Loud knocking on startup gc8 - TriStateTuners.com :: Home of Tristate Auto Enthusiast

MPowerKai · 05-18-2007, 01:30 PM

Sooo this morning I started up the car and there was a loud knocking coming from the engine. I let it idle for a couple of minutes and it went away. Would could be the cause of this problem?

Also it vibrates a little bit when idling, anyone know what to do about that?

The car has 90k on it. I brought it to a shop once to get some work done (gauges installed) but I think they wacked my car up. As soon as they were done I was beat for my money, none of the gauges worked, The alarm stopped working the day after, it has a hard time starting up in the morning after you don't drive it for the night (I think there is a short somewhere) and other small misc things that came up after the gauges were "installed"

CHAOS · 05-18-2007, 01:32 PM

sounds fishy to me man... could be rod knock... could be something loose...

MPowerKai · 05-18-2007, 01:38 PM

Quote:

Originally Posted by CHAOS

sounds fishy to me man... could be rod knock... could be something loose...

But wouldn't rod knock stay and not go away?

sisforsurfing · 05-18-2007, 01:48 PM

Was it sitting for a while before you started it this time?

redline · 05-18-2007, 01:50 PM

Piston slap? hydraulic lifters? as long as it goes away after it warms up you should be good. I know GM is famous for this.

grimm · 05-18-2007, 01:51 PM

vibrates when idling... do you mean it's a rough idle? do you have any EM? My car's idle is a bit rough here and there, but mine is do to the pulleys..

MPowerKai · 05-18-2007, 02:04 PM

Not rough idle, the rpms are steady. The car just vibrates. I was thinking it might be time do change the timing belt.

Yes, it does go away after a couple of minutes. I was just about to ask if it was hydraulic or manual lifters

Signatus230 · 05-18-2007, 04:56 PM

Hmmm, any way of getting a vid? I have amazing experience with Rod knock...

Have you driven the car since this occured? What happens when you step on the gas, any noise at all?

Have you recently changed anything exhaust related, or just anything in particular, could be a loose bolt.

As for the vibrating, could be the motor mounts are going, badly.

Wait, what gauges did you get installed?

teh DIRT · 05-18-2007, 05:04 PM

I think your knock might be a ticking. Maybe a loud ticking. Lifters is my guess.

MPowerKai · 05-20-2007, 11:21 AM

Maybe. I recently changed it from a magnaflow exhaust to a 06 wrx exhaust. After that incident I kept on drivint it. It hasn't done it since that time. I took it offroading yesterday and it was great. I dunno. Do I have mechanical or hydraulic lifters? I plan on doing the tune up myself.

RUBASU · 05-22-2007, 10:36 PM

car has hardened mounts on it. causes more vibration to transfer through out the car

Signatus230 · 05-22-2007, 10:43 PM

That could be the cause, but if it is a louder ticking noise, I doubt that. Renegade_ has hardened engine mounts, and there is no ticking. Not sure about the inside with the idle and vibration.

redwrxwagon02 · 05-29-2007, 02:12 PM

that is very typical on those cars the motor will periodically on a coldstart knock a little with high miles nothing to be worried about though just keep doing regular oil changes and check for metal filings

Renegade_ · 05-30-2007, 12:43 AM

The boxer motors tick a crapload at idle anyway even if they are as healthy as ever (in my experience, mine just ticks in normal operation but there is absolutely nothing wrong with it). Having any kind of hardened motor mount won't be the cause of any kind of "knock"... a video would be the best way for us to tell you what it is.

And timing belt should be fine. I am on factory timing belt at 117k miles and basically I was told by Ryan at 1320 that I should be good for a little bit longer but as a rule of thumb I should just get it done whenever possible.

MPowerKai · 05-30-2007, 08:30 AM

Quote:

Originally Posted by Renegade_

The boxer motors tick a crapload at idle anyway even if they are as healthy as ever (in my experience, mine just ticks in normal operation but there is absolutely nothing wrong with it). Having any kind of hardened motor mount won't be the cause of any kind of "knock"... a video would be the best way for us to tell you what it is.

And timing belt should be fine. I am on factory timing belt at 117k miles and basically I was told by Ryan at 1320 that I should be good for a little bit longer but as a rule of thumb I should just get it done whenever possible.

I would make a video however it hasn't done it since that day. The slight vibrations in the car during idle I think might be a bad plug or something so I'm going to change the plugs and do a basic tune up and see how that goes.

redwrxwagon02 · 05-30-2007, 10:26 AM

hell my car vibrates at idle and my plugs are brand new all subies do it just cuz its horizontally opposed its like riding in a car with a v8

RUBASU · 05-30-2007, 07:13 PM

t-belt was done on the car not that long ago about 20K or so. It is well known in the subie world that the rs's tended to suffer from piston slap on cold starts until it gets warmed up. As far as the vibrating is has hardened mounts through out and they will causemore vibration to be felt in the car at idle since they transfer both noise and engine vibration greater then the spongey stock rubber mounts.

RUBASU · 05-30-2007, 07:16 PM

also what red says. the boxer engine next to a five cylinder is probrably one of the most unbalanced engine designs there is on the market. the have a tendency to shake and vibrate more then your everyday typical engine design simply because of howthey are built.

Renegade_ · 05-30-2007, 08:17 PM

Technically, by engine theory, the flat four engine design is one of the most ideal engine designs on par with the straight 6 and the v12.

