Never personally dealt with a timing chain issue, so I'm clueless about it or even if thats the problem, its just what popped in my head. Gf's 97 corolla started having a very noticable knock after getting off the highway. It's got about 150k on it and she is unaware if the previous owner ever replaced the timing chain. She's only had the car about the past 20k, roughly a year or so. Engine ran fine with the noise before she parked it for the night, and she told me the harder she accelerated the louder and obviously faster it would get. At idle the loud knock occurs approx 2 times per second (inline 4 cyl) and thats all I got on it. Any ideas?

4/7/2008 9:41:53 PM

have you checked the oil?

4/7/2008 9:55:13 PM

Yeah, thought it might have been running dry, but it was right at full. And the oil/filter gets changed regularly.

4/7/2008 9:59:32 PM

you sure its not the balancer or pulley coming apart?

4/7/2008 10:01:21 PM

Not sure, I didn't look at the pulleys very closely, the outer accessory belts were changed a while ago (4 or 5 months) if it helps. It'll be tomorrow before I can take a look at it again.

4/7/2008 10:06:41 PM

^^^yeah, def. do that first. that'll tell you/us a lot and possibly eliminate a lot of needless speculation.

it's definitely not the timing chain, because it doesn't have one. 97 was the last year they had a belt as far as i know.

if it's for sure a "knock" and not a "tick", i fear she may have starved it for oil and it's got a rod knock. how long was she on the highway for? it's all too common to cruise along on the highway slowly sucking/leaking oil with no indications of a very low level, then as soon as you make a maneuver (like exiting) the oil sloshes away from the pickup and engine = fail. unfortunately, the list of things to cause that sort of noise is short and they other don't happen often. especially since you've narrowed it down to being rpm related.

now, if it's a higher pitched tick we need a much better description because there's a laundry list of possibilities. even then it's mostly a blind guess unless there's something really specific/obvious in the description.

[Edited on April 7, 2008 at 10:08 PM. Reason : nm, late post, you already checked it]

[Edited on April 7, 2008 at 10:08 PM. Reason : .]

4/7/2008 10:06:53 PM

It's definitely not a tick, it sounds like a wrench being hit against a valve cover or aluminum head would be the best way to portray it, kindofa hollow knock. I doubt its an external oil leak, checked the fluid level and the filter/ground for any leaks, thinking maybe an oil passage blocked? She was only on the way to school, on the highway maybe 20 minutes tops.

Oh yeah, is it an interference engine?

[Edited on April 7, 2008 at 10:13 PM. Reason : forgot]

4/7/2008 10:11:47 PM

in my experience a if its a rod knock you'll know it pretty quick... like when you see the rod outside of the block.

4/7/2008 11:48:26 PM

I do think that the 4AFE/7AFE engine family is interference.

Definitely a timing belt and not a chain. Now here's one other thing it could be: I wonder if the timing belt idler pulley is coming apart.

Last surgery I did like this, on my dad's Toyota T100. Timing idler pulley bearing shit the bed, and what I thought was a rod knock was that pulley slapping around (read: no balls left in the races). Oh, and the water pump (driven by the timing belt) had seized.

If it does it all the time, under load or coasting or cruising, then I'd look elsewhere besides rod and main knock, unless the bearings are just that pounded out.

If it does it primarily under load, then, well...you gots some bearing issues and pretty soon, Rod City, here we come.

4/7/2008 11:55:38 PM

holler at me if you swap out the 7afe.

if your motor doesnt blow, give it to me as a donor motor for our rally car plz

4/8/2008 12:00:05 AM

gasoline.....matches.........

4/8/2008 12:02:57 AM

then answer the door

4/8/2008 12:12:28 AM

Hrm, I dont suppose I could just tug on the pulleys and find out if one of them is wobbly. It makes that noise all the time from idle to full load, so I'll try to look at them more closely. Her father called the mechanic today and he said he could drive out to where she parked it, check it and give an estimate.

4/8/2008 9:27:01 AM

you could take the belt off and start it up for a minute or so and see if the noise goes away

4/8/2008 10:12:51 AM

sounds like rod knock

let engine warm up.

while engine is running:
-pull spark plug wire for one cylinder, check for sound
-sounds still there, replace wire, pull next one

keep going to the sounds stops. when the sounds stops, thats the bear that is spun.

drop oil pan, replace bearings, go drive

4/8/2008 10:47:20 AM

good luck.



[Edited on April 8, 2008 at 11:18 AM. Reason : make sure you pull plug wire with your hand only. ]

4/8/2008 11:15:01 AM

^^no, that's not even close. for finding a cylinder that's not firing for whatever reason, sure. many a motor with crank/bearing issues still fire just fine and have perfectly acceptable compression.

a knock MIGHT stop if it's not getting the force of combustion, but 9 times out of 10 it doesn't make a hell of a lot of difference. definitely doesn't make a damn if it's a main or thrust bearing issue.

[Edited on April 8, 2008 at 12:04 PM. Reason : .]

4/8/2008 12:01:06 PM

Quote :

"sounds like rod knock let engine warm up. while engine is running: -pull spark plug wire for one cylinder, check for sound -sounds still there, replace wire, pull next one keep going to the sounds stops. when the sounds stops, thats the bear that is spun."

what the fuck. i see you still haven't graduated from idiot university.

4/9/2008 5:58:48 PM

Quote :

"sounds like rod knock let engine warm up. while engine is running: -pull spark plug wire for one cylinder, check for sound -sounds still there, replace wire, pull next one keep going to the sounds stops. when the sounds stops, thats the bear that is spun."

considering the crank puts upward pressure on the rod during compression, and the pressure increases during ignition, there is no slack, that makes no sense even with no fire, you still have pressure in the cylinder

you get rod knock between the intake and exhaust at the top of the stroke

easiest way to tell is to get someone experienced to listen to it, i could tell you in about 10 seconds if its in the valves, rods, mains or accessories

4/9/2008 9:27:48 PM

yeah i have blowed up more than a couple engines, me and rod knock are old friends

4/9/2008 9:36:31 PM

4/11/2008 4:38:54 PM

Ok, just as a follow up to this. The engine had to be taken out, and from what I can tell a piston had to be replaced (sorry this is from the gf, couldn't get a chance to talk with the mechanic) including new rings, etc. So I guess it was rod knock. Whatever the hell it was, she just spent $1700 on the damn thing, so anything to look out for? The mech told her to take it real easy for the first few days.

4/27/2008 9:40:59 PM

wow, spending $1700 on a 97 corolla with 150k miles?

4/27/2008 10:40:22 PM

take it really easy for a couple days means he probably/hopefully did a full rebuild and wants the rings to seat properly. i would change the oil in 500 miles as well.

of course girls dont know anything about taking it easy. probably going to race around in it still and fuck it up again. 1700 fuck taht.

4/27/2008 10:55:36 PM

never mind, missed last update

[Edited on April 27, 2008 at 11:14 PM. Reason : ]

4/27/2008 11:13:25 PM