I have a 2000 F150 with a 4.6L V8. My truck only has 33K miles and is run about once per week (usually pulling the boat). A few weeks ago, I started it and a big puff of blue smoke came out of the exhaust and then it went away. I immediately checked the oil and the level was fine. I thought it was a fluke until it happened again about a week later. I believe this is an indication that oil is somehow seeping into the cylinder when it is sitting possibly through a bad valve.

I'm concerned since the truck only has 3K miles before the warranty is up. I've taken good care of the engine and have used premium oil so it definitely isn't due to neglect.

Any thoughts on what the problem is? Our comments would be appreciated.

Kirk Grassett

 

Take it in now and at least have them document it at the service dept my thought is its probably not a valve beacause they breathe so well but more likely it is the dreaded leaking head gasket and instead of leaking on the outside it is leaking on the inside also check your oil fill cap for condensation you could be getting anti freeze in your oil

 

When you open the oil cap, what are you looking for exactly?? I know sometimes when I go to add oil, the bottom of the cap has this tan milky substance on it . . . which I thought was normal. So is it??

 

Milky white in the oil only means 1 thing .... water has gotten into the oil pan. You've probably got a blown head gasget. Don't wait any longer, get it to the dealer before your warranty is up.

Larry

 

Definitely take it in asap however do not let them just fix the head gasket. if it has leaked coolant into the crankcase for an extended period of time (more than just a few days) it will eat your bearings in the bottom end of the motor which will definitely shorten the life of the engine. This happened to my mother in laws new yorker it had a mitsubishi motor with an internal water pump that leaked into the crankcase undetected until it started to smoke like a james bond movie

 

Don't think you have a head gasket leak just because of that milky substance on the bottom of your oil cap. That substance represents only condensation mixing with the oil on the cap itself. It usually means you are running the engine for a short time then turning it off. The engine isn't getting hot enough long enough to boil the condensation out. If you look down the hole and see it on the cams or when you change the oil, then I agree you have water in the oil.

 

I'm thinking that maybe it is just a leaking valve guide seal. Quite possibly if it was run everyday it would not smoke on start up. As for the somewhat milky residue on the underside of the oil filler cap this can be attributed to short trip operation with the engine not reaching operating temp. Usually not a call for concern.

 

Thanks for all the feedback fellas. I'm under the impression it's just a short trip symptom. Only noticed it after changing over to Mobil 1, thought it might be due to the different oil.

 

It sounds like valve guide seals to me. It wouldn't hurt to change the PCV valve just in case it is the problem. Warm the truck to operating temperature then let it idle for five minutes. Rev the engine while watching the tailpipe. You'll see a puff of smoke if it the valve guide seals. It is a common 4.6 issue. Watch Crown Victorias pull away from traffic lights and you'll see the same puff of smoke. It really IS NOT a big deal. I sure Ford won't do anything to help you unless you are burning at least 1qt every 800 miles, which is very unlikely.

 

if you still see blue smoke after the truck is all the way warmed up then there is a problem because these trucks have big cats that once hot should get rid of any smoke that the engine puts out!

however there is record on this board of the short run syndrome. where you run the truck for a short period then shut it off then when you start it again you get the blue smoke puff. it is usually and inconsistance occurance. even the 5.4's do it.

do a search on "blue smoke"

if you really want to tell if your valve guides are bad get the truck good and warmed up (by driving NOT idling) and find yourself a big hill or mountain road. on your way DOWN the hill/mountain road let off the gas for a few seconds, look in your passenger side rearview mirror then punch it, if you get blue smoke you need valve guides.

remember short trips are the WORST thing you can do to these trucks. Next would be letting them sit for long periods of time.

keep us posted-

 

My 98 4.6 has done that before. Ill let it sit for 3-4 days in the garage (mostly under heavy snow, salt) and ill go start it and a puff of blue smoke come out the tailpipes. I think its just a little oil that got past the valveseals. It never does it when i drive the truck everyday just when its been sitting for a few days. But then again, i did come home from college last week and it had been sitting for 5 straight weeks and it cranked right up with no smoke whatsoever.
The white milky stuff is just a little condensation where evaportated moisture has collected in the oil filler neck. My advice-take it to the dealer and have them look it over so that you can cash in on the warrenty if something happens. Also after lettting your truck sit for a week or so, let the truck warm up for approx 2 mins before driving it off and also make sure the truck's engine temp gets to full operating temperature. Engines that start then stop without ever getting the engine warm dont live long lives.

 

HCMQ,

ALL engines use some oil, and cats DO NOT do well at removing oil smoke from exhaust. The little bit of oil we are talking about here and occasionally lots of oil will not harm the cats. When I worked at a auto repair shop, we had several cars come in with blown seals on their turbochargers. They smoked like crazy even with "big cats". After we replaced the turbos and drove several miles, the cars ran fine, had no visible smoke, and passed their emissions tests.

My truck has the puff of oil smoke, but mostly only after it is hot and has idled for a while. I think this is because the cats cool somewhat at idle while manifold vacuum is high. It also does it on startup occasionally. It DOES NOT smoke on deceleration even while manually downshifiting. I have observed the same type of issues on several Crown Victorias with the 4.6. Others on this board have noticed this as well. My truck runs fine and passed the emissions test better than my wifes' van with 60,000 miles.

 

I think mine did this for the first time this morning. I moved my truck about a half turn of the wheels last night to finish putting dressing on the tires and shut it off. It only ran for about 3 or 4 seconds... then, this morning when I cranked up, it idled rough for about 10-15 seconds and DEFINATELY blew a puff of smoke.

Should I be alarmed? I've since shut the truck off and restarted with no apparent sign of problems but, I'm still concerned.

Thanks guys...

RP

 

nope nothing to worry about.

brent, I know that every engine uses a little oil?? I never said anything to the contrary.

trust me when I say that the catalytic converters get rid of a lot of smoke, that is what they are there for. I never said that smoke couldn't get past them. And I never said that they would be ruined by the smoke.

what I said was that if a lot of smoke is getting past the cats all the time you really have a problem and need to worry about it. I also said that a little puff of blue/white smoke is prolly nothing to worry about.

I also never said anything about downshifting?? I was talking about a downhill test for a valve seal concern.

Settle down Beavis!

 

So the short run, secondary start up with a puff of smoke is normal? What causes it?

RP