406 SBC Problems to Resolve This Winter

If you have a new 6 quart pan or one with all the oil drained and a new filter installed.
Pour in 6 quarts of oil and 1 quart for a standard size filter, so 7 quarts,
Start the engine, let it warm up and drive it around the block,
Turn off the engine and check the level of the oil on the dipstick,
File a small line into the dipstick where the oil just showed as full.
That's it.
If you are running twin oil filters and remote oil coolers, this will change and you need to compensate for the additional oil in the system.
An 8 quart pan would take 8 quarts and 1 quart for the filter and so on...
If that is the case, a stock oil stick will show the level keeping it below the crank because it is mounted at the pan line which shows the relationship of oil height in the pan?






Windages trays do work BTW...and I have built many engines with them.....but they are 100% unnecessary on the street and reap zero benefits unless you spend a lot of time above 5000rpm.......
The down side to windage trays is the lack of oil they spray upwards to the lifters.......if using a windage tray for flat tappet application.....one should run the lifters with he EDM hole at the bottom to help lube the heel of the lifter.......I will not build a customer an engine with a windage tray for the street....and I know that L-82's and LT--1's came with but I wonder why.....especially the L-82....
I like the Moroso oil pump rear baffle for hard launching cars with a stockish style pan......cheap effective oil control there.
Jebby
I'm just wondering if you actually have a 6 quart pan or maybe a mismatched or wrong dipstick for your setup?
I purchased one crate engine from a major supplier.
After all the problems I had, I said never again.
I used a local, well respected builder this time around.
Another issue no one ever asks , how is the crank case ventilated. That in and of itself on a built motor. Will cause leaks from blow by. Something the best of the best motors have. And why performance motors use vac pumps to clear the crankcase. I have seen small amounts of oil pushed out of a dip stick tube only under heavy loads b/c the crank case is Un-ventilated. And make it look like a pan leak. I have also seen Chevy's only after a hard pull leak out of the china wall. While daily driving results in zero leaks.
Its not always easy to find an issue. But its even harder to find what caused it to begin with. And a well done repair should cover both topics.

I will borescope the intake manifold, check the head bolt torque....and if necessary pull it apart. I have this winter to get it fixed and back in the car.....and the last thing I want is all these problems next spring.
Last edited by Shovels and Vettes; Dec 11, 2021 at 12:56 PM.
The Best of Corvette for Corvette Enthusiasts

Another issue no one ever asks , how is the crank case ventilated. That in and of itself on a built motor. Will cause leaks from blow by. Something the best of the best motors have. And why performance motors use vac pumps to clear the crankcase. I have seen small amounts of oil pushed out of a dip stick tube only under heavy loads b/c the crank case is Un-ventilated. And make it look like a pan leak. I have also seen Chevy's only after a hard pull leak out of the china wall. While daily driving results in zero leaks.
Its not always easy to find an issue. But its even harder to find what caused it to begin with. And a well done repair should cover both topics.
As for the oil leak...yes the front seal is leaking. But its not the cause of all the leaks INSIDE the bell housing. There is oil all over the INSIDE of the bell housing. And its not the china wall, or anything else on top of the engine....I have checked it many many times.
As for ventilation, I have the Wagner adjustable PCV valve, adjusted as instructed, on the left valve cover, and on the right, I have a K&N air breather. There is no oil being pushed out of the dipstick.
So, now what?
Pulling the damn engine and starting over.
Last edited by Shovels and Vettes; Dec 12, 2021 at 06:04 AM.
As for the oil leak...yes the front seal is leaking. But its not the cause of all the leaks INSIDE the bell housing. There is oil all over the INSIDE of the bell housing. And its not the china wall, or anything else on top of the engine....I have checked it many many times.
As for ventilation, I have the Wagner adjustable PCV valve, adjusted as instructed, on the left valve cover, and on the right, I have a K&N air breather. There is no oil being pushed out of the dipstick.
.
So, now what?
Pulling the damn engine and starting over.
Leaking into the interior is only one possible consequence of a bad heater core it can also get plugged up with ****.. And Inside the bell housing is were all oil ends up from leaks on the back of the engine. It in and of itself is not a indicator of the source.
Vent the crank case with something more then a PCV valve no matter who its made by or how fancy it may be.
Last edited by C3TPI; Dec 12, 2021 at 03:27 PM.

Vent the crank case with something more then a PCV valve no matter who its made by or how fancy it may be.
What I do know is this. There is NO smell of coolant inside the car. There is no coolant in the carpet. There is no coolant draining out of the hole in bottom of heater core housing. The heater is very effective and can roast me out of the car. SO.....I don't think it is plugged, and I don't think it is leaking. So.....now what? There is also no other visible evidence of coolant leaks anywhere externally. The car was NOT blowing white smoke, and it was running great, with absolutely no symptoms of any coolant leaks internally.
I will say I pulled all the plugs out today....and they have a brown tint to them. All the same....and the headers have the same brown tint inside.
As for the oil leak, I find it hard to believe oil coming from the front of the engine, or from the china wall, or the heads, or anywhere else would migrate the whole way to the top INSIDE of the bell housing, as well as leaking from the seam between the bell housing and the Borg T10 transmission. There is wet oil on the pipe plugs in the back of the motor, above the cam freeze plug. But there is now oil everywhere....a huge f***** mess.
I have TWO problems here.....and I am looking for answers. The engine is almost out of the car. Once out I will be looking everywhere for causes of these two issue
As for ventilation.....I have no idea why I would need a vacuum pump. I have an open K&N air filter breather on the right side, and a Wagner PCV valve, which is more effective than a stock PCV, on the left side. Why is this not enough to ventilate a basic Chevy V8 that has 8000 miles on it. Why? And what type of ventilation system is available that would be better? Answers. Another point is that these 8000 miles of driving have been at normal street speeds, I have only taken the engine to 6000 RPM once, most of the time I don't exceed 4000 RPM....and that is rare. With this engine, there is so much torque, I have no need to push it any harder....I am going 70 mph without pushing it. Why does this engine need a vaccuum pump?
Last edited by Shovels and Vettes; Dec 12, 2021 at 12:22 PM.
Do one at a time so you can pinpoint which may be the issue.
Another thing you could check is to see if the lower radiator hose is collapsing under pressure.

Someone didn't do a thorough enough job of cleaning things up before assembly.
You should take the time to open the oil filter and see what you find inside.











