oil blowback in airbox

[cj_92Bronco]

hey yall, my '92 302 has been having some weird problems involving the airbox. The pvc hose from near the oil cap to the underside of the airbox is thowing alot of oil under the air filter. Not only is it making a huge mess, but all of the blow back is like a yellowish white cream color. any houghts?

CJ

 

[Justshootme84]

Check for water/coolant getting into your oil. Go ahead and change the oil filter, and cut open the old one. I found a chocolate-milky-colored sludge inside mine.

 

[cj_92Bronco]

yeah thats what my dad just told me also. i have no idea how to go about getting water out of there. i change my oil every 3 months so i really dont get why i just changed it and it already has that $hit in it.

 

[barrett86]

how much oil have u been putting her, and wUT weight are you using.

 

[cj_92Bronco]

i usually check it about every 2 weeks cause burn alil oil and i have a small leak. i use 10w 30

 

[barrett86]

hmm well im unfortunately at a loss. maybe one of the moderators would know trying asking seabronc or broncobill man.

 

[green streak]

is it running hot? could be a blown head gasket/cracked head......maybe.

 

[Broncobill78]

If your oil is that foamy cream/yellow color then JSM84 is right & you've got coolant in your oil. You can change your oil to remove it but the unfortunate fact is that you *most likely* have a blown head gasket. Head gaskets usually fail as a result of overheating. The only cure is going to be to do a compression ck to see what each cylinder is running, when you find two adjacent cylinders that read low then you've found your leak & will know which one is blown. That's really kinda moot because head gaskets come in pairs and most guys just go ahead and replace both once they've gone thru the hassle of taking the top end of the engine off. To replace them you'll need to remove the distributor, intake manifold & then the individual heads.

How's the oil level itself ? It usually reads a bit high when this happens since the coolant is mixing with the oil & raising the level. While it won't FIX the problem you can do a lot to save the lower end of the engine (crank, rod & cam bearings) by changing the oil frequently. With a coolant leak I don't know that the weight of the oil matters much, the important thing is to change it often so you're running oil & not an oil/water mixture. It won't take too long to scorch the bearings with a mix like that and then the only real solution will be a short block.

Have you had any work done to it lately ? I've seen coolant contamination after a rebuild because the head bolts weren't sealed. Some of them pass thru water passages and if they aren't sealed with silicone the coolant will leech into the crankcase, same thing can happen when using simple beads of silicone instead of actual gaskets on the intake manifold, so if the truck is new to you or of someone has cracked open the top end this may also be the reason.

 

[90-BRONCO325]

My 90 Bronco is doing the same thing. White milky liquid in the air box and on the oil cap itself. Mine's not running hot, just normal temp. I just had the rear main seal replaced because it was leaking oil like crazy. But I still have oil in the airbox. Someone told me to check the pcv valve. Could that really be the problem?

 

[Burns]

My 90 Bronco is doing the same thing. White milky liquid in the air box and on the oil cap itself. Mine's not running hot, just normal temp. I just had the rear main seal replaced because it was leaking oil like crazy. But I still have oil in the airbox. Someone told me to check the pcv valve. Could that really be the problem?

That's what everyone keeps telling me, blowback from the PC(V?) valve. I get a little oil in the airbox, but it never seems to get more than a little bit until I clean it out, then it comes back.

 

[cj_92Bronco]

to answer BroncoBills question, i dont think my engine is running hot. it has plenty of coolant in it and AS LONG AS the temp gauge is running correctly, which i think it is, then i think its all good. Yeah i think its time for a valve and compression check. How much do those gaskets usually run and how hard are they to install with a haynes manual?

 

[cj_92Bronco]

and no changing the PCV valve wont fix that problem cause i just changed mine and it didnt do a thing

 

[Broncobill78]

and no changing the PCV valve wont fix that problem cause i just changed mine and it didnt do a thing

OK, to reply to a few of the recent posters. Just how many miles are on the engines in question ? I used to see this A LOT in our high mileage cruisers, with them it was a combination of worn cams & worn valve seals. The worn cams would allow more blowback thru the carb because the valves weren't closing right when they should have been and the problem was worsened by the fact that oil was seeping up past the worn valve seals. The end result was a 1/2 qt of oil in the air filter every 500 miles or so. To be honest with everyone my 88' is the *newest* Bronco I've ever owned and I'm still learning my way around the fuel injection but it seems like a simillar problem. Changing the PCV valve won't change anything because it's *designed* to allow gasses from the crankcase to reenter the intake manifold to be re-used & burned by the engine so any oil mist in the head is going to be picked up by the PCV & transported to the airbox, that's what it's *supposed* to do.

