Rattling on part throttle!

[cheekychimp]

I blew an oil cooler line the other night but fortunately I was only driving back from the train station. The idiot light never came but when I saw all the oil in the drive way after I got home I shut the car down immediately. I've got no light in the yard, so I left the car overnight. I checked the oil level the following day and it was pretty much empty. I'm sure I continued to lose some oil after I shut the car down but I have to resign myself to the fact that I must have been driving for several kilometres on very little oil immediately before reaching the house. And yeah I do have an oil pressure gauge sitting on the shelf that I have never got round to installing. Live and learn /ubbthreads/images/graemlins/banghead.gif

The mechanic says he is worried about oil starvation and bearing damage and said he could hear noise on his test drive after replacing the cooler and lines. I took the car for a run last night and I couldn't hear anything that wasn't there before. I've noticed a slight rattling sound on part throttle for some time when the engine is cold but it disappears as soon as the car warms up, especially after getting into boost.

I thought this car had OEM EVO Pistons which I'm pretty sure are not forged so I don't think it is the pistons. I can't believe this is bearing damage because if it was I'm pretty sure it would be present all the time. Thing is now though, I've started worrying about what that sound might be. It sounds like a loose butterfly valve in the cyclone or throttle body that is rattling but I don't think it is because again I can't see any reason for either to disappear once the engine has warmed up and seen boost. Piston Rings?

Anyone got any experience with noises that disappear after warming up that I might investigate or a description of bearing damage noise? If not, I guess I'll have to change the oil out again in a week and drop the pan to check for damage. Do I see new pistons, bearings and rods in my future?

 

[GSTwithPSI]

Every 4G63 I've ever owned has had its own little special noises like that. I used to worry about little noises like you're describing, but after a decade of hearing that kind of stuff, I feel like my mind has started tuning out everything but the real bad sounds.

If your oil light is currently functioning, then it should have come on if the oil level got ridiculously low. If it is indeed working, and never came on, I'd bet you dodged a bullet. If there was enough oil pressure to keep the light off, there's a chance the bearings had oil the whole time. On my last motor, I had the stud for the water cooled OFH come loose while driving down the road and sh*t out all the oil about a mile from my house. I didn't notice until the oil light came on, at which point I immediately shut the car down. After getting the car home, I dumped in new oil, and the car ran fine for thousands more miles.

There are a bunch of things that could make the noise you're hearing. Lifters, failing timing tensioner, piston skirts wearing, even the turbo. I seriously doubt it's a bearing noise, as they typically don't go away. The just get worse, and do so very quickly.

Honestly, Paul, I don't think you have anything to worry about. If you really want the piece of mind, drop the pan like you mentioned, and see what there is to see. In my past experience, when things like bearings and major engine components started to fail, they failed hard. It was never really a slow progressive thing.

I know what it's like to have a scare, and start playing the what-if game in your mind afterwards. I would just do all the noninvasive checks that you can, and if everything checks out, leave it be.

 

[cheekychimp]

Brett,

Thanks for taking the time to reply with that because it does really put my mind at ease. I too have never experienced major damage ocurring progressively. It's usually pretty quick and pretty dramatic. Stuff works and then it just doesn't until it's fixed. Hopefully this is just another one of those annoying little character traits that I'll never get to the bottom of ... at least not until it has been replaced by something else /ubbthreads/images/graemlins/rofl.gif

Paul.

 

[FlyingEagle]

As stated above, does it sound like the lifters have all bled back up, assuming they bled down?

 

[cheekychimp]

No, the lifters actually sound fine! I replaced those a few months back because the old ones definitely were making noise. The new 3G ones eliminated it.

 

[EHmotorsports]

My initial thoughts were tensioner issues or cooler bracket/mounting tab broken or lose. Might check the cooler lines routing and cooler for anything lose.

 

[thomcasey]

Might be a little noise from the balance shafts. Mine get a little "buzzy" between 2-3k rpms when the car is cold (though much colder here in Indiana than HK), But once it warms up a bit it goes away.

 

[cheekychimp]

Thanks for the replies guys. I'll be sure to check these suggestions out. After driving the car for a few days, I am convinced that there is no bearing damage but you're help has pursuaded me to start looking for possible causes to this rattling noise.

 

[desant78]

a few months ago we had a 1g come through our place, and it had a slight bearing failure. Car ran fine, but there was a constant "no good" noise coming from the motor. Pulling the oil pan, it was clear that metal shavings were present. Also, by inspecting the crank, #3 rod cap was starting to become discolored from heat, and #4 rod cap had slight coloring. When we pulled the caps, it was evident #3 failed and starved #4.

At the very least, I'd pull the oil pan and valve cover and see if I find any metal or indications of heat. If all seems well, I wouldn't never debate again if anything is damaged. Good luck, hope my story helps!