Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Elmstoneboy]

2.6 V6 CDX 2001  Auto 57,500 miles genuine, engine bay like new. Had it now for 6 months, and put about 2,500 on the clock. Had a full major service, oil change all round and Cam belt and tensioners changed, engine and gearbox ECU's updated to latest versions.
No fault codes.

I occasionally get a quite rattle a bit like a piston slap. Engine will run as quiet as you like for most of the time
but sometimes, if I stop at a junction it will then pull away with this rattle which will then slowly go away. More noticeable
at higher revs and pulling harder. Not very loud, but there. Speed of rattle seems to match engine speed. I don't think its cam followers, seem too low in tone. Did have cam rattle, but treatment seems to have cured it. Also think it's too loud to be injectors. No rattle if just revved up when stationary, only when under load. Engine temp doesn't seem to make any difference.
Could it be the auto gearbox?   Will check tomorrow to see if rattle speed changes with gear change.
Car had been SORN for 1 year before I bought it, so wondered if rings might be a bit sticky.

Any ideas
Ian

[chrisgixer]

Heat shields on cats etc?

[Elmstoneboy]

That's a good one, hadn't thought of those.

I think the sound is a bit more mechanical, but I will check them out at the weekend.

Ian

[chrisgixer]

Big jubilees sort them usually. Hope it's that. Doesn't sound like lifters, or exhaust gaskets so not sure what else

[minifreek]

Is it top or bottom rattle...? or hard to pinpoint...?

It could be that it needs an oil change...?

Usually get a rattle like this after head gasket change and not doing the oil change too....

[Elmstoneboy]

Thanks for the replies minifreek and chrisgixer

Pretty sure its not the Cats, the sound is too deep and mechanical, but will still check tomorrow.
I don't think it's the gaskets for same reason. Had the full major service with oil changes all round about 500 miles ago to start off with a clean sheet, also updated engine and gearbox ECU's. Sound was there before and after service.
The best description is still a quiet piston slap, (can you get that these days)? but only sometimes when pulling away from stationary or low speed, goes away when cruising. Tried listening out the window, but I don't think you can hear it outside of the car.  Doesn't do it if just revved when stationary.
Hard to tell if it's top or bottom, but as it only happens when applying power I would go for below the heads.
Could it be sluggish knock sensors, although not getting any fault showing.
So I still need to check the Cats, but don't hold out hope for these.
Again, could it be gearbox (Auto)?    Was laid up for a year before I bought it, could the piston rings be stuck up?
It's a really nice car and in near mint condition with only 57500 on the clock. Genuine going by the near new look of the engine bay. But this silly noise sometimes just takes the edge off the enjoyment.

I had a 2.5 V6 manual CD for 14 years before this one, and never noticed it on that, so not my driving.

Any more ideas.

Ian

[chrisgixer]

Only other thing that comes to mind is the Dearly departed Paul Lovejoys cracked flex plate.

[Elmstoneboy]

Haven't heard that one before, please explain further.

[chrisgixer]

Starter for 10

http://www.omegaowners.com/forum/index.php?topic=94195.15

Video further down.

...?

[chrisgixer]

Or this one? More of a single knock though.

http://s1086.photobucket.com/user/paullovejoy/media/003.mp4.html

[Elmstoneboy]

No, neither of those, thank god, first one much too tinny and loud and the other one just nothing like it.
I'd really be getting worried if I had those.

I'm still sticking to piston slap, but why on an engine with low mileage. Going by the rest of the car, I wouldn't think it had been thrashed.

I'll just have to stare at it tomorrow, usually works.

Thanks for the ideas

Ian

[chrisgixer]

No, neither of those, thank god, first one much too tinny and loud and the other one just nothing like it.
I'd really be getting worried if I had those.

I'm still sticking to piston slap, but why on an engine with low mileage. Going by the rest of the car, I wouldn't think it had been thrashed.

I'll just have to stare at it tomorrow, usually works.

Thanks for the ideas

Ian

While staring, take a video? With sound obviously? 

[Elmstoneboy]

One last stab at possible cause before I get paranoid.

A better description would be a quiet rattle a bit like a diesel and only sometimes when pulling away.
Gets a bit louder with a heavier foot. Doesn't do it when just revving the engine and quiet when cruising.

Could a faulty knock sensor cause this without bringing up a fault code? or would this be a higher pitch.

Just given it the petrol treatment and now running a tank of V Power.
Might be wishful thinking, but, is it getting quieter

My previous 2.5 V6 Manual didn't have this rattle and I had that for 14 years. Maybe it's a 2.6 thing.

 

[kcl]

Have not so far seen/heard a 2,6 which would run as sweet as 2,5/3,0 (not too many 3,2 here so can not tell). Also 2,6 seems to vibrate more than its predecessors, they knock, rattle, whine, no matter how well maintained. Just poor engines, peculiar design in many spots, they all use some oil, they tend to leak something even with reasonable mileage etc etc.

[omegod]

I can only speak from my 2.6 experience but mine was sweet as until I started to get a tappet noise occasionally from the rear of the drivers bank then all hell let loose and the crank seized. Oil pick up blockage caused a spate of problems on here around the same time and left me with the opinion that the 2.6 was more susceptible to this, If I was to buy another V6 the first thing I would do is whip off the sump and clean the pick up!