A little four cylinder eye candy (of sorts)

[86rocco]

A friend of mine trashed his big buck Esslinger 2.3L racing head. One of the rocker arms came out jammed up under the cam resulting in all four cam towers breaking. We're at bit of a loss to figure out the chain of events that lead to this happening.

Esslinger head.jpg

[Hotz]

Incredible, the next cylinder head will have to be strengthened with plate screws is to strengthen

[86rocco]

I don't think lack of strength was the problem. There was some sort of failure in the valve train, all 8 valves had made contact with the pistons that contact almost certainly caused the rocker arm to dislodge which in turn caused all of the other damage. The fact that all the valves made contact suggests that there was a timing issue but there was no evidence to suggest that the timing belt had skipped a tooth, the only other thing we can think of that could have cause the valve/piston contact was that the hydraulic lifters pumped up holding the valves off the seats at TDC. The cylinder head was fairly new, all of the valve train parts were spec'd out and supplied by Esslinger, the engine was operated within design specs, oil pressure was in the normal range, the engine performed very well right up to the point of failure so what set this unfortunate chain of events into motion is, as yet, still a mystery.

[Hotz]

Maybe over rpm, (Fluctuation) may be the main reason, the set remained synchronized but the valves had their time changed. (ripple effect)

Or maybe the problem relief valve oil pump, (much oil pressure) hindering the work of the hydraulic lifter.

I believe it is the best explanation for the problem.

The Camshafts broke into many chunks?

[jfholm]

Whatever it was, it is heart breaking at best.

[86rocco]

It wasn't over revved. Excess oil pressure is something we've considered, if that's what it was, it's an intermittent problem, we put another head on the block, it fired up okay, the pressure seems normal but closer

Amazingly, the camshaft appears to have survived in tact except for a couple small nick that will polish out. It's steel billet cam so its very tough however we do still need to double check and make sure it's not bent.

[ivanhoew]

rocco , is it feasible to machine down the pillars ,and bolt on new towers and then line bore it all to reuse the head?

[86rocco]

It might be possible to repair the casting with either bolt on or weld on replacement towers, it's most likely however we'll end up just replacing it instead.

[John]

I have been running a supercharged 2.3 in a mini-mod pulling tractor for years and have always suspected that the hydraulic lifters were pumping up and causing the valves to stay open long enough to cause a backfire. This confirms that suspicion to me at least. It would be interesting to try solid lifters.

John

[86rocco]

We've got considerable experience with hydraulic lifters in 2.3L racing heads, we've never had something this extreme happen before. Usually if you got anti-pump up lifters and valve springs with adequate seat pressure the valve train is reliable up to at least 8000 rpm.