: Oil leak and low oil pressure

05-03-12, 11:49 AM
Before I bring her to the dreaded mechanic I thought I'd post up in hopes of someone pointing me in the right direction.

This started a few months ago as a PCV issue. Took a 300 mile trip to come home and find my entire intake soaked in oil, and I mean puddles. Never had this problem before. But it wasn't coming from the vacuum side behind the TB. It was being pushed out from the passenger valve cover to the intake tube. I installed a check valve which caused the oil to seep out of and soak the motor.

Tried a few things including two catch cans and a pressure venting oil cap. I got it to the point that oil is not getting to the intake. But the leaking is slowly getting worse and oil pressure isn't as good as I'd like. Dropping to the low 20s at hot idle, mid 30s on the highway at around 2000 rpm.

Did a cylinder balance test with HPTunners (where the PCM shuts down one injector at a time) and all cylinders were within 3%. Plugs looked good except #8 which had some oil on it. Did a leak down test on that head and all those cylinders held good pressure.

The oil is coming from the top of the motor so I pulled the Maggie last night. Nothing really got my attention as being the source of the problem. There was oil everywhere. It mostly comes down the front of the motor but the oil pressure sensor and the sensor next to it were soaked. I could see the oil traveling from the front to the rear but doubt it could go from rear to front.

Cleaned it the best I could and put her back together.

Next step is to change the oil and I might go ahead and order some parts (oil pressure sensor, cam position sensor which are next to each other right? and a new valley cover gasket).

BTW car has been running perfectly all this time.

Thanks for any input you guys might have.

PS Looks clean under the valve covers so it seems to be leaking between the Maggie/intake manifold and block.

05-03-12, 12:32 PM
Sorry to hear about this Tony. If you think it is coming from between the maggie and block then the valley cover gasket seems like the first suspect, but I doubt it is the actual cause of the problem. Could you have something clogged that isn't allowing the crankcase pressure to equalize and you are building up pressure that is forcing oil out wherever it can go? Clogged arteries such as PCV valve would come to mind, but you said that was fixed.

Unfortunately head gaskets and piston rings come to mind if you have combustion chamber pressure entering the crankcase. I think you should do the leak down test on the other bank of cylinders as see what you find. Hopefully neither of these things is your issue.

Also, I only know a little bit about this stuff, I have no direct experience, just trying to throw out suggestions.

05-03-12, 01:18 PM
Didn't get the PCV problem fixed, just dealt with the symptoms.
But I was thinking about a blockage. And depending where it's blocked, it might account for the low oil pressure. I'll change the oil and open the filter in the next couple days.


05-03-12, 01:30 PM
Something clogged would be the "desired" problem as opposed to, say, rings.

I was thinking of you doing a compression test on each cylinder, but you mentioned doing a leak down test. Is that equivalent?

Could an oil passage allowing oil to return to the pan clogged? Maybe I'm not understanding the problem quite right.

05-03-12, 01:39 PM
Something clogged would be the "desired" problem as opposed to, say, rings.

I was thinking of you doing a compression test on each cylinder, but you mentioned doing a leak down test. Is that equivalent?

Could an oil passage allowing oil to return to the pan clogged? Maybe I'm not understanding the problem quite right.

Leak down is better than a compression test, but I only did it on the head I thought was the problem. It's a PITA just to get TDC on these motors.

The cylinder balance test should be like a compression test. It shuts off injectors one at a time and notes how hard the engine has to run to hold a certain RPM. So if a cylinder has a problem, it would be way off. But they were all within 3% which is very good.

I've been on google and other LS based forums so much lately that my head is spinning. I've heard horror stories about doing an engine flush. I'll start looking into if there's a way to do it safely.

05-03-12, 02:04 PM
I would consider seafoam (or equivalent) crankcase/oil treatment before you change the oil. That might help clean some things out and surely can't hurt in this situation for the $8 or whatever it costs.

05-03-12, 03:13 PM
^^^ Yeah, that.

I know you can get a coolant system flush and a transaxle (not Vs, of course) on FWD cars ... can you get a service shop to do a lubrication system flush?

05-07-12, 04:02 PM
Any updates Tony?

05-07-12, 05:41 PM
Still scratching my head. Changed the oil, and the pressure is back to normal.
I reversed the flow of the PCV and no more leak. I'm guessing it was seeping out rather than leaking. But now the oil is is being sucked into the catch can, filling it, then making its way to the intake.
So now I'm looking for an oil clog or a PCV clog. The crankcase gases only flow one way, but it's the wrong way.
Pulling the valve cover tonight.

