UPDATE:

Replaced plenum yesterday, still pinging. Now sure that it's not the cause, but I can't figure out how that much oil got in the intake. There was A LOT of oil in the plenum, too much. Made me wonder about the PCV valve, but I took it out and shook it and the valve inside still clicky-clacked. Sprayed it out with carb cleaner just to be sure.

I do have some questions about the intake manifold integrity I'd like to run by some folks.

I'm gonna post up a few pics, sorry if you're bandwith challenged:

First 3 pics are the plenum pan after I pulled it. Oil is clean as I just changed it: Notice that the oil got underneath the gasket, the gasket didn't blow. Almost like the bolts backed out, but that shouldn't have happened as they had threadlocker on them. They we just as tight as the others when I "broke" them backing them out. Second pic is a side view, I didn't move the pan, just the camera angle. You can see it started leaking about mid pan and moved backward. Third pic is the gasket removed and you can clearly see whree there was oil underneath gasket along the rear seams.







Next photo is the inside of the plenum. The oil is much darker and dirtier, which made me think it came from the PCV as that blowby would be dirtier mixing with exhaust gases, but there's just so much oil for blowby! That made me think the PCV is bad as that the only way dirty oil could get back into intake if the rear plenum pan oil leak was clean.



Last pic is some metal separation happening in the keg. I don't know if you can see it from the pic, but the cracking isn't visible at all on the fuel injector side, but there is a ton of metal separation on the runner side. The cracking is so unfiorm and similiar that it makes me think the pan was built in sections and welded together in segments. Also, not all the runners are separated that badly. Anybody ever seen this before?




Any help on what my issue could be at this point would be greatly appreciated.

Here's what I've got going thusfar:

- Engine won't ping cold, will ping hot. So I'm guessing it's not timing related.
- The 180* t-stat did let me set into the throttle a little more before it pinged than the 195* t stat. I cannot run a 180* without getting a CEL, I've tried all week and I get one every morning.
- plenum gasket is brand new.
- Have done a complete tune up and verified that all ignition system components are in good working order.
- coolant leaking issues have been resolved. Small leak in lower hose and freeze plug were fixed. No apparent leaks but I will continue to monitor.
- no visible signs of coolant/oil mixing. Will monitor oil consumption closely now that plenum gasket is replaced.
- I have pics of the cylinder heads' intake chambers and they were pretty darn clean, down to bare, clean iron. Don't think carbon build up is a problem.

Help at this point is needed. I am going to pull the front O2 sensor and inspect and spray off with electric parts cleaner, but I'm not hopeful this is the cause.

What's next? head gasket leak? cracked head? broken oil control ring? Mechanic doesn't think its a bent valve as the idle is too smooth. It might be head pulling time.

 

what runners are those? (#'s)

edit... looking @ it again it looks like #'s 5 & 7 correct?

Do you have 2 cats, 1 coming off each e-mani? If so... you may have a cat that is clogged which may have contributed to the cracks.

My 2000 5.9 motor had both cats clogged, passenger side inlet temps were > 700*, driver side > *650. the PS #8 cylinder lost it's exhaust valve seal and I had no compression in it. I suspect that those cylinders are leaking on the intake side which may be causing your ping. those cracks are definately not right.

 

and what is that blue goop on the gasket? If it is sealant, it is not applied correctly... you need to form a bead around all bolts as well... there should be no breaks in the bead. also, did you apply the sealant @ the corners of the intake?

and why are there numbers on the plate? (seems odd).

 

Steve, those are the forward most runners (#1 and 3) that appear cracked. You can see the fuel rail test port upside down (signifying driver's side), but there's not the curve in the back of the intake for the distributor, plus there's no bolt hole at the bend where it is on the #7 runner. Very strange I know. Never seen anything like it.

There is only 1 cat on the truck, The exhaust mani's have been replaced with Gibson headers that go straight to the y pipe to the one cat. It's not a Cali emissions truck. I double checked that when I had the cat replaced and when I pull the exhaust manis to add the headers.

That "Blue Goop" is actually impregnated into the plenum gasket. That's what I PM'ed you. The gasket came from Felpro that way. The new one had no such blue filler, just a flat black gasket.

The numbers on the plate are whatever the aluminum was stamped with. You know, like they stamp lumber when you buy it. Just printing on the aluminum, (probably grade, gauge, thickness, etc.) It came from Hughes with that on it.

I have some more pics of the inside of the cylinder heads intake runners I want you to see. They look as though I'm missing head gasket and that might be the big problem. I want you to take a looksy in a minute and tell me. Let me upload them....

 

Here's some pics of the head intake runners. It appears as though maybe there is some headgasket material missing but IDK for sure. I'm not sure how far the head gasket runs under the head. I know the heads hang over the actual engine block quite a bit and basically support the intake manifold. I wish I had moved the pillowcase further down. I didn't notice this when I was working on it, but the camera flash illuminated the area much better than I could see.

 

OK, my bad for assuming the test port was @ the rear like mine. what I said does not apply then if its # 1 & 3. the head gasket in that area is normal, the head gasket is pretty tough.

leme take a minute to re-read what you've done...

 

are you at the stock gap? I dont remember what that is...

When you checked the vacuum, was it steady? is it still steady?

edit: and did you flush the fuel rail?

and also worth mentioning... Gary (IIRC... VW&Dodge) had an issue with his fuel sync related to the dist. that was yanked during a rebuild. IIRC when he had it set correctly it fixed his problem. I dont remember his exact problem as it was over a year ago but I do remember going thru a lot of debugging steps on it and it was determined that his fuel sync was off. Again, I dont remember what his exact problem was... I do a search and see if I can find the thread... Is it possible your distributor is loose or your cam sensor is loose?

 

here is the thread I mentioned... his problem was not pinging, it may be worth reading it anyways...


https://dodgeforum.com/forum/showthr...el+sync&page=3

 

disty was tight yesterday when I was working on it. I grabbed it and twisted to verify when I had the intake off.

I did clean the O2 about an hour ago and saw a ring of black carbon on the bottom. Cleaned it and reinserted it. Banged on the cat while I was under there and heard a buzzy rattle, like the last time the magnaflow cat failed, except this time wasn't as loud.

Took it out and romped on it hard to get the cat nice and hot. Stopped by the local park and got out to smell the exhaust, smelled weird. Not exactly like fireworks, but something not right. I'll take it to the exhaust shop this week (hopefully Wednesday) and get it checked out.

 

stock gap is .040 I'm running .045 with an MSD ignition. Previous tests have been more than fine with that spark gap.

Vac was steady at 21inches at idle. I've been a little confused on this, as the FSM states that a plenum leak actually increases vac, but several members here have state you lose vac with a plenum leak.

Fuel rail was squeaky clean, as were the heads due to the amount of cleaner I've run through it.

I'll check into the fuel sync as well. What's the ideal, +4?