[68WarDog]

Oil pressure suddenly dropped from 50 psi to 10 psi at 900 rpm idle. Pulling the pass. VC. Idiscovered 2 broken rocker arm trunnion . Could this be the cause of this significant pressure drop?

[Firebob]

I'd say the breakage was caused by the pressure drop, not the other way round. Just a guess.

[70pontiaction]

If the trunnions broke at speed, you may have two of your lifters out of their bores laying in the lifter valley..... Not really an insignificant thing.

That WILL drop your oil pressure (don't ask how I know.....).

I'd pull that engine out and figure out exactly what happened!

Good luck!

[intense]

Originally Posted by 70pontiaction

If the trunnions broke at speed, you probably have two of your lifters out of their bores laying in the lifter valley..... Not an insignificant thing.

That WILL drop your oil pressure (don't ask how I know.....).

Good luck!

Ditto. That's what happen to me !

[68WarDog]

All this sounds interesting, but other than busted trunnions, increase lashes to approx. 0.25, yes that correct, the lifters have remained in their bores. PR appears unbent.If after replacing the 2 rockers and no affect on pressure. I will remove engine

[Firebob]

What brand and material are the rockers made from?

[STEELCITYFIREBIRD]

Interesting, on the same cylinder or two ex's or two intakes? Breaking two doesn't sound good, if push rods were still in place. Hope that's all it is.

[A.W.Dille]

Originally Posted by Firebob

What brand and material are the rockers made from?

I know the engine quite well as I have assisted 68WarDog with the build on this car for several years now. The rockers are JBP (Jim Butler) and the engine was done at a very reputable shop so I know the valve geometry was set right. This is baffling me on why this happened also. This is one sweet engine with a solid roller and idles at 750 in gear. I'm going to help change out the rockers this weekend and see what we end up with. The engine may be on it's way back out but won't know for sure until we spend the day going through everything.

[dataway]

Was it the rear cylinder on the passenger side?

[HWYSTR455]

You don't have to pull an engine if you break a rocker trunion, and if the lifters got kicked out of the bores all you have to do is pull the intake and valley pan.

It's possible that the lifters were just kicked above the galley feed by the lobes, and that would show a loss of psi. If they were kicked all the way out of the bores, the push rods would not be visible from the valve cover area. (and that's a bummer). I've seen push rods drop through the valley area and that's a bummer too.

I wasn't aware that Butler makes rocker arms, what type are they, roller tip or full roller?

You break a trunion on a full roller, full body aluminum rocker, and there was some major interference. Either coil bind, piston smacking the valve, a retainer contacting the guide/seal, or something (debris) dropping between the coils.

It's not common that happens on both valves on the same cyl, and I would be sweating the thought of the piston smacking them.

On the other hand, if they are just roller tip type stamped steel ones, they could have just fatigued, or maybe some debris went into the fulcrum area. I've seen OE 1.5 rockers on high lift cams fail this way because the slot isn't long enough too.

Personally, if they are anything but full roller, full bodied rockers arms, if you're running a solid, and/or any kind of spring psi, you need to change them up.

Take pics and post, I'm curious.

.

[61-63]

I'm curious too. What ratio were they? Aluminum or stainless? Full roller or roller tip? What was the resulting open distance and spring pressures open and closed.

I'm not making any judgements here about anything or anybody I would just like to know what happened.

[70pontiaction]

The lower oil pressure could be some debris in the oil pump bypass. That's fairly common, too.

[68WarDog]

PS VC removed and found more than 2 dozens small needle bearings laying inside the heads. Maybe from the broken trunnions? These are steel full 1.65 roller rockers with 455B markings. Anyhow the engine will be removed, and inspect check ball to see if one of those bearings are lodged in the check ball. But won't know until engine is out. Won't be using this style or brand of rockers again. Anyone familiar with them? Not 100% sure where I source them.Oh yeah,both rockers came off #4 I/E.

[68WarDog]

Unfortunately, not familiar with this new Nexus 6 phone on how to post pictures, but can send to someone to post. Thanks

[johnta1]

I would be wondering about the same cylinder having the broken parts?

Does the piston move?

Valves not stuck?

[68WarDog]

Pistons and Valve moves freely. No unusual engine noise, looked down and noticed oil pressure gauge had dropped from 50 to 10psi and immediately shut down engine.

[68WarDog]

Here's my plan. Drain oil and filter through t shirt. Remove oil filter, cut open for inspection. Then with drain plug still out, and about an hour later, as a flush , pour gallon of Marvel M oil down oil return holes ,filter it as it leaves pan. Remove engine and pull pan,keeping engine right side up to prevent any possible dislodging of particles from falling back into engine. Am I missing anything?

[STEELCITYFIREBIRD]

A leakdown test or simply putting compressed air into that cylinder, and listening for leaks .
Checking the height of the valve stems compared to their neighboring cylinder should give an indication if there is a valve or seat problem or foreign object present. Dropped seat or pulled valve head, depending on if taller or shorter height
On the other side of the rocker, you possibly could have a damaged lifter.
I think you ran out of lash to break the rocker/s pivots. Therefore i'd bet the problem is in the valves/seats.
No broken valve spring/s?

I'd pull the engine intact, wouldn't try to "flush" engine blindly.

[61-63]

Originally Posted by 68WarDog

Here's my plan. Drain oil and filter through t shirt. Remove oil filter, cut open for inspection. Then with drain plug still out, and about an hour later, as a flush , pour gallon of Marvel M oil down oil return holes ,filter it as it leaves pan. Remove engine and pull pan,keeping engine right side up to prevent any possible dislodging of particles from falling back into engine. Am I missing anything?

The only thing I would say is that if you get a lot of trash in the "t" shirt as you drain the oil through it, or you find fine stuff in the pan, the only way you are going to get all of it out of all of the oil galleries is to tear the engine down completely, including removing the gallery plugs, and blow/wash/clean them all out with gallery brushes.

[HWYSTR455]

Dang. Needle bearings, yeah, I would have to say a teardown and cleanup is the safest approach. You might be able to clean it up to reduce enough risk without a teardown, but there will still be a risk.

If you're pulling the engine, teardown is a logical step.

Lemme guess, these are PRW rockers? If so, that would be the second time I've heard of failures. You need to take a pic or check the docs from the builder to see exactly what they are, so all know for sure. For situational awareness.

If the pushrod didn't bend, I would probably rule out loss of clearance, and lean more towards a rocker failure/defect.

.