05-15-12, 05:16 PM
Found the compression gauge and checked the drivers side.

#1 170 psi
#3 195 psi
#5 110 psi :nono:
#7 170 psi
I'll be doing a leak down test on that side when I get access to a compressor. But #5 jumped up to 145 when I put some oil in the cylinder then 170 when I put some more. So it seems to be rings.

I'm lost when it comes to internals. Anybody know what's involved? I'm assuming the engine will need to get pulled. Is it possible I could get away with only changing the rings, or does this always end up being a bigger issue? Also what else should I change since I'm in there?

Any ball park figures would be appreciated before I start looking for a shop to bring it to. Motor has 53K on it, and since this happened at the worst possible time, any upgrades are out of the question. Just wanna get my baby right again.

Funny cuz the car runs perfect. :hmm:


05-15-12, 06:53 PM
... #5 110 psi :nono: ... But #5 jumped up to 145 when I put some oil in the cylinder then 170 when I put some more. So it seems to be rings. ...

Funny cuz the car runs perfect. :hmm: ...That's the exact procedure to determine whether it's the valves or rings. Sorry, it's the latter and not the former.

I'd suspect that it's not putting out as much power as it should but is just being masked by the other cylinders. *

Then, you gotta ask, why the heck is #5 having this problem so prematurely? The only thing I could think of it a manufacturing defect ... a casting flaw or something.

Good luck, Tony.

*EDIT: Say, could that explain why you're not putting out another 20 or more rwhp?

05-15-12, 07:09 PM
Just realised I didn't post this earlier. Before this all happened (few months ago) I found I had a lean condition at WOT. Turned out that the intake tube got loose and was letting in unmetered air. Obviously I didn't catch it in time.

05-15-12, 07:47 PM
Man oh man sorry to hear this Tony. This stuff does have a tendency to happen at the worst times, but it all eventually turns back around. I don't know much about engine building but I'm pretty sure the motor needs to come out, heads off, and the oil pan pulled to get access to the crank and remove the piston. The obvious suggestion here for a boosted motor is forged (and maybe dished for lower compression) pistons to replace the stock hypereutectic ones. An overdrive crank pulley while you've got the engine out and you'd grab a bunch of extra boost that forged pistons and slightly lower compression could make good use of.

At the same time however, the mp112 is going to become less efficient and hotter as you spin it more than it is now, so the most desirable choice would be to sell the 112 and upgrade to make a tvs or other fit, but that's in a dream world, not the real world. I'm sure the shop you settle on can help you decide the most worthwhile upgrades within your budget while everything is apart.

*EDIT: Say, could that explain why you're not putting out another 20 or more rwhp?

Remember he doesn't have headers...:thepan:

05-15-12, 08:12 PM
The 20 rwhp is purely a geographical issue lol

Yeah I know about all the boost-friendly mods. But I'm in the middle of moving, TWICE, plus other issues so funds are tight. But she's been like this for 4K miles (did I mention it runs perfect) so if I could somehow hold out a few more months........

05-15-12, 08:17 PM
The 20 rwhp is purely a geographical issue lol ...:histeric:

If you move far enough, you'll get that 20 rwhp. :rofl:

Sorry, Tony. Just trying to cheer you up.

05-15-12, 08:32 PM
Thanks, it's my friends birthday and I'm on my 7th or 8th,,,,,,,,or there abouts, drink. So everything is rosy


Seriously though, do you guys think I'm pushing it, considering it's been like this so long? Again it's the timing, otherwise I'd be looking at this as an opportunity.

05-15-12, 08:49 PM
Honestly I can't say what if any damage you could do by holding off a couple months, but if I were you and the motor was otherwise running fine, I would be hard pressed to crack it open when it sounds like you have enough to deal with right now. How many miles are you driving a month?

05-15-12, 08:53 PM
Could've sworn I posted this already......


Considering it's been like this for 4K miles and runs really nice, if you drove the car you'd think I was full of Shit, do you think I'm pushing it if I give it more time before I fix it?

05-15-12, 09:54 PM
Tony, you won't hurt a thing.

I'd stop at 9 ... or maybe 10, though.

Put that last round on my tab. :alchi:

05-15-12, 10:10 PM
Sounds like it could be a broken ring land or a minor burnt/chipped piston. You still have decent compression in that cylinder so you should be ok to baby it. Only downside is if it gets worse you may need to bore the cylinder when you do repair it. If waiting means you can go forged out possible stroker then I say wait.

