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I have a 1970 Olds 442 that was brought to me that is experiencing excessive oil leaks. After I added some dye, with the black light I found the source of the leak. It's getting pushed past the o-ring on the Holley Hyperspark distributor. It doesn't do this at idle, only at RPM or when you drive it. I've ordered another set of o-rings, however I'm concerned the may be more of the symptom and not the cure, as with these Mondello V/C's there is no source for crankcase ventilation. Any suggestions on a set of V/C's that would clear roller rockers but still have PCV provisions?
I used M/T old school valve covers on my latest build and then doubled thick gaskets and the clearance is fine for my Harlan Sharp roller rockers. I even added baffles under both holes in the valve covers so they could be used for breathers or a PCV. Two thick valve cover gaskets provided enough clearance for the roller rockers....
^^^ This, breathers do not relieve positive crankcase pressure.
Sorry, I have to disagree. The breathers are open to the atmosphere and most certainly do relieve crankcase pressure. Thats how millions of cars and trucks were up till the mid 60's when PCV systems came along for emissions reasons. The PCV setup only recirculates the blowby through the engine and burns the fumes. It does not relieve pressure any better than the open breathers.
69Charger,
With the breathers there really should not be any pressure to push oil out around the orings on the distributor unless you have a real excessive amount of blowby. How snug does the distributor fit ?
Fix the distributor leak, you are likely on the right track replacing the O ring.
Drill a hole in back side of oil fill tube, install generic Mr Gskt or equivalent PCV grommet, insert PCV valve there and run short hose to appropriate port on “carb.” I can’t tell what you’re running there.
69Chgr----thanks. I actually have the OEM PCV setup on the engine and it runs off a port in the front of the manifold and then I have two breathers in both the valve covers. We tested the engine and ran lots of dyno pulls without the PCV but I wanted to have it installed just to be sure internal pressures were good. The system is working fine for me. I can send more pics if you wish.
You can see the PCV in this recent engine photo....
Engine photo showing the PCV....
Last edited by 442Dude; August 24th, 2021 at 03:10 AM.
Thanks everyone for the positive suggestions. This engine was one of the last engines that Joe Mondello built before he passed away per my customer. I believe that when it was dyno tested that it had a Pertronix distributor, then the customer changed that out for a Holley Hyperspark to go along with the Holley Terminator system. That is when I think this leak probably started. I will take everyones advice here, really like the idea on the oil filler neck and the PCV port. It does not leak at idle, only at RPM.
69Chgr---good luck. FWIW.......I also am running the Hyperspark distributor in my engine. We ran mine with a stand alone HEI for my dyno runs and then I converted everything over to the Hyperspark and the SNIPER Quadra Jet system.
Sorry, I have to disagree. The breathers are open to the atmosphere and most certainly do relieve crankcase pressure.
They do relieve crankcase pressure, but it is not positive relief of the pressure. The old road draft tubes did have sort of a vacuum effect when driving down the road at speed.
Well, after replacing the o-ring on the Holley Dual Sync distributor I still have the same oil leak. We got sidelined however when I pulled the distributor with the bronze Comp 442 distributor gear to find it worn excessively. This engine has a Lunati Roller cam, so the bronze gear had been installed. After research, I installed a polymer gear from BOP Engineering (outstanding support by the way) and averted a possible failure there. However back to the oil leak debacle around the o-ring of the distributor. It won't leak at idle, only when you go drive it. So I guess now it is time to go after the PCV route to mitigate crankcase pressure.
I still think you are missing something. With the two breathers on the valve covers there should not be any pressure in the crankcase. At least not enough to be pushing it past the distributor o-ring. I would expect the front or rear crank seals to leak first. Are you absolutely sure it isn't leaking from the intake or valve covers and just ending up at the distributor ?
The pcv will just be covering up the problem. That is if it helps any. Early engines did not have pcv and didnt leak at the distributor.
Do you have the gasket under the distributor, thin paper type.
There should be no gasket on an Olds distributor. That's a Chevy thing. The O-ring is the seal. Since the OP has an aftermarket distributor, I'd check for either an o-ring groove that was machined too deep or an o-ring that is the wrong cross section.
I still think you are missing something. With the two breathers on the valve covers there should not be any pressure in the crankcase. At least not enough to be pushing it past the distributor o-ring. I would expect the front or rear crank seals to leak first. Are you absolutely sure it isn't leaking from the intake or valve covers and just ending up at the distributor ?
The pcv will just be covering up the problem. That is if it helps any. Early engines did not have pcv and didnt leak at the distributor.
Thanks Bill. However, yes, I am absolutely 100% positive that it is not the intake manifold, as we use engine oil dye, then after the car is ran and driven, it is brought back in the shop, all lights turned off, and use the black light to detect where the leak is coming from. The intake manifold is 100% dry, however you can see the perfect yellow flourescent ring of oil around the distributor, and leaking down the sides of the block and over the starter and oil filter. I also thought it had to be the intake, however the dye tells the story very well. At idle it doesn't leak at all, however at RPM it leaks horribly.
I'm with Joe P on this one. Seems like a case of aftermarket parts not up to spec. Do you have access to an OEM distributor? The O ring grove can be checked with calipers and compared with OEM. Perhaps a O ring with a thicker cross section can be tried.
