Massive oil leak sometimes

[Wozny]

I've got a 92 Chevy with a 5.7 auto. It leaks oil so bad I can hardly bring myself to get in it and drive it. It does not smoke at all ever out the tail pipe. But I can't figure out where the oil is coming from and most of the time it doesn't drip at all. But sometimes if I get off the highway and look underneath its leaking from about a dozen spots like somebody poured a quart of oil all over it. But most of the time when I look underneath, even when I pull over on the highway quick, I can't see a single drop. I got some of the flourescent dye with the special glasses but if I can't even see a single drop, which is most of the time, I don't see how thats going to work. It never leaks from just idling, at least I've never seen it

 

[454cid]

What areas do you see the oil?

Look at your hoses/lines that carry oils..... power steering, transmission cooler, oil cooler.
Look at the oil filter adapter, hydrobooster if you have one.
Oil pressure switch.

 

[Wozny]

What areas do you see the oil?

Look at your hoses/lines that carry oils..... power steering, transmission cooler, oil cooler.
Look at the oil filter adapter, hydrobooster if you have one.
Oil pressure switch.

Thanks, Its crankcase oil and I only see it when I get underneath it. Its more towards the back of the engine, drips from ten different things all at the same time. When it leaks, it leaks like crazy. Whats the hydrobooster? Didn't think about the oil filter adapter. Is the oil pressure switch behind the distributor? I thought that was a oil pressure sensor. When it leaks it really leaks but most of the time I don't see any drip at all. It seems to dry up like someone wiped it with a rag. In fact I've driven it maybe 300 miles and have only seen it leaking one time. I'll drive it some more

 

[Schurkey]

Faulty PCV systemcan cause pressure in the crankcase, which will push oil out every orifice.

Excess blowby is effectively the same as a faulty PCV; either one can build crankcase pressure.

The excess pressure SHOULD vent to the riser between air cleaner and TBI unit; but if that's been disabled or the hose plugged, it clearly can't work properly.

 

[Donald Mitchell]

The oil cooler gaskets above the filter.

 

[Wozny]

Faulty PCV systemcan cause pressure in the crankcase, which will push oil out every orifice.

Excess blowby is effectively the same as a faulty PCV; either one can build crankcase pressure.

The excess pressure SHOULD vent to the riser between air cleaner and TBI unit; but if that's been disabled or the hose plugged, it clearly can't work properly.[/QUOTE

Thanks, I did check the PCV first thing, it was fine. There's no blowby, and all 8 pistons have great compression. I didn't know about the riser, I'll check it when I get home Friday. Never noticed it, this is a newest Chevy i've ever had

 

[Wozny]

The oil cooler gaskets above the filter.

Thanks, I'll check that when I get home Friday. I thought I saw a cooling pipe. Wherever it is, its worse when I'm going fast downhill, I think. The only time I saw it leaking was when I pulled over fast after going down a pass. I just really need to spend more time driving it. Last time I took it to town it never leaked a drop but it might have been too low on oil to leak. I'll keep on driving it and checking

 

[jaywestfall]

My 5.7 Vortec has a small leak in the block, so I am constantly checking oil especially after long drives.

Engine change in my future....

 

[texas tough]

one way to tell if your crankcase pressure is getting too high, your dipstick may be popped out of the tube. take the oil filler cap off at idle,, is it blowing alot of pressure out of there?

 

[454cid]

one way to tell if your crankcase pressure is getting too high, your dipstick may be popped out of the tube. take the oil filler cap off at idle,, is it blowing alot of pressure out of there?

It helps to have the fan off/removed when doing that. I suppose even having the truck warmed up, so the fan wasn't so positively engaged would help. It's like feeling for a light breeze in the middle of a tornado otherwise. The oil fill on the big block is right up front, so maybe it's not as bad with the small block that has the oil fill on the valve cover.

Something else I've done, is use a piece of toilet paper to gauge the air coming from the oil filler.... did that with the Saturn, which blows more air than the heater.