hey guys, tonight i noticed my motor making a weird noise. it sounds like a slightly noisy rod, or something in the valvetrain, and does it above 2750 ish rpm (i got it to do it anywhere from 2750 to 4200 , but didnt feel comfortable holding it at like 5k to try it. It makes this metal on metal tapping/knocking noise when vacuum is between 5 and 15 in hg. If i let off the gas all the way and let it go to full vacuum it goes away, and if i get on the throttle enough to take the boost gauge to 0 or higher, it goes away, but will stay making a pronounced knock around 15 in hg. any ideas? i need to know what to do, i am terrified i will need a motor after borrowing money to replace a bad tranny. thanks, mark
check oil or change it and get an oil analysis (but without a baseline you may not get a full report)
how could it be a spun bearing dependent of throttle position? wouldnt it do it regardless of throttle position? i checked it today when getting gas and it was good, right up to the full mark on castrol syntec blend 5w30. also it is less than 1k out from the last oil change, and is still making 75 psi consistent oil pressure at cruising rpm. wouldn't a rod bearing problem cause a drop, or at least fluctuation in oil pressure
that makes sense to me, but wouldnt a wot pull to like 6k make it knock more, or going wot at 3k make it knock still? ps>thanks for the help
not sure. as i never was physically there when it went out. just heard it over the phone. but its possible that spinning it fast enough could get it to balance itself back out. eventually i would think it would get so bad that it will either shoot through the block or head, and/or something just plain break edit: don't quote me on any of this. this is just what it sounds like to me, i am in no way a mechanic or anything of the sort. best guy to ask IMHO would be Will
thanks for the help man, in fact i just pmed wjm and kingwrex asking for info about it. lol i have had 2 motors that spun bearings (a 2.5 mazda v6 and a 4g63 built) and neither one of them would go away, certainly not at high rpm, but that sure is what it sounds like.
I would check and make sure you don't have any exhaust leaks since you had the downpipe off for the tranny swap. Also check the oil like has been suggested. Drain it into a very clean container and see if there are any flakes or if it is glittery. I hope it doesn't come to this but I have a long bock in great shape sitting in my garage.
Rod knock. Sorry. Check your oil. If there is metal in the oil on the dipstick (like small speckles) then you are toast. At that point (which I'm 110% positive), DO NOT drive the car or run the engine anymore. It will cause further damage to the engine. You'll need to replace: Block assy Oil pump Oil pan clean baffle plate REALLY good (or replace) Oil cooler Plus all the required gaskets and such. Sounds like a good time for the 2.5 STi block. injectors, fuel pump and a turbo would be wise as well.
Is it a knock, or a slight tick? I noticed mine ticked along time ago when pressing the throttle and stopped when I let off or put it in neutral. I had kingwrex look at it and he didn't think anything was really wrong just noisy lifters.
i am the one who bought bc2003uga's car. had it 3 weeks and it popped. sounds exactly like the same symptoms i had...as stated before...drain your oil in a clean container...shine a light in it and stir it...if it looks like a pretty gold or copper color....go ahead and bite the bullet. you will like the new found power...but also, don't run it anymore...heads aren't cheap! i got lucky with mine and didn't have to replace them!
agreed. i had an sti not long ago with the same symptoms and it ended up being rod bearings that were oil starved wich caused to much clearance and the piston was ever so slightly hitting the head.
Ya, i've seen a ton that hit the head after the rod bearing was done with playing w/out oil. scoobaru's STi would have the same symptoms as the OP as well.
Design flaw? No. Failure rate from factory quality issues? Less than 0.01%. How to prevent? Check your oil! Keep it full. Change it on a normal basis*! *Normal basis: Every 3,000 miles/3 months, whichever comes first. Before AND after each track day (road course, more than 4 hrs total track time) Also, using QUALITY oil helps a ton.
I am covered there, probably wasting money changing high grade synthetic every 3000, but I sure as heck do it! I have been doing some e-research and have come across people with issues regarding the oil pump pick up. There was also some controversy regarding synthetic oil not being very good for our engines. I don't know how much merit that has?
Its the Mobil 1 that has issues. Otherwise, anything else thats synthetic has not had the widespread failure like Mobil 1. The pickup tube issue is only on a small percentage of EJ257/EJ255 and causes complete and total engine failure.
The only reason I am curious is because I have had intermittent lifter noise here and there which seems to be common. Kingwrex just gave my car a thorough once over incl. oil change and test drive so I am sure it's OK. Is there a certain oil weight and/or brand you would recommend? I am running Amsoil.
the 02's have more lifter noise than the 03+ engines. So thats normal. Just check it at every refuel and change it every 3k and you are good.
It sounds like it *might* be your boost control solenoid ringing... have you changed something with that lately? Siegel
update- i drained the oil and it looked okay, maybe a tiny tiny little bit sparkly at the bottom of the very clean pan, but it seemed pretty normal. Im not sure what to think. I don't understand how a rod knock could go away at 5500 rpm if you nail it, but at intermediate vacuum it would do it, but both throttle and letting off and letting the motor build full vacuum makes it stop, The dipstick looks great, and i kept a quart or so of what i drained out, and it looks okay. what the hell else could it be? it definitely sounds like a rod noise, but a rod noise would get louder at higher rpm regardless of throttle position/boost/vacuum level wouldnt it? also wouldnt a spun bearing most definitely change oil pressure in some way? thanks guys, mark
no i haven't. It has been out of the wastegate circuit for awhile. (when i first got the car it would overboost, oscillate between over and underboosting then settle around target. I had will look at it at SOG and he said it was normal and needed a tune. to be safe i disconnected the bcs and run straight wastegate pressure (around 7 psi) mark
Is your BCS connected electronically? what BCS is it? It's the solenoid ITSELF that can make a clicking / ticking sound. Siegel
it is the factory bcs and it is still hooked up. electrically. do you think i should unplug it and see what it does?
That boost issue sounds like the $.16 mod of changing the restricter pill. Have you checked the diameter of that little thing?
yeah i thought so too, it didnt have one in it, and will suggested checking that, so i picked up the correct one and put it in the right place and it didnt help.
I hate to say it but are you sure you dont have anything loose in the engine bay that would be hitting metal as the engine vibrates? I had a terrible tapping sound but it turned out to be one of the airbox clips tapping against the inner fender, at idle it was nothing but as the motor got load it would start ticking. Otherwise you could get an automotive stethoscope and feel around the motor while a friend revs the car to isolate the noise.
I couldn't find anything loose, i thought of that too. I need to get a stethoscope. I checked the oil like 5 times today (and it is 1 day old, like 100 miles on it) clean and clear, not a single metal or dark particle any time i checked it. since the oil is clean and it doesnt do it revving up to redline in idle, im gambling on it not being a rod, and i HAVE to drive it lke 4 hours tomorrow, so like i heard mike (liquidforce) say in another post, if i drive it at 4k at 80 mph for 4 hours and it doesnt blow, its not a rod problem, and if it is i will be buying that motor from him.
i hope not rick lol maybe it fell down when i took the ic off and us in the oil pan now lol it magically made it through the intake valves
bump. Nice meeting you tonight. Like I said earlier, I'm stumped as to the sound. Definately not rod knock, something's just loose, maybe a motor or tranny mount, or something to do with the clutch/flywheel assembly.
You need to follow through on the stethescope idea. Just get a long screw driver and put your ear to the handle and start poking around. I did this with scoobaru's car and it was quite evident which cylinder had the bad bearings.
hey Will, think it could possibly be that powersteering knock that happened on my car? Granted it's happening at a lot higher RPM than mine did, but never know.