Oil Consumption Mystery Solved!

[Trudy Carp]

Along with the other problems I've been having, excessive oil consumption was a huge issue. Well, Keith at Denver Isuzu is a god! He told me to replace the egr tube, asap! It seems that when this little ditty gets carboned up inside it begins to restrict flow. This pressurizes the crankcase and pushes oil past the rings and pcv valve in minute amounts so it's burned off.
This starts a chain reaction, the more burnt oil in the exhaust the more carbon deposits build and restrict the tube. By the time you start noticing a little exhaust smoke, she's already in trouble and can't breath. He says it's pretty common for 99-02 3.5 blown engines to have a solidly blocked egr tube and an empty crankcase. Every engine replacement gets a new egr tube.
The average person would never link this tube to oil consumption, thinking the pcv system is the problem because that's it's job. A new tube is the easiest way to deal with it, especially if you have over 25k miles and this has never been cleaned out or replaced. Mines not totally blocked, but just enough. My new tube is on order and I'll keep you posted on the results once it's replaced. Hope this helps the rest of you that have been driven nuts trying to solve this and maybe save a few engines out there.

[johnnyapollo]

Supercharged engines get a new EGR tube and I haven't noticed any change in oil consumption since the SC was installed.

-- John

[Ldub]

Supercharged engines get a new EGR tube and I haven't noticed any change in oil consumption since the SC was installed.

-- John

Trudy, correct me if I'm wrong, but did you mean the EGR tube from the exhaust to the EGR ?

Or the one from the EGR to the manifold.

[tom4bren]

Can you post the part number for that tube. Better yet, can you get the mechanic to point to it for you so you can take a picture & post it for us?

[nfpgasmask]

Yeah, I would be interested in testing this also. My VX drinks lots of oil.

Bart

[tom4bren]

Page 6A-29 of the shop manual shows the EGR Pipe. I assume that is what is being replaced.

I'm due for an oil change. I'll see if I can check/clean it then.

[nfpgasmask]

Yeah, would it be easier to clean it or replace it?

Bart

[circmand]

Great work apparently not all Isuzu mechanics suck It seems this is the kind of thing they would have made known a little wider when they found it out.

[biju]

Along with the other problems I've been having, excessive oil consumption was a huge issue. Well, Keith at Denver Isuzu is a god!

Hi Trudy.

Yes, Keith is a nice guy. He services the Axiom now and again as the regular mechanic (Import Specialists) don't have a computer that can 'chat' with it.

Glad your EGR fix seems to work. For now.

What I mean is, keep us posted with a more longer term update.

I myself - well, I have seem to have luck by simply having my EGR system & Throttle body *cleaned* out every 15k and don't seem to have any measurable build-up or oil consumption.

Again - keep us posted. See you around the area!

-biju.

[autox-racer]

Well I opened my PVC to atmosphere and blocked EGR with a plate and still had oil consumption. I ran like this for a year so I am not convinced the tube is the issue. I think it is the oil ring/piston issue.

[ZEUS]

Yeah, I think the title of this thread will end up being changed - or should be. I'm not convinced either. Def. worth a look though!

[blacksambo]

Where is Tone on this EGR issue? He always seems to speak common sense.

[Trudy Carp]

I was so excited to here that an Isuzu dealer actually knew how to properly deal with VX issues, I wasn't totally clear on how this happens, left out a detail.
The egr restriction causes the computer to slightly richen up the the fuel mixture. This washs out the rings and the oil becomes slightly deluted with fuel. This also contributes to pcv restriction within the lines. Denver Isuzu charges $208 to run a special chemical cleaner through the system to clear the tube and all the lines. The gas in the oil slowly damages the bearings. Since the computer made the adjustment, you may only see an intermitant check engine light in response.

[Trudy Carp]

I must start by apologizing for the errors in the explanation for how the Egr tube started it all. This was originally spread out on 5 pieces of Post it notes and after many interuptions, it still took me half an afternoon to finish the post. I called Keith for a clarification.
Once a small amount of carbon starts building on the inside of this tube, the computer reads it's effect on flow and riches up the fuel. This washes out the rings and small amounts of raw gas begin to contaminate your oil, bearings don't like this. After a short while, combustion gases start getting past the rings placing more crankcase pressure on the pcv system, sucking gas diluted oil up into the intake to further add to the carbon buildup in the tube and confuse the computer. ( ever have an intermittant CEL that kept insisting the upstream oxy's were a problem?) It was not the egr tube that would be plugged on blown motors, it was the pcv valve and lines. The fuel contaminated/low oil conditions damaged the rings. Mine is scheduled for this service and I will share my results.

[Bieredalsace]

I was wondering where the 12 qts of oil went before my engine seized on the interstate. Sumunabeech! Well I have a 2001 engine in the VX now and hope I don't have that EGR problem again.
Thanks for solving the mystery!!