He'd have to tear the block down to do NDT of the bores anyway, which would leave the bare block light enough to fling into the bed of another truck.

This stuff is easy if someone else is doing it!

 

Could be a major concern as in a cracked cylinder wall which, I've seen twice. To test it, you'd need the heads back on and by running pressure into the coolant system and rotating the engine by hand very slowly, you'd see that leaking like an SOB thus shooting out of the spark plug hole in fact. The reverse also works - sometimes. Remove the plug of the suspected cyl and attach compression to a spark plug adapter and thread it in by hand. Run the compressor and watch the radiator for bubbles. Again ROTATE the engine slowly, very slowly by hand and, when that piston comes down below the crack, there she blows!

Some were a pain to track down as it only happened when the engine was hot vs. cold. so, sometimes, testing it shows nothing when cold or warm. Hot and, it will open up and start leaking. However, you'd know if you had a coolant leak as you'd be blowing through it like mad and / or , you'd also smell and see it coming out the exhaust as well.

But, rust is NOT normal on the inner combustion chamber walls. They are normally shiny. If there's rust, that means that something is oxidizing inside the chamber and, for that to occur, that only means one thing- in the presence of water. Rust stains are a result of cast iron particulates being driven into the combustion chamber from the leak / weep area.

Sounds like you've got more going on there than meets the eye. If there's a crack there, that will also create another issue with compression. On the compression cycle, that forces the fuel mixture and air into the cooling system, depending on how much it opens up when hot.

Platinum plugs should not be used on these trucks and, if it wasn't mentioned before, it should be now.

Now, one other thing is that - you can also have a bad coil or coil driver CKT that will throw the same exact codes and cause the same exact running conditions (minus the oil/fouled plugs.) Now, if the plugs were wet, it also could have been gas instead of oil which, would have been a result of a bad coil or coil CKT.

But, since your 100% sure it's motor oil and NOT fuel, then, our failure mode changes from electrical to mechanical failure of either something in the valve train / head or, at the piston level.

Now, since you've got decent compression all the way around minus No 8, it is quite common with a CAT that is clogged to burn out the exhaust valve on cyl No 8 thus, no compression. The intake valve is usually over-heated as well thus the need to replace both.

Now, Magnum heads, in general are notorious for dry cracks and, depending on where the cracks are, it will suck oil from the oil passages, valve guides etc. Then, we have valve seat cracks, chipped valves, etc, etc, that also cause the same thing.

I would first have the block dyed and tested for cracks. No sense dumping money into a bad block.

Now, what comes to mind is, we've got one cylinder that's funky but, the rest were fine. Now, it was stated that there were MULTIPLE misfires on many cyls. This leads me to believe that an electrical failure may need to be factored in as a possible failure mode. When one starts seeing multiple misfires across all cyls or, on both banks, something that feeds the system is most likely faulting and, usually it's either the fuel pump or coil / coil CKT. Now, if it's just one bank, this can be the result of a bad ground at the head. Just another possible failure mode.

The probability that all of a sudden, all cyls are fouling out due to oil is highly unlikely, (unless you had a failed intake gasket or, the wrong one was put on, or, it was not installed correctly) and, that oil that you see on the plugs would otherwise, be burned off IF it was firing under normal conditions.

It is possible to have NO IGNITION at the cylinder level thus leaving the oil from the compression stroke along with fuel on the plug. Some oil is always going to be evident on a non-firing cylinder. Not too much, but, there will be some.

Now, if it's totally covered in oil, then that's another issue due to either a valve-train, ring or, as stated above, an intake gasket issue thus sucking in oil around the perimeter into the intake port thus, the reason for not showing up in the runners.

CM

 

All parts for reassembly on there way, Now for some more questions.

1.Head-gaskets cleaned off block, any type of cleaner to be used aside from just scraping gasket off?
2.any type of bolt conditioner go on head bolts or just dry?
3.are there torque/specs somewhere here on DodgeForums.com?
4.if i could get the cat. off i wouldn't have to ask this.... if it was clogged, how would i know for sure? After my original plenum fix I went from 12mpg to 14.9-thinking that was pretty good for a 4x4 [I assumed the cat was ok]


Thanks to all contributors....again

 

Make sure the gasket surfaces are CLEAN. The least bit of residue will ensure you get to do it again.

I just put 'em in dry, or maybe with a bit of oil. On the GM motors that I have done, bolts that go into the cooling jackets get a bit of permatex on 'em.

Torque specs should be in the shop manual that you can download in the FAQ section.

Clogged cat generally shows itself as reduced power, engine won't go over a progressively lower RPM (as the cat gets more plugged...). I have a pressure gauge that I use, just drill a small hole in the pipe before the cat, stick the gauge port in there, and start the engine. Anything over about 2lbs pressure is considered "bad". I know not everyone has one of those.......

 

Looked around the FAQs and didn't see any service manuals...search didn't get any hits either.

 

Service manual PDF download.

 

unbolt your exhaust at the "y" pipe where it meets the manifold, theres 2 bolts on each bank and if it starts running smoother after that, then you have a bad cat, personally my cat was good, but due to the highly restrictive nature, and clog prone design, i opted to cut it out anyways. if you have a pre '98 you have the dual 2" inlet single 2.5" outlet cat, post '98 ('98-'01) you have a single 3" inlet single 2.5" outlet cat.


from your pics of the head, it looks like both intake and exhaust valves have chunks missing out of them, and as far as the rust patch goes, that could be cause by coolant seeping into the cyl. from that chipped valve, and its possible that it took out a portion of coolant passage in the head as well. I would deffinatley consider going to some edlebrock heads as oppsoed to the magnum heads.

 

I'll give ur cat test a try once i'm up and running.....it never threw any codes but that plenum was leaking at least a couple years.
#8 had the cracked exhaust valve. #6 cylinder wall had the "spot" on it...the #6 in-tank valve had a build up on it that made me suspect of a coolant leak....but it was my best compression cyl. @ 150.

 

Took 4 1/2 hrs [dialup here] but, it's just what I needed

 

omg i didnt think dial up exsisted anymore. lol.