Broken Rocker

Hey guys.. how's it going?

Here's a question for you experts...

My son was complaining about a lack of power in his E30. He went and bought new plugs and replaced then himself. When I looked at the old plugs, I saw that one looked "wet". I asked which one it came from but he didn't bother looking at the plugs as he removed them.. Well the plugs didn't help and the engine was WAY overdue for a valve adjustment. When we removed the valve cover we had a nasty surprise.. The #3 intake rocker was broken off on the valve side of the rocker shaft. Now the dilemma, remove the head or try and pull out the rocker shaft. I decided that removal of the shaft was possible if the radiator and AC radiator was removed. We were able to pull the shaft out ~14 inches and we got to the #3 rocker to remove it.

OK so we got a new rocker but the #3 cams were in the compressed position, so we had to put the timing belt back on so that we could rotate the engine 10-15 degrees so we could slip the #3 rocker back on the shaft. As we worked the shaft in and placed the other rockers back on we reversed the engine rotation back to it's original position. We took extra care to make sure the rotation of the engine crankshaft and camshaft remained in sync(we didn't remove the flywheel to ensure that the crankshaft was on the mark, but I'm pretty sure it was OK).

Next we adjusted the valves to .010 (in the proper order) and made a couple of rotations to double check that each cylinder was at TDC when adjusted. Everything was good and there was no slop. Then we put everything back together, filled with water and did a final check. When we turned the engine, it started right up , but there was a definite loud clacking sound coming from the engine (seemed to be from the valve area).. Major downer....

Today my son removed the valve cover and I checked everything out. Everything looked good. I didn't have time to do the full rotations and recheck the valve clearances but the few I could check manually, seemed good. We continued the rotations and all the valves and rockers and moving well. I decided to crank the engine with the cover off of try and pinpoint the trouble. I removed all spark plug cables and the cable from the coil... Everything looked good as the starer cranked the engine...

Now I figured, why not start the engine with the cover off? Replaced the cables on the plugs and coil. Unfortunately, I could not get the engine to start even after waiting quite a while in case I flooded the engine. I also checked that we were indeed getting a spark from the plugs. We'll do a more thorough check of everything tomorrow.

I was worried that I possibly shifted the timing belt off by one tooth and then the valve(s) were hitting a piston. But if that were the case... I wouldn't be able to rotate the engine manually.. Right? It would jamb when rotating the crankshaft with an ordinary socket wrench. My sons friend who works at a German auto shop, said that if the timing belt were off, the engine wouldn't run well. It did run well except for the clacking.

So...

Any ideas as to why the rocker broke? Simple mechanical fatigue? The engine does have 200+k miles on it.
Any thoughts on the possibility on the belt being of by a tooth? Results an/or consequences?
Any other possibilities for the clacking? Piston trouble?
I don't have a compression tester but I'll either borrow one or buy one to check the compression.

Well thanks for reading..

Peter



Edited 1 time(s). Last edit at 06/09/2010 11:03PM by sdp.

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sdp


OK so we got a new rocker but the #3 cams were in the compressed position, so we had to put the timing belt back on so that we could rotate the engine 10-15 degrees so we could slip the #3 rocker back on the shaft. As we worked the shaft in and placed the other rockers back on we reversed the engine rotation back to it's original position. We took extra care to make sure the rotation of the engine crankshaft and camshaft remained in sync(we didn't remove the flywheel to ensure that the crankshaft was on the mark, but I'm pretty sure it was OK).

Peter

I think you must mean the lower pulley instead of the flywheel, right? Did you re-use the old timing belt? If you did, I think you probably should plan on going back and replacing it right away, unless it only had a couple of hundred miles on it. When you put the new belt on, you can make sure all the marks line up right. Then there won't be any doubt you have it right. "Pretty sure" isn't the same thing as "absolutely sure." I wouldn't trust an old timing belt that I was only "pretty sure" was on there right. Put a new tensioner and water pump in there while you're at it.

John

x2 what John said. Hopefully, you didn't bend any valves but you need a new timing belt then a compression test to see if you still have compression. These engines are definitely not supposed to make clacking sounds from the valve train (it that's what it was and not pistons hitting valves).

alan

Yeah, I knew I should have ordered that belt. When you are rushed to get the car going and you take shortcuts.. well....

But what gets me... If we did miss putting the belt back on by a tooth and the valves were indeed touching the pistons.. Wouldn't I feel it when rotating the engine. Wouldn't it jamb?

And yes to John.. I meant the pully on the toothed timing flywheel.

I forgot to ask... I know there is a timing mark on the crankshaft that is visible when the belt pulley is removed. Are there any external markings on the toothed timing flywheel to line with something on the engine body?

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sdp

But what gets me... If we did miss putting the belt back on by a tooth and the valves were indeed touching the pistons.. Wouldn't I feel it when rotating the engine. Wouldn't it jamb?

It seems like you would feel it if the pistons hit the valves, so maybe that's not what you hear. I also doubt that the engine is built so that being off one tooth would cause things to hit, but this is one of those things that falls in the "pretty sure" category. I don't know it for sure. The only way to be sure things aren't hitting that I know of is to make sure all the timing marks are lined up right. Maybe the sound you hear is what these engines sound like when they're one tooth off time and it will go away when you put it together right. I hope so.

John

Perhaps.. I was looking at your pictures from the broken spring thread.. I noticed (and remembered) that the pistons were notched to clear the valves... Maybe if I'm off by a tooth, the valves might just be touching and would only be "heard" when the engine was running and not hand turned.

