Welcome to the North American Subaru Impreza Owners Club Saturday April 19, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Built Motor Discussion

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 08-06-2011, 02:33 PM   #1
Ryan314
Scooby Guru
 
Member#: 82989
Join Date: Mar 2005
Chapter/Region: NESIC
Location: Maine
Vehicle:
2002 WRX
Hybrid VF22

Default Valves hitting pistons... Now with pics

So after researching and finding out that a timing issue will not cause valves to hit the pistons (valves hit valves with a timing issue, causing bent valves etc. etc.), what DOES cause valves to come in contact with the pistons? Improper lash setting?
* Registered users of the site do not see these ads.

Last edited by Ryan314; 08-22-2011 at 08:16 AM.
Ryan314 is offline   Reply With Quote
Old 08-06-2011, 02:43 PM   #2
Nappula
Scooby Newbie
 
Member#: 260249
Join Date: Oct 2010
Location: Finland
Default

Valves hit valves if timing between two camshafts is incorrect.
Valves hit pistons if timing between camshafts and crankshaft is incorrect.
Correct me if my way of thinking is incorrect.

(Of course there is the possibility if the whole desing in engine components has gone wrong-> piston going too far out to deck + extremely high or advanced valve lift)
Nappula is offline   Reply With Quote
Old 08-08-2011, 03:05 PM   #3
Ryan314
Scooby Guru
 
Member#: 82989
Join Date: Mar 2005
Chapter/Region: NESIC
Location: Maine
Vehicle:
2002 WRX
Hybrid VF22

Default

Thank you.

Anyone else?
Ryan314 is offline   Reply With Quote
Old 08-08-2011, 03:09 PM   #4
Crazy_pilot
Scooby Newbie
 
Member#: 164242
Join Date: Nov 2007
Chapter/Region: E. Canada
Location: Toronto
Vehicle:
1992 SVX
2008 Spec B

Default

Interference engine means that if the engine is grossly out of timing (ie; timing belt breaks while engine is running) the valves can colide with the pistons. Non-interference (like the EG33) mean that the valves to not have enough travel to strike the pistons regardless of timing.
Crazy_pilot is offline   Reply With Quote
Old 08-08-2011, 04:48 PM   #5
Alaskan EJ20
Scooby Specialist
 
Member#: 160040
Join Date: Sep 2007
Chapter/Region: AKIC
Location: Anchortown
Vehicle:
2002 Bugi / 1993 L
Symmetry Tuning

Default

^^ wrong. interference means the intake and exhaust valves run on different cam shafts (DOHC) and if incorrect timing they will interfere with each other or pistons, (SOHC) non interference heads can still have bent valves but only by hitting pistons. hope this helps.

too much AVCS adjustment can cause valves to hit pistons aswell but this is another can of worms.
Alaskan EJ20 is offline   Reply With Quote
Old 08-08-2011, 04:52 PM   #6
kellygnsd
Scooby Guru
 
Member#: 32669
Join Date: Feb 2003
Chapter/Region: SCIC
Location: Rancho C
Vehicle:
2007 2.34LR, EFR7670
LINK G4 hybrid STi

Default

Look at you engine without the timing belt covers on it. it all depends on where you belt slips that determines what makes contact. I for some reason you slip the belt around the crank pulley and all the cam gears stay engaged on the belt during that event you would have a good change of valve to piston contact. If a cam gear slips in relation to the others you can have valve to valve contact.

You can also easily have valve to valve contact when timing the motor if you don't follow the service manual instructions in regards to what direction to turn the camshafts to get them lined up.
kellygnsd is online now   Reply With Quote
Old 08-08-2011, 05:01 PM   #7
kellygnsd
Scooby Guru
 
Member#: 32669
Join Date: Feb 2003
Chapter/Region: SCIC
Location: Rancho C
Vehicle:
2007 2.34LR, EFR7670
LINK G4 hybrid STi

Default

Quote:
Originally Posted by Alaskan EJ20 View Post
^^ wrong. interference means the intake and exhaust valves run on different cam shafts (DOHC) and if incorrect timing they will interfere with each other or pistons, (SOHC) non interference heads can still have bent valves but only by hitting pistons. hope this helps.

