987687 Posted February 27, 2012 Share Posted February 27, 2012 Just wondering if you guys think this knocking noise is rod knock, or what. It does it cruising at about 3k RPMs. It did it the whole entire way from Maine to NYC, and back. It was a little disconcerting at first, but I started to ignore it.. But doesn't really do it when not under load (which is why I had to rev it a bit), and totally goes away when at WOT. I really don't think it's the tensioner flopping around, I'm running coverless and it stays perfectly put. Ignore the smoke... something is leaking oil onto the y-pipe... Quote Link to comment Share on other sites More sharing options...
987687 Posted February 27, 2012 Author Share Posted February 27, 2012 Also, I should mention. The engine is fully up to temperature in the video. I had driven it probably 20 miles prior, so oil and all that was up to operating temp. Quote Link to comment Share on other sites More sharing options...
AdventureSubaru Posted February 27, 2012 Share Posted February 27, 2012 Sounds the same as my 2000 Outback on cold start. Mine goes away after warming up. I've assumed it to be piston slap. at 297k I'm not too concerned. When it goes, i'll just replace it. Quote Link to comment Share on other sites More sharing options...
987687 Posted February 27, 2012 Author Share Posted February 27, 2012 Ya, mine make a pretty terrible noise when it's cold. But that vid is warm. Which is why it has me slightly more concerned. Quote Link to comment Share on other sites More sharing options...
Robert Harik Posted February 27, 2012 Share Posted February 27, 2012 (edited) Ya, mine make a pretty terrible noise when it's cold. But that vid is warm. Which is why it has me slightly more concerned. Its always hard to tell from a video, but it does not sound like a rod. Since its louder at start ( cold ) maybe piston slap. Get an automotive stethoscope and look/ listen around. Accessories ( alternator, power steering pump, AC comp.) can make a lot of noise. Pull off your accessory drive belts , if the sound is still there( wasn't an accessory) you will be able to hear the engine much better. Run the engine till you can hear the noise, and start pulling/grounding plug wires or shorting out plugs one at a time till you find the offending cylinder( noise will change, get much softer or disappear when there is no fire on bad cylinder). Also the timing belt tensioner can make clicking /knocking sound when worn( with a stethoscope you will be able to find out where the sound is coming from). Edited February 28, 2012 by Robert Harik Quote Link to comment Share on other sites More sharing options...
987687 Posted February 28, 2012 Author Share Posted February 28, 2012 Its always hard to tell from a video, but it does not sound like a rod. Since its louder at start ( cold ) maybe piston slap. Get an automotive stethoscope and look/ listen around. Accessories ( alternator, power steering pump, AC comp.) can make a lot of noise. Pull off your accessory drive belts , if the sound is still there( wasn't an accessory) you will be able to hear the engine much better. Run the engine till you can hear the noise, and start pulling plug wires or shorting out plugs one at a time till you find the offending cylinder( noise will change, get much softer or disappear when there is no fire on bad cylinder). Also the timing belt tensioner can make clicking /knocking sound when worn( with a stethoscope you will be able to find out where the sound is coming from). The could sound is definitely piston slap, and that's loud enough to cover this noise. I'd call this a cross between ticking and knocking. It's more pronounced than valvetrain noise, which it also has... The stethoscope is a good idea, as is checking the accessories. As you can see, the AC is disconnected as it doesn't work anyway. I can also pull injector plugs, that way the ZAP ZAP ZAP noise of spark jumping won't confuse noises. Or electrocute me I don't think it's the timing belt tensioner, since I don't have covers I can see it. It's my understanding they slap up and down when they make this noise? Mine stays rock solid, I actually got a shot of it in that vid to prove. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted February 28, 2012 Share Posted February 28, 2012 Auto or manual trans? A cracked flexplate can make a clicking/knocking type sound. You can get an oil analysis test to find out if it's a bearing. Did you notice if it seems to come from one side of the engine? Or front/back? Quote Link to comment Share on other sites More sharing options...
Ricearu Posted February 28, 2012 Share Posted February 28, 2012 Sounds pretty rod knocky to me. Hate to say it but roommate's postal does the same thing. Quote Link to comment Share on other sites More sharing options...
987687 Posted February 28, 2012 Author Share Posted February 28, 2012 It's an auto, I thought about cracked flexplate. I checked the bolts, and they're all tight. So it's not that. I can't tell where it's coming from, the valves make a lot of noise too... I'll probably send the oil off at the next oil change... if it makes it that long... Quote Link to comment Share on other sites More sharing options...
ccrinc Posted February 28, 2012 Share Posted February 28, 2012 That engine has solid lifters. I would suggest the problem is that you need a valve adjust. They can make an awful noise when they get too tight. Emily www.ccrengines.com Quote Link to comment Share on other sites More sharing options...
Robert Harik Posted February 28, 2012 Share Posted February 28, 2012 (edited) The could sound is definitely piston slap, and that's loud enough to cover this noise. I'd call this a cross between ticking and knocking. It's more pronounced than valvetrain noise, which it also has... The stethoscope is a good idea, as is checking the accessories. As you can see, the AC is disconnected as it doesn't work anyway. I can also pull injector plugs, that way the ZAP ZAP ZAP noise of spark jumping won't confuse noises. Or electrocute me I don't think it's the timing belt tensioner, since I don't have covers I can see it. It's my understanding they slap up and down when they make this noise? Mine stays rock solid, I actually got a shot of it in that vid to prove. I don't know about yours but my injectors/ plugs are hard to get to. You can use a regular test light , hook the test light ground to an engine ground and either pierce the plug boot with the sharp end of the tester( when you want to ground out that plug) or you can stick straight pins into each boot and then touch it with the tester probe. Edited February 28, 2012 by Robert Harik Quote Link to comment Share on other sites More sharing options...
