95 bronco 302 smoking

[ants95bronco]

So in december of 2010 i had my engine rebuilt by a highly reputable shop in phoenix arizona.. just as the engine went out of warranty it began smoking for a coupke seconds after being started. My father a former ford heavy line tech told me not to worry it was nost likely a valve stem seal so i left it alone.. so a coupke days a friend was driving behind me and said when i took off from a red light it puffed smoke a tad then stopped.. so i called the guys i had build it and told them about it.. they requested i replace the pcv valve and pull the plugs and take photos of them.. so upon pulled the plugs they looked normal on the tips with a greyish white color But cyl 8 had oil on the threading all the way up to where the plug bevels..and cyl 5 looked like it had a touch of oil on it as well.. well ive been asking around and have been told it may be oil rings, valve guides or seals.. so im puzzled on who to believe so any input is appreciated..

 

[Rons beast]

Hey Ants,

Your father is on the right track. When an engine blows oil smoke on startup and acceleration, the valve seals/ guides are most likely the problem.

If the rings were worn and allowing oil in the cylinders, the engine would smoke all the time.

The oil on the plug threads is probably oil seeping from the valve cover seals. That could also indicate that there is a restriction in one or more of the oil return passages. That can cause oil to back up and get sucked into the valve guides, and seep from the valve covers.

I have encountered this on a few engines, most that unlike yours had poor maintenance, and one with a wayward nut blocking the oil passage.

You may want to pull the valve covers on the oil fouled plugs and take a look. 

Good Luck  

 

[ants95bronco]

Mm ok well i got it going to a shop to get a comp and leak down test on thurs so well see what they say.. i hope its just valve stem seal or even the guides would be ok just as ling as its not the rings... something i forgot to mention is after my friend tild me about it smoking on acceleration i experimented with it and found on some occassions it will blow a bit it if its idling and i pop the hood and hit the throttle all the way and then it kinda lingers for a minute then stops.. and i was playing up in the hills of idaho earlier and im not positive but when i was coming ba k down hill i think it started smoking when the frot end was down hill the stopped once i leveled out but id have to try to get it ti do it again..

 

[Rons beast]

The smoking when the truck is not level and when you hit the throttle is further info that leads me to believe valve seals are the problem.

A leak down and compression test will not uncover bad valve seals.

BTW, deleted your double post.

 

[ants95bronco]

Mm thank you i try to delete it but couldnt figure it out.. i thought a leak down is to test the valve guides and seals? but i guess thats usfull info.. and as for the truck not being level i wasnt positive about that i was also throttling it when i noticed smoke come out but i can go back to that spot and see if its from not being level tommorow..

 

[Rons beast]

It's just an issue when valve seals are bad, ( the vehicle being off level) .  The oil in the top part of the heads can't run down the returns as fast, and gets built up some. If the valve seals are bad and the intake vacuum gets the chance it will **** some oil into the cylinders. The result is some bluish smoke out the tailpipe, that goes away when the truck is level...or closer to level.

Everything you have described has pointed to the valve seals.

BTW...a leak down test will provide info on the condition of the valves, and weather they are seating and sealing well.  It's not for the valve stem seals that are suspected with your Bronc.

Good Luck  

 

[ants95bronco]

Ok so what am i looking for when i pull the cover? will i be able to see the valve seal clearly?

 

[ants95bronco]

Ok so i pulled to valve cover and i seen nothing wrong.. no oil passages were blocked and the inside was very clean no sluge build up or anything for that matter i tried to take a mirror and play with it to see if i could get a look at the stem seal but had no luck.. the shop i was gunna take it to suggested i out diesel 15w-40w in it and use lucas oil treatment with it as well to see if that helps?.. i described my symptoms to him and he believe its mostly valve steam seals but believe the ring may be involved? My engine builder said they think i should just get the seals replaced.. so i think im just gunna het the money to do the seals and hope its not anything more..

 

[Rons beast]

Don't put diesel oil in your engine.  A rebuild from about 52 months ago may benefit from a heavier oil, like 10W 40, or 20W 50 since you're in Az. but that will most likely not fix your problem.

You can try the Lucas additives. I have had good luck with Lucas power steering sealer in the rack in my Lincoln.

The valve seals are probably your problem.  I see no indication the rings are an issue since the engine isn't smoking all the time.

It's very difficult/ impossible to see bad valve seals. 

Good Luck with it.

 

[Grizz]

Its suprising to me how many people have had this kind of problem with there rebuilt 302 from an outside source.  I have guided them into dismantling there block when it comes back from the machine shop to do and overall visual and clearnce check.  in some cases its understandable that a person may not have the know how or enviroment to dismantle a motor but the added ease of knowing what has been done and knowing as well that everything is put back the way it should be pays off greatly down the road. 

not wanting to sound like i am talking down.

from past experience this is what i have learned. 

i just advised my boss yesterday about this.  He is having issues with his motor not even turning over and its a freash rebuild not even a week old.

so to make it short if you have time and know how or curiosity it is always best to do it yourself. 

to comment more on the smoking, to see if your piston rings are the cause pour about a cap full of motor oil into the cylinders through the spark plug opening replace plugs and so forth and crank over.  if the smoke disappears then i would say the rings could be the issue.  if not start with what is simple and cheapist.