Rocker Arm Failed. What now?

#1

As some of the Southeast folks know, I lost power after three laps in Sunday’s race at Road Atlanta 3 weeks ago. The car was running fine, then lost power, ran rough and sounded ugly.
I opened the valve cover this weekend and found that the #6 rocker nearest the intake manifold and firewall was broken (see pic). Bummer. All other rockers appear to be fine.

So, what now?
The head was 6 months old from a remanufacturer. I talked with them and they will replace the rocker, but questioned if maybe the timing was off and a piston/valve jam had broken the rocker.

Is this a random part failure or a result of timing misalignment?
I think I can replace this rocker without removing the entire head by sliding the rocker rod out a bit. (there is a thread on this in e30tech).

To slide out the rocker rod, I’ll need to open the cam cover,etc. and will check the timing alignment at that time.

Any comments or good ideas? I want to fix this quickly so I can keep racing.
Thanks for the help.
Jon

#2

According to the rules and everyone on this board that rocker can’t possibly be broken. Especially if it is new.

I’d suggest you look at it again more closely.

#3

Before disassembling anything, pull the timing covers and check cam timing. I rather think that if the cam timing was off enough to allow a piston to hit a valve, you’d have had other symptoms. But check the timing to be sure it is right.

#4

IndyJim wrote:

[quote]According to the rules and everyone on this board that rocker can’t possibly be broken. Especially if it is new.

I’d suggest you look at it again more closely.[/quote]

Unless the eccentric clearence was too tight/loose.

#5

IndyJim wrote:

[quote]According to the rules and everyone on this board that rocker can’t possibly be broken. Especially if it is new.

I’d suggest you look at it again more closely.[/quote]

It’s not broken, the other 1/2 just came loose. Put some JB weld on it.:laugh:

Seriously, I agree with Jlevie, if it was cam timing you’d have more damage in other parts of the valve train/engine.

John

#6

Hmm, JB Weld great idea, but not legal. The hot setup would then be to crack them, fix them in such a way as to increase timing.

As long as everything is perfectly adjusted and never falls out of spec this should never happen. Sound reasonable to do a valve adjustment every session or maybe that is overkill every other session should suffice.

I’m sure the shop just had them loose or too tight and it is their fault.

#7

There’s lots of posts on broken rockers here and else where. A small majority of folks seem to believe that OEM rockers (from various manuf) are pretty rugged as long as the valve gap is adjusted properly. I bet that your timing belt turns out to be ok.

Other folks believe strongly that rocker arms are often manufactured poorly with voids the weaken them or casting marks that cause stress concentrations. But other folks say that those problems only apply to early rocker arms.

All it would take is for an eccentric to not be tightened enough. When it loosened a gap would open and the rocker arm would get hammered. That’d probably break a rocker pretty quick.

#8

As much fun as it to dip into our online source for bad attitude :stuck_out_tongue: I have a few serious questions. My aim is to get some good info on the history of the head and see what you guys think is reasonable. Those who know me know I am ignorant about much of this. Just trying to learn.

The remanufacturer… I am not asking to name names, but knowing the price of the head may help us understand the implied expertise in the rebuild. I assume that doing a valve adjustment would be the last step in delivering a remanufactured head, right? Do things “settle in” after a couple hours of running (meaning you have to adjust valves again)? Were new rockers installed during the rebuild?

Time on the head… How many track hours did you get out of the head? When was the last valve adjustment?

Collateral damage… Once it started running bad, did you shut down the engine immediately or run it for a while? When a rocker fails, does it instantly booger everything else up?

Sorry to hear about your troubles, Jon.

Steve D.

#9

You should re-adjust the valves after the initial adjustment on a refurbed/rebuilt head. How many miles did you put on them? I

Its hard to see in the pic, but were these all new rocker arms that were put in? I.e. the thicker replacement parts, or were they the “old” style?

If it was new, I bet you just got a “Ranger Special” rocker arm. Sucks, but you can replace it without pulling the head…so you got that going for ya.

