My '90 5.0 uses a qt about every 600 miles. Milage is slightly over
100,000. Will admit over the years I've downshifted a lot to slow down.
Obviously it could be the rings but could it also be worn walve stem seals? Is there an easy way to tell which one it might be like if the compression tests ok then are we looking as worn valve stem seals?
Well, there are a couple of ways to tell. If you start the engine up and it puffs out smoke, it's the valve seals because you are burning the oil that has leaked past the seals when the engine was off. If you slow down by downshifting and when you accelerate again, and it smokes, it's valve seals. Why? Because when you deaccelerate by downshifting, your throttle plates are closed and you have a lot of manifold vacuum. That vaccum sucks in the oil past the valve seals. Then when you accelerate, the increased air/fuel charge sucks it into the combustion chamber and it is burned. Unless the maintenance was completely ignored, I'd guess that it is valve seals. They will deteriorate with age while a piston ring will not.
Kruse--Thanks for your input. I've always maintained the car well with oil changes at the prescribed intervals. This may explain why the hydrocarbons on my biannual smog test keep going up. Frankly if it needed to be rebuilt I was considering a high horsepower crate engine from Ford Racing.That would keep it going another 15 years.
Even as an experiment, changing the valve stem seals can proove fruitful.... This can be accomplished without removing the heads and rates about a 4 on a
1 - 5 scale of difficulty.
If the oil ring are worn, one would expect the compression rings to be in the same shape. A cylinder leak test is not a be all/end all test without other tests being done (aside from the fact that a cylinder leak test can only suggest the condition of the compression rings). The puff of smoke on start up is usually a good indicator of stem seal concerns.. the only sure way of confirming this is to visually check. It is more than likely that there are many more trouble free miles to be had from your car with a simple repair.
the only real way to tell is to put engine under hi vacumme situation if i were you i would go down a long hill and use only gears to break closed throttle running at hi rpm thus putting max vacume as possable on valves and seals occasionally punching it to make it smoke
have some one follow and observe but hey what do i know i am just a real ford mastertech
i have seen guys replace valve seals based on jims advice and they have found no change after repair if ya dont believe me go rite know start up a new car try a ranger its ez to see on them lmfao
It seems the moron troll doesn't know the difference between oil smoke and unburnt fuel smoke. It's obvious with all the post this guy is a hack that is jealous of good mechanics. He is the number one reason NOT to take your car to a dealer.
Good info! Hey regarding the troll. I know some of you use a "killfile". I assume it is a file of usernames/email addresses your newsreader client uses to "ignore" certain annoying people's posts. I wanted to share with those who use Outlook Express how you do the same thing. Just click a message from the troll and go up to "Message" menu and click on it and then click on "Block Sender". If you never see the troll's message, you are (a) never frustrated by his stupidity / meanness; and (b) you are never tempted to feed him a response. I think Trolls live for that response. Deny him his food and maybe he'll go away. And in the mean time, for you, it's like he's not there anymore anyway :)
How, I've got no idea. But I have had it happen on multiple occasions that something would get corrupted and it could no longer download new messages and other stuff. I just walked away from it...
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