Quote:

It is well known in the subie world that the rs's tended to suffer from piston slap on cold starts until it gets warmed up.

It is? where you hear that from? I've been over on RS25 for a LONG time and by no means is piston slap normal.

RUBASU · 05-30-2007, 09:30 PM

here are some posts about piston slap on RS25 that I found in about 2 min. of searching. And I never said that it was normal I merely said that is a known problem that they tend to suffer from. I did not say all of them suffer from it but it is a known problem.

http://www.rs25.com/forums/showthrea...ht=piston+slap

http://www.rs25.com/forums/showthrea...ht=piston+slap

http://www.rs25.com/forums/showthrea...ht=piston+slap

http://www.rs25.com/forums/showthrea...ht=piston+slap

http://www.rs25.com/forums/showthrea...ht=piston+slap

http://www.rs25.com/forums/showthrea...ht=piston+slap

05-18-2007, 01:48 PM	#4
sisforsurfing Tri-State Post Whore Join Date: Mar 2005 Member #267 My Ride: 2003 WRX wagon iTrader: (2)	Was it sitting for a while before you started it this time? __________________ *To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.*

05-18-2007, 01:50 PM	#5
redline Tri-State Post Whore Join Date: Aug 2005 Location: Kaiserslautern, Germany Member #784 iTrader: (1)	Piston slap? hydraulic lifters? as long as it goes away after it warms up you should be good. I know GM is famous for this. __________________ 2006 Evo 9 Special Edition

05-29-2007, 02:12 PM	#13
redwrxwagon02 Tri-State Post Whore Join Date: Mar 2007 Member #4044 iTrader: (0)	that is very typical on those cars the motor will periodically on a coldstart knock a little with high miles nothing to be worried about though just keep doing regular oil changes and check for metal filings __________________ oh thanks!

05-30-2007, 12:43 AM	#14
Renegade_ Tri-State Post Whore Join Date: May 2006 Location: NNJ/NYC Member #1912 My Ride: 1J Swaggon iTrader: (2)	The boxer motors tick a crapload at idle anyway even if they are as healthy as ever (in my experience, mine just ticks in normal operation but there is absolutely nothing wrong with it). Having any kind of hardened motor mount won't be the cause of any kind of "knock"... a video would be the best way for us to tell you what it is. And timing belt should be fine. I am on factory timing belt at 117k miles and basically I was told by Ryan at 1320 that I should be good for a little bit longer but as a rule of thumb I should just get it done whenever possible. __________________ To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.

05-30-2007, 10:26 AM	#16
redwrxwagon02 Tri-State Post Whore Join Date: Mar 2007 Member #4044 iTrader: (0)	hell my car vibrates at idle and my plugs are brand new all subies do it just cuz its horizontally opposed its like riding in a car with a v8 __________________ oh thanks!

05-18-2007, 01:32 PM	#2
CHAOS TST Ruined My Life! Banned Join Date: Jun 2006 Member #2120 My Ride: 1984 Cadillac Brougham iTrader: (1)	sounds fishy to me man... could be rod knock... could be something loose...

05-18-2007, 01:51 PM	#6
grimm Tri-State Post Whore Join Date: Dec 2006 Member #3058 iTrader: (2)	vibrates when idling... do you mean it's a rough idle? do you have any EM? My car's idle is a bit rough here and there, but mine is do to the pulleys..

05-22-2007, 10:36 PM	#11
RUBASU Noob-Jersey Join Date: May 2007 Member #4671 My Ride: 07 MAZDA SPEED3 iTrader: (0)	car has hardened mounts on it. causes more vibration to transfer through out the car

05-30-2007, 07:13 PM	#17
RUBASU Noob-Jersey Join Date: May 2007 Member #4671 My Ride: 07 MAZDA SPEED3 iTrader: (0)	t-belt was done on the car not that long ago about 20K or so. It is well known in the subie world that the rs's tended to suffer from piston slap on cold starts until it gets warmed up. As far as the vibrating is has hardened mounts through out and they will causemore vibration to be felt in the car at idle since they transfer both noise and engine vibration greater then the spongey stock rubber mounts.

05-30-2007, 07:16 PM	#18
RUBASU Noob-Jersey Join Date: May 2007 Member #4671 My Ride: 07 MAZDA SPEED3 iTrader: (0)	also what red says. the boxer engine next to a five cylinder is probrably one of the most unbalanced engine designs there is on the market. the have a tendency to shake and vibrate more then your everyday typical engine design simply because of howthey are built.

05-30-2007, 09:30 PM	#20
RUBASU Noob-Jersey Join Date: May 2007 Member #4671 My Ride: 07 MAZDA SPEED3 iTrader: (0)	here are some posts about piston slap on RS25 that I found in about 2 min. of searching. And I never said that it was normal I merely said that is a known problem that they tend to suffer from. I did not say all of them suffer from it but it is a known problem. http://www.rs25.com/forums/showthrea...ht=piston+slap http://www.rs25.com/forums/showthrea...ht=piston+slap http://www.rs25.com/forums/showthrea...ht=piston+slap http://www.rs25.com/forums/showthrea...ht=piston+slap http://www.rs25.com/forums/showthrea...ht=piston+slap http://www.rs25.com/forums/showthrea...ht=piston+slap Last edited by RUBASU; 05-30-2007 at 09:32 PM.

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