alright guys, I've got another LT1 oil leak question.

Had a rear main seal leak a while back and fixed that with a new seal.
Last spring I took care of the dreaded intake manifold leak, too.

Since then, up until the end of last fall, the car hadn't marked its territory anywhere at all. (Which is rare for my car.)

So now I've got another motor oil leak running down the driver side of the bellhousing and dripping off the bottom that seems to be a bit faster than the old leaks I've had.

I've also noticed that after my cars warmed up and I come to a stop my oil pressure guage seems to dance around for a few seconds before it steadys out again, and once in a great while it never stops dancing around no matter how long I let it idle in place after stopping.

I think I've narrowed the leak down to the oil pressure sensor on the back of the intake manifold, but I'm not completely sure. From what I've heard they used to leak all the time on the old school SB GM V8s. I've reached my hand around the back of the manifold and felt fresh oil on it, but not specificly the sensor itself... kind of everywhere on the back of the manifold, but my guts telling me the sensor's the problem. I highly doubt the old rear intake manifold leak came back, since I did it by the books when I fixed it: felpro gaskets, high temp RTV along the front and back of the block, and torqued all the manifold bolts in order to spec.

I've also had a dancing oil pressure guage can mean a vacuum leak or a main bearing on its way out-- which I'm sure neither of these are the case.

So in the end of this long essay I just typed, what I'm asking is can an oil leak at the oil pressure sensor cause a dancing oil pressure needle? If that's not the case, any other possible places that this new leak be coming from?

 

on the oil leak. personally i would pop the intake since its an easy job. lay some new RTV down. and replace the sensor. with some good goo around it. and the dancing oil psi. might not be as bad as you think. it could also be the oil level sensor at the bottom. weird i know but my 94 383 did the same thing. it would dance around and i knew i had a good 5 quarts in it. and once i replaced that for whatever reason it stopped.

 

chances are that its the intake. like 1slo already said, just do it again, and while its off replace the oil sending unit. have you ever replaced the sending unit?

 

1slo_camaro - I'm thinkin poppin the intake manifold off and replacing the sensor and RTV to see what happens is what I'm most likely gonna do. I've still gotta run to autozone and get a price on a new oil pressure sensor, but from what I understand they're pretty cheap.

I'm gonna be doing some clutch work on the car within the next week or two so it'll be ready to go on the road at about the same time the snow and salt up here's done. Now that I'm thinkin of it, with the tranny, clutch, and bellhousing out I should get a pretty easy shot at the back of the intake. I'll just replace the sensor alone before I put the car back together. If I'm still gettin the oil leak then I'll know its coming from the back of the manifold again.

As for the oil level sensor-- are you sure this could effect the movement of the needle? I can see it reading consistent low oil pressure like if my oil levels low or I'm running a super thin oil. But its got 5 quarts of Mobil1 10w30 in it, the same oil I've always put in it since I've owned the car long before the oil pressure needle started twitching. And once the needle stops dancing around after a few seconds it sits at the same pressure it always has.

Smoke Em - when you say 'sending unit' youre talking about the sensor itself right? Just wanna make sure I'm not messin up the vocab or overlooking anything important. I've actually never replaced one but it doesn't look hard at all. I know on the old GM SB's it was towards the back of the block, the 93-94 LT1's were above the oil filter on the drivers side, and 95-97 LT1's were on the back of the intake manifold below the EGR valve.

Looks like I just have to unplug the electrical harness and use a combination wrench to unscrew the sensor itself from the fittings right? I'd imagine before I put the new sensor on I should clean the threads up on the fitting and possibly use some kind of sealer on the threads?

 

To install the new sensor, use either pipe thread dope or teflon tape. If you don't, it'll leak past the threads. If you use teflon tape, make sure you wrap in the right way, or it'll still leak because the tape will be unwinding itself as you screw it in. Wind the tape so that as you screw it in the tape is being smoothed into the threads.

 

any updates??

 

So was it the intake or oil sensor fitting leaking???

I love how no one updates threads with the solution around here.

 

Its been two years and the problem still hasn't been solved, not sure what else it could be. Its a pretty slow leak, maybe a drop or two a day, so I haven't really bothered much with it. Still starts on the back of the block near the intake manifold and oil pressure sensor, then runs down the drivers side of the bellhousing and along the bottom of the tranny.

I had the intake manifold off a couple months ago when I did my cam swap, so I was extremely careful and meticulous when re-installing it. Cleaned the **** out of any surfaces that touch each other, new gaskets, ultra copper permatex, and torqued exactly to shbox's specs.

While I was in there I took a look at the sensor itself and it was bone dry. However, it was wet around the base of one of the small hex shaped fittings that attach it to the block, so the leak may still have been coming from that or the manifold but not sure. Just to be safe, I unscrewed both hex fittings, cleaned their threads, threw some ultra copper on them and reinstalled them.

The leak never really went away, though it is slower. Looking back on it, I wish I was more patient and waited till the parts store would open the next morning and bought some permatex thread sealer for the oil sensor fittings instead of using ultra copper, which is mainly just used for making gaskets. It was 1am, and I was nearly done with my cam swap and really anxious to start the car up.

Sorry I never followed up on this thread as I really do appreciate anyone who took the time to give input/advice, but I'm very busy almost everyday and don't spend a ton of time in front of the computer, and like I said before, the problem isn't exactly fixed yet.

 

Well, I'm a complete dumbass.

It never occurred to me that Dex-Cool is a brownish color, kind of like motor oil. Realized the other day that my "oil leak" is really a coolant leak. I took a good look under my car and noticed that the banjo bolt coolant fitting on the back of my driver side head is rusty and looks like its in bad shape. There is a little bit of coolant I can see running under it and down along the back of the intake mani near the oil pressure sensor, then down along the driver side of the bellhousing.

Coolant evaporates/runs off really quickly, doesn't leave as much evidence as motor oil does, so it was pretty hard to see. I'm actually pretty glad it was something other than motor oil, as I don't think I could have done a more clean and careful job when I re-installed my intake manifold after my cam swap last spring.

Sooo my next question is this: has anyone been able to successfully remove and replace the banjo bolt and two seals on the back of the driver's side head while its still in the car? How about the passenger side? Might do both sides just to be safe.

I do have a set of AI 205 heads planned to go on next spring, so I could always wait till I do my head swap. I'd rather take care of the problem now though, since there's still another month or so of summer left.

 

Yes they both can be romoved in the car. Take your time, lay across the motor. Dont forget to clean the surfaces really well.

 

If the bolts are still from the factory, it is an odd size and will not fit a standard or metric wrench very well. I can't remember the size, but the newer (not sure if they're discontinued?) bolts were something like an exact 14mm fit. You can try a couple of wrenches and see which one fits the best and see if it will come loose. If not, I've always had good luck using large vice grips and a hammer. It will mark up the bolt, but it will come loose.
If your coolant is a brownish color, it's time to flush that **** out and replace it.