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.

[gtimk5]

I have found most rattling in mk3s to be the heat shield on the engine pipe.
Thats 99% of the time. A hose clamp around the base of it fixes that rattling every time.
Andrew

[Jmac]

Ah thats right mate it is too right at the base of the downpipe a 60mm ish hose clamp will be the go, yeah the little tacks break and they rattle like hell. Good one man its been a while since i did one of them. Back in VW nearly had to fit a clamp to EVERY one
Cheers
Jmac

[jmystaki]

Thanks for all the advice.

More to add to the story:

First took the car to a VW “specialist” without looking at the car, said yep, it’s a ping. He said that head is full of carbon, you have a hot spot and the compression is increased. $1000 to pull the head off, clean the carbon and open the ports up.

Somewhat shocked, I took the card to HiTech in Alexandria. We took the car for a drive, he said he has seen many pinging Golfs and my car was not pinging…..

Frustrating….

I have dropped the car back to the specialist this morning and he was still insisting that it is a ping, I have agreed that he will test the car today.

Regarding the spark plugs, it was 100k and they had the originals (I think), in any case I replaced these with the new Bosch Plat/Iridium plugs ($90 for the set)

I have some clamps at home and will attempt to put one on the base like it has been suggested thanks !

Question:

How can I prove one way or the other that there is a ping?

Given I have taken this to a few people and there seems to be disagreement……

[gtimk5]

I get a heap of Mk3 golfs in my workshop and none of them ping, I would be flat out replacing pistons and heads if they were.
I had a Mk2 GTI with a 2E motor in it and that pinged a bit in trraffic if the temperature got up a bit. Thats lot of stop/go type stuff. It was fine when driving normally.
Mk3 golfs run a cooler thermostat to the earlier golfs.
Andrew

[Biggles]

We have the same model with just under 100K, except it's the 2.0 auto. It has pinged under load as long as we've had it (4 years I think). It's far more prevelant when a/c on and at fairly low revs. Knock it back to 3rd and it goes away. Is more prevalent with 91RON. Hope yours is no more serious than that. Cheers.