pcv blowback
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pcv blowback
Oil has been blowing back through the pcv fresh air hose, enough to blow the pcv filter off its plastic holder and ruin a new air filter in weeks. What's my problem? Someone told me that I had worn rings. The truck-90 F-150 302-has got about 140k on it and it seems awful soon for my rings to be worn that much. Thank in advance
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Joined: Sep 1999
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From: Indiana
pcv blowback
First off, make sure your PCV system is working, pull the PCV valve out with the motor running , put your finger against the hole in the bottom of the valve, it should have a strong vacuum pull. ( it should suck your finger against the hole )if it doesn't replace the PCV valve, or with the motor off you can shake the old valve and hear it rattle, it should rattle. If you replace the valve and it still has no vacuum the PCV system is clogged. If you have vacuum , then the compression rings are worn, I have seen many 302's with blow by with a lot less miles than yours. If you find you have a good vacuum pull , to check for blow by , take your oil fill cap off while the motor is warmed up and running, it will have what will look like thin smoke coming from the fill hole, you may need to hold a flashlight at a side angle to shine across the hole to see the smoke, thats if your working in the sunlight, from your discription its either the PCV valve is stopped up tight or you do have blow by, in that case (you have blow by) your 302 is history.
Posting Guru
Joined: Jun 1999
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pcv blowback
The item is called a crankcase breather filter,but it's not the one that fits in the air filter box. Here is how it is stated in the DORMAN catalog,there part # is 493-274; [Ford 5.0L 1996-80.Replaces Fram CA1510A,Motorcraft FA-1068.Located in the rear intake manifold underneath the PCV valve grommet.{this is strange as I thought they were all on the valve cover?}This filter cloggs with sludge preventing the venting of gases from the crankcase.A clogged vent filter can lead to blown seals,rough idle and other engine problems.]
From the picture in the catalog,it resembles a 5/8" reg. socket with slots cut in it and filled with a coarse steel wool and capped off to prevent the steel wool from falling out.It doesn't specify cars or trucks?I sure wish someone knows or has actually verified that this component does exist on the 5.0L.I have seen this "slug" in the CHAMP Item catalog also.Maybe a FORD Tech could clear up this mysterious part!
Phillip
From the picture in the catalog,it resembles a 5/8" reg. socket with slots cut in it and filled with a coarse steel wool and capped off to prevent the steel wool from falling out.It doesn't specify cars or trucks?I sure wish someone knows or has actually verified that this component does exist on the 5.0L.I have seen this "slug" in the CHAMP Item catalog also.Maybe a FORD Tech could clear up this mysterious part!
Phillip
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pcv blowback
PCV filter is fine and I have vacum at the valve. Couldn't see any smoke at the fill cap, but I held a piece of paper over the fill hole and snapped the throttle, and it was definitly blowing back. So it's my rings? If so does where can i get a good, cheap rebuild kit?
Posting Guru
Joined: Sep 1999
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From: Indiana
pcv blowback
I don't know about the filter mentioned in the other post, I guess you could put your piece of paper by the PCV valve hole on the back of the intake see if it moves or see if you can see any smoke there, but I'd say your motor's shot, as I said in my other post, I couldn't count the 302's I've seen with blow by, maybe you could find a low mileage engine in a wrecking yard. good luck!
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Joined: Jul 1999
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pcv blowback
Super,
if an engine is exhibiting such symptoms, what your guess as too how long the death march will be. I seem to recall seeing some wispy spoke coming from the oil fill hole on my 135K 4.9L .
I'll have to have a closer look...
if an engine is exhibiting such symptoms, what your guess as too how long the death march will be. I seem to recall seeing some wispy spoke coming from the oil fill hole on my 135K 4.9L .
I'll have to have a closer look...
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Posting Guru
Joined: Sep 1999
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From: Indiana
pcv blowback
Vapor, A lot of it depends on how long you want to put up with it, ruining air filters, oil slobbering out around the oil fill cap and fanning out over the valve cover or covers. They usually start getting down on power also as the compression rings get weaker. There is not really a set time frame on how long it will last, could run for quite a while, just won't run well. What happens is the compression leaks around ( blows by ) the compression rings and blows back into the crank case . With these compression pulses blasting into the crankcase it tends to push the oil back out through any place that the pressure can be releived, oil fill hole, PCV valve opening , sometimes the dip stick tube, thats how it pushs the oil back into the air breather and has your air filter soaked in oil.
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From: saramento usa
pcv blowback
I shopped around and bought my 351W Long Block from Autozone for $1,000 without the core exchange. If you've got a like core, you can knock $200-$250 off when you return the core.
Slik
Slik
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pcv blowback
When you snapped the throttle, the engine vacuum goes to 0 anyways, I went and tried it on my 97 Dodge Stratus and got a very tiny bit of blowby. When you put the piece of paper over the oil fill hole, did it have even a tiny bit of vacuum?
Posting Guru
Joined: Sep 1999
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From: Indiana
pcv blowback
Josh, there is no vacuum at the oil fill hole, the vaccuum we are talking about is at the PCV valve and hose its attached to, the PCV valve will take care of a small amount of blow by , but after the motor gets worn bad enough (compression rings) the volume of crankcase gases become to much for the PCV valve to handle so it starts puking it out ( the crankcase gases with oil mixed in) this is blow by.
Posting Guru
Joined: Sep 1999
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From: Indiana
pcv blowback
Josh , I didnt see your first post if you are getting a little vacuum pull at the oil fill hole this is OK, sometimes you can barely feel or see it pull,with you laying something over the fill hole. Its actually the PCV valve system doing its job, with the motor running and PCV valve in place, and with the oil filler cap off, you are creating another place for the PCV system to draw its air, other than where it would normally draw it through crankcase breather element. And since thats a bigger hole it will draw its air from there until you replace the cap.
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Joined: Jun 1999
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pcv blowback
Tom, We have the same problem right now with a 300ci I6. I checked the compression, and #3 cylinder is only half of the other 5. Don't want to do it, but the engine is going to need new rings as a minimum. I suggest you check your compression. You can buy a good compression gauge from Advance Auto or Pep Boys for about $25.
Good luck,
-- Dean
Good luck,
-- Dean