Constant Oil Leaks

[clinem03]

76 u15 Wagon, original 302 (with some fixes/upgrades but mostly stock), manual 3 speed. I use 5 qt's 10W 40 oil with a qt of Lucas heavy duty oil stabilizer/ leak stop.

I have had constant issues with oil leaking from my engine in a few main areas

1. The oil filler cap
2. The rear passenger side valve cover
3. I went through 2 Fuel Pumps (manual) as oil started spraying out the weep hole on both occasions. I have not had this issue for almost a year now
4. Rear wall/seal on the intake manifold (I removed it, restored it and replaced it and am now not having issues)
5. Heads - likely a blown gasket as they appear to be original to the 302

I have come to the realization that it is time for a full engine rebuild and am working on setting that up for spring next year as I believe I have a blown ring...and well, its just time as everything else has been rebuilt or replaced. In the interim I am looking for some guidance as the oil leaks are now getting worse (at the oil breather cap and the rear passenger valve cover) and I would like to see if there is a temporary fix to get me to spring as there is a bit of smoke coming from the engine bay when driving her. It appears to be coming from the oil hitting the manifolds.

two questions:
1. I cannot for the life of me find a new gasket for the oil filler cap. I looked all over, and even asked the parts stores but it doesn't appear anyone sells one. My buddy who has a speed shop, gave me the one thats on there now, it was a 'paper' one that immediately stopped the leak. I think it was a Mr. Gasket one he had laying around. I believe it has reached the end of its useful life as the leak has reappeared (after about 1 year of use)
2. I added an oil filter cap on the read passenger side valve cover. Some oil was leaking out, but not a ton. it is now super saturated with oil which I think is causing more oil to get through. Can I cap it off? Is there a better option than what I have on there? (see photo)

 

[1970 Palmer]

There's ways to actually test your engine to help diagnose what needs to be repaired. Even if the repair ends up requiring a full rebuild, it's in your best interests to actually know what to look closely at when it's torn down. A compression test will tell you which cylinder might have the broken ring. A leak down test will tell you about your head gaskets, etc. How is the oil pressure (use a test gauge in psi), hot/cold?

The first thing that jumps out to me is why does it require zip ties to hold the PCV hose on? The hose (should be) under vacuum, not pressure, unless this engine has a ton of blow-by. You can test by just removing the cap, then place your palm over the valve cover hole. If it has excessive blow by, you will never get it to stop blowing oil out until it's repaired

What kind of oil baffle does that aftermarket K&N cotton style filter have? I bet nothing? Does the valve cover have a baffle?

Diagnose first, then make your repair plan.

 

[Timmy390]

Just off the description it sounds like excessive blowby or a non-functioning PCV system. Oil mist mixes with air and it's trying to escape through the fill hole (heat rises). Baffles in the valve cover help but mist still gets by.

You could swap to newer F150 or van valve covers and have a better fill hole. I did that on my 351W,

Tim

 

[clinem03]

There's ways to actually test your engine to help diagnose what needs to be repaired. Even if the repair ends up requiring a full rebuild, it's in your best interests to actually know what to look closely at when it's torn down. A compression test will tell you which cylinder might have the broken ring. A leak down test will tell you about your head gaskets, etc. How is the oil pressure (use a test gauge in psi), hot/cold?

The first thing that jumps out to me is why does it require zip ties to hold the PCV hose on? The hose (should be) under vacuum, not pressure, unless this engine has a ton of blow-by. You can test by just removing the cap, then place your palm over the valve cover hole. If it has excessive blow by, you will never get it to stop blowing oil out until it's repaired

What kind of oil baffle does that aftermarket K&N cotton style filter have? I bet nothing? Does the valve cover have a baffle?

Diagnose first, then make your repair plan.

This is great advice, thank you! Need to go do some research on performing these tests as I havent done them before. I added zip ties as the line was in rough shape, they are just extra support from the line slipping of (which hasn't happened). The valve cover has a baffle, but the drake/K&N filter does not.

