SteveG75

Couple of questions for the gurus on the forum.

Seems like my engine builder used the old high volume, high pressure oil pump. Reading 40 psi at idle and 70 psi at 2500 rpm HOT with the 10W40 I am using for break-in. Does this seem out of line?

Also, couple of annoying leaks. Small drip from bottom of bellhousing that I am hoping is not the new rear seal. Hopefully just oil working its way down from above. Also, oil pooling on the back of the block below the distributor. It looks like the distributor is leaking but I am pretty sure there is no pressure at that point. Pulled it today and recemented the gasket plus managed to get about 1 1/2 turns on the small pipe plug just to the right of it in the block. I know that is where other SBC take the oil pressure readings (mine is above the filter), so assume that is seeing the full 70 psi. May have to pull that sucker and reinstall with teflon over the weekend.

Anyway, pressures OK? Any advice on the leaks or am I just going to be stuck with them. Also thinking about going to 0W30 synthetic after the break-in is over. Opinions?

Thanks guys. Later.

vettfixr

Hi Steve
I think I have the same problem. I run a high volume, high pressure pump too with much the same gauge readings. I replaced the oil pan with a one piece unit thinking it would cure the problem but it's still there. I think the pressure may be blowing past the rear main seal. The seal is only a few years old and probably has less than 5K miles on it so I don't think it's wear. Mine drips right from the inspection cover on the bellhousing and there are no leaks from the valve covers. I'm kicking myself for not changing the spring in the pump to reduce the pressure when I had the pan off a month ago. If no one else posts another point of view I think we'll both be pulling the pans and replacing the springs in our pumps.

jackson

Steve & vettfxr:
Sorry to hear that ... but probably need to change the oil pump spring to lower pressure. Hi-Volume OK for street clearances ... Hi-Pressure usually is trouble.
Jack

SteveG75

Just drove 10 miles tonight. Small drip from below but big (teaspoonful) puddle of oil on back top of block, driver's side. Seem to be coming from the distributo but that makes no sense. Figue I will go reseal the pipe plug tonight.

Off to get dirty.

Steve

8T1-7T9 BIONIC VETTE

I don't know if this will help you....I had oil drips under engine around oil pan rear area.....Since I had just replaced the oil pan gasket....after discovering oil still dripping,.....I got the good type valve cover gaskets with the metal inside....oil leaks stopped. It was dribbling down from above. Good Luck hope you find your leak.... :seeya Cappy

Captain Morgan

I too have been fighting leaks that appeared to be from right below the rear main but it was from the valve cover gaskets. I have a high volume, high pressure pump too. I had been using the thin rubber valve cover gaskets but went to the thick cork and so far, no leaks. Every time I would change gaskets, it would be okay for a couple months, then start leaking again. We'll see how long it holds up with the thick cork gaskets. However, you can't use cork with synthetic oil so I'm stuck with dino at least until I change gaskets again. I may go to the good gaskets with metal in them if these cork ones don't hold up.

Corellian Corvette

Steve

Let me know what you find! I have this same leak (about a teaspoon full) on the drivers side below the oil pressure sender. That, in turn, leaks down the side of the block and shows up as a really small drip on the bottom of the bell housing. Sounds exactly like what you describe.

I *think* the problem is really small leak in the intake manifold. Although it appears to be coming from the distributor, I just don't see that being the issue. I didn't recall having this problem until I changed my intake manifold. My thought is that I may have left a small area in one of the corners poorly sealed -- just enough so that when the oil pressure goes up it leaks.

I've cleaned that area 100 times and let the car run for an hour just watching to see where the oil pools from and it never happens. Then I come back from a 20 min cruise and BAM, there it is again.

Frankenvette

I just finished replacing my rear main seal only to find that da*n small drip at the bellhousing. I am also using the Felpro one piece oil pan gasket and the blue vulcanized rubber valve cover gaskets that are suppose to be excellent at sealing. I have already fixed the leak coming from the oil pressure sender by using teflon tape and new brass adapter. After replacing the rear main seal, I had no leaks for a few days. Then came out to the garage one day and there was a small puddle under the car and the drip sitting on the lower bellhousing. Can't for the life of me figure this out. I'll be reading the post with great interest.

