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What is "blow by"? More newbie questions.


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Saw this on a few messages ("no blow by!"), I'm assuming it has to do with the engine, oil loss consumption? Are there oil additives you can use to prolong engine life (common to the 4.0 in Cherokees/Comanches?). Something like slick 40? While I'm here, what oil do most of you use? Best plugs? Filters, etc...?

 

Best way to get rid of and keep surface rust off?

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Be best if you asked this in the Tech section.

 

But......I'm sure Pete will move it ;)

 

"Blow-by" is normally caused from the piston rings wearing out, and the 'oil pan' being pressurized. causing the pressure to escape to the easiest source, which is the CCV system (Crank Vent Circulating System) which ends up dumping oil into your air filter.

 

There is really no additives to solve this problem. The only true 'fix' is an engine re-build, IE: re-bore the pistons bores, over sized pistons, and new over size rings. This is were you hear the term ".030 over" meaning the bore was re-bored at 30 thousands over stock bore.

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So.... if my air filter is "oil free", I'm not experiencing blow by?

 

Yes, if you don't have any oil in your air filter, that is a good sign that your engine is in good shape and the rings are not worn out. Also a good "check" when buying a used car.......check the air filter for oil residue.

 

You still can experience 'blow-by' not showing up in the air filter, cause some one disconnected the CCV system, but you would see oil dumping out all over the top of the valve cover. I've seen used cars with "corks" stuck in where the CCV tubes should be.......tell sign that there's a problem.

 

Oh......and we're talking about engines with high mileage......like over 100K+ on the clock, that's also a good sign to look for blow-by, (worn rings)

 

And Thanks Pete for moving this :D

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Billy, the 4.0l engine is built like a brick sh@t house, and is tough to kill, many can easily go over 200k with proper oil changes and maintenance.

 

As the other guys said , Oil in the air cleaner could mean the engine is worn and the rings are allowing excess blow-by and this is more likely in neglected high mileage engines above 150k miles. But it is also very common for these engines to have a defective pcv system, a plugged CCV vacuum line which is the small vacuum line that comes from the intake manifold to the top, rear of the valve cover. The larger hose that connects to the top front/center of the valve cover to the intake air filter is the return hose to recover any unburned fuel gasses in the pcv system. If the vacuum line is not doing its job, and is not creating a vacuum to flow the gasses through the system, the pressure builds inside the engine and it blows the gas out the larger hose, often including engine oil into the air cleaner.

The ccv vacuum line can be plugged at the intake by carbon deposits, and can be cleaned using a wire. The hose should also be checked, I found a piece of silicon inside mine that stopped the flow.

 

Motor oil, I use 10-30 motor oil in my 4.0l'trs and 258's, the brand is not very important. I have been using Wally Worlds " Super Tec" oil for a few years now and have been happy with it. Any oil you use that meets the API certification recommended by the manufacturer of your vehicle will basically work the same.Change it regularly , 3-4k with a decent filter and you should be good. I have also been using Fram filters for years with 0 problems, although some will say they are bad filters. I use the Wally World filters as well, which are actually well made and cheap. But you are free to spend as much as you want on any filter if it makes you feel better, or gives you peace of mind. Point is, I have not had any issues using these products in many years and on many different vehicles, foreign and domestic.

 

Spark plugs , I have been using AC Delco, bosch and autolites for years with little to no issues, the standard plugs work well for these engines. Personally I don't like champion plugs, had way to many problems with the few I did buy. Including having three blown centers, and I mean the center of the plug literally blows out, come apart while driving! Not only myself but my Bros truck with chumpions! Anyway maybe I have been unlucky with them but I will never buy another chumpion plug. Also, avoid using the platinum plugs with the 4.0l's they tend to foul easily.

 

Surface rust, can be stopped by either sanding out the rust and refinishing the surface with paint or using a rust stop jelly that can be purchased at any auto parts store.

 

I have a set of 235's on my stock Comanche, same size as a 30" tire, don't think you are going to shoehorn anything larger without rubbing.

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So.... if my air filter is "oil free", I'm not experiencing blow by?

 

For your truck, that is correct. But if you engage in exchanging posts with Chico, you will also most likely experience "blow by". :D

 

Wahoo is correct. Especially if you sit on the tan couch in between us.

 

Plugs: Plain Champions. Run a search and you'll see many arguments over what to use.

 

Oil: I use Castrol high-mileage. Run a search and you'll see many arguments over what to use.

 

Air Filter: Whatever is at the auto parts store. I don't think anybody has argued over this yet, so maybe we can start one now.

 

DO NOT USE FRAM OIL FILTERS. I KEEP HAVING THIS PROBLEM THAT I GET OIL IN MINE :D

 

WOW :eek: A Comanche that only runs on three tires.

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Great info, thanks.

 

How about cup holders?

 

Haven't figured that out yet. Right now I'm strapping my Big-Gulp to my Fire-Extinguisher which is buckled in with the seat belt on the passenger side of my bench seat.

And I lied. I used NGK's...........

I think......whatever Eagle used

Bloody short-term memory loss :mad:

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I put a fram oil filter in with my last oil change. Then everytime i went to park my truck my oil light started coming on (this also happened in a few of my other cars with fram filters). Somehow the fram filter was restricting oil flow. I replaced it with a napa gold (which are actually wix filters) and the problem went away. I will never use a fram filter again.

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I put a fram oil filter in with my last oil change. Then everytime i went to park my truck my oil light started coming on (this also happened in a few of my other cars with fram filters). Somehow the fram filter was restricting oil flow. I replaced it with a napa gold (which are actually wix filters) and the problem went away. I will never use a fram filter again.

wierd... wix is good stuff thats what we use at the garage i work at. i like the fire extinguisher idea, ill have to remember that

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Pennies spent on oil filters are pennies worth while. Buy the cheapest oil you can, but spend some coin on the filter. You really do get something for the money. Fram just happens to have some sort of design or quality control issues.

 

Well I buy some sort of high flo oil filter from my local parts store and is not the cheepest by any means its just a little cheeper than fram.

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So....ORCA, if money isn't an issue, what is the best oil filter?

 

Can I answer that????? :roll:

 

At one time I always used Fram filters.......until one day, while lurking around here......and reading all the 'bad' things about Fram, and seeing the info above (which I bookmarked) I switched to Purolator filters, AND if you go to Advance auto, the Purolator filters are the same price as the Fram filters, about $3.59, and every once in a while, they have - Buy one, get one free, So I stock up, and walk out the store a happy consumer :D

 

And........I use to have the oil light come on at start up with the Fram, and since I've change brands, never happens now ;)

 

Should you run out and spent $12 for an oil filter??? That's your call. I wouldn't, cause if you change your oil every 3-4 thousand, the $4 filter will do the job, cause you should change the oil filter at every oil change, not every other like some "books" say :roll:

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