460 oil consumption

[viven44]

Ok I want to talk about oil consumption.. I’ve roughly put about 700 miles on the build and wanted to wait until I addressed all the low level oil leaks (valve covers, etc)

The 460 on the bronco is using oil  and a lot. A quart every 300 miles or so. No leaks anywhere…. No smoking..

Compression is excellent on all cylinders so I don’t think anything malicious in the short block.

Possibly valve guides…. Would high mileage oil help any here if so?

But my top suspect is my PCV valve. I kept the original and it routes to the Edelbrock. There is very strong suction while idling. I guess I should remember that at idle the PCV should be partially closed, but not sure if that’s the case here…

Big Blue 2WD seems to have a valve of some kind ahead of the PCV valve, I’ll see if I can find a pic. That entity is missing on the bronco ..

I’m running conventional 10W-40

[ArdWrknTrk]

You need to partner up with Rene on the vanishing oil.

I don't see how you could be burning a quart every 300 miles and not have a huge blue cloud following you everywhere.
Valve guide seals would be smokey when you started the Bronco and when you let off the throttle (intake vacuum sucks oil past the guides)

But if it's not on the ground and your plugs look good the only other place it could be going is into the coolant system.
Is your antifreeze murky brown?
Do you have an oil slick on top if you remove the radiator cap?

The PCV is meant to be a controlled vacuum leak that allows engine vacuum to pull combustion byproducts and condensation vapor out of the crankcase before it creates sulphuric acid in the sump.

Is the PCV hose full of oil?
Not oily, as normal, but like you're using it as a funnel.
Again, you'd see this coming out the exhaust and your plugs would foul.

[viven44]

Jim, negative on the coolant. Still green as can be. Nothing murky.

On the PCV, my hunch is there because

-- plugs are not fouled but don't look great either
-- there isn't blow-by if I start the truck with PCV valve removed and valve cover opened and let it run/get hot... there might be very mild blow-by which is hard to see... but if I let the PCV valve do its thing inside the valve cover (Suction) and then remove the PCV valve, there is all kinds of smoke/vapor/blow-by coming out of the valve cover

The hose is pretty empty when I pull the valve... but there is little left in it because the strong vacuum does a good job of emptying it... but I can definitely see the inside of the valve all oily.

[ArdWrknTrk]

The valve is going to be oily, that's it's job.

I'm not sure what you mean by "all kinds of smoke/vapor/blow-by"
There's always going to be some. No engine has 100% ring seal.

Maybe you should do a leak down, or at least compare all 8 cylinder compression numbers?

A quart every tank!?!?
Something is very wrong.

[viven44]

PCV on Big Blue 2WD



What is that quarter-turn valve looking thing ? The bronco is missing this at the moment.. It is probably in a storage box somewhere when I removed the 460 from the pickup

[viven44]

It has been a while since I ran compression but the last time I ran it, think the compression numbers were acceptable.. those plugs are the old ones I pulled out when it was still running on the 4180.. they were badly fouled. The new plugs after 700 miles don't look anywhere as bad. Not as good as Gary's that he posted recently but you can tell they are starting to get fouled.

I spot checked a couple of cylinders recently to see what the new timing chain did  to the numbers and the numbers are still in the same range...

[85lebaront2]

That is a hot idle compensator. It opens with high underhood temperatures to lean the idle mixture slightly. They have been on some carbureted engines since the 60s. Carter AFBs had them in the main body between the secondary clusters.

[viven44]

Thanks Bill, it seems that the hot idle compensator shouldn't affect PCV function if I am not mistaken. That is a good bit of knowledge to remember.

[ArdWrknTrk]

I've seen them in vans, but never in a pickup.

[viven44]

Yes I agree it is not normal... on Big Blue 2WD where the compression is definitely more questionable (few cylinders close to 100 while others in the 120s), I do not lose any oil whatsoever (up to 2000 miles I have gone where I saw maybe the oil 1/8 - 1/4 inch down on the dipstick). I was losing a quart every 50 miles when I first bought the truck!

I am planning to add a witness catch can see if this picks up anything abnormal. Also going to replace the PCV valve while at it. I did install a new PCV valve on Big Blue 2WD early on.

https://www.amazon.com/dp/B081N392BN/?coliid=I1NZ8HU7ZC92TL&colid=3IGQF00LDI4AO&psc=1&ref_=cm_sw_r_cp_ud_lstpd_BSN7PFWA4M8NH11YAXT1

[ArdWrknTrk]

And now you are with Rene....

[viven44]

I think I know the thread you are referring to. I was loosely following it.

Going back now, I notice Matt saying something interesting

mat in tn wrote

one of the fixes was where the later versions had the pcv draw connection moved to the front of the plenum between the front two runners instead of at the rear.  the best correction that I can recommend is a catch can. this should get mounted to the firewall higher than the pcv to allow drainback into the valvecover and then a longer hose connecting to the intake. or you could source a later model upper which can bolt on perfectly. catch cans are used more in high revving, high stress situations like road course racing but you can use one too.

Does this mean drain back would occur when the can fills up entirely or a combination with the can filling up... ?

It makes sense for the PCV hose to be higher to allow drain back with or without catch can.

