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'03 Legacy GT with engine knock?


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17 replies to this topic

#1 shortlid

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Posted 01 September 2008 - 09:36 PM

OK, my Mom came-up this long weekend with her '03 legacy GT sedan automatic with 68k on the clock. It is not heavy but under half throdle going up hills it seems to be slightly knocking. Took it for a drive three times with the windows down each time it did it. Seems to be fine at high rpm above 4,500?? :confused: I put 4 oz. of Marvel Mystery oil in the gas tank to see if it is carbon deposits. Changed the plugs to NGK platnium just 10,000 miles ago and replace the air filter this weekend?:clap:

It also seems to have developed a belt squeal above 5,000 rpms?? Tried the alt. tensioner on the belt that runs the alt. and the p/s pump. Still there, maybe will try the A/C belt tensioner next?:confused:

#2 GeneralDisorder

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Posted 01 September 2008 - 11:58 PM

It is not heavy but under half throdle going up hills it seems to be slightly knocking.....Seems to be fine at high rpm above 4,500?? :confused:.....It also seems to have developed a belt squeal above 5,000 rpms??


These could be related - you may have a timing belt tensioner bearing going out or something similar. Bad bearing have a way of making knocking noises and then making nasty squealing noises as the RPM's increase.

If the belt goes because a tensioner locks up, or strips the teeth off because the cogged idler, there's about an 80% chance you'll do serious damage to the valve train at least.

GD

#3 brus brother

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Posted 02 September 2008 - 03:19 AM

The General makes some interesting observations.
Since common things happen commonly, I would try running a few tanks of premium grade gasoline if you aren't sure the sound is ping or knock.

#4 shortlid

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Posted 02 September 2008 - 06:32 AM

These could be related - you may have a timing belt tensioner bearing going out or something similar. Bad bearing have a way of making knocking noises and then making nasty squealing noises as the RPM's increase.

If the belt goes because a tensioner locks up, or strips the teeth off because the cogged idler, there's about an 80% chance you'll do serious damage to the valve train at least.

GD


I hope this is not the issue. But she does have a 100,000 warrenty on the car she got from the stealership, but down time would be a bumer. Will try plus gas next time.

Does the phase III EJ25 need plus in the GT??:confused:

#5 OB99W

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Posted 02 September 2008 - 08:11 AM

[...]It is not heavy but under half throdle going up hills it seems to be slightly knocking.[...]

Part-throttle going up hills is a typical condition that can induce "knock" (pinging). If that's what you're hearing, try a tankful of premium gas and see if it goes away. However...


It also seems to have developed a belt squeal above 5,000 rpms?? Tried the alt. tensioner on the belt that runs the alt. and the p/s pump. Still there, maybe will try the A/C belt tensioner next?:confused:

...as GD suggested, the squeal is a concern. You could temporarily run without the accessory belts (just be ready for no steering power assist), and if you still hear the squeal, GD's case is more likely.

#6 shortlid

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Posted 02 September 2008 - 09:31 AM

Part-throttle going up hills is a typical condition that can induce "knock" (pinging). If that's what you're hearing, try a tankful of premium gas and see if it goes away. However...


...as GD suggested, the squeal is a concern. You could temporarily run without the accessory belts (just be ready for no steering power assist), and if you still hear the squeal, GD's case is more likely.


You guys are freaking me out. This car is not abused driven at 55 max by my 65 year old mother. Oil changes done every 4,000 miles or 3 months by myself.

1. Are bad bearing common in EJ25's?:confused:

2. Are tensioners more common to fail?:)

3. Guess I could take a belts off for a few minutes and rev the engine.;) (But she is headed down to NY today!)

#7 brus brother

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Posted 02 September 2008 - 11:02 AM

To repeat: Common things happen commonly.
In problem solving 101, I was taught that if you hear something clipping and clopping down the road, chances are that it is a horse and not a zebra! (unless you live in Africa)

Try premium gas and disconnect belts as instructed.
Save the freaking out for special occasions.:banana:

#8 shortlid

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Posted 02 September 2008 - 02:44 PM

To repeat: Common things happen commonly.
In problem solving 101, I was taught that if you hear something clipping and clopping down the road, chances are that it is a horse and not a zebra! (unless you live in Africa)

Try premium gas and disconnect belts as instructed.
Save the freaking out for special occasions.:banana:


OK, got MMO in the gas tank trying higher octane if not a fix. Then belts But I really doubt slight knock just at mid-throdle, is a bearing but I have been wrong before.:-\

Anyone think the NGK plat. plugs may have something to do with this?

#9 OB99W

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Posted 02 September 2008 - 03:18 PM

[...]Anyone think the NGK plat. plugs may have something to do with this?

Assuming you got plugs of the proper heat range, it's not likely.

As to the squeal, you might want to closely check the crank pulley. Although it would be unusual for a six year old model to have a problem with it, a loose pulley or failure of the rubber between the two halves can cause squealing.

#10 shortlid

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Posted 02 September 2008 - 04:45 PM

Assuming you got plugs of the proper heat range, it's not likely.

As to the squeal, you might want to closely check the crank pulley. Although it would be unusual for a six year old model to have a problem with it, a loose pulley or failure of the rubber between the two halves can cause squealing.


What is the best way to check this?? Guess I can do it when the belts are off!;)

#11 johnceggleston

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Posted 02 September 2008 - 06:03 PM

What is the best way to check this?? Guess I can do it when the belts are off!;)


a loose puley will wobble when the car is running, maybe for a bad pulley as well. wobble is bad.

#12 shortlid

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Posted 02 September 2008 - 06:48 PM

Did not notice wobble while the car was running and I reved the engine from the TB buterfly.

