Rebuilt LKO head, snapped exhaust rockers

[itsnotme1988]

I recently had a cylinder head rebuilt for a 1993 Saturn SL1. I just got it reassembled and tried to start the car only to have all four exhaust rockers snap off. What could have caused this? Cam timing was set correctly and system was primed before attempting to start (turn over until built pressure with no plugs installed.) Had a *pop* once I tried to start the car with plugs installed, pulled the rocker cover and found all four arms broken.

[2000mc]

I would try looking over at Saturn S-Series - SaturnFans.com Forums

[ssnsvibe09]

Did you turn the engine over by hand after the rebuild? How many times did the engine rotate during your no plug mode?

With all of the bottoms broken off... I wonder if your valves were seized or maybe your hydralic lifters were seized in a extended position.

It might be possible that the rocker shaft was torqued down during the rebuild without the valve train being verified for range of motion.

The damage is done...what is next? I hope that they are reasonably priced.

I have rebuilt several engines over the years, my insight is available if you want it, for the way ahead.

[user removed]

Had to be valves hitting pistons. No other way I have ever seen all exhaust rockers broken.

regards
mech

[ssnsvibe09]

I was thinking the same thing, the one pop???? throws me off. Must have sounded like a 10000 hp diesel starting when the clanging, banging and snapping got underway.

Itsnotme... you may have been lucky enough to have just the rocker arms failing as a weak point compared to bent valves or pistons with vent holes in them.

Reinstall replacements, and verify timing, and hand crank the engine (in the designed direction...) I have seen that mistake cause some grief too, to verify timing throughout the cycles and alignment of the reference points.

There are days like that where I am glad that the liquor store is not within walking distance. Something like that deserves a quart...

[slownugly]

double check timing before ordering some rockers. while you are checking timing might be good to do a leak down test to see if valves bent. if timing was off they probably wont warranty the head. did you install new timing chain, guides, and tensioner?

[itsnotme1988]

Yeah there is some surface rust. It was clean when I reinstalled it but I'm assuming it (the rust) was more or less just from sitting on the car for a few days before I tried to turn it over and/or from cleaning out the rocker cover with brake clean. There's also a bit of surface rust on the new headbolts too...





Never heard a knock between the valve/piston just a pop after it turned over maybe 3-4 times. I'm going to pull the TCC on my next day off and double check the timing then pull the head again to check the damage.

No I did not turn it by hand first. Got in a rush and ****ed that up...not the first time I've done a head job either and the first I forgot that key element. Just love that feeling of flushing $200 down the drain...

Would love to do a DOHC swap just don't have the time/money so figured this made the most economic sense.

[ssnsvibe09]

How much is a new gasket for the head?

I see that the rocker arm shaft still has the bearings from the destroyed rockers. Did you take them off the shaft yet?

A part of me is hoping that the bearing were siezed in position and that the rocker could not rotate over...

[itsnotme1988]

Not sure on just the h/g. The bearings all seem to turn freely but I haven't paid much attention to them. Will check that soon though. I know one I messed with seemed to move fine though.