Broken Rocker Arm

[niki_west]

Hi all,

I recently purchased a 1981 Targa with a 3,2 motor that had the top end rebuild with 4K miles on it since then.

As I was driving it home it was clicking a little bit from the right cylinder bank. I thought, it's been sitting for a while, maybe the valves need adjusting. The noise kept getting louder and the when I got off the highway it was really loud and the engine wasn't firing on all the cylinders. The drive home was approximately 200 miles. Oil pressure was around 5 bar the whole time. (The Targa makes a lot of wind noise!)

I got a friend of a friend to come by and listen to it and he popped of the right upper valve cover. The middle rocker arm fell out.....The other thing he noticed straight away was that the inside of the valve cover was dry. Bone dry, not a drop of oil on it.
His assessment is that the oil line to that side is blocked and the cam ran dry.

Does anybody have a picture of what the inside of a normal valve cover should look like? I pulled the one off the left side yesterday and it is dry also!

All I know now is that I will now be getting some experience with the engine from my dream car! I wanted to do that sometime, not be forced to do so at the beginning!

Thanks for the help!

[tharbert]

If it was running dry, you'd see the damaged cam lobes and rocker faces easily. Post a pic of the cam and rocker, especially the rocker face that rides on the cam.

Did the rocker break? Or, was it just loose? The rocker shaft, if not positioned property and torqued correctly, can "walk" out of it's bore.

If it's actually broken, they are designed to break upon valve/piston contact but damage isn't normally avoided. Hope you don't have to go there...

[JFairman]

If the rocker covers were dry that's real bad. You say the motor was run like that for a while? The damage from lack of lubricating oil will damage the valve train and cams real fast. If thats really the situation then the top end will need to be removed and repaired.
The cam spray bar on each side has 3 oil holes per cylinder and one of them for each cylinder sprays oil straight up so the oil from it splashes off the inside of the upper cover and splatters all over in there to lubricate all the moving parts and carry away heat. The other two spray bar holes for each cylinder spray oil directly towards the cam lobes and rocker arms.
Oil also goes through passageways in the cam tower to lubricate the cam journals.

The inside of the upper covers should be getting wet with oil sprayed up at them as soon as oil pressure is developed. Oil pressure usually builds up between 1 to 2 seconds of the starter motor being turned over with a good battery.

[RedCoupe]

Just to satisfy myself that there isn't a blockage within an oil gallery inside of the crankcase, I would pull off the upper cover on the opposite side of the engine and see if it looks normal or if it is also dry.

[Mitch1]

Sorry to read this. Trying to think how oil line to cam tower was plugged or restricted. Was the oil dropped when upper valve cover removed? Curious what oil filter looks like.

[snbush67]

What was the oil pressure like while you were driving? If the oil was bypassing the cams I think that it should have indicated as high.

[niki_west]

I'll post a couple of pictures tonight of what everything looks like right now.

The intake rocker arm for cylinder five is broken in half.

I popped off the left intake valve cover and it is also dry.

The engine is still in the car, so I don't know the extent of the damage yet. I have a couple of other projects with higher priority right now, so I'm not sure about when I'll be able to drop it out.

As I was driving the oil pressure was near the top of the scale the entire time. What would the pressure be in a properly running engine?

The oil was changed with the filter to Mobil 1 5W-40 shortly before I got the car. I need to drain it and see if there are any filings in there. With the way the rocker arm looked, I would be surprised.

[RedCoupe]

With 5W-40 oil, the pressure shouldn't have been at the top of the gauge, so this is a further indicator of a blockage. I think I would refer to a diagram of the oiling system to see if I could pinpoint where the system is plugged.

[JFairman]

I think you should have a little chat with the person you recently bought this car from . . .

[tharbert]

^^^what he said^^^ I was trying to reason through how a rocker could break other than valve contact with the piston. There is the fatigue factor. I guess it could break if the rocker seized on the shaft due to lack of oil or maybe a combination of fatigue and resistance on the shaft. I would think, at that point, the lobe and rocker face would have significant damage.

As Mr. Fairman points out, those little holes in the cam spray bar are a favorite place for debris to lodge. Not sure one or a few being blocked would cause the whole system to run higher pressure. The manual says to remove that spray bar and flush when rebuilding. When I tore mine down, I found a little bit of sealant in one hole so I can understand the requirement to R&R the bars.

