just another snapped timing belt

[ricktb]

I snapped a timing belt, heard what sounded like a crunch. I pulled the valve cover and about 10 of the rocker arms were popped off the ball joints, and 3 were completely loose and laying down in the oil wells. So clearly the valves must have smacked the top of the pistons. Is there a way to check if the valves are bent without removing the head? from the top they look stright but its tough to tell. Could the rocker arms be designed to pop off to prevent valve damage in this event? Can I still do a compression test somehow?

When the belt snapped I was barely boosting maybe 5 psi in second gear, going about 55km/h so less than 4500 rpms but I'm sure the engine got a few more revolutions in there before it stalled.

The reason I dont want to pull the head is because the exhaust mani bolts are seized on there and i've stripped one a little already trying to remove it.

Also how hard is it to remove the intake manifold? is there bolts tucked way under neath? Thanks for the input.

Possibly looking at a head rebuild or whole engine depend on damage. Anyone know any good shops in Alberta, Canada?

 

[TofastForU_99]

If you need some help with a head rebuild we offer great rebuilds to high performance builds all at great prices. Here is a link feel free to check it out or call/email us with any questions.

DSM Race Heads

If you do build the head yourself Bogus pretty much has a thread on each step that needs to be done

 

[BogusSVO]

There are some special tools needed for valve guide replacement.

Then the seats need to be cut to index the guide center line to the valve seat.

Chances are just lapping valves with new guides not work and have the valve seal.


You may want to book mark this link.

http://www.dsmtuners.com/forums/articles-miscellaneous/450429-bogussvo-how-links-other-info.html


Now some reading for you.

http://www.dsmtuners.com/forums/newbie-forum/341028-4g63t-head-oil-port-mod.html

http://www.dsmtuners.com/forums/cylinder-head-short-block/420045-how-have-4g63-head-rebuilt.html

http://www.dsmtuners.com/forums/cyl...0613-why-not-let-your-head-belt-surfaced.html

http://www.dsmtuners.com/forums/new...face-4g63t-cylinder-head-mls-head-gasket.html

http://www.dsmtuners.com/forums/cyl...how-measure-4g63-cylinder-head-thickness.html

http://www.dsmtuners.com/forums/cylinder-head-short-block/413772-how-clean-head-gasket-surface.html

 

[Breezio69]

Ouch!

I am kind of curious why you wouldn't work through the bottom end with the piston to valve contact? If it were me, id pull the pistons, clean them up and take them to a machine shop to get tested for cracks. I would be more worried about that than the head really... you could drop $1000 into the head and slap it on there for 500 miles and have that piston that looked like it took the initial hit to the valves fail. Now your at square one only worse this time.

And you aren't really limited to finding a head in your area. There are 4-5 on here right now for super cheap. Sure it would be a few extra bucks to ship it, but they aren't as scarce as you'd think. And it would be much cheaper than a full rebuild and you could look into the rotating assembly. Think about how hard those pistons actually hit the valves...

Your already 2/3 of the way pulling it down, may as well do the rest for reassurance. If anything your out a set of rings.

Edit: FWIW, I know this is a COMPLETELY different scenario as far as motor type. But a few years ago I built a big bore stroker motor in a quad. The first time around (yes there was two times rebuilding this) I tested and reused the timing chain, it was within spec at the time. Took the 11 hour drive to Glamis and on day 4 of 5 out there the timing chain stretched and skipped some teeth on the cams, had piston to valve contact. When I got home and tore it down the piston (Wiseco) was cracked in 2 places around the inner skirt near the wrist pin, also took out the lower rod bearing as well and trashed my freshly ported and polished head that was built to the tits. Ended up adding another $900 to my already $1700 rebuild for not going through everything and reusing 1 stock part on it, and the upgraded chain was only $80.

Ive learned after that its better to be safe than sorry... And these guys are spot on with do it right or do it twice!

 

[ricktb]

bah i was so looking forward to spring to rip around now this dammit.

 

[ricktb]

back in business.. head rebuild complete and runs goood

 

[ricktb]

High 5's all around