Oil Consumption Mystery Solved!

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08/30/2007, 11:14 AM
Trudy Carp

Oil Consumption Mystery Solved!

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.
08/30/2007, 11:20 AM
johnnyapollo

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

-- John
08/30/2007, 11:23 AM
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?
08/30/2007, 12:10 PM
nfpgasmask

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

Bart
08/30/2007, 12:15 PM
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.
08/30/2007, 12:26 PM
nfpgasmask

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

Bart
08/30/2007, 12:32 PM
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.
08/30/2007, 12:34 PM
Ldub

Quote:

Originally Posted by johnnyapollo

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. :confused:
08/30/2007, 02:15 PM
Zorak

This is certainly not unique to the VX, or even Isuzu. Try googling "egr oil consumption" and see how many links you get. There seems to be a belief out there that malfunctiooning EGR and oil consumption are related, but I was not able to find any explanation of how... :confused:
08/30/2007, 03:04 PM
biju

Quote:

Originally Posted by 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!

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.
08/30/2007, 03:37 PM
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.
08/30/2007, 04:15 PM
Bieredalsace

So thats where all the oil went!

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!!
08/30/2007, 04:18 PM
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!
08/30/2007, 04:40 PM
blacksambo

Where is Tone on this EGR issue? He always seems to speak common sense.
08/31/2007, 04:00 PM
Trudy Carp

Clarification on the process

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.
08/31/2007, 08:34 PM
IndianaVX

before my vx threw the belt, i was looking at different instrument "snakes" , and rifle cleaning brushes, just for the purpose we are talking about, cleaning that tube......if its the same one im thinking about, you can see the end of it in the throat of the trottle body. 7.62 seemed a little too tight, and i didnt go real deep at all. plus i think there is a bend or two in there, so thats why i was thinking about an trumpet or french horn snake. these snakes are like a tightly wound spring, thats kinda stiff, but will go thru tubing and corners and such, and they have a stiff NYLON brush on each end. the whole snake thing is about 3 feet long. feed thru the throttle body, come out at the egr? my idea was cut short, and still have the stuff, but not the vx to work on.
i had also been using sea foam deep creep spray down that tube, as it breaks up carbon making it easy to scrub away, but i dont know how well a nylon brush would hold up with the spray. if it would melt the plastic, also why i was looking at the rifle bore brushes.
sitting here thinking aobut this, i wonder, if after soaking the tube in deep creep, and letting it soak for a bit.....if the "right brush" could be tied to a light, yet strong string, then, feeding that string into the tube in the trottle body. attach a shop vac at the egr, suck the string thru the tube, and out the egr, shut off vac, and pull the brush up thru the tubing, and repeat. dont know, wish i could try that one out. sigh

well, ill quit rambiling, but i know that tube is always dirty on mine, and when i clean my egr, i always cleaned that tube best that i could,but i never felt like it was the best cleaning that could be done.............
09/01/2007, 08:56 AM
UtahVXer

Check out this EGR "How to "

This link has been posted a few times before; maybe it should be referenced permanently somewhere, since it is a common persistent issue.
http://isuzufaq.ibctech.ca/#faq1
09/01/2007, 06:55 PM
Trudy Carp

Clarification!

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.
09/01/2007, 07:19 PM
etlsport

quick way to check on whether or not this is happening to you would be getting your oil tested... http://www.blackstone-labs.com/

i had mine tested not too long ago... no abnormal traces of fuel found in my oil.. i burn about 1 qt every 3k
09/02/2007, 06:52 AM
Ldub

Quote:

Originally Posted by 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.

What's the point of getting the EGR tube serviced if the rings are, as you say, damaged? :confused:
09/06/2007, 03:31 PM
Trudy Carp

Results of egr clean

It has improved the way she runs, better smoother take off. Still plan a set of plugs this weekend. I can read my oil dipstick better. Oil was so diluted, the dipstick just looked wet top to bottom, couldn't establish a level. Now, after a week on this oil change, the oil is thicker and you can easily determine the level. Still doesn't smell of fuel, yet.

Bottom line, not all of us will be lucky enough to avoid a blown engine in spite of the egr service. I'm sure, in a lot of cases, it'll be "too little, too late". I fully expect mine to go bang. It was pretty bad, you could smell fuel on the dipstick 1000 miles after a fresh change. I'm thinking I already have the beginings of bearing damage and am debating getting the bearings replaced while I still have a good motor to do it to. Waiting till she blowns doesn't leave you much to work with.

