4.3l vortec engine sludge, manifold leak

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i own a 2002 blazer and have owned it since it was new. it has always used Mobil 1 and changed regularly. about six months ago i heard a terrible tapping when i started the engine. After about 5 mins it went away. i changed the oil which was only 1500 miles old and the noise did not appear again for 1000 miles and it started doing it again. it was confirmed that it was a stuck lifter and that those engines had a habit of lower intake manifold gaskets leaking antifreeze into the crankcase. After feeling pretty comfortable that this was indeed the problem i took the manifold off and found the engine to have a fair amount of sludge in it. I am not a pro mechanic but it looked pretty bad to me. i could take an lift it up with a screwdriver in places. Anyway, i cleaned things up as well as i could and put her all back together. Here is where i actually ask a question. I am not really a fan of additives ect but im nervous about the sludge that is in the engine now. I filled the crankcase with walmart 10w30 and plan to run it 1000 miles then change it back to the synthetic. The truck has been back together now for 4 days and seems to run great. One thing i noticed is that the new oil i put in still looks brand new on the dipstick. i would think it would get dirty fast due to all the [censored] in the engine. this leads me to believe that it is not cleaning up anything. I have run rotella in some of my other gas trucks for a long time and don't seem to have an issue with it so i was thinking about running that for a while due to the higher detergent concentration but im not sure. If anyone has had this issue before as it is different than some generic sludge problem due to laziness please advice or share your success story. I believe the engine is in good shape but i would just like to get the sludge out of it. It has 170000 miles so it would be considered high mileage. I have heard several methods of trying such as tranny fluid, MMO,SeaFoam,Rotella,Just run synthetics as they will clean it out slowly. Also im not sure if this is different due to the fact that the sludge is caused by antifreeze in the oil and not neglect.
 
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Sounds like a great candidate for Auto-Rx. The sludge was probably caused by the coolant leak, as these engines are normally know to be rock solid reliable and fairly clean inside.

Read the Auto-RX FAQ in the Additive section.

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I'm not normally a big fan of ARX because it seems to end up in every thread as the cure for every single engine problem under the planet. That said, your situation actually seems to warrant the mild cleansing and therapeutic massage that only the esters can perform. :D
 
Muddy oil results from oil in the water. What antifreeze did you reinstall? I understand that Dex cool is specified and that it actually eats away the gasket. I would switch to a HOAT such as Peak global lifetime coolant or use the old green coolant if you can find it, and avoid OAT based coolants or Dex cool.
 
I agree with Skibum. We see lots of problems on Macks at work that run Extended Life coolant. On them, it eats away at the thermostat 0-rings, especially any gaskets on aluminum pieces. It'll also eat away at silicon over time. I'd try something different than extended life so you don't have this problem again.
 
Run an arx as per the arx faq and it will clean things out nicely. Then go back to your M1 and do a few UOAs to make sure things are happy.
 
I have never tried Auto-RX, however I have used diesel oils in the past that I know will help clean an engine up, and also are great oils. If it were me I would get some Shell Rotella T (synthetic) and run that for your normal oil change interval.
 
Well, i bought the 90 dollar gasket from autozone that says "Features advanced technology impervious to coolant / oils.". that was the only thing that i saw different than the 30 dollar one so i put the extended back in it. It looks like other than the method, most agree that some mild type of cleaning is needed. So therfore most agree that just running synthetic and changing often is probably not sufficient? here is the link to the gasket that i bought.

http://www.autozone.com/R,1427079/vehicl...oductDetail.htm
 
Like mentioned above, traces of water and coolant in that area can make 'sludge'. Also, this motor can have fuel inj issues and have been known to leak fuel in the intake. The engine design is fairly old and while GM did a good job of updating it, it still has a tendency to be a bit more of a 'dirty' running engine. Don't know if yours still has EGR, but those that do are constantly carboning up and causing problems in the intake. Adding up all things, it can lead to sludge, and no oil is going to stop it from happening. Your M1 may have even done a better job than another oil--ya never know. I clean my EGR out every year and have cleaned up the intake as well. One of these years, it is not going to pass emissions without new cats and/or 02 sensors. The new oil is not going to clean up that much sludge. You either have to do it manually--PITA-- or try one of the many cleaning products that a lot of people on this site like. I have not tried them, so I can't speak to their effectiveness. At least pull off your valve covers and drop the oil pan to get an idea of your total problem. The good news is that the 4.3 is pretty well contructed, and will go tons of miles. You just have to deal with some other issues along the way.
 
had the same thing w/my 01 Blazer but I caught it before I had any lifter problems. I was also having a #3 misfire problem at the time. I ended up doing the LIM and the injector pod upgrade at the same time has been good since. the short version of the story is here
 
what is the injector pod upgrade? That sucks as i did not know about it and did not do it. the guy on your other post said this is a 2 hr job. He must be awesome because it took me longer than that to get mine apart.
 
The 3.8L we pulled apart (GTP) that had the LIM leak had a good inch thick layer of "sludge" throughout the engine. This is caused by the coolant mixing with the oil and apparently common with this condition in GM engines. This is according to a mechanic customer of mine who has had hundreds of them apart for this issue.

How old is the thermostat?
 
it was replaced about a month ago becuase the old one wasnt working properly and the engine was not getting up to full temp ever. it would get to about 155 and stay there. your buddy that has pulled apart the other engines with 1 inch of sludge, what does he do afterwards to get things back to normal. My sludge was no where near that bad. I didnt even have a layer persay. it was just collected in the low spots and stuff.
 
I have owned several old cars and have done most of the moderate engine repairs myself. I have never seen any oil alone do substantial cleaning. If you think there's enough sludge to cause blockages, get in the valve areas with a screwdriver, rags, and a shop vac. Sludge can starve valve seals and lead to future issues. Try to avoid losing chunks of sludge into the drain holes. Folks here rave about arx--- it's too pricey for me. I've run several OCIs with 1/2 can of seafoam in the oil, and it slowly helps, but doesn't get everything either. It HAS helped free up stuck lifters and maybe helped things run quieter after several doses.

It sounds like you have some comfort getting into things. Pop the covers and see what you can accomplish.

+1 on pcv service.

Meep!
 
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Originally Posted By: SnakeOil
I'm not normally a big fan of ARX because it seems to end up in every thread as the cure for every single engine problem under the planet. That said, your situation actually seems to warrant the mild cleansing and therapeutic massage that only the esters can perform. :D

If its known to fix problems, how can you not be a fan of something that works so well.
 
i will be popping the valve covers off to evaluate them in about a week. Ill post back on my results. if they are bad ill do my best to try to clean them up. I was really hoping to have alot of people saying just run synthetics or HDEO and it will clean it up, but that dont seem to be the case. Thanks for all the posts
 
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