I went and bought a new timing belt and compression tester today . We'll start dismantling AGAIN tonight... Ughhhh.

BTW.. I love the way you painted the air intake manifold and valve cover.. that was a nice touch!!!

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sdp


BTW.. I love the way you painted the air intake manifold and valve cover.. that was a nice touch!!!

That was Tyler, not me. I agree, he did a nice job on that.

John

Ahh yes.. I got the names crossed up. I wish I had the time and space to dig into the car like that

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sdp
Perhaps.. I was looking at your pictures from the broken spring thread.. I noticed (and remembered) that the pistons were notched to clear the valves... Maybe if I'm off by a tooth, the valves might just be touching and would only be "heard" when the engine was running and not hand turned.

I went and bought a new timing belt and compression tester today . We'll start dismantling AGAIN tonight... Ughhhh.

BTW.. I love the way you painted the air intake manifold and valve cover.. that was a nice touch!!!

Good...put the new belt on and triple check the timing

Installing the belt one tooth off in either direction will not cause valve clearance problems. It may cause almost unnoticable performance problems if it is one tooth retarded and perhaps a performance improvement if one tooth advanced...but not likely that any but Ove Kvam would see, hear or feel a difference

There used to be a kit available for the M20 that had an adjustable cam gear cog(the toothed wheel on the end of the camshaft). I seem to remember that it was adjustable for up to almost two teeth offset...so being off by one tooth isn't likely to cause any interference problems.

One thing that can and does happen is that the cam follower, wears a 'groove' in it's face the same arched shape as the cam lobe. This means that using the flat blade style feeler gauge will not give you the proper clearance. If this is the case, you need to use the 'wire' type feeler gauge to properly set the clearances.

See what happens with the new belt and a 100% positive belt/cog alignment. If the noise is still there then I'm betting it may be something like I described.

Well sumbeetch... I was off by 1? tooth. When we were lining things up I used the notched(blank) part of the toothed wheel to line it up with the line on the lower cover... Unfortunately, tonight I saw that mark I was looking for.. The line with the OT mark.. It's behind the cogs.... dang.. It was off by 3/8- 1/2 inch.. The marking is not in the blank portion of the teeth... So with the new timing belt in hand, I removed the pulley and the toothed timing wheel and saw the notch on the body and the mark on the crankshaft. I lined it all up and the timing belt fit really well.

So before I put everything back and check the valve clearances, I'm going to do a compression check to make sure nothing bad happened to the valves. At least you gave me some confidence that nothing bad happened...

We'll see.

I couldn't get a compression reading before I put everything back together again so I said forget it.. I don't understand why it wouldn't register. I tried a couple of cylinders. Whatever it is.. so be it.. We put it all back together and turned it over. It fired right up and worked like a charm. Woohoo... I don't know about the compression, but my son said he barely had to give it much gas and it took off. Good pick up.

The only bad thing was that I snapped the head off one of the 6 bolts on the crankcase pulley. The manual said about 82lbs of torque, but it snapped. Did I read it wrong and does anyone think it will be an issue?

Hmmm, 82lbs sounds more like the torque on a single large center bolt on a harmonic damper. A pulley bolt, especially if it is one of 6 would be much lower? Recheck the manual!! Wheel lug nuts are torqed to 75-90 ft pounds.

Is it possible the spec was 82 INCH-pounds not foot pounds?

alan

Another rookie mistake... It's 17 ponds.. I read the torque specs in the chart for Flywheel bolts.. Stupid me... the flywheel is at the clutch. Mistaken terminology. Live and learn. We'll tap it out some day when/if something goes south again.

Hmm, you've come this far. I might worry the lack of the bolt could set up an imbalance in the rotating mass in relation to the remaining 5 bolts.

alan

And if the others are overtightened AND have extra load due to the 6th being broken, chances are that they snap one after the other and then you're off for a longer journey.



Edited 1 time(s). Last edit at 06/14/2010 09:46AM by Michiel 318iS.

Nooo...I quickly put away the torque wrench when I snapped the 1st one... I did them by hand. That's what you get when you are in a rush to get the job done.

I wasn't reading the reassembly instructions because .. I know where everytyhing goes... But right there in the text it said 17 lbs but I was looking for it in the torque charts...


BTW.. The radiator tends to leak on the seam between the metal grills and plastic parts on the side. Are these things repairable? Or do I need to look for a replacement.?

Non repairable, replace the radiator (you can call a radiator shop to make sure, but I am pretty sure the plastic side tanks are crimped to the metal cross tube assembly with an O-ring for a seal. You could have a cracked side tank or crappy o-ring seal). When the radiator is out, access to the pulley bolt should be a lot easier!!

You obviously have the skills, just slow down, check, and recheck (measure twice, cut once as they say in woodworking)



alan



Edited 1 time(s). Last edit at 06/14/2010 10:57AM by alanrw.

I took a look at the pulley and forgot that we didn't put the belts on it (power steering and AC). Since the AC hasn't worked in a long time and since we had to disconnect the AC radiator there was no pint in putting it on. The steering rack leaks like a sieve, so my son wasn't putting oil in it. I don't know if that ruined the pump, but since the power steering wasn't working, we left that off too. So there shouldn't be too much pressure on the pulley other than holding in the timing wheel. and the belt for the water pump... I think we should be good for the time being.

Peter