427 FE sideoiler - Oil Consumption
 

I'm curious, how much oil loss/consumption would be considered "normal" of a 427 sideoiler.

I did my last oil change and topped off to the correct level. After driving most a tank of gas through (maybe 100mi for me) I checked the oil and it was still at an appropriate level though seemed a touch lower than i thought i remembered filling to. Then I did a longer road trip with the car, maybe 250mi in a single day, and near the end my oil pressure started becoming very erratic and dropping. So I immediately pull over and check the level and it is very! low. I add a quart and its still low. Another half qt brought it to proper level on the dipstick.

So when car sits in garage it has regular oil spots, but nothing excessive I would say. I don't see any exhaust smoke or indication of excessive oil burning. But by my account I'm losing close to a half qt of oil per 100 mi. Just wondering what you guys with more experience than I might consider typical on this platform.

Do you have a PCV? If so, before I even gave it much thought I would pull it, plug it, and drive for a tank-ful and see if my oil consumption disappeared.

I'm not sure if my engine has one - I'll check on it.

But assuming I have one, and that your change helps the situation, what is the indicated or implied issue?
That oil/vapor is being pushed through PCV and cycled into intake manifold and getting burnt off? Is plugging it considered a fix, or just a diagnostic step?
Just want to understand, thanks.

A PCV that sucks a large amount of oil is not an uncommon situation with FEs. If you really are losing a quart of oil for every 200 miles or so, and you don't have a big puddle on the garage floor, then it can only be disappearing for a couple of reasons. The easiest, simplest reason is that the PCV is sucking it in. If pulling and plugging the PCV, as a test, makes the oil consumption go away, then fixing it is relatively easy. You can then either: 1) Remove your PCV entirely; or 2) Baffle your valve cover on the PCV side. you might also add a nicer PCV valve, like the ME Wagner, along with an oil air separator. But if plugging the PCV as a test does nothing to the oil consumption number, and it really is about 1 qt. every 200 miles or so, then you'll need to look elsewhere.

There is a huge difference between leaking oil and burning oil. Sounds like you're consuming it. The pcv path is one. The others are not good news.

Note 1: Q: how do you tell a side oiler is out of oil?
A: It stops leaking

You might have a possible intake manifold leak as well, that's a somewhat common issue in the FE. If the PCV investigation yields no results, pull your spark plugs, see if any are oil soaked or discolored. That'll start you down the trail of learning where the oil is entering your combustion chamber(s). You'll need to start tearing into the engine to learn where the pil is entering the chamber to be burned. First step is pulling the intake and look for telltale signs of intake gasket failures and/or a poorly machined and fitting intake. If you find you have "Print - O - Seal intake gaskets, you may have found your issue right there. Good luck.

But as an interesting point that you rarely hear discussed, the oil consumption in my big beautiful FE is not consistent from the FULL mark down to the ADD mark. My consumption for the first half quart is noticeably faster than it is for the second half quart. In fact, my consumption trails off dramatically when the oil level hits around the half way down mark.

Thanks for advice thus far. One followup question. I always understood (at least with modern cars) the the PCVs purpose was to prevent rising crankcase pressures, which would result in oil getting pushed past the seals and such, ultimately leading to increased oil consumption. So forgive me if this is a dumb question but wouldn't closing off the PCV lead to essentially the same thing happening via some other channel?

I was a Product Engineer at GMC Truck in the mid-90s. At that time 1 quart per thousand miles was consider acceptable.

It was rare. Most didn't use enough to need oil between changes.

John

I did exactly what Patrick suggested.
ME Wagner PCV with an ADD W1 catch can plumbed between
the PCV to carb hose. The ADD Wi is a compact oil-air separator
with the novel idea of a dipstick to monitor oil level in the can.

Product info here:

https://www.addw1.com/collections/oi...-configuration

M/E Wagner Performance Products – High Performance Crankcase Ventilation Systems

You have a vent on the other valve cover that allows air to be sucked in. If you chose to dispense with your PCV entirely, you would still vent the engine. Most of us, but not all of us by any means, choose to run a PCV on the street as it keeps your engine a little cleaner on the inside. One old fashioned trick to monitoring crankcase pressure is to see if your dipstick is getting pushed up out of the tube (which is another vent, kinda). Plugging your PCV tube should tip you off pretty quickly as to whether that's the problem.

MD427 , yes ..... removing the PCV can increase crankcase pressures . Answer is simple ... a breather in the VC on each bank will let in enough air for that to not be a problem .
I tend to agree with others that the PCV is where I would start since this ( if I read your posts correctly ) just started right after an oil change and wasn`t building up over a time period .
I had to play around with a bunch of different PCV valves before I found the right one .
Pull a few plugs , with that much oil usage , they should be covered with oil .
The PVC check is the easiest one of the solutions to try first . I would tend to write off the VBC baffling as the problem just started and I`m guessing the VC`s have been on the engine for a while .

Here are two pics that might help. The first is my ME Wagner pcv valve, which is adjustable and I absolutely love it, along with my Moroso oil/air separator. The second pic is my baffled valve cover. Both of these tasks are really pretty easy. If your oil is being consumed by the engine via another path, then the difficulty level increases.

http://38.134.118.239/pcv_top001.jpg

http://38.134.118.239/baffle001.jpg

Catch cans installed to catch miniscule amounts of blow-by oil because that oil reportedly drops octane rating in half is a crock o bs. I've never seen a catch can on a street car ever have more than a teaspoon in it after thousands of miles. Most catch cans are installed on supercharged systems. My Kenne Bell on my Shelby GT came with one and it never collected other than a trace after about 10000 miles. Didn't solve a problem but didn't expose one either.

Now, if you have more than that, and I agree, then the catch can is providing a diagnosis of a problem. If you have a catch can and regularly collect lots of oil YOU HAVE A BIGGER PROBLEM. The catch can isn't fixing it. It's exposing it.

So if the OP wants confirmation that the PCV path is the cause of the lost oil then a catch can can help confirm that diagnosis. Perhaps a little sooner than removing the PCV system temporarily. The can confirms the diagnosis, removing the PCV infers it. But it costs more... In the absence of this kind of issue a catch can is only solving one problem: Adding more money to the seller's bottom line.

You can build a functional one for about $10 of parts from Home Depot.

Note my car with a SBF 427 didn't have a complete PCV path. Just some kind of K&N filter over the hole. It did show some oiling, but never enough to be a concern.

Anything that gives me an excuse to monkey with my FE is welcome.:cool:

Ah, a tinkerer. Can't dispute that. It was the one thing I liked about my Cobra. There always seemed to be something to do. I never did identify the source of some of the bolts/nuts on the ground. I concluded the gestation period of a mating bolt/nut pair is about 3 weeks.

To be clear we don't really know how long this has been happening. As said earlier, I've put 300 miles on the car in 6 months. But I bet the motor doesn't have a combined 300 miles on it in the 15 years prior to that. And an outside mechanic was doing the annual maintenance, and oil changes. It's possible that it has been like this for a very long time and we just didn't notice due to how infrequently it was being driven.

Make sure you have a baffle of some kind inside your valve cover blocking direct splash of oil on the PCV valve, if you do not have one you will burn lots of oil.

Ok. So we're going to make you drive the car for a tank of gas with the pcv plugged. I know it will be torture and you'll hate us for it but you started this and now the peanut gallery wants to know what's going on. ��

If your going to pull the plugs, run a compression and a leak down test. How was the motor broken in? Also what kind of oil are you using?