 

[clinem03]

Just off the description it sounds like excessive blowby or a non-functioning PCV system. Oil mist mixes with air and it's trying to escape through the fill hole (heat rises). Baffles in the valve cover help but mist still gets by.

You could swap to newer F150 or van valve covers and have a better fill hole. I did that on my 351W,

Tim

Is excessive blow-by something that can be fixed? What typically causes it?

 

[Timmy390]

Is excessive blow-by something that can be fixed? What typically causes it?

Typically an indication of a tired engine in need of a rebuild. Rings are letting combustion into the block. Excessive cylinder wall and ring wear

You need to preform a compression test to see if it's the rings leaking.

Tim

 

[56f100bbw]

Well somebody on this forum said if it not leaking it must be out of oil that’s my case mine always leaks somewhere transfer case transmission I gave up mop it up drive it and have fun

 

[clinem03]

Typically an indication of a tired engine in need of a rebuild. Rings are letting combustion into the block. Excessive cylinder wall and ring wear

You need to preform a compression test to see if it's the rings leaking.

Tim

Makes a ton of sense...thanks!

 

[clinem03]

Well somebody on the this forum said if it not leaking it must be out of oil that’s my case mine always leaks somewhere transfer case transmission I gave up mop it up drive it and have fun

hahhaa - agreed! I have been cleaning up oil for a while, but I don't like smoke coming from my engine bay with the oil hitting the manifolds. Thats hard to overlook...

 

[56f100bbw]

hahhaa - agreed! I have been cleaning up oil for a while, but I don't like smoke coming from my engine bay with the oil hitting the manifolds. Thats hard to overlook...

I think I would hate that too if you’re smoking on the hood I don’t have any of that no valve covers leaking I might have an oil pan leak but yeah I hate smoke

 

[Lawndart]

Don't be too quick to go for the rebuild - unless that is your goal.
Do a compression test.

 

[gnpenning]

While I'm more of a cylinder leakage fan you can learn a lot from a compression test. Cylinder leakage pin points more closely where the problem is.

Have you pulled your pcv and checked for vacuum on it? While it's running with the valve out can you see/feel blow-by?

 

[clinem03]

While I'm more of a cylinder leakage fan you can learn a lot from a compression test. Cylinder leakage pin points more closely where the problem is.

Have you pulled your pcv and checked for vacuum on it? While it's running with the valve out can you see/feel blow-by?

Yeah, it has vacuum. Working on the compression test…

 

[68rustbucket]

They all bleed a little.
OP said he poured in 5 qts of oil, then 1 qt of oil stabilizer. What’s the reading on the dipstick? I thought the SBF had a total capacity of 5 qts Using a standard oil pan.
as for the valve cover leak, I’ve tried every gasket made, no gasket just sealant, different valve covers, and mine also leak in the back passenger side.

 

[1970 Palmer]

They all bleed a little.
OP said he poured in 5 qts of oil, then 1 qt of oil stabilizer. What’s the reading on the dipstick? I thought the SBF had a total capacity of 5 qts Using a standard oil pan.
as for the valve cover leak, I’ve tried every gasket made, no gasket just sealant, different valve covers, and mine also leak in the back passenger side.

Here's my path to no leak valve cover on a Ford engine.

Use Steel valve covers.
OE covers, not China aftermarket steel, never chrome plated steel.
Aftermarket aluminum covers are OK
I have never removed an OE Ford valve cover that was not previously over tightened and has the bolt holes distorted.
They need to be fixed before you install the new gasket.
Lay the steel cover on a work bench with a sharp edge like a welding table. Hammer the bolt holes flat using the table to back up the edge.
Take a long straight edge and make certain the valve cover is actually flat and straight at the gasket seal edge.
Never use rubber valve cover gaskets. Only use cork valve cover gaskets.
Glue the cork gasket to the valve cover with contact cement. Gasketcinch (now an Edelbrock Brand) is my "go to" choice.
Wipe a very light coat of grease on the gaskets mating surface after they are glued. Any kind of grease will do for this.
Never use more than a 7/16" socket on a 1/4" drive ratchet to tighten the hold down bolts. The torque is very minimal only something like 10 to 15 INCH POUNDS OF TORQUE. Hardly anything, DO NOT OVER TIGHTEN, OR RETIGHTEN. If you over tighten the hold down bolts, the covers will always leak.