Hope some of you had low enough miles to take advantage of this info and plan regular servicing of the egr system.
09/06/2007, 07:38 PM
blacksambo

For whatever it's worth I queried my dealer about egr service and they stated unequivocally that there was no such thing. Yes, they advised leaving the whole thing alone and that in many years of Isuzu service they never have touched or replaced one. This seems funny versus all the wisdom expressing behavior to the contrary on this site, but so far both our '99's have never been touched in 100K miles???
09/07/2007, 06:27 AM
JHarris1385

Quote:

Originally Posted by Trudy Carp

I can read my oil dipstick better. Oil was so diluted, the dipstick just looked wet top to bottom, couldn't establish a level. Now, after a week on this oil change, the oil is thicker and you can easily determine the level.

HUMMMMM..........maybe this is my problem
I have NEVER been able to determine the level of my oil and could not figure out why. The dipstick looks wet 3/4 of the way up the whole stick with thin oil residue. SH1t something else to fix on it.
09/07/2007, 08:48 AM
nfpgasmask

That's really weird. Are you sure you are not overfilling? I change my oil every 3000 with Mobile-1 10W. After I change my oil, the oil is so clean it is hard to see on the dipstick, but you can certainly see a line going horizontally across the stick marking the level. After about 2000 or so miles, my oil begins to blacken, making the level very easy to detect. I have never noticed a gasoline smell on my dipstick. I will have to take a closer sniff next time I am under there.

My VX takes exactly one 5 quart jug of oil to fill her up. I burn oil pretty regularly as well. In between oil changes I probably will add at least a quart, maybe a quart and a half, depending on how hard I drive. I change my PCV almost every time I change my oil as well. I have no CELs and my VX runs good. I still worry however.

Bart

Quote:

Originally Posted by JHarris1385

HUMMMMM..........maybe this is my problem
I have NEVER been able to determine the level of my oil and could not figure out why. The dipstick looks wet 3/4 of the way up the whole stick with thin oil residue. SH1t something else to fix on it.
09/07/2007, 10:03 AM
JHarris1385

Quote:

Originally Posted by nfpgasmask

That's really weird. Are you sure you are not overfilling? I change my oil every 3000 with Mobile-1 10W. After I change my oil, the oil is so clean it is hard to see on the dipstick, but you can certainly see a line going horizontally across the stick marking the level. After about 2000 or so miles, my oil begins to blacken, making the level very easy to detect. I have never noticed a gasoline smell on my dipstick. I will have to take a closer sniff next time I am under there.

My VX takes exactly one 5 quart jug of oil to fill her up. I burn oil pretty regularly as well. In between oil changes I probably will add at least a quart, maybe a quart and a half, depending on how hard I drive. I change my PCV almost every time I change my oil as well. I have no CELs and my VX runs good. I still worry however.

Bart

Never sniffed her yet. But I swear I will now. I have always thought it was crazy that my dip stick looks like I have no oil at all in my pan. This is the first car that I have used syn in. So I just thought since it is better oil its clearer and thinner and runs off the stick. The stick as a whole looks wet to me, with a thin oil dark line on the outside edge of the stick. There has never been a clear line on the stick. But I know I am not using alot or any oil at all becuase I get with in 90% of 5 quarts in the tub when i drain her. I thought about buying a new dip stick. The ones that hase cut out spaces up and down it.
09/07/2007, 10:40 AM
nfpgasmask

I would try dipping first thing in the morning after your VX has been sitting overnight. Pull the stick and wipe it clean with a paper towel as far up as you can. Make sure it is nice and dry and then dip. After that, if you pull you should get a pretty clear line across the stick.

When I drain my oil, I jack up the right rear and the right front end while the plug is open, just get out as much oil as possible. It then takes exactly one 5 quart jug. Immediately after a fresh change, my oil is super clean and appears clear on the stick, but when I wipe on a clean paper towel, you can see the oil is the typical orangish amber color. My oil stays really clean throughout my 3000 mile invervals now also, since I ran some Sea Foam through the crankcase. Now, it only starts to darken up after about 2000-2500 miles, which I would think is a good thing....??

Bart

Quote:

Originally Posted by JHarris1385

Never sniffed her yet. But I swear I will now. I have always thought it was crazy that my dip stick looks like I have no oil at all in my pan. This is the first car that I have used syn in. So I just thought since it is better oil its clearer and thinner and runs off the stick. The stick as a whole looks wet to me, with a thin oil dark line on the outside edge of the stick. There has never been a clear line on the stick. But I know I am not using alot or any oil at all becuase I get with in 90% of 5 quarts in the tub when i drain her. I thought about buying a new dip stick. The ones that hase cut out spaces up and down it.