Groaning/grinding noise when cold when accelerating... need opinions!

[VS_wagoon]

I have an Ecotec VS wagon, it's done 218,000kms. It's in great shape and been well maintained, but around 5 or 6 months ago it started doing something wierd, and it's gradually gotten worse.

It only does it when it's cold(on cold mornings it is really bad - it will vibrate and idle quite rough until the engine has warmed up a little) - on really hot days it hardly does it at all.

When driving I always take it easy until it's warmed up, but regardless of the revs, it makes a groaning noise that I can also feel a little bit through the floor of the car, which makes me think it may be something big.

The strange thing is the noise is louder when going over undulations on the road, on a flat bit of road it can't really be heard usually. The noise is related to the engine revs, ie it changes pitch with the revs. I had a brief chat with a transmission guy and he said it doesn't sound like the trans(as it shifts perfectly), but could be a mount for the engine or trans.

It doesn't do it AT ALL when the car is warm, even at high revs, high load, whatever.

Only other thing I can think of is the bottom end bearing, I do recall about 50,000 kays ago when I had a big service the mechanic said it's leaking and 'will need doing soon'.

I've bad experiences with just handing cars over to mechanics with vague descriptions of a problem, usually they end up replacing lots of different things before finding the problem!

I'm hoping this problem will be familiar to someone! At least if, on the off chance, it's something relatively simple I may be able to do it myself. (ie anything that takes less than one day from first turn of a spanner to test driving the car again!)

 

[skootaroo]

Get a stethoscope and listen to your engine. Remove your engine cover and listen through the top of the plenum, then get underneath and listen through the sump.
Do it cold and do it hot, you will soon know where the noise is the worst.

 

[AttaBoy]

Do you have oil leaking out the rear main seal?? I mean lots of it?

 

[hako]

Could be one of the engine mounts that has slowly sheared since you first noticed the noise - the passenger side one is the worst.
The oil leak will only cause a small loss of oil - the rear bigend bearing will not get damaged as its always supplied with oil under pressure.
Another possibility is tyre noise - a lot of cheap imports feel and sound like you have solid steel tyres when they wear a bit - in the USA they tried to recall some brands sold in Australia.

 

[haloeight]

id put my money onm the engine mounts, also passenger side

 

[VS_wagoon]

I'll try the stethoscope(have to get hold of one first!) and have a listen, however it only makes the noise for a very short time when it's only idling. I'll get someone else to start it and I'll be ready!

I do have a small amount of oil leaking from the rear seal, but it's quite a slow leak.

The sound does seem like one of the mounts could be sheared off - but why would it go away completely when the car is warm? That's what has me confused, and thinking it might be a moving part/bearing etc.

OK, so is there any way I can check the mount, I'm guessing just getting under the car and having a look is enough? Hopefully no removal of hoses/steering components/transmission lol

Hako the tyres is an interesting theory, they are fairly cheap tyres, but the fact the engine has a rough idle/vibration and noise when you first start it makes me think it's the engine/mounts etc. I have recorded the noise onto my phone, now I just need to work out how to upload the sound file somewhere.

 

[hako]

You can put a block of wood under the sump and jack the engine up till it starts to lift the car....if a mount is sheared it will be evident as both are visible - the rear one you can check by shaking transmission side to side.
Another possibility is something loose in the muffler system but my first bet is an engine mount.