Good luck! Wait to see some pics here

[Flat6pac]

too many thoughtsat one time
put it in neutral,, have someone turn the key
with the valve cover off, youll see if there is an oil problem.
if you broke the rocker from fatigue, possible
if you were out of oil there should be wear on the face of the rocker and matching wear on the cam lobe.
can you rock the broken rocker
usually if a chain jumps the damage is on the exhaust side.

bruce

[JFairman]

Originally Posted by Flat6pac

too many thoughtsat one time
put it in neutral,, have someone turn the key
with the valve cover off, youll see if there is an oil problem.
if you broke the rocker from fatigue, possible
if you were out of oil there should be wear on the face of the rocker and matching wear on the cam lobe.
can you rock the broken rocker
usually if a chain jumps the damage is on the exhaust side.

bruce

I did that once with my 930 right after I got it... Then I spent the next half hour cleaning oil out of the AC condenser and off everything else back there. 3 thick streams of oil will shoot straight up out of the cam spray bars under starter motor speed alone.

[Flat6pac]

ben there, part of the learning curve....
bruce

[911pcars]

Originally Posted by RedCoupe

With 5W-40 oil, the pressure shouldn't have been at the top of the gauge, so this is a further indicator of a blockage. I think I would refer to a diagram of the oiling system to see if I could pinpoint where the system is plugged.

Oil blockage on opposite sides of the engine is a slim possibility, recent "rebuild" or not.

If the upper cylinder area has no lube, the cams and rockers would show signs of it. Please confirm.

It could be a "simple" and coincidental case of both lube bars clogged and not able to spray or other issues such as:

No oil
Oil pressure relief valve stuck open
Oil pump shaft broken
Oil pickup tube, broken
Intermediate shaft or gear, broken

Conduct more investigation (e.g. chain boxes) to understand the extent of the damage or lack of lube.

Unless there was an implied warranty attached to the sale, there's probably not much legal leverage on that front. But understanding the extent of any damage should be the topic to address. Is this DIY or are you handing this off to a repair shop?

Sherwood

[lindy 911]

If the engine still runs after a 200 mile trip, I suspect this is isolated to the upper end. If the spray bars were not working both cams and all the rockers would be trash. Rockers do break all by themselves. You might not be as bad off as you think. Just because the cover looks "dry" doesn't necessarily mean it is.

[snbush67]

Originally Posted by niki_west

As I was driving the oil pressure was near the top of the scale the entire time. What would the pressure be in a properly running engine?.

It should be about 1 bar per 1000 RPMs, So at 3000 RPMS it should be at 3. SO yours wasnt right, which means something was likely blocked.


If the squirterd are somhow plugged then it is understandable but If the cam squirters are damaged it is likely from when the engine was reassembled, do the test and see if they spray, if they dont then find out the cause.

[911pcars]

Originally Posted by lindy 911

If the engine still runs after a 200 mile trip, I suspect this is isolated to the upper end. If the spray bars were not working both cams and all the rockers would be trash. Rockers do break all by themselves. You might not be as bad off as you think. Just because the cover looks "dry" doesn't necessarily mean it is.

A lack of lube between rubbing parts generates much heat and wear, especially in a high load area between rocker arms and cam lobes. Valve guides will also lack adequate lube and they too might exhibit excessive wear. After a few hundred or thousand revolutions, material will have worn from those surfaces and clearances may increase beyond spec. The shorn material is steel particles, bronze in the case of valve guide material. It does not conveniently remain in the valve train area.

After examining the other engine access areas, suggest cutting open the oil filter and see what's in there.

Drain the crankcase and oil tank and see what's sticking on the magnetic drain plugs.

Take your rebuilding/refurbishing cues from the results of those inspections.

Sherwood

[niki_west]

Here are a couple pictures of the valve covers, the broken rocker and where it came from. It all looks rather dry in there. Keep in mind that I have only taken the valve covers off and have NOT cleaned anything.

[niki_west]

...and here are the views of a couple of other valves:

[Steam Driver]

From the pictures it looks to me like that there is a LOT of "dirt" in there for something that was supposed to have been worked on only 4K miles ago.