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Discussion in 'VR - VS Holden Commodore (1993 - 1997)' started by timc83, Jan 31, 2012.
It's not piston slap?
Yes that would quieten down when warm once the pistons expand. Can get that a lot with forged pistons. Would have thought an Eco would have to have pretty high mileage to get piston slap though, unless it hasn't been treated well?
It's one of the few things that goes away with heat.
I filled the petrol tank with 98 octane and starting up from cold and driving a kilometer, accelerating uphill, the noise has almost completely stopped....so it must have been pinging.
I had not used the car on LPG for a while because of a minor issue....I thought the rattle had suddenly got worse !
I wonder why it is having a tendency to ping ? I should check the timing, perhaps, and retard it a tiny bit. That's what I used to do with my old Peugeot to stop pinging....they have a tendency to do it when the head has been shaved too much. But why is my Commodore doing it, I wonder ?
Could have the incorrect tune? Maybe someone messed with when they fitted gas?
if its pinging the knock sensor should pull the timing????...to answer your other question why...shite fuel 91 is a crap fuel in aus..if your buying it cheap it may contain a lot of crap....95 is the min I run but only if I cant get 98....Im thinking you have gudgeon pin rattle which has prob stuffed the little end bearing...running higher octane fuel takes the load of a bit...Just drive it they will tend to rattle for years
Is this running a factory LPG system or aftermarket?
What plug gaps are you running?
It has an aftermarket LPG, with additive plumbed in to save the valves.
Plug gaps ? I am not sure...but they are newish.
I put in 98 octane but no difference, really. Maybe a tiny bit. And the spark plugs are newish.....I saw a mechanic and he said to check them.
I'm not sure what the solution is, but the key to the problem is that the noise vanishes TOTALLY when the engine gets to operating temperature.
It REALLY sounds like my old Peugeot when it was pinging. Does the balance shaft sound like that ?
Confused, a few days ago you said putting 98 in and the noise went away? If you were in or around Launceston I'd come and have a listen.
I was mistaken....the engine was hot at the time when I filled up with 98, and I went to the shops after that, left it for a little while, then drove home. The rattle seemed to be less, but I think it was wishful thinking. Sorry if I mislead you.
LPG requires a smaller plug gap as it is harder to ignite. It may pay to make sure what the plug gaps are.
When you switch over to LPG is there a light on the dash showing LPG? I'm no expert on LPG systems but I do believe they have different timing requirements and the factory fitted LPG systems tie in with the engine management system and possibly run a different timing map when on LPG. Maybe you need to have someone with LPG experience look at it and make sure the system is tuned correctly.
Plug gap ? The noise happens whether its on LPG or petrol.....
Yes, there is a dash switch, and I believe there is a separate ECU for the LPG...
I missed that. Might be time to take it to a mechanic to check, only so much we can suggest online.
If it’s a mixer system, the tune will be stock. Same tune between petrol and lpg. If it’s still pinging on lpg, it’s either tuned far too lean, you have a maf pipe leak (or maf damaged due to backfire), it has a massive vacuum leak or the ignition system has seen better days. Could definitely be a dfi module issue.
Have even seen it happen because of a slightly blown head gasket. Quite unlikely on the cast iron headed 6’s though.
Check the hoses that go to the throttle body, and the breather that will have been moved to after the mixer when the did the lpg conversion. There should be a plug on the throttle body port for that one.
Try recording the noise on your phone and upload the vid/audio file to youtube or a hosting site....If thats outside your scope of tech savvy have a look at the numerous commodore engine noise video's on youtube, pick one thats sounds the same...also read the comments on the video pages as sometimes the Op reports back with what the issue was
Thanks EYY and Wozza...they are both good ideas. Strangely enough, the mechanic's report on the receipt from the last service says that there is a leak in the intake manifold, but doesn't say any more.
The only thing that I can think of which fits the symptoms of the noise disappearing when it's hot are a vibrating heat shield or clamp on the exhaust. it REALLY sounds like my old Peugeot when it was pinging though.
Incidentally, people I have spoken to have asked me if it was an overhead cam or "the old pushrod Biuck lump", and I assume it is overhead cam. Some have said that 2 engine types came out in a VY. Here is a photo of my engine.
Nahh mate, it's just another evolution of that old lump of Buick cast iron and is definitely still push rod....
Nothing wrong with push rods, just ask any alloytec owner about his timing chains and if he's changed em yet
Leak at the manifold? Does it make a really loud sucking noise after a cold start? Is it using coolant?
Actually, I just found a loose hose on the inlet side and got all excited about quite possibly finding the source of the problem, but...NO. And after taking it for a spin to listen (rattle still there), I sprayed some "Start Ya Bastard" (pure ether) around the inlet manifold. No change in the idle speed, so no leak. DAMN !
No sucking noise, and no coolant loss.
"Ask any alloytec owner about his timing chains and if he's changed em yet"....???
I did not realize that timing chains were a known problem with these engines. But I wonder why the noise goes away when the engine gets hot ? That is the only symptom that keeps irritating me....it doesn't quite fit. Or does it ?
I am assuming that you are bit confused about your type engine. ( maybe you are not confused )
VY 3.8 litre 'Buick lump' / Ecotec push rod … should not have timing chain rattles.
VZ onwards Alloytech OHC 3.6 litre can have timing chain issues if the timing chain was one with identified problems early in the engine build series, or if the service history /oil changes were not carried out more frequently than Holden specified.
Well I wouldn't say that a 3800/ecotec V6 won't have timing chain rattle but it won't anywhere as bad as an alloytec one. I've had a 3800 V6 with a totally failed timing chain tensioner but it wasn't hugely noisy and still did a ripper burnout before I crapped the car. A timing chain rattle noise wouldn't really change much with temp either or not that I noticed at the time.
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