too much AVCS adjustment can cause valves to hit pistons aswell but this is another can of worms.
Actually you can have DOHC non-interference engines but they are rare and they would require a huge C.C.
kellygnsd is online now   Reply With Quote
Old 08-08-2011, 05:20 PM   #8
the suicidal eggroll
NASIOC Supporter
 
Member#: 51961
Join Date: Jan 2004
Chapter/Region: RMIC
Location: Broomfield, CO
Vehicle:
2005 STi
2012 WRX

Default

Quote:
Originally Posted by Nappula View Post
Valves hit valves if timing between two camshafts is incorrect.
Valves hit pistons if timing between camshafts and crankshaft is incorrect.
Quote:
Originally Posted by kellygnsd View Post
Look at you engine without the timing belt covers on it. it all depends on where you belt slips that determines what makes contact. I for some reason you slip the belt around the crank pulley and all the cam gears stay engaged on the belt during that event you would have a good change of valve to piston contact. If a cam gear slips in relation to the others you can have valve to valve contact.

You can also easily have valve to valve contact when timing the motor if you don't follow the service manual instructions in regards to what direction to turn the camshafts to get them lined up.
These
the suicidal eggroll is offline   Reply With Quote
Old 08-08-2011, 05:52 PM   #9
CKxx
Scooby Specialist
 
Member#: 33458
Join Date: Feb 2003
Chapter/Region: Tri-State
Location: PA
Vehicle:
Your BOV sounds lame
93 RX7+09 Forester

Default

Quote:
Originally Posted by Ryan314 View Post
So after researching and finding out that a timing issue will not cause valves to hit the pistons (valves hit valves with a timing issue, causing bent valves etc. etc.), what DOES cause valves to come in contact with the pistons? Improper lash setting?
If it is a gross error in timing, it certainly could.

Want to see my pistons...?
CKxx is offline   Reply With Quote
Old 08-11-2011, 03:31 PM   #10
tre mendez johnson
Scooby Newbie
 
Member#: 19034
Join Date: May 2002
Location: D.C.
Vehicle:
2005 saab 9-2x

Default

Does anybody know if there is a way to determine whether or not valves are bent or not, like rotating the cams to see if there is any difficulty.

The reason I ask is that my wife's 05 Legacy GT had the timing belt tensioner go bad (actually the bolt into the block sheared off) and caused her vehicle to stop running.

It got towed home from the dealership and I'll be replacing the timing belt to see if it'll start up. I'm wondering if this is a waste a time if there is an easy way to determine if stuff is bent up.
tre mendez johnson is offline   Reply With Quote
Old 08-11-2011, 03:34 PM   #11
Nathan Explosion
Scooby Newbie
 
Member#: 215525
Join Date: Jun 2009
Vehicle:
2006 WRX Wagon
WRB

Default

Quote:
Originally Posted by tre mendez johnson
Does anybody know if there is a way to determine whether or not valves are bent or not, like rotating the cams to see if there is any difficulty.

The reason I ask is that my wife's 05 Legacy GT had the timing belt tensioner go bad (actually the bolt into the block sheared off) and caused her vehicle to stop running.

It got towed home from the dealership and I'll be replacing the timing belt to see if it'll start up. I'm wondering if this is a waste a time if there is an easy way to determine if stuff is bent up.
Start with a leakdown test.
Nathan Explosion is offline   Reply With Quote
Old 08-11-2011, 03:55 PM   #12
scooby24
Scooby Specialist
 
Member#: 56414
Join Date: Mar 2004
Chapter/Region: MWSOC
Location: Olathe, KS
Vehicle:
2004 Forester XT 5MT
PSM

Default

Quote:
Originally Posted by Alaskan EJ20 View Post
^^ wrong. interference means the intake and exhaust valves run on different cam shafts (DOHC) and if incorrect timing they will interfere with each other or pistons, (SOHC) non interference heads can still have bent valves but only by hitting pistons. hope this helps.

too much AVCS adjustment can cause valves to hit pistons aswell but this is another can of worms.
Matter of fact, he isn't. Interference specifically implies valve and piston non-clearance.

http://mechdb.com/index.php/Interference_engine

non-interference engines will NOT run the risk of valves striking the pistons.

