Morning everyone and happy Friday!!

I've read quite a few posts about plenum leaks but I wanted to ask a little more detailed question on the topic.

I haven't recently noticed any of the following (I'm simply doing a major tune up and want to do everything necessary):

[ul][*]no noticeable drop in mileage recently, just not that great in the first place (12.7 mpg hwy/city mix)[*]no smoking other than an occasional grey puff at startup then no smoke afterward[*]no recent decrease in performance[/ul]It does however seem to burn a fair amount of oil.

Last night I took the air intake tube off the TB and looked at the butterfly (caked with dirty thick oil), Opened the butterfly and shined a flashlight down in, the entire bottom inside the IM was also caked with dirty oily residue BUT didn't see "pooling" as described in other threads. Just the dirty oily residue like you might see on your lawnmower motor.[8D]

SO the question is, does this seem indicative of a plenum leak?

 

heres another test.....( the PCV on my truck is passenger side... so... if yours is on the otherside.. just do the test as described..)
Take the vacuum hose off the passenger side of the intake that goes to your PCV... block it with a bolt or something... tape off or cap the port you just took it off of... now pull the breather hose that runs from your driver side valve cover to your airbox...off the air box...still connected to the valve cover...with the truck running..see if your getting a strong suction on the hose from the breather... if so.. its anothersign your plenum may be leaking... it was explained to me that the amount of suction here should be minimal.. or as it was put.. the vacuum should almost be neutral...You could take off the TB... ( about 15 minutes work...replace the gasket!!and a great chance to clean it and the sensors..) and get a better view of your plenum and intake.. I could actually see the blown gasket hanging inside.. mine was blown in three places...now... if your burning alot of oil... this doesnt mean your plenum is gone.. in fact.. you may have a bad blow-by problem which would mean oil getting blown into the intake past the valves I believe. I have been told thatheavy carbon build up could cause this... bad rings.... but... look at one thing at a time... check the plenum...mine was losing oil with nothing dripping on the ground.. and I couldnt see it burning in the exhaust....once I got the plenum off... it was no wonder. Let us know what you find!

 

hmm yeah if its caked with oil.. good sign of a leak,, I cehcked mine and didnt see anything cept for a slight film that I couldnt be positive was oil, since I could see the steel bottem..

 

Great info thanks for the help, I'll go check it here in a little while and let you know. Lord I hope I don't have bad rings...[:@]

I am leaving work early today and doing a TON of tuneup stuff to the truck the rest of today and all weekend which includes the TB, TPS, cleaning etc. etc. so we'll see. I'm just trying to identify if I DO have a plenum leak because that's probably the first task if it is...

I don't think I have the money to get that aftermarket plate so I might have to just get a gasket... Do you guys know if the autoparts stores typically cary that gasket or is it a Stealership item?

 

Everyones got them... you have choices.. I hear the Fel-pro set is really good..Victor Rheinz are good too.If your going to do the plenum.. your going to need..
All the intake gaskets... lower..( intake to head, and across the valley.. ) and the upper.. ( plenum..) you'll need a TB gasket,
You MUST replace the intake bolts..they are Tighten to Yeild bolts so one time use only..
might be a good time to do the valve cover gaskets too but its not necessary..in fact.. if funds allow.. since your gonna be that deep into it.. its a good time to do some preventative replacements.. I just did mine last week.. went ahead and did the timing chain, water pump, plenum, valve covers.. T-stat..bypass hose....( water pump? bypass hose for sure... its only a few bucks and you cant get to that sucker without taking all the brackets and alt and AC stuff so go ahead and change it... Thermostat too if you can swing it... 9 bucks maybe?? You get the idea...)I can give you a good list.. and theres a great DIY here that helped me a ton!.

 

Yeah, if you have a list that would be nice. I already have a big list of crap I'm doing but you mentioned a few things I hadn't thought of so yeah if you have it handy that would help a lot.

Most of what I'm doing to it I have printed or linked to on this forum for the DIY's (BIG help).

I probably will take the Valve covers off anyway I was thinking of powder coating them. I do powder coating...

 

Man.. have GOT to talk!!!!I was going to have mine powder coated.. but needed to get this thing back together.. I'll post a pic of the motor....my valve covers are black and the air cleaner is too.. cast aluminum...I want them done so we need to talk...
I think the plenum repair DIY has a list... you need to tell me what you want to do.. or should I say.. how much... plenum, water pump? T-stat? bypass.. ( I really think this is a MUST..) Valve cover gaskets... if you want... PM me with a list of things you want or can afford to do.. I'll help ya out...

[IMG]local://upfiles/84062/92469E22383A449C8BE7261CA7157FDD.jpg[/IMG]

 

PM sent

 

Ok guys and "Blaydrnnnr", so I was completely wrong, I just got the TB off and the bottom inside there is actually completely clean from what I can see...

I can't see so well back up toward the front of the IM but toward the back of it I only saw one little bit of oil, litterally 2 drops worth.

I'm starting to think my plenum is ok at this point.

The other question is, I do see where the oil is coming from and it's from the breather tube from the valve cover because there is some residue inside where the nipple come in to the airhat. I assume that is a little bit of blow-by correct? I assume it's ok to have a little of that right?

 

A little blow-by, a little bit worn engine - you probably have some high miles, huh. you can keep on going till you kill it.
from the prevalence of problems heard from owners all the time on this forum, it almost sounds like a good idea to "fix" the plenum even though you don't obvious evidence of failure? your call.