HELP! Valve interference after rebuild.

[Guest]

my 04 legacy gt did a big end bearing so i rebuilt it. new mains bearings/beb\'s/conrods/crank/head gaskets/all new seals/lapped valves and had valve tips ground to bring clearance back to exact workshop manual spec (most valves were only ground by one to two thou of an inch and one valve was ground 4 thou) put the lot back together exactly were it all came out and the whole timing assembly is new.i primed the engine for 40 sec to get it well lubed then plugged the cam and crank angle sensors and started it up...........it ran perfectly for about 10 secs then the momentary sound of valves interfering came from the right head and it stopped abruptly.

my guess is the tensioner somehow failed and gears jumped on the belt or can the avcs malfunction and cause interference?

[Kiwi_Fozze]

You sure you didn\'t drop a valve?

[pedro]

Pull it down...examine...diagnose.

Its hard to tell what the beer tastes like without opening the bottle..

[Stoffa]

My stab in the dark is maybe with the cam angle sensors unplugged while your priming, the ecu didn\'t know where the timing should be and caused the interference. But in saying that im sure subaru would have safety\'s in place so if the sensors all crapped out they would retard to timing to a safe point to drive without causing drama.

Maybe just a freak failure of the tensoiner causing the belt to slip?

Are they sodium filled valves on that model? Maybe caused took to much off grinding the valve tips rather than using correct shims/buckets and caused the valve to fail.

Did you manually rotate the crank before starting? I usually give the engine 2 full manual revolutions and check everything lines up again and make sure no valves are touching. But thats to double check as im not an overly experienced mechanic.

Im mostly self taught from doing and learning so maybe I dont know what im talking about

[Guest]

 B-MAGIC said:

hard to look at/to much to read

modified for easier reading.

[Guest]

 kwi_fozze said:

You sure you didn\'t drop a valve?

I\'m positive, i put the thing back together meticulously-tapped all valve assemblies lightly after retainers were placed in etc.pulled cam cover off last night and looked in and right side intake exhaust valves all seem bent.

[Guest]

 Stoffa said:

My stab in the dark is maybe with the cam angle sensors unplugged while your priming, the ecu didn\'t know where the timing should be and caused the interference. But in saying that im sure subaru would have safety\'s in place so if the sensors all crapped out they would retard to timing to a safe point to drive without causing drama.

Maybe just a freak failure of the tensoiner causing the belt to slip?

Are they sodium filled valves on that model? Maybe caused took to much off grinding the valve tips rather than using correct shims/buckets and caused the valve to fail.

Did you manually rotate the crank before starting? I usually give the engine 2 full manual revolutions and check everything lines up again and make sure no valves are touching. But thats to double check as im not an overly experienced mechanic.

Im mostly self taught from doing and learning so maybe I dont know what im talking about

yes i wondered about the cam angle sensors being unplugged too, but i would have thought that the car would not start without the ecu first establishing that the the cam timing is correct for start up or that the the avcs would even have enough potential timing adjustment to allow the valves to interfere at all?

i wouldn\'t think it was the valve tips that caused the failure as it would take much longer run time for them to mushroom and fail.

i did rotate the crank a lot manually on the engine stand after i had put the T belt on but i didn\'t go round till everything lined up again, although it was all absolutely perfectly aligned in terms of markings everywhere initially. just for note it was a T277 belt and had belt markings and was on in the proper rotational direction.

The more i think about it a freak tensioner failure is the only answer i can come up with but just to be sure does anyone know if i can just leave the crank angle sensor unplugged when priming or is there another way i can prime the engine while leaving all sensors plugged in so the ecu might potentially be able recognize all angles??? and was 40 sec or so enough to prime the motor?

[boon]

Unplug fuel relay would be my pick...

[Guest]

that is a good pick, where is it located? or can the injectors just be unplugged?

[Joker]

I reckon you got some cam timing marks wrong : have you doen a cambelt before?

on another note : you have already way more experience mechanically on a Subaru than me : is just my thoughts

[titian]

i always oil prime new motors with the spark plugs out...wont start then...also unplug the fuel pump...its not too difficult to do

[Jesus]

I just turn injection mode to off.

[lachlan]

the cam phasers wont have enough travel to cause the valves to do high fives with the pistons

[Jesus]

Did you perhaps get too excited and start it without putting the crank pulley back on? Woodruff key still in the crank?

[madmike]

Oh they make a mess if you do that!!

[madmike]

 Jesus said:

Yeah but whos that silly!?

Me...

Spat the woodruff key out as i shut it down..

LUCKY!!!!

Hang on... Weren\'t you there when i did it Jesus?

[Guest]

 JoKer said:

I reckon you got some cam timing marks wrong : have you doen a cambelt before?

on another note : you have already way more experience mechanically on a Subaru than me : is just my thoughts

yeah i\'ve done them a couple of times and i\'m aware of making sure you align everything before taking the cam belt off too-otherwise you might slightly damage or bend valves due to them interfering with each other as they close.......although it is quite unlikely. And i did triple check all markings plus arrows on belt etc for rotational direction.

[Guest]

 lachlan said:

the cam phasers wont have enough travel to cause the valves to do high fives with the pistons

What about the valves doing high fives with each other? which then results in high fives all round :-\

[Guest]

 Jesus said:

Did you perhaps get too excited and start it without putting the crank pulley back on? Woodruff key still in the crank?

no

[Guest]

So i\'ve made a bit of progress with this now. Pulled cams out and found that passenger side intake cam middle bearing had heat stress marking on it and bearing cap and race in the head had heat stress marking too. i wonder if i over torqued by accident and it caused it to near seize or something and make the cam gear jump the belt, has anyone ever heard of this happening before?

All passenger side intake valves are bent plus two exhaust valves and all the driver\'s side exhaust valves are bent and in all cases they\'ve kissed the pistons.

there are no other marks on any of the other cam bearing surfaces at all.............so could the passenger side intake cam near seizing cause the other cams with bent valves to jump the belt???

The only other thing i can think of is that i have the incorrect head gasket thickness and this has resulted in the valves high fiving the pistons, the pistons are flush with the top of the cylinder when at the top of their stroke.

[Stoffa]

Were the cam caps in the right places?

[Guest]

 B-MAGIC said:

heads not skimmed properly?

I didn\'t have them skimmed, i\'m pretty sure it\'s the cam cap seizure issue-i\'m just wondering if it took a while for the oil to pick up. I would have thought 40 sec or so of cold crank would have had everything lubed thoroughly though.

[Guest]

 Stoffa said:

Were the cam caps in the right places?

yep went back exactly where they came from and on this model ej20 there are only two individual cam caps as the others form part of a bearing frame that also houses the oil control solenoid for the avcs intake cam gear so there really aren\'t many to confuse.

[Guest]

Who supplied the gaskets?

[Stoffa]

Maybe the oil galleries that feed the head were blocked, ive seen that before from using too much sealer between the block halves. it gets squished into the gallery and blocks it