It's a very simple definition. I don't know how you got your misinformation, but don't try to correct someone when you don't know what you're talking about.
scooby24 is offline   Reply With Quote
Old 08-11-2011, 06:39 PM   #13
2Fast4U1DAY
Scooby Specialist
 
Member#: 250152
Join Date: Jun 2010
Chapter/Region: Tri-State
Location: Pennsylvania
Vehicle:
2006 WRX Limited
OBP

Default

Quote:
Originally Posted by scooby24

Matter of fact, he isn't. Interference specifically implies valve and piston non-clearance.

http://mechdb.com/index.php/Interference_engine

non-interference engines will NOT run the risk of valves striking the pistons.

It's a very simple definition. I don't know how you got your misinformation, but don't try to correct someone when you don't know what you're talking about.
This^. An easier way to look at it is: An event that occurs when the valves and pistons (or if the timing belt snaps the valves on two different camshafts and possibly still the pistons) occupy the same space at the same time. They collide and sometime down the road (if its not taken care of) the head of the valve(s) pop of the stem and tear up the piston (and sometimes other pistons as well), the bore, and the head.
2Fast4U1DAY is offline   Reply With Quote
Old 08-21-2011, 04:17 PM   #14
Ryan314
Scooby Guru
 
Member#: 82989
Join Date: Mar 2005
Chapter/Region: NESIC
Location: Maine
Vehicle:
2002 WRX
Hybrid VF22

Default

Please take a look at these pictures and tell me if you think there is anything wrong.




Ryan314 is offline   Reply With Quote
Old 08-21-2011, 04:26 PM   #15
Adams Engines
Scooby Newbie
 
Member#: 289435
Join Date: Jul 2011
Chapter/Region: MAIC
Location: Baltimore, Md
Vehicle:
2005 STI 441hp
WRB Dynapack

Default

If you cant physically see they are bent. Assemble the head(no cams) with spark plugs.....have c.c. Facibg up and fill it with liquid......if it leaks out past valves they are bent(large amounts of carbon on valves can cause the same thing however usually will not leak out as fast
Adams Engines is offline   Reply With Quote
Old 08-21-2011, 04:27 PM   #16
2.5ReallySexy
Scooby Specialist
 
Member#: 167943
Join Date: Dec 2007
Chapter/Region: NWIC
Location: Vancouver, Washington
Default

^^^^^^ Seems good to me haha
2.5ReallySexy is online now   Reply With Quote
Old 08-21-2011, 04:30 PM   #17
Ryan314
Scooby Guru
 
Member#: 82989
Join Date: Mar 2005
Chapter/Region: NESIC
Location: Maine
Vehicle:
2002 WRX
Hybrid VF22

Default

Well the shop is telling me that I had intake valves hitting the pistons. I'm no mechanic, but if these valves were hitting the pistons for 7k miles, wouldn't my valves be damaged? I see no damage to the lip or anything. I have 15 valves with no bends to them what so ever, and one exhaust valve that cleanly snapped off and caused the engine to fail (obviously).
Ryan314 is offline   Reply With Quote
Old 08-21-2011, 04:32 PM   #18
Adams Engines
Scooby Newbie
 
Member#: 289435
Join Date: Jul 2011
Chapter/Region: MAIC
Location: Baltimore, Md
Vehicle:
2005 STI 441hp
WRB Dynapack

Default

Usually see contact marks on pistons and edge of valves but really need to look carefully
Adams Engines is offline   Reply With Quote
Old 08-21-2011, 04:50 PM   #19
Ryan314
Scooby Guru
 
Member#: 82989
Join Date: Mar 2005
Chapter/Region: NESIC
Location: Maine
Vehicle:
2002 WRX
Hybrid VF22

Default

Here are better pics...







Ryan314 is offline   Reply With Quote
Old 08-22-2011, 08:16 AM   #20
Ryan314
Scooby Guru
 
Member#: 82989
Join Date: Mar 2005
Chapter/Region: NESIC
Location: Maine
Vehicle:
2002 WRX
Hybrid VF22

Default

Bump.
Ryan314 is offline   Reply With Quote
Old 08-22-2011, 08:23 AM   #21
SW00P_G
Scooby Specialist
 
Member#: 5591
Join Date: Apr 2001
Chapter/Region: MWSOC
Location: Westerville, Ohio, USA
Vehicle:
2002 WRX
EJ257 Gt35r

Default

What are those scratches on the valves? What were the symptoms that caused the motor to be taken apart? Try to roll the valves on a flat sheet of glass to see if they are bent. Or assemble the head and use the liquid method.

