" without starting the engine, there is a pretty loud roar/groan/rumble, and I can feel the brake lines coming from the fluid reservoir vibrate.

Symptom 4:
The brakes, including ABS function, still seem to operate properly. If I stand on the brake, the car comes to a halt with no locked up tires.

Something that may or may not be related: I know my passenger side front wheel bearing is on the way out, but I doubt that has anything to do with this.

What should I be looking at first? This is my first car ever with ABS, so I'm at a loss. I'm a decent mechanic - when I know what the problem is!

Finally, the details: 2003 Max, 6 speed manual, HLSD, about 282,000 on the odometer but running strong (til now).

Thank you, gentlemen!

Jack

 

Check for a vacuum leak in the vacuum line running from the intake to the brake booster.

 

Will do in the morning. The thought occurred, since that's really the only line in that particular area. What's the easiest way to test such a thing, short of just replacing it?

Thanks,

Jack

 

Don't replace it yet. I'm kind of guessing and it's very easy to check.

With the car running spray some brake cleaner on it. When the spray hits a vacuum leak the RPMs will jump.

If you get a mechanics stethoscope you can maybe pinpoint the sound better. http://www.harborfreight.com/mechani...ope-69913.html

 

Neat trick - thanks!

 

Oh, any clues as to the mechanical "motor" type noise near the master cylinder when I turn the key to "ON"?

 

There is an electric pump as part of the ABS. The stethoscope will help you pinpoint the sound. I'm not that strong on ABS issues but if the pump is failing it could be a problem.

Also, make sure you're not hearing the throttle body open and close when you turn the key to on. That's normal.

The first thing I would do is find the source of the squealing sound.

 

So brake cleaner on and around the vacuum lines revealed nothing as I figured.

That squealing, which sounds a lot like some sort of compressed air sound but so much more intense, seems like it's coming more from the power steering area. I know there's a high pressure line there, because I replaced it two years ago (genuine Nissan part). No leaks, though. Freaking weird.

I'll look more closely at the noise near the master cylinder, but I swear I hear the throttle body AND this longer, drawn out sound. Since you said "pump", it *does* bear a resemblance to a pumping sound.

Gotta get the old girl up and running right again.

 

I would still say the 1st thing to do is find the squealing sound.

Also, figure out the ABS code. Your local parts seller should be able to pull it for you. Most cheaper code readers won't read ABS codes but there should be a specific code there.

 

Hi again, Derrick2k2SE (and anyone else willing to chime in),

I went to a local O'Reilley's auto parts and had them read the ABS codes - there weren't any, despite the fact that the ABS light was on while he read the codes. So now I'm not sure where to go. The ABS actuator still seems to be noisier than I remember when turning the key ON but not starting.

Any better way to diagnose the ABS issue?

Now the squealing:

There was a P1800 code. I replaced the VIAS solenoid and every vacuum line I could find as a precaution: every one I touched was dry and crumbling, so for $20 or so it seemed worthwhile. I cleared the codes for the P1800, but I still have one that keeps coming back that says "P1800 Pending". No idea what that means. Anyway, to eliminate power steering, belts, and accessories as sources of the noise, I removed the PS and alternator belts and ran the engine. The squeal was still present. (I did find, though, that my tensioner pulley bearing was shot, so replaced it).

Now, put it all back together, and was trying to figure out why the VIAS 1800 error was still coming up, and just for kicks used my finger to move the plunger on the power valve actuator. Lo and behold, I got some of that same squealing sound! After some playing (disconnecting the actuator from the linkage on the intake), it seems that the squealing is a result of the actual valve inside the intake. Does this thing have a seal or something that wears over time? I can tell that there seems to be play in the assembly - the shaft has play both in-and-out, and side-to-side. Not much, but putting pressure on it in various directions without actually rotating it causes different sounds. In fact, it's quiet when disconnected from the actuator plunger, but as soon as it's reconnected and tension holds it closed, the whistle starts to return.

Finally, just to make sure I'm barking up the right tree - if this intake valve IS the culprit, would that also cause the loud squeal at shutoff, as if lots of pressure is escaping somewhere? Or is that indicative more of the ABS problem?

Still feeling lost.

 

I don't think it's from the valve inside the intake. Here's a pic of the other side of the VIAS. These are of one I took off my car a few years ago. The shaft on the valve has a small amount of play in and out (less that 1 mm) and no side to side. There is a seal on the shaft but it won't leak after shut down since there's no vacuum.

You could have a leak inside the metal vacuum canister/actuator. The big plastic canister stores vacuum for the actuator. If the actuator has a leak in will bleed off the vacuum stored in the plastic canister even though the actual manifold vacuum goes away as the motor is shut down.

Try removing the line going from the intake to the plastic canister and capping it off. See if this gets rid of the squeal after shut down.

I don't think this has to do with the ABS problem though. If you're not getting any codes it could be the ABS computer itself. This is exactly what happened to mine. Light came on and ABS quit working but no codes. The owner of the shop I work at said it was the computer if there were no codes but I wasn't sure. Sure enough, swapped in a used computer ($200) and it came right back online. I don't remember any rumbling though.