Rattle under load when engine is hot

[jmystaki]

Hi,

I have a 1997 Golf 2.0 8v - with 104k kms.

When the engine is hot I get a rattle between 1.5k rpm to 2.5k rpm under load/acceleration.

Troubleshooting:

1. replaced the spark plugs
2. decarbonised the head and intake with a spray kit
3. running premium 98 octane
4. no noises when revving the engine at a standstill
5. no obvious loose items under the hood
6. does not rattle when the engine is cold
7. no engine light to signify pinging
8. compression test - pass
9. fuel economy good
10. no faults from the computer

any suggestions/help or similar experience would be appreciated.

Cheers

[bombsquad21]

My car did this the entire time I owned it..I fixed it by removing suitcase muffler!!

[Pullstarter]

Pinging maybe?

[Mrk_Mickey]

What kind of a rattle is it...ie, does it sound metallic, etc?

[jmystaki]

Thanks for the interest.

It does sounds metallic, but I cannot be too sure.

I took the car to Hitech and they said it was not a ping....

When the car is hot (20min driving) and low RPM, usually 4th gear between 1500 and 2500 under acceleration the is a light rattle rattle - 5 - 6 rattles and then you have reached higher rpms where you either cannot hear it due to the increased engine noise or it does not make the noise...

Seems to be when the motor is under lots of load...

With the AC on it is more frequent... i think because of the extra engine load....

[Bora Sport]

I am guessing that it is the aluminium heat shield on the down pipe.

[Pullstarter]

That really sounds like the symptoms of pinging to me...........but who am I to argue with hitech?

[jmystaki]

i am open to pinging....I have decarbonised the head, with a Jap fluid and with the can's the Subaru supply, changed plugs, put in high octane fuel...

reasons against pinging.....

1. no engine light
2. no real loss of performance ( expected from advanced engine timing )
3. no logs in the computer.....

I will have a look at the exhaust covers and see what's going on...

For the pinging, any other suggestions, things that I can try?

Cheers

[Jmac]

You wont nescessarily get an engine light if you are having a pinging condition, and i gather you are using 98 Ron. Mate give your Cat a bump to see if it may be breaking down, that is something to look at, like Bora Sport says check the heatsheild near the right engine mount. A ping is a Ping and it should be fairly obvious if it is. Most cars do ping now and again but this should go un noticed, its the pings that you can hear that are a worry and need attending, means there is some drama in the combustion chamber. Try a cooler set of plugs if you think it is pinging and look you may have a crap tank of juice.
Good luck
Cheers
Jmac

[Valver.]

The knock control in Mk3 8vs is rubbish. I don't think I've ever driven one running sub-95RON that hasn't pinged - this rings true for CL 1.8s as well. I wouldn't change the plugs, personally (provided they're the right ones), as that is only compensating for problems elsewhere. As said already, run some good fuel through it again - make sure you've flushed out almost all the old fuel first. It may not even hurt to replace the knock sensor as they can cark it without throwing a code.

It's unlikely to be bearing rattle at that mileage (!) - provided it's been even reasonably looked after.