And why is there only a pic of 1 piston and valve?
SW00P_G is online now   Reply With Quote
Old 08-22-2011, 09:47 AM   #22
Nappula
Scooby Newbie
 
Member#: 260249
Join Date: Oct 2010
Location: Finland
Default

By looking those pictures id say valve(s) have not been in contact with that piston(s). To be sure you must measure your valves.

You said there is just one damaged valve? If so, id say you had either bad valve or incorrect installation.
Nappula is offline   Reply With Quote
Old 08-22-2011, 11:53 AM   #23
Crystal_Imprezav
Scooby Specialist
 
Member#: 84105
Join Date: Mar 2005
Chapter/Region: SCIC
Location: I'm a Newbie
Vehicle:
2005 Super Slow STi
CGM

Default

What kind of pistons are those? They don't look like they have very much valve relief in them especially for oversized valves which I am not sure if you do or don't have.

Put the valve in a drill and spin the drill. If it wobbles at all the valve is bent.
Crystal_Imprezav is offline   Reply With Quote
Old 08-22-2011, 03:17 PM   #24
V8Slayer
Scooby Specialist
 
Member#: 111565
Join Date: Apr 2006
Chapter/Region: W. Canada
Location: Winnipeg
Vehicle:
1999 Legacy 2.5GT
Boosted & meth injection!

Default

Quote:
Originally Posted by Crystal_Imprezav View Post
Put the valve in a drill and spin the drill. If it wobbles at all the valve is bent.
I never would've thought of that, it actually sounds like a great idea!
V8Slayer is offline   Reply With Quote
Old 08-22-2011, 09:22 PM   #25
Ryan314
Scooby Guru
 
Member#: 82989
Join Date: Mar 2005
Chapter/Region: NESIC
Location: Maine
Vehicle:
2002 WRX
Hybrid VF22

Default

Quote:
Originally Posted by Crystal_Imprezav View Post
What kind of pistons are those? They don't look like they have very much valve relief in them especially for oversized valves which I am not sure if you do or don't have.

Put the valve in a drill and spin the drill. If it wobbles at all the valve is bent.
100mm Mahle 4032.

Here's the summed up version of what happened:

Long story short, I am in a huge battle with my machine shop right now. My hybrid motor snapped an exhaust valve clean off a month ago or so. The motor had 7k miles on it. Excessive driver's side head noise was reported to them when the motor had 2k miles on it. They instructed me to keep driving it. At 7k miles, an exhaust valve snapped off in the driver's side head. Go figure?

Here's where I'm at now. The machine shop is blaming it on a timing issue, yet my mechanic checked the belt and pulleys before pulling the engine and it did not skip timing or seize a pulley. The engine is now torn apart and I have NO bent valves. I have 1 cleanly snapped exhaust valve and 15 perfectly straight non-bent valves. And of course, a destroyed cylinder 2 and piston, and driver's side head.

They are claiming I had intake valves hitting the pistons. They insist to talk about this issue instead of the issue that really caused the failure, which was the snapped valve!
Ryan314 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
FS : oem engine parts. cams valve springs pistons eh69758 MAIC Private Classifieds 13 08-05-2011 01:41 PM
Rebuilt EJ255 Knocking. Valve? Rod? Piston Slap? Merp Built Motor Discussion 45 12-12-2009 09:45 PM
Setting timing belt, somethings not right... valves are going to hit pistons! enjoi926 Factory 2.0L Turbo Powertrain 12 07-26-2009 12:01 AM
Valve Tick/Piston Slap. Video inside, please help! Disco_Inferno Factory 2.0L Turbo Powertrain 18 07-07-2009 10:11 PM
Lose timimg belt, valves hit pistons? Y or N rallynutdon Factory 2.0L Turbo Powertrain 6 08-19-2008 02:31 PM


All times are GMT -4. The time now is 07:56 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.