Pressurized crank case?

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68383

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I didn't post this in the small block engine area since my question is about a 440.

Can someone tell me what symptoms I'd my engine would have if the crank case was pressurized, as well as what would cause the crank case to become pressurized?

Here's what I've been experiencing, which is what makes me ask:

- The engine idle was rough.
- I noticed some fumes coming out of my dipstick tube.
- I removed the repro, chrome breather (attached to a hose going to my air cleaner assembly) from my valve cover.
- Fumes were coming from the hole in the valve cover. The engine idle sped up slightly and it ran more smoothly.
- I inspected the inside of the breather and didn't see any obstruction.
- I removed the hose from the breather to the air cleaner assembly. It wasn't collapsed and there was no blockage.
- Then I replaced the hose and chrome breather.
- It seemed like I had choked the engine and fumes started to come out of the dipstick tube again.
- I replaced the chrome breather with the one I pulled off my engine last fall.
- Before installing the old breather, I inspected it. It didn't seem to have any issues.
- The engine behaved the same with the old breather as it did with the chrome breather.

I'm hoping this is unrelated... When I shut the car off, coolant was flooding out of the overflow tank I installed a couple of years ago. The radiator three row radiator has less than 1,000 miles on it and I haven't had any issues with the 16lb cap before. Someone mentioned that if there's a problem with a head gasket, my cooling system could be leaking into my oil system and pressurizing the crank case. I didn't see any white smoke coming from my exhaust pipes.

Tonight, I checked the oil to see what it looks like. The dipstick showed that it was nice and clean. The oil was changed last November and I've only driven the car about ten miles since then. I also checked the air cleaner assembly and filter (maybe 100 miles on the K&N filter I installed). The air filter was stuck to the inside top assembly, but it wasn't bound, like it was rubbing the inside of the air cleaner. It also seemed to fit fine inside the base of the air cleaner assembly.

I noticed the fumes coming from the dipstick last November. I pulled the PCV over the winter. It rattled when I shook it, but I replaced it for good measure anyway. The new one rattled before I put it on, but I can check for vacuum from it.

Any other ideas on my problem?

Thanks,
 
All engines will have some sort of blow by. The PCV helps but isnt enough on it's own to reduce the crankcase pressure to nothing. I would have it tuned as the rough running sounds more like a tuning and not-a-lot-of-miles type deal. On the overflow... The coolant will have to "find it's own level" again, as you drive it. So again, druive the car and dont sweat it.
 
My 383 used to blow the press on oil cap off when i accelerated hard,until i soldered a vacume line to it and soldered it to the air cleaner
 
I'd do a leakdown test on it. Sounds like you have excessive blow-by past the rings.
 
Is this just a stock motor or what? What compression ratio? Is it a fresh rebuild with low miles? Headers? Exhaust system? There are so many variables here you haven't even touched on.

One thing you need to remember is if you have 440 cubic inches pumping on top of the piston you also have 440 cubic inches pumping below the piston.

If this is a low mileage fresh rebuild (probably stock type rebuild, no honeing plate) then you need to drive it for awhile to seat the rings. If it's an older engine you should start with a cylinder leakdown test.
 
If it is an older engine with some miles on it pull the carb and check the PCV passages in its base-may be full of crap.
 
The engine was rebuilt before I owned the car. It's not a fresh rebuild. It's a stock engine with the exception of what sounds like a mild cam. The exhaust is all stock.

A compression test is next on my agenda, then possibly a leak down test. I was told if the compression results are poor, there's no point in doing a leak down test. I'll check the hose from the PCV to the carb, then pull the carb if I have to as well.

I also heard that blown head gasket, or cracked head or block, could cause my crank case to get pressurized.

Thanks again, guys.
 
Another sign of an over pressured crankcase would be oil leaking past the front and rear mains seals. And the dip stick will not stay seated on the tube.
 
As oldkimmer said.....replace the PVC hose. They are known to get soft and squishy inside or caked with oily crud, either one will plug it up.
 
slant6/4speed said:
Another sign of an over pressured crankcase would be oil leaking past the front and rear mains seals. And the dip stick will not stay seated on the tube.
Click to expand...

Rear main seal replaced last year, due to a leak. And it may be leaking again... I bought some UV dye to put in the oil to see where it's leaking.
 
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