dyeager535

Borke a rocker stud while driving. (approx. 1000 miles on engine rebuild, no problems noted before this incident) About 10 minutes after knowing something broke, engine started to smoke white out of passenger side bank, but not immediately after I knew something was wrong. Got gradually worse and worse.

Pull plug wires on cylinders 2 and 4, after I park it, no change in (bad) idle quality. Indicates cylinders are dead.

Start truck again after work, tapping sound from valve cover (didn't know problem at time) but idle is better, no smoke, and pulling wires from 2 or 4 result in decreased idle quality.

Pull valve cover, find broken rocker. on #6 exhaust.

Yesterday got the intake off, no lifter damage, no pushrod damage. However, in runners 2 and 4, I see oil weeping out of the PCV(?) "feed" holes in the base "runners". Got worse when I turned it over. The oil is very clean, just like it came from the crankcase. PCV didn't seem to be overly full of oil, but there can't be any other way for it to get into the intake where it was "weeping" from.

Only other indication something was wrong (perhaps?) is that the runner to base gasket on the 2-4 runners is black, soaked with (I assume) oil. Doesn't smell of fuel. Not sure if that is normal or not, have never pulled a TPI engine apart before. Can anyone comment on 2-4 gasket getting soaked due to PCV being "normal", which is fed there? The 3 other gaskets look brand new, bone dry.

The amount of oil I saw "weeping" was quite small, would anyone expect that to be a normal occurrence?? I just don't know how the bases are cast, perhaps the PCV "oil" puddles inside, and perhaps it doesn't see enough heat to burn the oil like other applications I see coated in burnt oil after many years. (or perhaps the burnt look just comes from age and dark oil?)

I just don't see the correlation between the #6 exhaust valve being shut, oil in the runners in the base, temporarily dead cylinders 2 and 4, and smoke only when cylinders 2 and 4 were dead, but not when engine had time to cool off.

Pulling the heads today or tomorrow, but I don't expect to find anything more than I already know. Hope not anyway!

Auggie

Let us know what you find??

Auggie

dyeager535

Well, if you are still reading this!

I screwed up on my initial diagnosis. Since the valves switch position on the back to cylinders (exhaust/intake vs. intake/exhaust) I mixed them up when the thing was still together. I actually broke the intake valve stud.

Machinist said he's never seen one break like that, it is actually a cone shaped break. The piece that broke off is basically hollowed out, that metal is stil attached to the stud. Imagine the stud looks like a sharpened pencil now. Since he said he's never seen it before, I hope that means its a fluke.

Anyways, now that I know it was an intake valve, some of it makes more sense.

Upon head removal, cylinder 6 was "full" of black oil. Not full, but there shouldn't be any, and there was a fairly good sized puddle in the cylinder. No scratches on cylinder wall all the way to the bottom, so hopefully no other damage was caused.

Since the intake valve never opened, it created extreme suction in the cylinder, so thats why the oil was puddled in the cylinder. Not sure how to explain the oil in the other runners though.

Also noticed on disassembly there was STILL (week later) a very large quantity of gas behind the intake valve in the port.

At this point I'm thinking the white smoke may have been oil just being pushed into the exhaust raw from cylinder #6 and "fogging" when it hit the warmer header metal down at the collector, perhaps combined with the overly rich mixture, which the ECM told me awhile after the stud broke.

Most of the plugs were very black with a coating of carbon, which luckily I could just wipe off. I'm sure that was the fuel from #6 being "sucked" back into the plenum and screwing all the other cylinders up.

Edit: Since many posts don't get closure, here it is for this one. Reinstalled the heads (ARP screwed in studs now) and no problems at all. So definitely all problems from broken stud on the one cylinder. Of course then I blew the rear axle up and broke the driveshaft.

Auggie

Man what a deal. Thanks for the end of the story, I hope.

Auggie