I'm with Joe P on this one. Seems like a case of aftermarket parts not up to spec. Do you have access to an OEM distributor? The O ring grove can be checked with calipers and compared with OEM. Perhaps a O ring with a thicker cross section can be tried.
Just happen to have one sitting on my bench O-ring groove measures 1.294" It is .110" deep. The distributor body where the groove is measures 1.515 od. The new O-ring from the Fel Pro gasket set is .140 thick.
69 Chgr---I have had two different distributors in my new engine---both with the O-ring seal as Joe mentioned. The latest is the same Holley Hyperspark distributor that you are using and mine does not leak. I have about 500 miles on the new engine so far with the two breathers and the PCV coming off the intake port on the W-30 intake.
I am also believing that either the O-ring is cut, failed, or is the wrong size as well. Have you pulled the distributor out and inspected it recently?
Also one more thing I will share from experience on my engines FWIW.....I run PCVs on both my new 455 BBO and my 496 BBC. On the Olds engine, we did not run a PCV when dynoing the engine and everything was fine. On the BBC, if I don't run a PCV it takes about 5-10 mins and my distributor seal will start leaking just like yours. I'm assuming there is too much internal crankcase pressure and that distributor seal is the weakest link. When I add the PCV back into the system on the BBC....no leaks. So I leave them both in and consider them necessary. I would try a PCV in yours and see if that's the trick.....IMHO....
Thanks so much for the feedback guys. Yes, I have an OEM distributor, and aftermarket Summit Olds Distributor, and now the 2nd Holley Dual Sync distributor. I got the same measurements that Bill K got on all 4 distributors. Yes this is my 3rd o-ring from Fel Pro.
442Dude - There is NO PCV at all on this engine. It has an Edlebrock copy of the factory 1970 aluminum distributor running a Holley FAST EFI system. I noticed where the PCV fitting usually is on most Olds 455's is plugged on this one and not in use. I am going to try to find the correct fitting that goes there (in front of carb) and a reference for that part would be appreciated.
Also one more thing I will share from experience on my engines FWIW.....I run PCVs on both my new 455 BBO and my 496 BBC. On the Olds engine, we did not run a PCV when dynoing the engine and everything was fine. On the BBC, if I don't run a PCV it takes about 5-10 mins and my distributor seal will start leaking just like yours. I'm assuming there is too much internal crankcase pressure and that distributor seal is the weakest link. When I add the PCV back into the system on the BBC....no leaks. So I leave them both in and consider them necessary. I would try a PCV in yours and see if that's the trick.....IMHO....
Thanks 442 Dude! Yes, I also had the same issue on my 440/512 stroker when I just had 2 breathers and no PCV. Then I went to the ME Wagner adjustable PCV Valve and problem solved. I am thinking that is the direction we need to go to next.
Note: I also installed a polymer gear on the new Dual Sync, as the bronze Comp Cams 442 distributor gear was extremely worn. The polymer gear from BOP Engineering seems to be the new Go To when using billet roller cams from what I have researched, but only time will tell.
My point about the thin gasket was to fix the leak, the distributor is not original equipment either. Seems like offering up a potential fix to the OP problem should be the goal, nothing more.
Check the tail pipes for any oil residue with the black light. If you see any dye it’s most likely a failed intake manifold gasket in conjunction with the leak at the distributor. That was the case with my oil loss. Top of the intake was dry as a bone, but was getting sucked out the exhaust ports internally (see my posts)
A few people have mentioned this before, and after speaking to the gentleman at OldsPerformance Products this makes sense. Also explains the prematurely worn distributor gear. https://oldsperformanceproducts.com/product/oiler-plug/
A few people have mentioned this before, and after speaking to the gentleman at OldsPerformance Products this makes sense. Also explains the prematurely worn distributor gear. https://oldsperformanceproducts.com/product/oiler-plug/
That could explain the distributor gear wear but would have nothing to do with your oil leak around the distributor. You should be able to look in the distributor hole with a small mirror and see if they have the correct plug in there with the hole. You might be able to see it without the mirror. Just getting ready to put the one in the 425 I am doing.
Are you SURE it's not leaking from where the manifold meets the block and heads? (And then pooling up in the ring around the distributor)
That little triangle is often the problem.
-peter
Can someone tell me where to get this fitting to setup the PCV like this one?
Almost looks like they pieced it together. Drilled and tapped the manifold into the valley area for a pipe nipple, then found a 90 degree rubber hose piece to go to the pcv valve. For some reason the 90 degree hose looks familiar ? I will have to take a look at my Wife's Riviera tonight. I might be mistaken but I think there is a rubber piece like that in the air cleaner.
Three choices to vent crank pressure blowbye. One is a PCV valves ala Federal emission laws. Open breathers feeding air into the air cleaner is another. The other is open breathers on the oil tube in front, or on the valve covers into the open air. I have run one on each of the valve covers and on the oil fill tube into the open air, for 35 years on my 455. NOT PC, but I have no desire to pump oily air into my intake and combustion chamber year after year.
August 23rd, 2021, 08:33 AM