[ArdWrknTrk]

In racing oil separators are set up like a cyclone to drain back into the engine.
It would be stupid to have it fill up and just be carrying around oil that isn't doing anything for lubrication.

Taken to the extreme you have dry sumps that reduce/eliminate windage losses, but the pump is drawing from that reservoir, like 5.0 high pressure fuel pumps.

If you really get crazy you put a vacuum on the whole crankcase reducing pumping losses as pistons rise and fall, shifting air around in the block.

[85lebaront2]

You havn't really had fun with a PCV system until you fool with one of the older Chrysler turbo 4 cyl. engines. On the NA carbureted or TBI engines there is either an oil seperator or two connections to the valve cover. Turbo engines use a cast aluminum valve cover with a nipple at what would be the rear of the head.

On that nipple is a molded rubber tee with one leg on the nipple, a special PCV valve that seals under manifold pressure and a pipe going to the air filter housing for air in or out. The early turbos had the throttle body before the turbo so the PCV connected there, that combined with the EGR feeding there created a nice mess.

With the intruduction of the Shelby designed TurboII system, the throttle body was moved to behind the turbo and the closure line was left in the air filter housing. Less oil in the turbo but you still at 14 psi boost ended up with oil in the air filter housing.

In 1991 the system was redesigned again, PCV valve is still in the molded tee and the closure line still goes to the now larger air filter housing. In this is an oil trap with a drain hose to the turbo oil return pipe on the back of the block. It has a check valve with a very light spring so the oil can only flow into the engine through that line.

If you can make a centrifugal seperator, air from the valve cover coming in at a tangent with a baffle so the liquid is kept in the bottom. Drain line through a weakly sprung check valve and the PCV valve drawing air from above the baffle. It might need a bit of capacity as it might not drain until the engine is off.

[viven44]

Thanks Bill, that's a very interesting idea... and along the lines of what i am thinking... If I can play with a off-the-shelf catch can and prove that I have an excessive oil catching problem, I'd definitely be interesting in finding an automated way of getting that oil back in. I don't recall if there is a second dipstick port on the timing cover or not.. that might be another way to get it in. Some of the catch cans come with a bottom drain hole.

My friend had a problem on his VW Jetta (2009) on the 2.5L engine where the PCV crank case vapors were not handled properly and it would go clog up and ruin the MAP sensor. The dealer told him he needed a new engine as they simply could not figure out what was going on !! He just had them install a new MAP sensor and drove it.. As a couple of years went by and the problem became so wide that a catch can became the permanent fix. That is the only production modern vehicle I am aware of that had an obvious PCV problem.

[ArdWrknTrk]

Plenty of vehicles with MAF TSB's.
You know the MAF isn't fouling itself!

The problem is the PCV passing too much oil, ultimately that there's TOO much blow-by because of crappy rings, cylinders or pistons push a lot of mist & vapor
.

[viven44]

As I pursued the PCV angle, I installed a new PCV valve today and also noticed that the PCV hose was pretty clean... I will setup a catch can setup ... but only as a precaution.

I am also considering the valve guides. If you recall in another post, I said there was smoking when revving at idle. I think a lot of it has gone away as I moved the accelerator pump setting on the carb to the leanest... I need to pay closer attention to any smoking like that now... whether it is smoking from running rich or from letting go of the throttle (Valve guides per your reply)...

I do not have history on this 460 (if it ran high mileage oil ever previously etc), except it came from a pretty original truck in very very good shape before it was totaled... the block had been painted blue, and the core plugs looked new, the valve trained looked great, timing set was retarded but no plastic gear, which indicates some level of rebuild and maintenance.  Based on history of that truck, the PO put about 200-300 miles a year and had it continuously registered... most likely oil changes at lube joints..

One thing of note is that the vacuum modulator on that truck had leaking for quite a while so ATF was being burned a lot!!! I wonder if excessive ATF burning can affect long-term characteristics that sort of morph into oil burning. The transmission fluid was very low when I got the truck

The other goof up was the water pump missed the plate, so they had bypassed the thermostat. So in the winter months it probably ran cold a lot.

If it is the valve guides, I do not want to get into it anytime soon. I am wondering if walmart supertech high mileage 10W-40 oil would be good to try...

[ArdWrknTrk]

Fuel is black, oil is blue.
Blue smoke on startup = intake guide seals.
The engine probably got a rattle can rebuild when they changed out the stripped cam gear and (hopefully) cleaned the shreds out of the sump pickup.

ATF isn't going to hurt anything. If anything it will keep the rings free and the valve stems lubed, like Lucas sells in a bottle for $25!  

[viven44]

I did not find any shredded matter and the inside was quite damn clean...

Speaking of smoke color. I am pretty sure it is light in color. Definitely not black.

Looks similar to the one below on Big Blue 2WD. I made that video as I was piecing that side exhaust ... it wasn't fully done yet

In that video you can notice the blue smoke on start-up (oil) and later with revs towards the end it is black (fuel). I need to document the same on the Bronco.

https://youtu.be/elPBmygZihs?si=aTdGLj-8RomF4Njg

[ArdWrknTrk]

Then it's not fuel.

"High mileage" oil doesn't really mean anything except it might have a bit more detergent to loosen up deposits.
But you said your engine is clean as a whistle (as is mine, that's been in for 16 years)