Might have dodged the bullet

[Axitech]

Took a ride in the Rail last weekend to Allentown. 100 miles round trip. On the way up, oil pressure dropped to 10 psi from 40 psi all at 3200 rpm. It came back as soon as I pulled over , shut down, inspected for causes, got back in and it was normal again.
Driving away, engine seems louder somehow. Stop, inspect again. No holes, drips, no huffing from road draft tube. Babied it home, and on the way, it felt weak. Inspected again. Nothing. Still loud somehow. Cylind r leakdown test results:
1 and 2 lose less than 5%
3 and 4 total loss, no pressure held. Cannot find where it is going. A little noise in the air intake feed for that carb, no wind from road draft tube or oil fill port, slight noise in exhaust after the 4-1 merge.
Tore engine out today, took left head off and found nothing. All pushrods were not loose. I did not think to check each for loose zero correctly because I honestly thought I was going to find pistons with holes, or a head destroyed.
On disassembly, I found, after I had removed the rocker shaft, that the rocker stud near cylinder 3 had walked out. I do not know if that happened during disassembly, or if it was already like that. I do know that nut resisted more than the other.
I’m thinking the stud started backing out, cocked the rocker shaft, and held the valves open slightly.
Thoughts?

_________________
He said to them, “But now if you have a purse, take it, and also a bag; and if you don’t have a sword, sell your cloak and buy one. Luke 22:36


The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.-Thomas Jefferson

[Axitech]

Oh boy, I posted the pics before really looking at them. It appears the leak is on the bottom of both cylinders at the head.
Going back out to examine them again.
_________________
He said to them, “But now if you have a purse, take it, and also a bag; and if you don’t have a sword, sell your cloak and buy one. Luke 22:36


The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.-Thomas Jefferson

[Axitech]

I did not notice any loose head nuts on disassembly, all had resistance. How much? I did not measure it.
No damage on head or cylinders visible after a quick soak in the tank. Is it possible this was all just a need to retorque on a more frequent schedule? Engine is just over three years old, and has close to 20k miles, all highway between 3000-4000 rpms/75-85 mph.
I don’t recall the exact compression ratio, but seem to recall it was set up around 9-9.5:1.
_________________
He said to them, “But now if you have a purse, take it, and also a bag; and if you don’t have a sword, sell your cloak and buy one. Luke 22:36


The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.-Thomas Jefferson

[modok]

As the heads warp the lower studs tend to get loose.

The lower air deflector plates appear to be missing, and that may have contributed to the problem, as well as using 10mm studs..... at least that how big they look. Although, I could be wrong.

[Axitech]

10mm , yes. Deflector tins are there, I removed them to inspect.
_________________
He said to them, “But now if you have a purse, take it, and also a bag; and if you don’t have a sword, sell your cloak and buy one. Luke 22:36


The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.-Thomas Jefferson

[modok]

you removed this?

[/quote]

[67rustavenger]

[modok]

I'm just saying that you'll be more likely to LOSE torque with the 10mm studs, all else equal. The head warps or the case warps is why it loses torque, so you use a smaller stud.....it puts less force on both parts, so they should not warp as bad, and a skinnier stud acts more springy too....

But, 10mm studs should work too, and make the engine stronger, but you put more force on the heads when it gets hot. So, maybe it got too hot, maybe the heads aren't made of a good material to handle heat, or maybe they warp some initially and need a re-torque but would be ok long term. I don't know, but I think if it had 8mm studs it would have lasted a bit longer, although.....whatever the problem is it would not have SOLVED it.

[Axitech]

No problem with hijack. I was wondering about it too! Thanks Modok, for the input. I’ll try retorquing and see where that gets me.
_________________
He said to them, “But now if you have a purse, take it, and also a bag; and if you don’t have a sword, sell your cloak and buy one. Luke 22:36


The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.-Thomas Jefferson

[Axitech]

No problem with hijack. I was wondering about it too! Thanks Modok, for the input. I’ll try retorquing and see where that gets me.
_________________
He said to them, “But now if you have a purse, take it, and also a bag; and if you don’t have a sword, sell your cloak and buy one. Luke 22:36


The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.-Thomas Jefferson

[67rustavenger]

Thank you Glen. Makes sense.

Axitech, You might want to consider lapping the cylinders tops to the heads (with valve lapping compound)before installing them again.
That way you'll know for sure that you have a true sealing surface between the head and the cylinders.
I do this on fresh heads and cylinders.

Good Luck.
_________________
I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!

There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo!

[mikedjames]

I had my prevois engine come to a halt with the rocker shaft nuts both coming undone on 3/4 side. Would do about 30mph on a levle road.
In that case it sas my mistake not torqueing up the nuts.



Later....

And I can vouch for 8mm studs holding everything in place. I have an S shaped conrod and mashed cylinder head and diced piston from dropping an exhaust valve at 60mph .

The 8mm studs were still holding it all together and managed to survive bending the con rod. ...

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Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[nextgen]

That bent rod is one for the books!!!! Never thought in that direction on that side of the rod, stunned!
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[liquidrush]

When I worked at the dodge dealer I had a caravan with a 3.3 come in with a severe misfire. Low compression and I pulled a cylinder head and found a piston not coming to TDC. WTF?? Pulled the oil pan and then the rod and that sucker was bent into an S shape and the thing still ran. Turns out it got a snort of water through the air filter and hydrostatically bent the rod. This was long before phones with cameras and all but I'll never forget that thing!

[mikedjames]