#13 bratman18

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Posted 03 September 2008 - 02:56 PM

I personally have heard SEVERAL of the newer 2.5 motors knocking!! They are not built like the old ones! All the ones I heard were with low miles as well. Its not a good sound I would personally be pissed if I spent that much money on a car and it sounded like that! Hope for her sake it will live for a long time but from the experience I've had with all the 2.5 motors they just don't! I have one right now that is of course, leaking from the head gaskets! B ut mine isn't knocking. But good luck!:-\

#14 GeneralDisorder

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Posted 03 September 2008 - 08:44 PM

You guys are freaking me out. This car is not abused driven at 55 max by my 65 year old mother. Oil changes done every 4,000 miles or 3 months by myself.


Calm down - I'm sure it's nothing you, or your mother did.


1. Are bad bearing common in EJ25's?:confused:

2. Are tensioners more common to fail?:)


Those are really one in the same question. The idler/tensioner pulleys basically *are* bearings. And more importantly than that, they are JUST bearings - nothing special about them. Almost certainly a 6k series 2RS-C3 of some sort.

As to how common bearing failure is I can say with great confidence that no one really knows. Being in the field of industrial machinery I have been over, under, around, and through that topic more times than I care to remember. I can tell you in general what the biggest causes of bearing failure are (in this order):

1. Over greasing (obviously not your problem)

2. Contamination or breakdown of the grease.

3. Mis-handling before or durring installation.

The bearings in the idlers and tensioners are sealed (the 2RS part) and come pre-greased. If the seal fails then the grease leaks out and what remains overheats and breaks down. That's fairly uncommon though so we can probably also rule out contamination or grease breakdown as with the low mileage the car has these are likely to be high quality and factory instaled.

If it indeed is a bearing failure I would put my money on #3. A simple drop from 24" to a hard surface will cause "brinnelling" of the bearing race and will cause premature failure. It's something that happens more than you think. The monkey's that package and warehouse bearings are just that - monkeys. They can and do drop things without telling anyone.

And of course it could have nothing whatsoever to do with your timing belt arrangement. That has yet to be determined. Pull off those accesory belts and do a test.

3. Guess I could take a belts off for a few minutes and rev the engine.;) (But she is headed down to NY today!)


Good idea!

GD

#15 shortlid

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Posted 03 September 2008 - 09:20 PM

Calm down - I'm sure it's nothing you, or your mother did.




Those are really one in the same question. The idler/tensioner pulleys basically *are* bearings. And more importantly than that, they are JUST bearings - nothing special about them. Almost certainly a 6k series 2RS-C3 of some sort.

As to how common bearing failure is I can say with great confidence that no one really knows. Being in the field of industrial machinery I have been over, under, around, and through that topic more times than I care to remember. I can tell you in general what the biggest causes of bearing failure are (in this order):

1. Over greasing (obviously not your problem)

2. Contamination or breakdown of the grease.

3. Mis-handling before or durring installation.

The bearings in the idlers and tensioners are sealed (the 2RS part) and come pre-greased. If the seal fails then the grease leaks out and what remains overheats and breaks down. That's fairly uncommon though so we can probably also rule out contamination or grease breakdown as with the low mileage the car has these are likely to be high quality and factory instaled.

If it indeed is a bearing failure I would put my money on #3. A simple drop from 24" to a hard surface will cause "brinnelling" of the bearing race and will cause premature failure. It's something that happens more than you think. The monkey's that package and warehouse bearings are just that - monkeys. They can and do drop things without telling anyone.

And of course it could have nothing whatsoever to do with your timing belt arrangement. That has yet to be determined. Pull off those accesory belts and do a test.



Good idea!

GD


I though we were talking about a failed MAIN bearing like on the crank shaft of the engine. If the bearing we are speaking of failing is just a tensioner or even a assc. like a alt. or P/S pump well heck that is easy to fix.:) Feeling much better now.

#16 GeneralDisorder

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Posted 03 September 2008 - 11:13 PM

I though we were talking about a failed MAIN bearing like on the crank shaft of the engine.


I can see the confusion, yes. Main bearings and rod bearings are not of the type which I was speaking. They are actually not really bearings at all - they are bushings in the strictest sense of how they are designed. But they do "bear" the load of the rotating mass so I suppose it depends on how you define it all.... but I digress.

If the bearing we are speaking of failing is just a tensioner or even a assc. like a alt. or P/S pump well heck that is easy to fix.:) Feeling much better now.


Yes it's a relatively easy fix - but be aware that if it's a tensioner or idler bearing and it fails before you get it fixed you will likely be looking at internal engine damage. All incarnations of the 2.5 are interferance.

GD

#17 ShawnW

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Posted 03 September 2008 - 11:54 PM

I think with as few miles as she is putting on the car take the plunge and have the timing belt replaced. This motor is considered a 7 year 105K interval.

Have them inspect all the idlers and tensioner. If the tensioner is leaking oil out the top of the "piston" replace it.

Have the coolant flushed and the thermostat and water pump replaced while they are in there. The oil pump and the cam and crank seals should be fine.

With a little luck you have solved the problem with this and if not you have your maint done for the engine for a while.

#18 shortlid

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Posted 27 April 2009 - 11:04 AM

:confused:Well, the car now has 77k and same squeal above 4,000. Bearings on idler pulley look goo no greeease leaking?? Other strage thing is it does not squeal when reved at a stand still? Will only do it under load like accelerating or if going down hill and go to Netural and rev to 4,000?? Anyone see a concetion in moving the squeal at 4,000 RPM's?




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