m20 -- rocker arm question (and more)

[[1990]525]

Hi guys. This weekend I completed my cylinder head removal&installation. Hoorah, although alas a problem has arisen! While driving about 40mph I noticed a tink tink tink which I attributed to the old volvo 240gl next to me. Stopping at the next stop light, idle was fine and the ticking slower. After accelerating (lightly) from the light, my revs don't hold and the tinking becomes more of a thunking. I pull over across traffic immediately and coast to the parking lot on the corner.

After undoing the oil cap on the valve cover, I could see that a rocker arm retaining clip had come undone. Following the tow home, me father and I pulled the valve cover and to our surprise all of the exhaust side rocker arm retaining clips had popped off and were either jammed against the side of the cylinder head or floating next to the rocker arms... Oh boy was this the result of a slipped timing belt? I don't think so.

Our best guess is that the clips either weren't fully clipped in... or were oriented in such a way that the feet of the clips either hit a cam lobe or part of it hit the valve cover. There was no sign of scuff on the cylinder head walls or the valve cover however.

After snapping the retaining clips back on the rocker shaft, we thought we might as well see what happens with the valve cover off when the car is run. It starts up perfectly and smoothly. After observing the cam and rockers for a few minutes we noticed that the exhaust clips which we had oriented approximately vertical to the cylinder head were slowly sliding down towards the exhaust side ports. This is how the clips were oriented after the cylinder head installation, as the intake clips seemed to snap comfortably leaning towards the intake side ports, it seemed logical that the exhaust clips would lean the other way.

Most of the exhaust side rocker arm retaining clips ended up coming to rest on the exhaust side, except for the one over cylinder #2. That clip stayed vertical to the cylinder head. I assume that is because the clip is slightly though not visibly bent from the rocker arm whacking it against the cylinder head.

So a few questions: How are the rocker arm retainers SUPPOSED to be oriented on the intake AND exhaust sides? Also, why would the cylinder #1 rocker arm now be slightly toward the front of the engine, ie not centered over the valve stem? Would this be because of a bent clip? Also, why did the clips likely pop off in the first place?!

Thanks for your knowledge guys!

[Robin-535im]

This may be completely off base... but in the m30 the rocker arm has a cylindrical shoulder (annulus) that slides over the clip and completely covers it - the spring loads it up against the clip and with the clip covered it can't come off. Could the rocker arms shafts have been installed backward and the clips are on the wrong side? I don't know if this is possible or if the same mechanical design was used in the m20 as the m30.

[[1990]525]

My clips are oriented like the painted one here, and if you move them to the position of the photographed clips they slide down while running the engine and rock with the rocker arms.

[E34-520iSE]

Easy peasy! Your clips should be straight up like the ones in the pic, but more importantly, check that the locking T-piece behind the toothed pulley wheel is FULLY ENGAGED into the corresponding 'flats' milled into the rocker arms. If it's badly fitted, or missing, then all hell breaks loose!
It sounds like your rocker arms have turned because the T-piece wasn't locked in properly. You're lucky you still have an engine.

HTH,

Shaun M

[winfred]

yep, you can see it in the picture just ahead of the oil spray pipe, probably popped out when the valve cover was off at one time and no one noticed, it's held in by the valve cover

Easy peasy! Your clips should be straight up like the ones in the pic, but more importantly, check that the locking T-piece behind the toothed pulley wheel is FULLY ENGAGED into the corresponding 'flats' milled into the rocker arms. If it's badly fitted, or missing, then all hell breaks loose!
It sounds like your rocker arms have turned because the T-piece wasn't locked in properly. You're lucky you still have an engine.

HTH,

Shaun M

[[1990]525]

Easy peasy! Your clips should be straight up like the ones in the pic, but more importantly, check that the locking T-piece behind the toothed pulley wheel is FULLY ENGAGED into the corresponding 'flats' milled into the rocker arms. If it's badly fitted, or missing, then all hell breaks loose!
It sounds like your rocker arms have turned because the T-piece wasn't locked in properly. You're lucky you still have an engine.

HTH,

Shaun M

Yeeup. I found out after going to lunch and a (single) clip springing off again that I was missing this -v--v- shaped piece. It keeps the rocker arm shafts from rotating (the exhaust shaft is now 180 degrees out). It turns out this piece fell off in the back of my van while transporting the cyl head. Doh.

Are the rocker arm shafts easy to rotate? Will the rocker arms need to be pulled off the valves?

[winfred]

they can be turned easy enough, if you don't care about scarring up the shaft (wouldn't be an issue till it's time to rebuild it) just grab the shaft with some vice grips, you may try a piece of leather to protect the shaft