5.0 fox blowing smoke help

Hudson N

Member
Aug 7, 2018
50
3
8
Queen creek Arizona
I've got a 1991 5.0, with about 104 thousand miles on it. I recently noticed that after I sit at a light for a minute and then start going again, it blows blue smoke out the back. Once I'm moving I dont really see any. Obviously its burning oil. Are my rings worn out? I put a new PCV valve in it but I couldn't get that mesh filter out from underneath it, could that be it? There is also some evidence that my upper to lower intake manifold gasket is leaking, could that be it? Anybody know if theres anything else I should be looking at and how to fix it?
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
17,025
5,468
193
polk county florida
Are you seeing and smoke from the dip stick tube or oil fill tube with the engine running?
do a compression check.
you may just need valve seals, has the car been sitting a long time?
 

ddtmoto

New Member
Dec 7, 2012
2
0
1
66
Yup, you're going to need a compression, and probably a leak down test. Step by step testing to determine your engine's overall health. Most likely Piston blow-by or seals. Start with the easiest stuff. Not that it's going to be easy....
If you're not in a hurry to tear things down, add a load of AT-205 to a fresh change of a heavier High Mileage weight engine oil....and see what spring time brings...?
 

Hudson N

Member
Aug 7, 2018
50
3
8
Queen creek Arizona
Are you seeing and smoke from the dip stick tube or oil fill tube with the engine running?
do a compression check.
you may just need valve seals, has the car been sitting a long time?
Theres no smoke coming from there. And as far as I know, the car never sat very long. I did see some evidence of dry rotting on the fittings for the vacume lines under the intake, and theres evidence that my upper and lower intake manifold gaskets are leaking, could that cause it? The thing just blows a little blue smoke after stoplights sometimes.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
17,025
5,468
193
polk county florida
The blue puff of smoke after idling for a time is usually valve seals, a leaking intake gasket could be too, check vacuum lines and the pcv valve and screen too. Valve seals, sometimes called umbrella seals, would be my guess.
 
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