987687 Posted February 28, 2012 Author Share Posted February 28, 2012 Pokin holes in the wire boots sounds like a really terrible idea. It will let spark leak out, let water in, and make a mess of expensive set of wires. They're only a year old, no way am I destroying them. My injector plugs are easy to access. It's hard to tell if it makes a difference when I pull the connectors off. It runs so rough. Quote Link to comment Share on other sites More sharing options...
Robert Harik Posted February 28, 2012 Share Posted February 28, 2012 (edited) You don't rip a large hole lol, you make a small prick with a sharpened probe or straight pin. No it won let the spark out or water in. Its your car though, so you have to be comfortable with what work is done. Edited February 28, 2012 by Robert Harik Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted February 28, 2012 Share Posted February 28, 2012 I've had to patch up plug wires where people poked holes in the boots. Tiny holes, only visible when you stretch the boot just right, but they still allowed spark to arc out. A dab of RTV can sometimes seal them back up temporarily. Unplugging fuel injectors is easier. Quote Link to comment Share on other sites More sharing options...
987687 Posted February 28, 2012 Author Share Posted February 28, 2012 ^ of course putting tiny holes in them screwed them up. I can't stand mechanics who do stuff like this. Quote Link to comment Share on other sites More sharing options...
Robert Harik Posted February 28, 2012 Share Posted February 28, 2012 ^ of course putting tiny holes in them screwed them up.I can't stand mechanics who do stuff like this. I am trying to help you , you don't have to follow my advice , but don't be rude. Quote Link to comment Share on other sites More sharing options...
987687 Posted February 28, 2012 Author Share Posted February 28, 2012 Sorry, I'm not trying to stir arguments. Quote Link to comment Share on other sites More sharing options...
WoodsWagon Posted February 28, 2012 Share Posted February 28, 2012 I am trying to help you , you don't have to follow my advice , but don't be rude. Giving advice that will cause more issues down the road is cause for being rude. Compromising high tension wires by poking holes in the insulation is a bad diagnostic method. That sounds like rod knock in your video. If it was piston slap it would do a steady smack smack smack at idle. Floating the RPMS around 3k and having the noise get worse or getting a back-rattle as you let the RPMS come back down are often signs of rod knock. A flex plate will often clank at idle too. My friends WRX sounded like yours does for about 5 months before it finally spun 2 bearings. He was hard on it too. So you may have some time before it dies. Quote Link to comment Share on other sites More sharing options...
987687 Posted February 29, 2012 Author Share Posted February 29, 2012 Is there any oil additive that'll help with bearing wear? Should I run really thick oil? Usually, I'm really opposed to magic in a bottle type fixes. But if it's going to blow up anyway, why not? Maybe it'll actually help extend the life a bit, obviously noting I add will fix the bearings... And I wouldn't be surprised if it is rod knock. The previous owner of this engine overheated it to the point of seizure, twice. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted February 29, 2012 Share Posted February 29, 2012 Definitely sounds like all the light rod knockers I've listened to. Pretty common on the 25D to hear that. I've torn several of them down just to verify. Wiped out bearing inserts is what I always find. The difference between that and piston slap is that piston slap is very rythmic sounding. It's a regular, timed slapping noise that doesn't sound like morse code. Same goes for valve adjustment. What you have sounds irregular. That is classic rod knock. That said - it could run that way for quite a while as long as you keep oil in it. GD Quote Link to comment Share on other sites More sharing options...
987687 Posted February 29, 2012 Author Share Posted February 29, 2012 It does lose a little bit of oil, but I don't think it's burning it. It leaks out of the separator plate onto the exhaust. That's why it's smoking in that video... When I was putting the engine in the car I sad eff it, it's not going to last long enough to matter. haha. I basically needed the car to be running RGIHT NOW, and that's what I had. I figured it was rod knock. It had piston slap (that's now pretty much gone away, wtf?). And it also has valve noise, pretty bad. But I figured that noise was something more bad. heh. It's already run about 2.5k miles like that.... Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted February 29, 2012 Share Posted February 29, 2012 Lucas Oil stabilizer might help. The biggest thing is to keep oil between the bearing and crankshaft so they stop hitting each other. Quote Link to comment Share on other sites More sharing options...
987687 Posted February 29, 2012 Author Share Posted February 29, 2012 I was thinking about the lucas stuff, although I've heard it gets frothy, or something like that. I don't have a whole lot to lose, let's call it an experiment... Quote Link to comment Share on other sites More sharing options...
Ricearu Posted March 1, 2012 Share Posted March 1, 2012 i used lucas stabilizer as 50% in a rod knock motor and ran it another 14 THOUSAND MILES says on the bottle you can use up to 60%. Also in my first legacy, I used it in the motor which smoked at 240k and kept driving it smoke free until just after 250k when the trans went south. that car was a hertz rental in its early life Quote Link to comment Share on other sites More sharing options...
987687 Posted March 1, 2012 Author Share Posted March 1, 2012 Cool! I'll pick some of the stuff up and see what happens! It'll make me cringe because I hate that type of thing, but hell! At this point why not! Quote Link to comment Share on other sites More sharing options...
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