oil puffing out of fill cap

geek · #1 (**permalink**) 09-03-2009, 02:38 PM

So I'm trying to bring back a 1966 F250 with a 352. I don't know the exact history but I don't think it has been sitting for an extened period of time but it hasn't seen much action over the past few years and has seen even less maintenance. It's new to me and I'm new to the 352. I am installing a new radiator this weekend (first things first).

Initially it was spitting oil out of oil cap causing a big mess. Replaced with new fill cap and drained the sludge out of it and replaced with actual motor oil. Now it's starting fine and sounds good and its not blue-smoking out of the tail pipes but at about about 10 miles into light driving it starts to puff smoke out of the fill cap. Also start hearing the lifters and knocking about the same time. On the whole it looks tight but the value cover on the driver side (with the fill cap) is lighlty oily but I assume this is from the puffing smoke. I'm not seeing any new spots on the driveway...

I'm still waiting for my manual to arrive from faxon so I don't plan on digging into it just yet but seeking info/guidance on what I should be thinking about and where I should start poking around. Thanks.

PROSTOCK · #2 (**permalink**) 09-03-2009, 03:20 PM

Sounds like excessive crancase pressure to me. It could be that its just plain old worn out...clylinders and/or rings. Could also be stuck rings if it has been sitting a while. But the fact that once it starts to warm up things start to rattle indicates it's just worn out.
My ole 352 sat for about 18years. I diddn't dare attempt to starrt I began with a teardown. After seeing the almost .010 / side wear in the cylinders I knew it was rebuild time. What I didn't know is that the friggin 352 pistons are prohibitively exspensive. I ridge reamed the cylinders, threw in new crank/rod bears, rings and lifters. That was back in 1997. Yes it runs great, but it does have blowby especially when under a load (its my log hauler). I have a 397 ready to drop in one of these days. Spending too much time playing with my kids and an Rx7

Mustang6147 · #3 (**permalink**) 09-03-2009, 03:33 PM

My opinion, is you have a couple of issue's going on... Sludge, put my mind to a clogged oil pickup, which would be inline with noisey lifters at higher rpms, (off idle) Smoke out the filler is a sure sign of broken or worn piston rings, but other things can cause this to... Crankcase pressure being one of them. SO is your PVC plugged with sludge also???

If it were me, I would try either kerosene in the oil, or motor flush. These products or things I recomend, are not common today with modern engines. Infact they went out back in the late 70's however your enigne is part of the era that it was normal. A good flusshing would clear the sludge, with out haveing to drop the pan. But if the pan is easily dropped, it is what I would do and reccomend...

tbm3fan · #4 (**permalink**) 09-03-2009, 04:50 PM

I would drop the pan and see what it looks like. I'm sure there is plenty of thick sludge which is why I wouldn't use a flush. If it also has the original timing sprocket, and if it had the nylon teeth, then many will be in the oil pickup screen for sure. All this could block the oil from moving into the engine if a flush is initiated. I would also remove the valve covers and look at the drain back holes front and rear in the heads. Wouldn't be surprised if the rears are compromised also.

Customcab · #5 (**permalink**) 09-03-2009, 05:53 PM

Other things to look at is the PCV. Usually as mention above your got worn rings. I having the same problem with a 300 engine. Runs like a scalled dog but pisses oil everywhere.

Mitch

banjopicker66 · #6 (**permalink**) 09-03-2009, 06:20 PM

You might want to check the drain holes in the heads. Since you had a lot of sludge it is probable that the drain holes are plugged with it. This is typical of this generation of engines and the oils they used. Modern oils do not do it as badly.
I am betting the drain holes are plugged. The engine sits at a slant, allowing the oil to drain to the rear. If the holes are plugged the valve covers will fill up with oil and it will push out the breather or filler cap.
Pull the valve covers, and look for the drain hole at the back of the head, and clean it out.

geek · #7 (**permalink**) 09-04-2009, 12:58 AM

Thanks for the ideas. I think I've created a little confusion.

First, the title of the thread reads "Oil puffing..." it should read "Smoke puffing..." but I can't edit the original post (or I can't find the right way to do it). Oil was spewing out of the fill cap initially but now that I've replaced the cap it's got a tight seal and it's only smoke coming from the vented dome cap. This is occurring at idle and I assume at higher revs but I haven't rev'd with my head in the box yet. By the way, it is guttless high revs result in very little low end power. It will get up to speed without issue but it takes it's own sweet time about it.

Second, the "sludge" I drained from maybe over stated. The oil was black as night and a very thick viscosity but it did flow from the drain plug, slowly but it wasn't curdled milk...

I will definitely pull the valve covers and look for plugged holes. With regard to pulling the oil pan, if I don't see thick sludge would a flush be warranted? If I do encounter sludge all over the place, what is the recommended decon process?

While in the pan, I will also be looking for timing sprocket teeth (and any other god-forbid shards and chunks).

Now, to the PVC. Like I said, I'm waiting on my service manual... are we talking about a vacuum port coming out of the top of the intake manifold? Because there is a pneumatic quick disconnect on the rear bumper that has a leaky seal and is pulling vacuum from the intake manifold, through a hose that runs from the rear bumper to a tee joint. I was planning on pulling and ripping it out anyway but could this be contributing to blow-by and if so, how?

Lots of rambling here on my part. Thanks for the time and info, it's much appreciated.