Notices
GX - 1st Gen (2003-2009) Discussion topics related to the 2003 -2009 GX470 models

GX470 engine noise when decelerating... RPM drops

Thread Tools
 
Search this Thread
 
Old Sep 3, 2014 | 12:39 PM
  #1  
shinbo's Avatar
shinbo
Thread Starter
Rookie
 
Joined: Dec 2008
Posts: 89
Likes: 3
From: PA
Default GX470 engine noise when decelerating... RPM drops

Hello everyone,

I was wondering if y'all can help me diagnose the engine issue I am having. The gx currently has 96k miles and I am planning on doing a timing belt and water pump replacement as I plan on keeping it as long as possible.

One new issue that crept up is that when going down the hill the car engine sounds like it's actually accelerating and the RPM drops to as if it was idling. Normally when going down the hill it usually stays around 1 or 2 on the rpm, it's noticeably different and just started happening recently.

Anybody have any guesses on what might be the cause of this?
Reply
Old Sep 3, 2014 | 12:44 PM
  #2  
470SNC's Avatar
470SNC
Pole Position
 
Joined: Jul 2014
Posts: 349
Likes: 7
From: CA
Default

you mean when the trans downshifts?
Reply
Old Sep 3, 2014 | 01:04 PM
  #3  
shinbo's Avatar
shinbo
Thread Starter
Rookie
 
Joined: Dec 2008
Posts: 89
Likes: 3
From: PA
Default

Sorry I am not very mechanically inclined... Just that when you let off the gas going downhill... usually the RPM stays relatively high and not at the same rpm as when you are idling. But with my car the rpm when going downhill is basically the same rpm at idle, but the engine sounds like its going faster.
Reply
Old Sep 4, 2014 | 06:30 AM
  #4  
chiph9's Avatar
chiph9
Lead Lap
10 Year Member
Liked
Loved
Community Favorite
 
Joined: Feb 2014
Posts: 3,653
Likes: 818
From: NC
Default

It has a grade sensor, and will normally downshift when you tap the brakes going downhill. Try doing that.

Chip H.
Reply
Old Sep 17, 2014 | 07:33 AM
  #5  
shinbo's Avatar
shinbo
Thread Starter
Rookie
 
Joined: Dec 2008
Posts: 89
Likes: 3
From: PA
Default

After not being able to diagnose the problem, I just decided to take it in for some 90k preventative maintenance anyways.

Timing belt, water pump, oil change, differential fluids, transfer case. And I don't really notice the RPM drop anymore

HOWEVER ... the engine noise is still there and after reading a bunch of forum topics. I think I am pretty confident in saying that the engine noise I am experiencing is a bad wheel bearing.

That being said I am obviously not mechanically inclined and will taking it to either the dealer or shops.

Can somebody explain to me if this is a job that any shop can do and doesnt require a dealer? I read a bunch about pressing and what not and I'm kind of confused what that means
Reply
Old Sep 17, 2014 | 09:10 AM
  #6  
chiph9's Avatar
chiph9
Lead Lap
10 Year Member
Liked
Loved
Community Favorite
 
Joined: Feb 2014
Posts: 3,653
Likes: 818
From: NC
Default

Any competent mechanic can replace a wheel bearing.

The bearings are a tight fit inside the wheel hub, and normally you use a hydraulic press to uhh, press them in. You want to use a press because it will (if used correctly) push the bearings in straight, so they're not ****-eyed.

In theory, you can use a very large socket and a small sledge to hammer them in, but that's not the best way to do it, as it's got way more chance of something going wrong. A press will be more steady & even.

Here's one from an S2000:

http://robrobinette.com/images/S2000...ntHubPress.jpg

Chip H.
Reply
Old Sep 17, 2014 | 10:56 AM
  #7  
shinbo's Avatar
shinbo
Thread Starter
Rookie
 
Joined: Dec 2008
Posts: 89
Likes: 3
From: PA
Default

ohhh I see. From some of the other posts, it made it seem like it is something specific you request. So a hydraulic press should be a fairly common piece of equipment most mechanics have them right?

So if the bearings are bad, can they just press it back together or would I need to get an entire new bearing for the mechanic to replace it with?

Thanks Chip
Reply
Old Sep 17, 2014 | 11:21 AM
  #8  
shinbo's Avatar
shinbo
Thread Starter
Rookie
 
Joined: Dec 2008
Posts: 89
Likes: 3
From: PA
Default

And what does repacking wheel bearings mean?
Reply
Old Sep 17, 2014 | 11:43 AM
  #9  
chiph9's Avatar
chiph9
Lead Lap
10 Year Member
Liked
Loved
Community Favorite
 
Joined: Feb 2014
Posts: 3,653
Likes: 818
From: NC
Default

You would use a new bearing. The part is around $180.

You could get it repacked (new grease put in) but afterwards you'd still be running on an old bearing and would likely end up replacing it soon afterwards anyway. You would maybe save $50, assuming the mechanic would be willing to do this (he may not, for liability reasons)

Chip H.
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
MattLS400
LS - 1st and 2nd Gen (1990-2000)
190
Mar 18, 2021 03:28 PM
Rayhan
Pacific
0
Jul 27, 2018 04:20 PM
alder8
GX - 2nd Gen (2010-2023)
3
Dec 22, 2015 10:55 AM
davids75
SC - 1st Gen (1992-2000)
7
Jan 6, 2013 08:16 PM
Rover
Performance
12
Sep 3, 2002 02:55 AM




All times are GMT -7. The time now is 08:12 AM.