Rattling noise when cold

[JimX]

I've got a rattling noise coming from the engine somewhere (seems to be low-down, not in the head) that disappears as the engine warms up. At first I thought it might be the cat, because I had a similar rattle in my Commodore and it was the cat, but that noise didn't go away when it got hot. I tried muffling the cat with a towel anyway just to make sure but that didn't make a difference.

It's hard to tell whether the noise is coming from the front or back, but my current theories one of the timing belt pulley bearings or maybe the clutch thrust bearing. I'm not sure if either of these noises would disappear with the engine warming up though. I don't think it's anything too far into the engine because it doesn't sound muffled by anything other than the firewall and bonnet.

Has anyone got any ideas?

[cooks44]

Have you got an A/M zorst?

I've got a similar rattle in mine, turns out it was just the bracket on my Apexi N1 rubbing against the factory rear exhaust mount.

I shift the rubber hangers around until the mounts have a bit of distance between them and it's fine for 4-5 weeks. Then it's time to move them again.

[JimX]

Yes, aftermarket exhaust. I guess that's possible, it might be something rattling on a flange and then as the metal heats up it kind of "seals" the gap so to speak. The noise isn't getting any worse (been this way for like 6 months now, maybe longer) so I'll get the workshop to take a look when I upgrade the dump pipe in a month or 2.

[dan_the_man]

I have a similar rattle when engine is cold. Apparently its the clutch.

[R3AP3R]

Hi JimX,

Did you ever solve this problem? If so, what did you have to do to fix it?

Thanks Mate,

Brad.

I've got a rattling noise coming from the engine somewhere (seems to be low-down, not in the head) that disappears as the engine warms up. At first I thought it might be the cat, because I had a similar rattle in my Commodore and it was the cat, but that noise didn't go away when it got hot. I tried muffling the cat with a towel anyway just to make sure but that didn't make a difference.

It's hard to tell whether the noise is coming from the front or back, but my current theories one of the timing belt pulley bearings or maybe the clutch thrust bearing. I'm not sure if either of these noises would disappear with the engine warming up though. I don't think it's anything too far into the engine because it doesn't sound muffled by anything other than the firewall and bonnet.

Has anyone got any ideas?

[JimX]

Jeebus, NOW you're testing my memory. Let me think.... Oh yeah, I remember now. It was my wastegate (internal). The pivot was borked due to having been welded shut at some point by the previous owner and then cut open again. The result was that it was sticking and not closing all the way when cold and rattling. I got it repaired at Garrett for around $150 (I removed/replaced the turbo myself), after which the noise stopped and I also noticed a power increase because the wastegate could then shut more easily and properly.

I did have another rattle more recently, this was due to a blocked lifter. I spoke to a guy at Autobarn who also owns a Skyline, asked him if he heard of anyone having problems with Motul oil, which I had just switched to. He said no, but asked if it was my first sump full of Motul. I said yes, and he said to his co-worker "What happens on the first oil change with Motul?" The guy said that you get a lot of blow by and a really dirty exhaust, as the Motul cleans out the old crap that was in there because it's got a lot of detergent in it. That's exactly what happened so it wasn't really the Motul oil to blame.

The car's running fine now. I have switched to Fuchs for now, because it's also meant to be a "clean" oil like Motul and Mobil. Apparently Fuchs make a lot of synthetics for other companies too and they re-badge it. I'll try Motul again if I have any problems with Fuchs.