Weird squealing noise?

[jbrittain1970]

Hi everyone! New to me NSX owner. '92, auto, 50k miles. LOVE IT.

When the car sits overnight and I start it, whenever I put it into gear to move, I hear this weird squealing noise for 4-6 seconds in the left front part of the car. Not a brake squeal. It's like some kind of motor or pump. It does that for the first 10-15 minutes I drive it, maybe 4-5 times during that 10-15 minutes and then it doesn't do it anymore, unless I turn the car off and then when starting it, it may make that noise once and be done.

And ideas? I had one guy say it could be an ABS "thing."

Anyone ever had this happen? Thanks in advance for the help!

 

[Old Guy]

Left, front of early NSX - I am thinking it is the ABS unit. I have a 2000 NSX which has the later ABS unit which doesn't suffer from the noise problems; but, early NSX ABS units have some issues. Open up the front hood and have someone listen while you do a start up to confirm that it is the ABS unit.

Do a search using the Prime search function with the terms 'exercising the ABS solenoids' and 'bleed the ABS system' for further illumination.

 

[jbrittain1970]

Thank you!!! Really appreciate the quick response. Will do that.

 

[dmartin149]

Mine does that occasionally too. Pretty sure it's the ABS.

 

[Honcho]

Welcome to NSX Prime! Your NSX looks gorgeous!

Based on your description, the noise is almost certainly the ABS pump. On the 91-99 NSX, the ABS uses a pump to create brake line pressure, which is stored in a rubber bladder inside a steel globe. You can see the globe if you look under the main ABS valve unit. When ABS activates, the bladder releases the pressure through four solenoids to the brake calipers. When the bladder starts to leak, the system will slowly lose pressure until the pump kicks back on to charge it up. Similarly, the four solenoids will eventually start to leak at the O-rings due to grit getting into the system and cause the same issue. While the O-rings are replaceable, the steel globe is sadly NLA. You can live with the problem for many years since as long as the pump can get the system back to its working pressure, you'll still have ABS functionality. Eventually, though, the leak becomes too severe and the pump will run and run until it cuts off on its heat protection circuit. At that point, you'll lose ABS.

Most people elect to upgrade the system to the 2000+ ABS unit, which does away with the pump and globe setup. However it too has been discontinued. However, you can use the AP1 S2000 unit with a conversion harness. I do and it has been working very well.

 

[asylum]

Welcome !
ALB pump. ok if it happens from time to time. If the pumps starts too often, perhaps something is not keeping the pressure. This old system can become tricky and it is important to maintain it to keep it alive as long as possible. I suggest to do the solenoid flush regularly.

ABS