engine smoke - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

ofinterest · 07-18-2007, 18:36

i have a 1995 crown vic 4.6 romeo. it smokes on start up and acceleration the smoke color is blue and smells like oil it only uses approx 1 litre of oil in 5000klm.i have read that these cars with higher milage have valve seal issues.it has 208000klm on the engine it starts and runs great lots of power very little blow-by and the oil remains very clean between oil changes.do you think this could be a valve seal issue???

rescue76 · 07-19-2007, 01:59

Every oil change I put in a quart of lucas oil...does wonders for leaky valves.

dryelf327 · 07-19-2007, 10:17

The 92-95 4.6s were notorious for leaky valves. You're only burning approximately 1 quart per oil change and everything looks clean and good when you change it, I say don't sweat it and keep driving her. With the mileage you have (206k km = approx 130k miles) you're not losing too much oil in between changes. Just continue to monitor it.

RickMN · 07-19-2007, 20:27

If the oil is only on start-up, that points to valve stem seals rather than worn valve guides. Here's the reason--when valve stem seals age, they crack. Any oil that's left on the top of the valve at shutdown flows through those cracks and down the valve guides. Sure, the guides might be worn a little, but if the valve stem seals weren't cracked, they would do what they're designed to do--seal the valve stem. Now, having said all that, you may still have a case of bad valve guides. You're getting blue smoke on start up because the cat converter hasn't warmed up enough to burn off that oil. If the valve guides are worn to the point where engine vacuum is sucking oil down the guide, that might not show up on a warm because the converter is hot enough to burn it off. On the flip side, all that extra oil would cause your converter to run hotter than usual. And it would result in even lower post cat O2 sensor readings because the extra burn off would use up all the available oxygen in the exhaust stream. Bottom line, only a compression test can tell you if you have worn guides. You'd have to do the test at least twice to see if the valves are wiggling in their guides. Valve stem seals are cheap and the job isn't too hard.

Nathan in MN · 07-20-2007, 23:03

Yep, the early 4.6s develop bad valve seals after awhile...it's pretty much inevitable. For the trouble and expense of putting in new seals, you can put an awful lot of oil through it, so I'd say just let it smoke a little. Won't hurt anything, and it sounds like the oil consumption is low enough that you don't even need to worry about topping it off all the time (not to say that you shouldn't keep an eye on it, but you ought to do that whether it's consuming oil or not).