Follow the above guidelines, you will never have a problem.

The same guidelines work on Ford pan gaskets. Just add a small dab of RTV in the four corners. Because of the loose end seals, it's best to glue the gasket to the block if you're working upside down with the engine still in the vehicle.

It's not rocket science, not a secret, just attention to details.

 

[m_m70]

I thought the SBF had a total capacity of 5 qts Using a standard oil pan.

Bronco pan is 6 qts

 

[00gyrhed]

First let me say these old engines were never meant to be leak free. We can make them leak free but it is usually temporary unless gaskets and seals are upgraded.

We also forget these days just how nasty and prevalent crankcase gases are. I once read that something like 70% of the total pollutants that entered the air from an automobile was from the crankcase before the PCV systems were installed. Back before PCV Even brand new engines would very quickly deposit oil all around the old vent tubes. In the 60s and 70s people would disconnect PCV systems and just allow them to vent though breathers like you have on one side of your engine, These breathers quickly became saturated. Even on brand new engines, so its not just a worn engine. Even today if you open up the manifold of a modern fuel injection system you can tell where the dirty oil mist enters the manifold. This is caused by a number of things in reciprocating machinery not just piston ring blow by. I have noticed in by long life that high lift cams will increase crankcase gas output. The old dip tubes on model A engines that dipped down into the oil to oil the rod bearing produced a lot of crankcase gas. Filling your oil level high enough that the rods hit oil will also increase the crankcase gas output. there are other factors but its not created by only blow by.

Run your compression check but it won't confirm you have excessive blow by. It will only tell you if you have poor compression. Which may not be due to worn rings.

Pull your PCV out and run it at a high idle. The crank case gas should be visible coming out under this condition but unfortunately you have no idea what would have been normal in the days before PCV. Even some brand new engines will often emit a yellowish oil laden gas that is high in carbon monoxide. This is actually normal and increases with engine rpm, and oil around the breather would actually be normal. Especially if you run that basically stock driveline at highway speeds ie. 3500 rpm cruising. That why the automobile manufacturers put it in the air filter can so gasses would get sucked into the engine from both directions if the crankcase gas was too much for the PCV valve.

Does the engine make good power, does it start and run well, does it smoke, does it idle or run rough?

Never rebuild an engine based solely on compression. A very slightly bent valve will make you think an engine is in need of a rebuild. I never pull an engine out to rebuild it without pulling the heads first. You have to pull them anyway why not leave the block in the truck. You will be able to see the condition of the cylinder walls and the valves of cylinders with low compression. Unless I have a rod sticking out the side I am hesitant to pull it out for a rebuild without pulling the heads first. Many times in my life a buddy has pulled out an engine only to find the very little ring ridge and the cross hatch still very visible on the cylinders without any scarring what so ever, along with almost perfect bearing inserts.

 

[1970 Palmer]

First let me say these old engines were never meant to be leak free. We can make them leak free but it is usually temporary unless gaskets and seals are upgraded.

They were not originally built with the idea they should leak. Dried out gaskets, seals, worn out parts, and blow by are some of the reasons old engines leak or drip oil. Stock, original equipment, correctly installed gaskets and seals do their job of oil retention just fine.

We also forget these days just how nasty and prevalent crankcase gases are. I once read that something like 70% of the total pollutants that entered the air from an automobile was from the crankcase before the PCV systems were installed. Back before PCV Even brand new engines would very quickly deposit oil all around the old vent tubes. In the 60s and 70s people would disconnect PCV systems and just allow them to vent though breathers like you have on one side of your engine, These breathers quickly became saturated. Even on brand new engines, so its not just a worn engine. Even today if you open up the manifold of a modern fuel injection system you can tell where the dirty oil mist enters the manifold. This is caused by a number of things in reciprocating machinery not just piston ring blow by. I have noticed in by long life that high lift cams will increase crankcase gas output. The old dip tubes on model A engines that dipped down into the oil to oil the rod bearing produced a lot of crankcase gas. Filling your oil level high enough that the rods hit oil will also increase the crankcase gas output. there are other factors but its not created by only blow by.

