Rb20Det Exhaust Valves Stuck

[Whatskid]

As the title states, pulled up at a set of lights a few days ago and she popped backfired and died.

The crank kept spinning and ripped the timing belt to pieces, pulled the head off and every exhaust valve is bent and stuck open and a few on the intake side slightly bent, does anyone have a clue what would cause this. Will be getting a valve tool and pulling them out over the weekend. I just can't understand why, on the brighter side the pistons still seem pretty good with only light scraping in the grooves.

[Missileman]

that's what happens when timing belts shit themselves, time for a low K wrecker motor.

[Whatskid]

Being a fairly new gates belt i couldn't see it as a problem. They way it looks is the top end locked up first while the crank kept spinning and tore the belt up

[GTSBoy]

Weakest link in that chain is definitely the belt. Blame that before blaming anything else. More importantly, because it was recently changed means that hands have recently been involved in the front end of the motor. So that means that something was either not put back right or something foreign was left in there are also possible causes for the belt to crap out.

[Whatskid]

This is true, it was done just before I bought the car, all up was about 18thou kms done. Bottom ends getting checked tonight, a mates got a reco head ready if I decide to go that way.

Mine also had titanium valve springs I'm assuming they'll still be sweet

[Plattsy]

if belt was recent i would be taking action against person who fitted it..

[Whatskid]

It wasn't in my name when it was done so it's just really unlucky on my part I guess

[Missileman]

theres a lot more grip for the belt on the cam gears, so if that locked up, I would expect the only damage to the belt would be a few rubber teeth missing down the bottom

[Whatskid]

That's all it is stripped teeth, but for what ever reason the top end stopped, every valve on exhaust side stayed open

[Missileman]

any of the valves broken, any missing retainers, does the belt look new? always possible it dropped a valve.

[Whatskid]

None a broken just bent. I counted atleast 17

12 on exhaust and the few on intake.

It's a pain to diagnose because it would have to have bent ever single valve in a very short time before it stalled

[Whatskid]

And if the timing belt went first it should only have bent the open valves on both sides before it stalled. I just can't wrap my head around how all exhaust valves were open. Unless each valve bent 2 by 2 until it locked up and stripped the belt

[GTSBoy]

You can bend them all. The cams keep spinning a short time with nothing but inertia to power them. As valves get bent they unload the lifters and then stay away from the cam lobes so you get all sorts of chaos going on. After a couple of turns of the cam the whole lot are stuffed and then the motor stops and it's all over!

[Whatskid]

^ were finding solutions lol

I'm thankful this all happened at idle not full boost my hks cams came out completely unscaved, we also thought the lifters may have seized and caused said chaos aswell. Ill know some more when I actually get the valve tool and pull the rest of it apart I guess

[Piggaz]

Did the oil pump shit itself? Mine did, exhaust cam welded itself to cam caps and seized the engine. All exhaust valves bent.

[R31 POWER]

Whatskid are you in perth? If so I have a free RB20det head you can have.

[Whatskid]

I don't think so, still had good pressure before in carked it. And there was oil throughout the cams. The whole motor/box is coming out anyway fora thorough inspection before I put it back or buy anything.

RB power- I'm a nsw kid, and my mates got a head in his shed ready if I need it. Appreciate the offer though champ

[Whatskid]

R31 power* my memory is great

[R31 POWER]

Haha all good dude, i double checked your user name to

[Whatskid]

Haha the whole thing is just pure luck, cams are fine and pistons are fine. Just lifters/valves that ate it