whining on deceleration

[markdav]

Car: 2000, 2.7, Manual, USA

This just started yesterday after a 40 minute freeway drive. I decelerated in 4th from around 70 to 50 with foot off the gas and a medium pitch whine / whistle started emanating from the rear somewhere. I pumped the gas briefly and it went away. A few minutes later, same conditions, same noise and I pushed the clutch in this time and the noise went away.

It is definitely a whistle rather than a screeching sound. Clearly audible above the engine noise. Starts after a long deceleration (>10 seconds) from high speed - tried this again this morning at lower speeds and no problems.

At one point I thought I saw my oil light flicker on but this could have been an illusion. Does it sound like an oil pump issue? Oil is up to mark and recently changed (<1000 miles ago).

I know this is thin information but it is hard to reproduce the conditions in my garage so hard to localise. Everything sounds fine when idle. Any pointers in terms of what to look for first, next would be great.

Thanks, Mark.

[markdav]

Just saw that Jeff740 had a similar issue http://www.renntech.org/forums/index.php?showtopic=10178 . any other possibilities? Why would the strut cause the whining under these conditions?

cheers, Mark.

[markdav]

Further info.

* Definitely related to engine revs. Clutch in/out does not make a difference.

* Only get noises when the engine is up to temperature

* I can hear a very faint screeching sound at around 3K revs

* The louder whistle sound appears around 3K revs but only on deceleration from 65-70mph.

* no warning lights on at this stage (will check my obd tonight to see if there are any temp codes)

From other posts thinking could this be oil separator? How do I test the separator? Is 47K a reasonable MTBF (or MMBF :) ) for a separator?

[Loren]

Is it coming from the front or the back?

I have heard of a similar problem with the EVAP canister in the front.

[markdav]

Definitely the back.

[markdav]

Another day, another update. the dreaded 1128/1130 codes have appeared. I changed my MAF sensor back in April so unlikely to have gone so quickly. Will do the oher standard 1128/1130 checks and report back.

M.

[markdav]

Resolution:

I changed the Oil Separator over the weekend (mine is the vertical lollipop type). Followed the procedure in this post be NotMyCar :http://www.renntech.org/forums/index.php?showtopic=4794 . Great advice about the hose clamps.

Additional advice

- the 2nd tube down (passenger side, half way down) is also awkward to get off. I found that removing the electrical connector next to it helped though this is a bit tricky to get back on without long nose pliers.

- When you separate the filler tube, it is a real bugger to get the top part off - even with hose clamp pliers. Alternative - if you top tube has a flexible joint and you can squeeze it over to the right (looking from the back forwards) past the engine cover mounting socket. Once it is over there - much easier to access the separator bolts and hose clamps. Get teh 2nd tube free before you do this though (see above).

- you need a small wrench/socket set to get the top bolt out. The "normal" sized wrenches hit the oil separator body and you can't quite get on the bolt. Once you have gone past 1/4 turn, you can do the rest with your fingers.

After the repair, the engine idled poorly - almost stalled but I remember from other posts that the engine management system needs a few runs to re-calibrate. Within 3 drives, the car is running well and idling properly. I think you can reset this quicker by taking the battery off for a couple of minutes.

As far as the old unit goes, it did not appear to have a tear in the bottom tube but it was deformed quite badly (almost like there was too much vacuum and had collapsed inwards). Not sure why I got the whine on decelleration but it has gone away and so has the P1128/1130.

Hope this helps.