Regards,

Jim

vettfixr

Well it's nice to know that I'm not alone in this. :lol: In response to all the posters I've used the thick cork gaskets and now I have the rubber with the steel shim. There are no oil leaks (white glove test) from the valve covers or from the galley plugs. the oil drips from the inside of the inspection cover on the bellhousing so I don't think It's coming from an external source. Here's a question, do any of the manufacturers make a "high performance" rear seal or do we just go with the typical Fel Pro replacement. It would seem that with all the problems people have with the rear seal someone would have come up with a better mousetrap.

gerry72

Their are leak detector kits, I believe Eastwood has them, that will allow you to determine the origins of fluid leaks. Generally, you introduce a florescent dye into whatever fluid you have leaking, turn out the lights and hit the engine with the light to make the dye light up. It saves a lot of time and grief when you're chasing down leaks and is the preferred method used by professional mechanics. It beats throwing labor at the problem until it goes away. Most of the time, valve cover gaskets or intake valley gaskets are going to be the source of oil leaks.

vettfixr

Thanks Gerry. I might be looking into one of those. I'd hate to drop the pan and everything again only to not solve the problem.

Scooter70

Add my name to the list of people chasing down oil leaks.... One was at the front of the oil pan and the other was the drips at the bottom of the bellhousing as others had described. After buying two different Fel-pro one piece gaskets I figured out this past weekend that the timing cover is messed up. That's why the front wasn't sealing. D'oh! Looks like I'm replacing the timing cover before April.
For the rear, I figured it was the rear main seal, so I replaced that. It didn't look all that bad when I pulled the old one out. (well, I did completely trash it getting the thing out)
Now people are saying that the RMS may not be the problem with the rear drips that we're seeing..... I changed the intake gasket a year or so ago because that was leaking badly on the sides. I thought that it was sealing well in the back, but I hven't taken a good look at it in a while. This motor is really making me
:mad . If I had the $, it'd be gone and a nice 383 would find it way in there.

Anyone want to buy the '75-'79 Fel-Pro one piece oil pan gasket that I bought and tried? It's the one as a kit with the bolts included.

BeaterShark

Steve, the high pressure/high vol oil pump should not be causing problems. That is what they use on the new cars. My Yukon/Firebird has 50/40 psi at idle.

I think the dripping on the bell housing is from the pool on the back of the block. I'd also bet that the leak is from the intake not sealing very well with the block.

Kingt

This is an age old problem with the small block design. I've had this problem a number of times, even on rebuilds with less than 500 miles. It's very fustrating. A few years back there was a company in Arizona (Michael Manufacturing) that modified small block rear main bearings by adding two small grooves on the lower half of the rear main bearing. The grooves went from the inside edge of the bearing, at an angle, to almost the rear of the bearing. This design allowed excess oil to be routed toward the inside of the engine instead of against the rear oil seal with minimal effect on the oil pressure curve across the bearing. I used one on a small block I built in the mid eighties.
No rear main leak! Perhaps it was coincidence? Regardless, the engine did not leak. I also have seen this bearing design offered for the Chrysler Hemi. I believe I saw it in an issue of Hot Rod or one of the other car mags. I'm re-building my 77 now and I have designed and machined a fixture to make this mod on rear mains. It's almost imposible to do without a fixture since the bearing grooves are on a compound angle. I've searched the internet for the company without success and suspect they are no longer in business. If anyone would like more info e-mail me.

Tom73

Chevy never used a high volume oil pump on a production classic chevy small block and only used a high pressure pump on a few of the solid lifter engines, never on a hydraulic lifter engine. (The current small block is a totally different animal so cannot speak to those.) For street use I would not use anything other then the stock type pump. A pure race engine may require something different but again that is a different animal.

tom...

SteveG75

Well, everyone thanks for the advice.

Drove to work, no leaks. Drove home, with a quick stop at BK, leaks. Really does seem to becoming from either the distributor or the back wall of the block by the manifold. My engine builder has a 800 tech line so I'll be calling them tomorrow.

Really seems to be leaking from the distributor so probably get a new gasket tomorrow on the way home and try it again. Seem to rememebr it leaked a bit back there before the rebuild as well. Probably the replacement distributor or maybe expansion rates of the aluminum heads/manifold on the iron block.
:smash: :smash: :smash:

Corellian Corvette

Please let me know if that works! I'd love to get mine solved too :)

Dr_stingray

well i didnt read everyone's post because i was getting bored reading the same stuff over and over again, so if someone already said this stuff im sorry! But i too had the same leaks coming from my valve cover gaskets, and the oil pressure gauge which is next to the distributor, I tightened up the guage a little and that quit leaking, and i changed the gaskets to cork, well the cork didnt work so i moved on to the rubber ones and that seemed to do the trick! But mine would only leak at high rpm's, what about yall?