Major Oil Leak Question

I have a 2000 4runner:

I was in the car, getting ready to back out and had it in park. By mistake, I floored the accelerator rather than pressing the brake. I heard something “blow” and the engine started growling unusually, no clicking or anything. I turned it off. Then the engine started to leak an alarming amount of oil onto the driveway. Any ideas what I may have done to it. The leaks seems to coming from the center rear of the engine and is dripping down. Sorry I can’t be more specific. But it’s not a small leak, there’s a lot of oil.

You will have to get under there and look to see where the oil is coming from. If you have good karma, you blew the oil filter or and oil line. If you see any holes in the oil pan or side of the block, a connecting rod probably has broken and punched a hole(s) into the engine.

Good luck on this.

The center rear usually points to a rear main seal. Some revs should not cause this to blow unless (and theorizing only here) the PCV system is plugged up and excessive crankcase pressure blew the rear seal out.

This could cause oil puking and odd noises. IF this is the case then the transmission would have to come out.
If the trans is out the torque converter seal should also be replaced at that time (automatic) or the clutch assembly if the vehlice has a manual transmission.

At this point, do NOT drive it or it’s possible that any doubts about the engine being good or not may be completely removed.

I would first think it was the oil filter. The rear main is a possibility …but it would be the first time I’ve heard of this type of catastrophic failure.

The oil filter should be obvious. It should be soaked and still dripping.

thanks for the input so far guys. Going off of what you’ve said so far, why would revving the engine in park cause the oil filter to blow in the first place?

I don’t think the revving had anything to do with it. I think it was ready to fail anyway.

I’m going to go along with the rear main seal theaory, only because I had this happen to me in a rental car back in the '80s. It’s rare. I’d never heard of it before. The only way to tell for sure is to see where the oil is coming from.

When an engine revs to high RPM and when the oil is cold, developed pressure will rise to the pressure regulator lift point. If the regulator bypass passages or the spool valve itself cannot handle the flow, it is possible that the line pressure could go higher than the set level. You obviously have a major leak we are hoping the oil filter seal is the culprit. This would be a cheap fix you don’t want to miss so take a look.

Another cheap fix is a leaking oil pressure sender unit.

If you cannot find the location of the leak, top off the oil; start the engine; look to see where the oil is dripping from or flying out of; and then quickly turn the engine off again. If you are unwilling to look or do not have the capability, have the 4runner towed to a mechanic for a professional diagnosis.

Again hoping you have had good luck.

Well I had one guy look at it, he said a connecting rod broke and busted a hole in the oil pan which is the cause of the leak. Not good news. Getting a second opinion later though I guess a broken rod would be pretty obvious. Thing is the noise the car was making after it happened was not as terrible as the sound people always associate with a rod breaking. So all I can do is hope. I mean a broken rod means a new engine right? Sucks mostly. Thanks for the help so far.

Reving an engine beyond it’s design limits, even for just a second, usually has catastrophic consequences…

True, but I’m surprised the ECU let him do that. Actually, I’m surprised anyone would do that anyway. The sound would send shivers down my spine. I wonder if there’s some other detail missing from the story. Like really low oil.

Yup, you’re lookin’ at a new engine. Chances of the rod not having destroyed the cylinder are pretty much zero, and I’m sure the rest of the engine didn’t take well to running with a sudden loss of oil.

Well I was in park so I killed the engine immediately. Don’t think oil was low initially. I check it every time I fill up on gas and haven’t had leaks previously.