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So I was out letting the mustang run for a bit today, as it is still winter here, so the car is still in storage, when for some odd reason, I get a check oil light once it warmed up to about 150*...
I didnt see how this was possible, because the car has never burned oil, and wasnt leaking from anywhere that I could see. The ground beneath the car is fairly clean, and no oil patches were present.
So i open the hood with the car still running, and check the oil. As soon as I lifted the dipstick out slightly, it started to hiss like there was an enormous amount of pressure behind it, and it was blowing hot air at me!!
Now ill be the first to admit that I've never checked the oil with the car running before, so is this kind of pressure normal?!?
The oil level was a little low, but by maybe a 1/4 quart...

I just need to know if something is seriously wrong with the car, or if this kind of pressure is normal...

Thanks in advance...
 

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don't do that!!

:eyebulge: Only check your oil with the engine off and give the oil a few moments to return to the crank case. this is the only way to know what the oil level is, also have the car on level ground when you check it.
Every body changes the pvc valve if they have back pressure in the motors but here is something not everybody seems to know its not covered in my hanes repair manual that I have seen.
My 95 GT 5.0 has the pvc valve at the rear of the intake it also has a oil seperator screen below the pvc valve and Ford "I think" says to change or clean it every 30 thousand miles. I bought my GT with over 150 thousand on it and I don't think it had ever been changed. I had to use a slide hammer with a sheet metel screw attached to get it out. "take your time and just bump it gently till it comes out." it had a lot of build up on it. after I changed it I cleaned the engine up and I haven't noticed any more oil leaks or oil in my inlet tube where the filler cap hose goes into it. I'm not sure where you PVC valve is on that year model if it is in the valve cover there is a filter element in the cap on the older ford motors that I have had I use to just buy a chrome cap and put a new pvc valve in them.
I hope this helps:wavey
 

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The engine is a professionally built 306ci with only about 10,000kms on it, so thats like 6000 miles. When the engine was rebuilt, EVERYTHING was changed over/replaced/refurbished... So I am really hoping the PVC valve doesnt already need to be changed.
I realized that this problem has exisited for quite some time, if it is a problem anyway... Because when I shut the engine off, even last fall when I still had it on the road, you could hear a slight hissing of something de-pressureizing, and now i know its located at the dipstick.
The previous owner said he had a breather on the oil cap for awhile, but it seemed to have caused idle quality issues, so he switched back to a polished stock replacement.

Other then this, the car seems to be running fine... No other leaks, throttle response is awesome, I just cant explain it....
 

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Hmmmm???

do the 88 have a breather tube that goes into the air inlet tube between the maf and the throttle body like the 95?? if it does it would be just open to the inlet side and if there was a build up of pressure in the crank case it would likely blow an oil mist into the tube. check for that if it is made that way.:wavey
 
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