We've had the car for many years, and while it's due for a tuneup the oil is changed regularly. 95% of startups are normal, but in the last month we've had about three where it sounds like marbles are loose in the engine. It misfires (I think) and makes a *very* loud metallic rattle. I think 'Damn - there goes the motor' but then after about two seconds it stops, and the engine is once more smooth and quiet. Any ideas? Injectors?
Just a guess, oil related issue and piston slap??
When was the last oil and filter change?
Maybe a filter with bad anti drainbck valve, is it generic.
No, the car is misfiring when it happens, and it's only occasional. It's also loud enough that if it were piston slap, the engine would be toast. I've heard the Toyota 'dry bearings startup sound' and this isn't it.
How old are plugs and wires, is the coil under the cap, they can get oiled up and short when damp.
That wouldn't explain the loud clattering noise.
Oh really, you said it missfires, what do you think spark plugs do, wake up.
Look butt head I never said detonation, you ass wipe, said missfire, you said it needs a tune up, maintain the dam thing and it wont sound or run like shit.
I'm trying to be patient with you, Ransley, but you're making it difficult. The car is misfiring when it does this, but only then, and the noise is *extremely loud and metallic*. If it were detonation the motor would be toast. I'm asking about the clattering. I know what misfiring sounds like, and the clattering isn't misfiring. Please step back and hopefully one of the techs will have an idea.
I can suggest that you learn to read for comprehension, but I can't make it happen. The car runs fine the 99% of the time this isn't happening. What I wrote was that the car is *due* for a tuneup, not that it's running poorly.
I gritted my teeth when you first started posting bleeding obvious suggestions here with little or no punctuation, in the hope that you would improve. You did, but you still feel the need to make a contribution whether you have a clue or not. I'm going to put you on Ignore now, but I'll first suggest you read slowly and carefully, and only make suggestions when you actually have an idea.
If this coincides with misfiring then I would suspect oil leaks into a cylinder or cylinders. Oil reduces the octane rating and will make it more likely to knock. If this isn't a case of lubrication problem and piston slap, then I'd check for oil leaks into the cylinder(s) and spark knock (detonation).
This should be easy by checking the condition of the spark plugs. See:
Now I wouldn't say that occasional detonation or piston slap will toast the engine. These actually happen frequently. The new Toyota/ Lexus 3.5L V6 just about all have piston slaps when cold. One owner even reported 3 other new Lexus ES's tested piston slap while new on the dealer lot.
BTW, from what you describe, I th> =A0 =A0 No, the car is misfiring when it happens, and it's only occasiona= l.
Also, I think it may be possible to check the knock sensor (I'm not sure if measuring it with a voltmeter helps.) and monitor the engine timing. If the knock sensor generates an output and the engine timing retards, then that says something.
I think it may be less of a lean mixture (injector) problem, because it would run fine afterwards.
I was thinking more like a physically malfunctioning injector, but again, it's odd that it goes completely away, and only happens once in a while, and only on startup. Does the knock sensor even come into play at idle? The problem only occurs at engine speeds way below 1k RPM. This engine doesn't use a separate cold start injector, right?
I'll check the plugs for signs of oil. The engine has about 187k miles on it, so if it's leaking it may be time to get a newer car. Shame if so, because it's never used oil. I find it hard to believe that detonation could make that much noise at such a low speed, but I can't think of a better explanation, either...
When the plug's off, note any carbon deposit pattern on the piston top that you can see. Note if there is a carboned-up top with a clean ring around the piston outer edge (oil control ring problem). If a single larger lump -- valve stem seal leaks.
If plugs otherwise look fine, I'd use a can of Techron Fuel System Cleaner (stronger than "fuel injector cleaner") and consider changing out the $20 fuel filter in the engine bay. Be careful of seized flare nut - twisted fuel pipe results.
If that 95 has OBD-II (even if pre-1996), then a new fuel filter should help rid a pegged max positive short term fuel trim and lean driveability problem (lean related spark knock), if that's the case.
Just my 2 cents.
I'll look at the plugs and see if the piston top is visible. I'll also use the techron. The fuel filter is fairly recent. Thanks for the advice. If it looks like minor leakdown, I'll try high-mileage oil with seal conditioner. We'd like to get one more year out of the car, if only because we had the CV joints and brakes done last Fall. Will a standard plug wrench work with this engine? I had an '87 Celica that needed a deep-well plug wrench...
Ok, I just had an unpleasant thought, which should be fairly easy to check. If there is a substantial oil leakdown into the cylinders (or even just one) maybe it's accumulating enough oil to cause something approaching 'water lock' on startup. The compression would shoot way up for a few revolutions, until the oil got cleared out. Maybe a broken valve oil seal?
Leftie wrote:
A standard 5/8" wrench with a standard 6" 3/8"-drive adapter works fine. This is the socket (Craftsman #43324) I use:
Probably no need to turn the engine to BDC. You can only see a small portion, but you should be able to tell if there is excessive carbon build up.
Suppose there is no lack of lube and piston slap, as you said. Then other reasons for the spark knock (which would sound like marbles rattling around), are lean condition and high compression ratio from carbon build up.
The interesting thing is that it goes away after a couple of seconds. That's why I originally thought it was lube/piston slap kind of a problem.
Valve stem seals are responsible for most of oil consumptions. That's why I wondered about the carbon on piston. I say piston because we can't see the valve normally. It's usually a lumpy carbon area next to a clean spot, which is different from a clean ring around the outer piston edge for oil control ring problem. If you see the spark plug oily only on one side that's a tell sign too of stem seal leaks. (Oil leaks result in wet gummy type of coating. Rich mixture results in dry type of carbon.)
I don't think you're leaking that much oil -- otherwise you'll see it in oil levels, which you said is fine.
Now, > =A0 =A0 =A0Ok, I just had an unpleasant thought, which should be fairly e= asy
I replaced the plugs today. I didn't see what I expected to see: all four plugs looked great for plugs at the end of their 60k mile service life. Nice even grey color with a hint of brown, no deformation or melting from detonation, just normal wear at the gap. I only looked at the top of one piston, but it looked clean. The oil is down half a quart, but that's with a whole Winter's driving. No smoke at startup. I half expected to be able to reproduce the noise by letting the car sit for several days, but it started and ran fine. Aside from eliminating oil leakdown as a suspect, I still haven't a clue...
The damned online manual confused me by specifying a "16mm spark plug wrench." The guy at NAPA had no idea what that meant, and just gave me a socket for the plugs I was buying (NGK platinum tip). I think that
16mm may be the width of the whole socket, so it fits into the well, but they don't label sockets that way.MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.