Timing Chain Guide Broke inside Motor

[sickamaya]

I am so pissed!

I have been preparing the time location and money to remove the timing chain guides due to the rattling under the valve cover. I have read forums for a long time now, and even had 2 different chain removal guides printed out.

Unfortunately, my dumb *** waited too long. Monday night... I was driving southbound on I-35, and all of the sudden the engine seemed to lose power. I didn't hear any loud clanking or knocking or grinding, but then again.... I was listening to my stereo prettly loudly. At any rate... the car would no longer accel.
As soon as this happened... I knew what it must have been.

Sure enough, the upper timing chain guide broke off it's mounting bracket and was launched along the pathway of the counterclockwise moving timing chain. Well, that little metal rectangular piece couldn't curve along the exhast cam sprocket so it bent and wedged with so much force that the sprocket on the exhaust cam snapped off and also cracked the valve cover.

Amazingly, the upper timing chain is still intact. Now.... I guess what I need to find out is whether or not this is salvagable. I found a used exhaust camshaft for $50, but then there runs the problem with the valves being bent.

Now, the exhaust camshaft valves all seem to be closed.... (full upright position). Could this be because they are bent?

Somebody gimme some input on this deal because I am so ashamed!

[jdm_s14_zenki]

flow test the head to see if valves are bent or seals are bad. you cant really see with the naked eye sometimes. take it to a machine shop and they'll test it for you.

[misnomer]

It's an interference head engine-- if the timing chain wasn't turning one of the cams, odds are good your valves got nailed by the piston. The valve springs will push the valves to "full upright position" if there's no cam to keep them down.

Odd, when my upper guide broke, it just sort of sat there on top of the chain for days without any issues. Guess I got lucky.

[sickamaya]

Okay, so given the feedback you have posted, let's say that the exhaust cam stopped spinning.

So it goes as such then?

I'm trying to base this on logic of what exactly happened in sequence under the hood.

If the timing chain didn't break, but the guide wedged into the corner from the clockwise turning of the timing chain, then it wedged only to abruptly break the camshaft sprocket from the exhaust cam and continue turning both the intake cam and the exhaust sprocket and maintained tension from the tensioner, etc. (It's evident that the sprocket continued to rotate past it's detachment point) So, does this stand to reason that the momentum from the exhaust cam rotation would have cause the exahaust cam to "wind down" with it's rotational speed or would the valve springs in combination with the exhaust compression push the exahust valves closed without the possibility of the required force to open them again (given that the lobes require so many pounds of force to push the valves open).

I have a couple of pictures I can post.

I've been frantically searching online for a couple of weeks now and have not found anyone with the identical incident.

I did a leakdown test the other day with a homemade leakdown tester. The results were a bit astonishing to the point of disbelief. No apparent evidence or noises coming from the exhaust or intake manifold, and just about 5 to 6% leakdown. But, I don't know if the amount of compression PSI matters. We were applying about 165 PSI and it would leak to about 160 PSI on all four cylinders. Needless to say I took both camshafts off so all valves should be closed. Is this a friggin miracle or what?

Screw this attachment size limit. Check this URL for my catastrophe....

Thank you for your help.

sorry about the actual image sizes.... i'll have to adjust that later.

http://www.sickamaya.net/240sx/

[NIK90s13]

Man if the leak down held, I would go with the new cam. You got nothing to loose but time. Try it out!

[jdm_s14_zenki]

you are one lucky guy. i broke my stock cam and a few rocker arms one time, also bent like 6 valves...it was a disaster. so i rebuilt my head with all aftermarket, and sometimes its difficult to dial it in right, but once everythings tuned and ready to go, you will love it. they're selling aftermarket cams for pretty cheap now, if your funds allow, should try some out. maybe like a 255/264 combo or 264/272 combo. dont get to large of a lift though, id do 10.5 mm max

[projectRDM]

Forgive my being an asshole, but what kind of preparation did you need to remove the top guide?

You need a 10mm socket, 12 mm socket, and 15 minutes of your time. If that requires prep work you're in for a rude awakening when you have to do shit like change oil or a light bulb.

[aznpoopy]

ah that sucks.

why did you wait so long? you don't have to buy anything except rtv and the gasket. some people even get away with just reusing the gasket... oh well.