I suspect your cam timing is fine as well, its very easy to time these motors as the marks on the head, block and sprockets are very clear to see. Certainly check that first.

Steve D. - to answer your question, if it is just a broken rocker arm, no it will not booger everything else up…unless the broken piece(s) bang around in the head and cause more damage, which is rarely seen.

#10

Steve brings up an good point. One level of reman reuses parts like rocker arms, shafts, cam, etc if those parts are within spec. The higher level replaces all parts subject to wear with new parts. The cost of that level of rebuild is quite a bit higher than that of a generic reman. Knowing what the head cost would be a good indication of how much was new.

#11

Jones wrote:

[quote]You should re-adjust the valves after the initial adjustment on a refurbed/rebuilt head. How many miles did you put on them? I

Its hard to see in the pic, but were these all new roc… blah blah blah… more Jones useless gibberish…blah blah blah[/quote]

I too want to hear the valve adjustment schedule.

#12

When I replaced my rocker arms last year, I was told to adjust the valves every two weekends.

Now that I have finally learned to adjust the valves, I intent to follow that schedule.

#13

Lots of good input, thanks. I’m not sure what Indy Jim is getting at…but no more pictures.

Here’s some more info: The reman head cost about $500 and is reported to be OEM spec - nothing special. I don’t know if the rockers were new or re-used. The head comes with the valves not adjusted; I did that the first time last November when the head was just installed.

The head had about two NASA weekends (four races + quals) on it prior to RA.

In fact, I did adjust the valves on Sunday morning prior to the Sunday race. I was just trying to get them set well, after the head had a few hours on it. As some have mentioned, perhaps this rocker was mis-adjusted or loosened during the race. It did run fine for three laps, then went bad, so probably the eccentric loosened and then the rocker got ‘whammed’ once and fractured.

After the issue started in the race, I went on for about two more laps (of course), because I was having fun and doing ok vs. the competition (other than being down on power, the care was doing well in the rain. :silly: ) There appears to be no collateral damage.

A new rocker is on order; about $20 plus shipping.

Thanks again for the input.
Jon

#14

alfageorgia wrote:

IndyJim’s just a disgruntled employee who calls and b!tches at his company’s customer service to make himself feel better. However he’s upset because…

Billet rocker arms, which never break, were once allowed and now aren’t, despite negligible if any performance difference. The rule change was made based on someone on a forum somewhere on the internet who took a couple of camera phone pictures of rocker arms on his kitchen counter and stated some ‘truths’ about changes in designs and reliability without any empirical data, tech bulletins or manufacturers confirmation.

…I think.

Hopefully we’ll discover that the rocker arm that broke in your head was an old design or that the eccentric is really loose (on the end that broke), etc… corroborating the theory behind the justification for the rule change and proving IndyJim wrong.

#15

beating a dead horse, but the old rocker rule never allowed billet rocker arms - they were required to be the “exact same size and shape” as stock. Jim received a verbal allowance in error.
thanks,
bruce

#16

Actually, the rule permitted billet arms, but those widely (albeit expensively) available are not the same size and shape as stock.

Steve D.

#17

So along this same logic are forged pistons legal?

Same, size, compression? Weight isn’t specified in any documentation I can find?

Certainly a bigger performance advantage to these vs. a billet rocker but it isn’t really specfiically mentioned in the rules?

Interesting thread here on them…

http://www.e30tech.com/forum/showthread.php?t=72634

#18

Steve D wrote:

[quote]Actually, the rule permitted billet arms, but those widely (albeit expensively) available are not the same size and shape as stock.

Steve D.[/quote]

so if they’re not the same size and shape as stock, how did the old rule allow them?
bruce

#19

If they weren’t legal why was the rule changed, might be another way to look at it?

Forged pistons? What about those?

#20

The rule was changed because people were inexplicably reading more into it than expected.

The rules state the things that are allowed, not the things that aren’t allowed.
Forged pistons aren’t mentioned, so they’re not allowed - that should always be your first line of thinking. If you disagree on a point, you can make a written (email) request to Carter for a ruling.
thanks,
bruce