To get back to the original question for a moment, how does the il on the *dipstick* look ? Is it the same cream color or are there any small greenish bubbles in it ? If it looks just fine & the level is correct then the problem is something else. Also, performing a compression ck is rarely a waste of your time so I would still advise doing that just to rule out the head gasket as well as getting a baseline.

 

[cj_92Bronco]

when i check the dip stick it doesnt have any abnormalities at all, its clean and brown

 

[Broncobill78]

I'd ck it closely to be sure there aren't any small greenish bubbles on it but if not then you're in good shape & what you're finding in the airbox is just blowby that the PCv valve is sucking out of the cylinder head. You *may* have worn valve seals that are contributing to the problem or it may just be the normal blowby for the milage & wear that your engine has. Without being able to look at it it's hard to say. You have to remember that the *job* of the PCV valve is to ventilate the crankcase & to transport those gasses back to the intake side of the engine to be burned. This is a normal thing to see in a high-milage engine. If this were a 10K rebuild then yes, I'd have some concern but unless I'm mistaken that isn't the case here. You've got worn rings, worn valve seals & a worn cam, all of which will contribute to this problem. Best advise I can give at this point would be to wipe out the airbox with paper towels and monitor just how much blowby is being deposited between oil changes. If the dipstick is clean then there isn't any coolant in the oil and what you have is just a normal high-milage pushrod engine. Be aware of it & keep am eye on it but that's really about it until you're ready to rebuild/replace the engine which might not be for another 5-10yrs

 

[madmax]

I'd ck it closely to be sure there aren't any small greenish bubbles on it but if not then you're in good shape & what you're finding in the airbox is just blowby that the PCv valve is sucking out of the cylinder head. You *may* have worn valve seals that are contributing to the problem or it may just be the normal blowby for the milage & wear that your engine has. Without being able to look at it it's hard to say. You have to remember that the *job* of the PCV valve is to ventilate the crankcase & to transport those gasses back to the intake side of the engine to be burned. This is a normal thing to see in a high-milage engine. If this were a 10K rebuild then yes, I'd have some concern but unless I'm mistaken that isn't the case here. You've got worn rings, worn valve seals & a worn cam, all of which will contribute to this problem. Best advise I can give at this point would be to wipe out the airbox with paper towels and monitor just how much blowby is being deposited between oil changes. If the dipstick is clean then there isn't any coolant in the oil and what you have is just a normal high-milage pushrod engine. Be aware of it & keep am eye on it but that's really about it until you're ready to rebuild/replace the engine which might not be for another 5-10yrs

you could just pull the hose off the air box, at that point before the filter the vacuum would be basically nothing, it goes into the box mostly to burn the fumes. Also try pulling your upper intake manifold, check for oil in the lower intake manifold, i noticed that when i changed the fuel injectors so I disconnected the hose from the air box and the back of the upper intake manifold, then I screwed a plug into the back of the manifold to prevent a vacuum leak and added a short section of hose to angle it down. Had no problems with the back right and left plugs wanting to foul ever since (the oil appeared to be condensing in the lower intake manifold, probably shouldn't be running 10W30 in that engine any more), very slight wisp of smoke from it if their's no air current, but you can only see it when the light catches it just right. Yea it pollutes a little more with the normal 130k blow by and normal oil fumes not being recycled into the engine, but I'd rather not **** dirty air into my engine.

Right now if I were to start it up it'd smoke like **** from all over the place, but that's cause it ain't been driven much in the past year as I've been restoring the body, sadly I've not got much time to work on it, just an hour or two here and there but I'm mostly done.

 

[barrett86]

lol, well switch to 5w-30 , watch ur leaks , and if ur running fully synthetic like me then it will find any and all leaks on your truck man, ? for you did u by any chance switch from convential oil to synthetic back to convential oil, if so that maybe helping to your problem.do any oil change and id advise going to synthetic oil and go to 5w-30, easier on our old girls, and they like it better too , being cold, my warm-up time cut in half.did u say that u changed ur PCV vavle. if so try changing the cap and hose too.sometimes its always good to replace stuff when having issues.let me know thanks.

 

[Broncobill78]

sometimes its always good to replace stuff

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