A Positive Crankcase Ventilation system is one of the greatest improvements ever added to an internal combustion engine. It works well at keeping the crankcase pressure from blowing oil out of the engine. Informed mechanics even knew this back in the 60's and 70's. Unlike most of the federally mandated emission systems added during this period the PCV system did not reduce horsepower or reduce fuel mileage like the retard ignition and cam timing systems did.

Race engines built today run belt driven crankcase vacuum pumps to reduce crankcase pressures to increase horsepower. High performance motorcycle engines have windows cut into the cylinders below the ring travel to reduce the crankcase pressure and produce "free horsepower". Reducing the crankcase pressure is much more than just controlling oil retention.

When you open the manifold of an engine, what you are looking at is the engine temperature hot spots where engine oil has burned like at the exhaust heat by-pass that keeps the carburetor from icing.

Long duration cams cause many blowby problems in a low RPM street engine. They are intended for (and work well in) high RPM applications.

Run your compression check but it won't confirm you have excessive blow by. It will only tell you if you have poor compression. Which may not be due to worn rings.

Pull your PCV out and run it at a high idle. The crank case gas should be visible coming out under this condition but unfortunately you have no idea what would have been normal in the days before PCV. Even some brand new engines will often emit a yellowish oil laden gas that is high in carbon monoxide. This is actually normal and increases with engine rpm, and oil around the breather would actually be normal. Especially if you run that basically stock driveline at highway speeds ie. 3500 rpm cruising. That why the automobile manufacturers put it in the air filter can so gasses would get sucked into the engine from both directions if the crankcase gas was too much for the PCV valve.

The PCV hose attached to the OE air cleaner does not suck gasses into the engine. It actually does just the opposite. It's a fresh air supply that's "FILTERED AIR" to supply air to the breather, then flows to the engine valley, they gets removed by the PCV valve on the opposite side valve cover.

Does the engine make good power, does it start and run well, does it smoke, does it idle or run rough?

Never rebuild an engine based solely on compression. A very slightly bent valve will make you think an engine is in need of a rebuild. I never pull an engine out to rebuild it without pulling the heads first. You have to pull them anyway why not leave the block in the truck. You will be able to see the condition of the cylinder walls and the valves of cylinders with low compression. Unless I have a rod sticking out the side I am hesitant to pull it out for a rebuild without pulling the heads first. Many times in my life a buddy has pulled out an engine only to find the very little ring ridge and the cross hatch still very visible on the cylinders without any scarring what so ever, along with almost perfect bearing inserts.

I would completely agree, you should spend some time to diagnose the engine first with some simple tests, figure out what's wrong, then put the repair plan together. In an early Bronco, you have a ton of working room. It's not a 428 Cobra jet with Thermactor tubes in a 1970 Mustang or Fairlane body. The easy way is to pull the engine out, mount it to an engine stand, do the repairs, and save your back. I'd bet most of the Classic Bronco owners on this site are "as old as" or even "older than" the Bronco they are working on.

Just an "old guy" opinion, John

 

[73azbronco]

start here, simple, whats your idle vacuum? Driving at cruise say 45mph vacuum? Decel from 45mph vacuum? Proceed from there. And, as noted, the filter valve breather is more for a lawnmower engine than closed evap ish system, get a pcv valve on that thing, bet oil problems go away. PCV is a valve because when you go WOT, and crank pressure increases because of blowby, which is normal in small cases,, valve shuts, prevents oil everywhere.

 

[Gsxr7000]

No valve cover leaks here, but I have a rear main seal that leaks like a fresh spring out of a mountain... I'll have that addressed when the Ax15 goes in.. it drives me nuts.