Grinding Rattle at low speeds

[anphoto]

Morning Guys, went for a long drive yesterday, what an awesome car the Legnum is on windy roads, just ask the barina driver who couldn't keep up with the station wagon :wanker:

But when i had to turn around, at low speeds, there is a grinding rattle coming from underneath the car. in reverse, and 1st gear, once i get up above 30k's i cannot hear the noise anymore.

Any ideas what this could be, also on the way back from the drive (i said long, but only 60k's round trip) the gear change was a bit more sluggish than normal, transmission overheating maybe?? I don't have a cooler on it.... I'm hoping it's nothing serious, as i haven't had the car that long And i wasn't accelerating hard either, just enjoying the drive out...

 

[qball]

Have you flushed/changed the transmission fluid yet?? My gear changes were heaps better after doing mine, the fluid came out chocolate brown not ruby red so you can see why gears changes could be worse

 

[mallen]

Drive faster

 

[naughtika]

Drive faster

was gonna suggest the same... drive above 30km/h ALL THE TIME!!

 

[pu-11-me]

Check the Automatic transmission thread in the INDEX, you may find something useful in there

You will find that heat will be your problem though i think

 

[anphoto]

thanks for this guys, i have also noticed a "pulling back sensation" when driving downhill, almost as if the transmission cannot decide to change down / up or just stay in gear

 

[Hotwire]

Alan, when heading down a hill, the car senses the increase in speed, and if there is no accellerator input, the car will drop back a gear, slowing the car. If you watch the gear indicator in your dash you will see it shift, 5-4, or 4-3 depending on your speed. This is normal, don't worry about this.

 

[naughtika]

try resetting the ecu.. might help if its auto..

 

[BuzzPuppy]

And please don't wreck the Red Super VR-4 Galant *hopes*

 

[dimi_108]

Have you done a transmission flush and service yet?

And like Lee said, the INVECS transmission will shift down on its own when you're going downhill.

 

[bradc]

The rattling could be something else though other than the gearbox, like the exhaust rattling or something. Does it go away if you put the car into neutral, and if not, what happens if you rev while in neutral?

 

[anphoto]

revving in neutral causes the rattle too i got the guys i bought the car from to check out the transmission earlier, found the fluid to be very low. they topped it up for me, advised me to take it easy until next week, then they would be able to do a flush / gasket / filter change on the transmission. However, the gear change is much smoother after topping up the fluid. I will ask them about the rattle when i take it in next week. All under the warranty apparantly, so it's not going to cost me a cent

 

[bradc]

Check your engine mounts. I've heard of 2 VR-4's now with random rattling coming from them due to expired engine mounts

 

[Hotwire]

^Brad - what would you look for in a stuffed engine mount (never seen one)

 

[whiteleg]

torn or crushed rubber. I would guess that most legnums could do with replacing as they are of similar age and mileage. The problem is getting them. You can get custom ones made but it takes a couple of days usually.

 

[Hotwire]

Thanks! Next question - where are they on a legnum? Easily visible?

As you can probably guess, lately I've heard a few random rattles that seem to be under mild load only when accellerating through 2-3,000rpm, and bloody hard to repeat so I've never been able to replicate it while stationary or while driving with my mechanic in the car.

 

[whiteleg]

They are not easy to get a good view, there is one on the gearbox, engine, cross member front and one at the back. The 2 side ones keep everthing at the right height so if your gearbox is touching your cross member like mine they are stuffed. The front 2 are to keep it all inline and stable but if stuffed they will cause a shuddering noise.

 

[bradc]

Matt explained it well. The back one is virtually impossible to see unless the car is up quite high and you have very good light.

The front one and the two side ones are easier to see though.

 

[anphoto]

ok, after another trip to the mechanic, he advises that it's nothing to worry about - it's the heat exchanger on the exhaust, and when it's next in for service (about 3000k's) that he will fix it, he also advised, that if it get's worse, i should take it back straight away for further investigation. Oh well, watch this space :S

 

[SiliconAngel]

All four of my engine mounts are REALLY easy to see at the moment I'm gonna give them a good looking at as I have to release three of them anyway...

Sounds like you're on the right track, Alan. Just remember that even if your car's under warranty, allowing your fluids to drop too low might cause permanent damage that's at best going to be a massive inconvenience... and at worst won't be covered at all. At the end of the day its your car so the buck has to stop with you.