S52 - Reversed Cam Trays

[mecheng]

I posted this in the parent forum but I haven't been able to garner a response. It's a bit of a barren wasteland there.

I pulled the head off the engine I'm rebuilding and started fiddling with the tappets. From what I've read it seemed like they should all have a certain sponginess to them, but of the 24 tappets, only three of them were at all pliable. Then I took a look at the cam trays and started to think it might be possible that the last person to pull the head off (it's clearly been worked on before) replaced the trays in reverse. This would have effectively starved the tappets and cam journals of oil for however long this engine was run after the head work, but if this were the case I'd have to think there would be far more damage than I'm seeing. A couple journals are scored but nothing that would indicate catastrophic lack of lubrication... Also I'd have to think that the guy couldn't have been so inept as to overlook something so critical.

Let's assume that they were installed correctly, is there a reason I can only manipulate three of them with my fingers? Should it take more force than that to compress them?

Then let's assume the opposite is true and the guy really was completely aloof. Would there in fact be considerably more damage? Are the tappets seized? Can they be repaired or should they be replaced?

For what it's worth cylinder's 1/2/3/5/6 all passed a leak-down with flying colours, cylinder 4 flunked (60psi) and there's also no indication that the pistons and valves have been formally introduced to one another.

Cam Tray

Cam Tray Closeup

Cylinder Head Closeup

[kronus]

the cam trays have an A (for exhaust) and an E (for intake) stamped into them. which one came out of which side of your head?

it's pointless to speculate otherwise.

I was not able to compress any of my hydraulic lifters by hand, and the engine works fine assembled with them.

[mecheng]

the cam trays have an A (for exhaust) and an E (for intake) stamped into them. which one came out of which side of your head?

it's pointless to speculate otherwise.

I was not able to compress any of my hydraulic lifters by hand, and the engine works fine assembled with them.

Sure I do know they're embossed, but I didn't pay attention to which came from where until I became suspicious of the lifters. But fair point re: speculation. Perhaps my concern should instead be why three of the 24 could be compressed by hand. Thanks for your insight.

[sweet3]

Typically none of them should be able to be compressed by hand once they have oil in them. If the lifters have been bled (removed and cleaned the oil out), then yes they will be able to be compressed.
If cylinder 4 failed a leak down test, that sounds like it has a cracked head or a blown gasket.

[mecheng]

Typically none of them should be able to be compressed by hand once they have oil in them. If the lifters have been bled (removed and cleaned the oil out), then yes they will be able to be compressed.
If cylinder 4 failed a leak down test, that sounds like it has a cracked head or a blown gasket.

I've torn it down to the short block on an engine stand and there's no evidence of a blown gasket or cracked head... I'll know more once I pull out the crank and star measuring tolerances and gaps.

[M3PO]

None of the lifters should be compressible when they come out of the engine. That likely means that the check valves are stuck open which is allowing them to bleed down. If you disassemble and clean them, when you put them back together, they will be easily compressible by hand because only the spring inside will be resisting the force.

[wilholl]

I've torn it down to the short block on an engine stand and there's no evidence of a blown gasket or cracked head... I'll know more once I pull out the crank and star measuring tolerances and gaps.

sometimes the cracks are hard to see.
cylinders 3 and 4 are the usual areas for cracks, #4 is probably the most often. Look carefully!

[mecheng]

sometimes the cracks are hard to see.
cylinders 3 and 4 are the usual areas for cracks, #4 is probably the most often. Look carefully!

Shite. Okay will do, thanks for the heads up.

[M3PO]

Shite. Okay will do, thanks for the heads up.

Yep, usually from the water jacket to the valve seat. My head was cracked in that location and then repaired by the PO. It then proceeded to crack from one valve seat to another due to the welding stresses I assume.

[mecheng]

Yep, usually from the water jacket to the valve seat. My head was cracked in that location and then repaired by the PO. It then proceeded to crack from one valve seat to another due to the welding stresses I assume.

Took shots all around cylinder four's head, no sign of any cracks thank god. Makes me wonder what's going on with the rings/cylinder/piston... guess I'll have to wait until I go diving with the measuring tools.

Pic 1

Pic 2

Pic 3

Pic 4

[M3PO]

Pic 1 is where they usually crack in my experience so you are probably good to go.

[CoreyZ]

Isn't it impossible to reverse the cam trays anyway because of the thrust bearing surface on the intake cam?