05-16-12, 09:50 AM
Thanks guys. I got it to the point where she's not losing too much oil. Very little in the catch can, and only a few drops on the floor. Used to be either the motor was soaked or the PCV system was sucking in maybe 1/2 qt an hour. :(

So unless something changes, I'm gonna hold off and weigh my options. A beater is not out of the question at this point.

05-16-12, 06:06 PM
Damn sorry to hear all of this. If I were you I would try and drive it as little as possible and certainly not to far from home.

As for funds being tight if you pull the motor yourself and take it somewhere you could probably get away with a reasonable price out the door. Good luck Tony.

05-17-12, 10:44 PM
came across this and thought of you. specs according to GM

oil psi minimums - hot

6 psig at 1,000 engine RPM
18 psig at 2,000 engine RPM
24 psig at 4,000 engine RPM

05-18-12, 05:27 AM
came across this and thought of you. specs according to GM

oil psi minimums - hot

6 psig at 1,000 engine RPM
18 psig at 2,000 engine RPM
24 psig at 4,000 engine RPM
I've seen that on the Vette forums a few times. I doubt anybody would trust that with there car lol

05-18-12, 10:04 AM
yeah, no way. ...but I'm just sayin'.

05-21-12, 11:20 PM
Hey Tony I just came across this thread on corvette forum that is similar to your situation: http://forums.corvetteforum.com/c6-forced-induction-nitrous/3032659-blown-ls3-blowing-oil-under-boost-5-cylinder-low-compression.html

Different recommendations, some say keep driving it, some say open it up before you do more damage. Apparently oil in the cylinders can cause detonation.

A worthy note is that ECS (East Coast Supercharging) said that they can replace a piston in about a day. That of course is for a corvette, but still an interesting piece of information.

05-22-12, 06:00 AM
Thanks Tom, I'll look through it when I get to work. Chances are I've already seen it lol
Luckily I don't have any oil in, or getting to the combustion chamber.

Did the leak down over the weekend. Confirmed that 5 was blowing right through the rings. 7 and possibly 1 look tired, but I doubt I would've noticed anything if they were all like that.

Also considering pulling the motor myself, but it's a lot more involved than just wrenching and pulling it. So we'll see.

05-22-12, 08:31 AM
That was actually very helpful. Obviously I didn't find that one.
If ECS can do the work without pulling the motor I can get this done much sooner. Never put any real thought into getting more power, so I'd be perfectly content with having my car "right" again.

Thanks again :highfive:

05-22-12, 12:27 PM
Unfortunately I really don't see then being able to replace a piston without pulling the motor. There is no room to pull the pan off to get to the crank.

How many miles on your motor? If they are going in, you should at least rering and new bearings.

05-22-12, 01:03 PM
I agree with you on not having room to drop the pan. On the Vette forums they talk about raising the motor and lowering the craddle to make room. It would be great if this was possible on a V, I'll have to find out.

Yes, springs and bearings where my minimum. And the motor has 53K.

05-22-12, 01:48 PM
FWIW pulling the motor was not a huge task. If you have the tools and a little bit of time you can save yourself a lot of cash going DIY.

Not sure where you are located but I'm in southeast pa and wouldn't mind helping. Been there done that with my cam, ls 7, header install.

05-22-12, 01:58 PM
Thanks for the offer but I'm way out in long island for now. Hopefully I have time to figure out what i'm gonna do with it. She's been running fine the last few days making short trips to the train station.

05-08-14, 04:43 PM
Quick backstory. A couple years ago I noticed an oil leak in the garage but the car was running fine. Long story short, took me a few months to find the problem which turned out to be blow-by in #5 cylinder. I had already put a few thousand miles on the car with no smoke or noise and still making decent power. So I kept driving the car till I decided what to do. Spoke with a vette shop last year and they wanted to change the block. I plan on keeping this car, and with the original diff it would be nice to have a numbers car in twenty years. So no-go on the swap.
A few weeks ago I pulled the motor apart and this is what I found

http://i80.photobucket.com/albums/j177/Gxxr1/20140419_130841_zpswvewob2d.jpg (http://s80.photobucket.com/user/Gxxr1/media/20140419_130841_zpswvewob2d.jpg.html)

Broken ringland, as suspected. Everything else was in great shape. Put her back together with some new parts and was sweating the first time I turned the key.
This was almost two weeks ago and she's been running great.

Just thought I'd finish the thread with an answer in case it comes up in someones search.

Tony :D

05-08-14, 06:43 PM

05-08-14, 08:45 PM
nice job...thanks for the update

05-08-14, 08:57 PM
Great news, Tony. So nice to hear all's well on Long Island.