Right, we're the ones that are stupid because we're the ones saying the valley/intake are connected to the crankcase. Just get out of here, it was fine here for 4 years without you spreading inaccurate information.

 

no one said the plenum wasnt a design flaw, all we have said is that its not the cause of sludge, yes it can allow anything in the crankcase to get pulled into the intake, hence the well known (documented and supported right here) issue which is diagnosed by looking down the TB for pooling oil. You are making claims about the plenum causing sludge bc it allows blow by into the crankcase. are we on the same page here?

Now the thing to remember is that blow by escapes the cylinders by getting past the rings (hence the term 'blow by'. We are on the same page still?

now how does the leaky plenum exacerbate that? answer, it doesnt, it allows the gases (which are irrelevant) to be pulled into the intake, the issues come when the oil gets pulled in and fouls plugs, as well as the extra air thats getting in which the computer doesnt know about causing the engine to run poorly.

how does burning oil and blow by (which doesnt really burn unless you are running very rich) affect sludge which is defined as a thickening of the oil?

o and BTW the PCV valve was put in to create a vacuum in the engine and pull the blow by gases through the cylinders to burn any contaminants rather than dump them on the road the way old cars used to.

we just want you to explain (which you have failed to date) how the plenum causes sludge, it doesnt allow any excess material into the oil it just causes poor running and oil consumption.

 

Your theory of improper maintenance is wrong. The factory recommended oil change interval for my '99 Dodge 3500 van is 7,500 miles and the factory recommended filter change interval is 15,000 miles. The vehicle has been maintained per factory specs.

As far as your plenum "explanation", do you not understand what the plenum is? It combines air and fuel and feeds it into the combustion chamber. When the plenum gasket leaks, oil enters the plenum, where it combines with fuel and is then either burned or recirculated in the engine. Do you know what one of the primary causes of sludge is? Fuel contaminating the engine oil. So your claim that oil being contaminated by fuel in the plenum doesn't cause problems is obviously wrong on just that one point alone.

Since you seem rather under-informed on this issue, you should read AMSOIL's expansion upon Chrysler's TSB. The plenum on my van looked like the one pictured in Figure 1.

 

That's not describing exhaust fumes getting into the crank case. You're saying oil getting into the intake, into the cylinder, and back into the crank case is causing a problem. And you're off your rocker if you're going that long on your oil and filter.

 

the intake manifold doesnt mix the air fuel mixture on MPFI engines the way it doesn on carb (or even TBI) engines, the fuel is sprayed right onto the backside of the valves limiting the area which the fuel is in (and hence the location of the oil contamination in the fuel) and allowing much better control of the a/f ration, you pull oil in and burn it when the plenum goes bad, this causes problems but not sludge, and not additional fuel getting into the system, it will foul plugs and carbon up cylinders (quite possibly leading to excessive wear from the abrasive properties) but it will not cause sludge, sludge is a thickening (increase of viscosity) of the oil, fuel dilution REDUCES the viscosity of the oil since fuel is a solvent. You also need to keep in mind that a cold engine runs rich (open loop) which causes fuel to leak past the rings into the oil, a good long run cooks this out of the oil (solvents typically evaporate at a relatively low temperature). If you need i can very likely get a Tribologist involved in this who im sure would be more than happy to correct you on your misconecptions about sludge.


yes 7500 was the recommended oil filter change on my 02 as well, however most peoples driving falls under the 'severe' driving pattern, due to short trips, idle time in traffic. If you are one of the people who gets on the highway and drives for an hour or more at a time, then you are likely fine at 7500, i have oil analysis reports from Blackstone on my 02 at ~7200 on the oil. (i dont pretend to know your driving habits, or what interval is appropriate for you, only you know those details). With modern synthetic oils you can easily go 10k miles on an oil change, mobile one is even backing 20k on their annual performance (i think) oil.

 

Real cute, that_guy. "you're off your rocker if you're going that long on your oil and filter" So you're smarter than the automotive engineers at Chrysler that devised the oil and filter change intervals for their engines. Golly geez, u iz reely, reely smart and them thar engineering doobies iz poopy heads.

In actuality, you just admitted that the engines in question have a design flaw and the factory recommended oil service intervals are inadequate. Thanks for finally admitting the truth. Of course, this means you won't get a check from Chrysler this week for your bot services.

 

I never said the engines didn't have flaws (the plenum gasket is definitely a flaw), I said what you're describing isn't possible. You're just too busy spewing **** to think it through and realize the valley is not the crank case. And for the record, yes oil analysis would indicate that the oci specified in the manual is in adequate for most people, as sharp pointed out. And maybe if your engine is sludging, it's because it's not being properly maintained. It's not because of a defect.

 

shrpstr325: I hate to quote experienced automotive engineers and lubrication engineers because you appear to have a problem with reading and/or reading comprehension, but let's try this once again. I don't know why you find this so difficult to understand: A. Plenum pan gasket leaks cause engine spark knock. B. Spark knock leads to sludge formation. C. Sludge formation leads to constricted oil passages which result in oil pressure loss.

Chrysler TSB 09-05-00: The vehicle operator may experience an engine spark knock during acceleration and/or an increase in the amount of engine oil consumed by the engine.

AMSOIL TSB MO-2005-09-30: Engines produce considerably more NOx during knocking combustion than normal combustion. The effect on motor oil is that the NOx reacts with fuel and oil condensed on combustion chamber surfaces to form hard deposits as shown in Figure 3. The photo is taken from a 1999, 5.2 L, V8, Dodge Durango. When NOx in the blow-by reach the crankcase, it will acidify the oil and react with fuel compounds absorbed in the oil. These reactions produce surface deposits and solids known as sludge.

 

That still isn't blowby getting through the plenum like you were saying. Do you have trouble speaking?

Someone as cocky as you sounds like a mustang driver. Don't you have a crowd to go run down?

 

All in the same post you went from praising the engineers and calling that_guy an idiot to, these engineers are wrong and the oil change intervals are too long.

Seriously? All throughout this thread you do nothing but contradict yourself. You say the engineers know what they're doing with oil viscosity and how Chrysler put out TSB's and everyone on this forum is so stupid compared to them, then you go and blame the engineers at Chrysler for "a design flaw and the factory recommended oil service intervals are inadequate". My Durango had been poorly maintained before I got it and I did the kegger mod and replaced the plenum with the aluminum kit from hughes and the oil valley and heads were in great shape. Yes I haven't seen in the crank case yet but I'd be willing to bet it's pretty clean down there. Chrysler does give out advice for multiple oil change intervals for both conventional and synthetic oil. Maybe, just maybe you're following the wrong one with your driving style. Regardless, a 1 ton van from this time period absolutely should have had it's oil and filter changed more regularly, unless you're constantly on the highway for long trips not towing or hauling anything. Still though, I won't go over 5,000 miles even with synthetic. Different quality of oil will also give different results.

Oh, and by the way, my Durango has 265,000 miles on it. Still had the stamped steel plenum on it 10,000 miles ago when I replaced it.

Better maintenance intervals, they're nice, you should try them sometime.