I recently was given a 97 f150 with the 4.6 v8. It's got around 160k on it.

It leaks oil on the ground where it's parked. I'm having a hard time pinning down exactly how fast it leaks oil. One week it needed over a quart. Then for the next 2 weeks it didn't seem to need any, then after that it dropped again. But there's no questioning that it's making a decent oil spot in its parking spot.

It also gives off a smell of oil burning, it's most noticeable on startup with a hot engine. but the smell comes from under the hood rather than the exhaust as far as I can tell. Though I wouldn't be surprised to know that it was also burning oil in the cylinders, that is probably not something i'm going to stress about in a 20 year old free truck. Mainly I am interested in the burning smell/dripping oil.

I haven't done a lot to try to pin down the leak yet. When I was under it to change oil, I noticed the oil pan was pretty noticeably oily. Maybe leaking from the gasket there because there was more liquid oil there than anywhere I've seen on or around the engine block. So that might explain the oil on the ground, but I don't think it explains the burning smell because why would oil from the pan wind up on the engine block?

Today when poking around under the hood I noticed a part that has a bunch of oil on it that I'm pretty sure ought not to. It's the thing that goes into the engine behind the oil fill cap. Behind as in closer to the cab.

I'm going to attach a picture (if it lets me as a new member). The picture isn't from my truck, i found it on the internet. Ignore the red arrows I didn't put those there. The part I'm talking about is the one past the oil cap that has an elbow and then is wrapped in what looks to me like pipe insulation. I guess I don't even know what that part is. I'm not a car guy by trade but I've got a decent set of tools and can follow instructions so if it's not too bad of a fix I'd like to try.

Is it common for this to leak and is it usually indicative of a larger problem? Or just a failed part on its own. And is this part leaking likely to cause the burning smell or is that unlikely. When I was looking at it, it wasn't dripping oil or anything but it was definitely well coated with oil more than any other part around it.

Thanks for any help and suggestions.

 

PCV valve.
If that drips oil it could leak down on an exhaust manifold and stink. Usually oil on the block won't burn until it reaches the exhaust manifold.

If the PCV valve and corresponding tube on the other side are neglected, it can blow out the rear main seal which would leak a significant amount of oil. And leaking out the rear main can drip onto the exhaust crossover pipe and burn stink.

Start by replacing the PCV valve and making sure that ALL OF THE VACUUM LINES on the engine are in good condition and do not leak. Plan to replace them all; since the PCV valve has been neglected, I would expect there to be other parts that also need maintenance.

 

Perfect, thanks for that information. I've replaced a PCV valve before on a different vehicle so I probably should have known this one.

On rockauto I see they have a 25 foot roll of 8mm ID vacuum hose for $135. Is that an excessive amount or price to pay? And would that be the correct diameter for all vacuum lines, or would there be different diameter lines in different places? And finally, does replacing vacuum lines entail significant disassembly of other parts for access, or are they pretty easy to get to? I googled for diagrams and there are some but they're pretty basic 'blueprints' that I'm not completely sure I'll be able to translate to identifiable parts under the hood. Might be a good learning exercise.

 

Sam is spot on with advice to replace vacuum lines. What I did was unhook ONE end of each hose on the engine, marked where it went, looked to see if a size was stamped on the hose, if so estimated the length you need. If no stamping to show hose size, clip off a small piece. Do this to EVERY hose you can reach, then go to the parts hose and guessetimating, buy what lengths and sizes you need. There are 4 sizes total if I remember correctly. Good Luck.

 

If a vacuum hose leaks, you will have idle problems, vacuum operated HVAC problems, or CODE set.......... worry about the oil first.. External could be the PCV valve, valve cover gasket, or pan gasket. I have tightened cover bolts 1/2 turn on older engines when leaks were showing. ........ also a BAD PCV valve can make the motor suck oil into the intake manifold and end up burning it.................... not to say vacuum hoses are not important, but that's not your problem TODAY.

 

Thanks for the replies. I replaced the PCV valve today. It seemed like the vacuum hose slipped onto it awfully easy for it to get a good seal (probably because of the oil on it?) so I put a hose clamp over it. I feel like I notice it's idling smoother from replacing it but I could be imagining it. There's no diagnostic codes or other issues you said so I think I agree with you that figuring out why we're losing oil might be the priority for now. Doing all the vacuum hoses also seems kind of intimidating and would like to know for sure that it's got some life left in it before I do that.

From the top down, things look fairly clean as far as oil goes, though there's spots where oil has dripped onto the exhaust thing that comes out of the cylinders on the passenger side of the engine below the spark plugs. I think that is possibly related to the oil that's been leaking from the PCV valve.

But I happened to shine a flashlight above the passenger side wheel and noticed that the exposed parts there are coated with a significant coating of liquid oil. So that has me pretty worried now. This weekend I will lift it up and try looking closer from underneath. And maybe remove that wheel to get a look in from the side.

I've only been under it once and I was changing oil at my dad's place so i didn't have my ramps or stands so there wasn't a lot of room that made me want to explore around, and it was getting dark and getting at the oil filter on this truck completely sucks so I was really focused on getting that done before I got stranded out there for something as stupid as failing to change oil.

so i think a closer look around under better circumstances will hopefully give out some more info. im sure i will be back on here either tomorrow evening or saturday with more questions and pictures.

i appreciate the input so far.

 

get on the ground on the passenger side and slide under the truck (make sure the truck is not going anywhere) look at the center of the engine and trans, there will most likely be oil there, follow the oil up the passenger side of the engine, above the starter, look closely it's either leaking from the rocker/valve cover which will be above the exhaust manifold OR it's leaking from below the exhaust manifold between the head and the block

up higher is rocker cover gasket leak
down lower is head gasket leak

both are fairly common

 

you can also get a spray can of degreaser from the local parts store.. Spray it on the oily areas and let is soak in for 10 minutes... wipe off everything you can with some paper towels... take your time... now it will be easier to see NEW oil leaks. If it don't leak setting in the driveway, then drive a couple miles and look again. Don't wait 2 weeks until oil is EVERYWHERE to try to figure it out...... also look around the oil filter.. o-ring not seated or out of groove can cause leaks also.