Well it was fun while it lasted !! My newly built and installed 455 is spewing oil from the rear main seal area . After adjusting ,fine tuning ,and dialing in I got this motor running really well . After a good ride today I really got in it and turning about 5000 rpms in 2 nd (turbo 400)I seen a big puff of smoke behind me and when I got home noticed oil all over the back of the oil pan including starter and oil filter as if something just let go . After jacking it up and cleaning everything down cant really tell where it came from .it isn’t leaking while sitting . Tomorrow I plan on running it while watching for any leaks .have 40 lbs of oil pressure at idle and motor always runs cool. I’m running a pcv valve to the front of my quadrajet and breather cap on the opposite valve cover with no visible smoke or blow by . If the motor has to come out i would really like to take it to and Oldsmobile expert and have it checked out and repaired properly . When this motor was built we did use the ford 460 rear mail seal . Thoughts? And thanks

 

The first thing I would check is the rear manifold seal. Get yourself a mirror on a stem and a flashlight and inspect the seal. Rear main seals don't usually blow out that fast.

 

Did you offset the parting lines? Seal installed facing the right direction? Freeze plug from the rear of the cam, or distributor lube freeze plug pop out? Leaking from the back of the intake?

Thoroughly clean the suspected leak area. Go go to your nearest auto parts store, get a small bottle of air conditioning oil with the fluorescent dye. Pour a little in the oil, run it for a while. With a black light it will be obvious where the oil is coming from.

 

i cant say how the seal was installed ,that was done at the machine shop .it never leaked through 3 hours of run time on the stand ,and about 700 miles in the car.Definately not the end rail on the intake manifold (thats nice and dry)its difficult to see the two rear plugs in the block but both appear to be in place .the dye might be a good idea to try .imo it has to be coming from either the rear main seal or the oil pan gasket just not sure why ?in any case ill clean things real good and run it for a while tonight and try to nail it down.

 

By the way, they make dye for engine oil. Not sure how the AC oil dye would mix with engine oil. I remember years ago that the 460 Fords had rear main seal issues if the seals were installed "dry" without some assembly lube on the seal and crankshaft.

 

Of course, I have to ask the obvious based upon where you stated you found oil - starter, back of oil pan and the oil filter itself. Working your way down from the rear of the manifold - if you see no leaks at the rear edge manifold edge seal (it's dry):

(1) The oil filter is not seated correctly. Warped/Bad oil filter?
(2) Oil filter housing assembly gasket not seated properly (loosened up) or faulty gasket?

 

Chief i believe the reason its all over the place back there is because i have no transmission dust cover which would allow the torque convertor and flywheel to sling oil around .new oil filter ,filter housing ,and everything is tight .i just ran the motor for 10 minutes or so getting it up to temp and reving a bit ,climbed under while running it and no visible signs of oil leakage.is it possible it could only leak under heavy load ?it would seem if it came from the rear main seal it would leak while running?especially with the car jacked way up in the front .im not ruling out the oil filter just yet though because i did just change it napa gold.thanks for the replies

 

Jeff,
Do you have the correct breathers / pcv system hooked up on the valve covers ?

 

Bill yes i have a pcv valve in the passenger side valve cover hooked up to front of quadrajet, and a breather cap in the other valve cover.

 

They make dye for every fluid in a car, the problem is nobody seems to stock it (around here anyway). I doubt a little a/c oil would hurt anything in a engine, especially if it’s not going to be in there long.

 

Subscribing.

 

everything remained dry under the car after running twice now on the jack stands still no idea when the oil came from. they dont carry the dye at my local auto parts store so ill order some to have on hand .i guess ill have to go pound on it some more to see if it happens again .ill add to the thread when i find something

 

After taking the car for a good hard drive i got a lot of oil dripping out the back end again .seems to only leak under load.still not sure if its the rear main seal or the rear oil pan gasket .as i said before this thing was bone dry for quite a bit of run time .so what could cause this?excessive crankcase pressure? blow by ?faulty installation of the rear mail seal ?i will need to do some testing but, it looks like it will come out before the cold weather gets here (which won't be long in the northeast) any recommendations on top notch oldsmobile builders in the upstate area ? if i dont find one local BTR in rochester ny should be an excellent choice.

 

I would DEFINITELY grab a small bottle of UV/fluorescent dye, add to oil and view w/ a black light. You'll readily find this leak. If you can't find it at one store - go to another. Most automotive stores have it on-hand.

 

ive been thinking about this .if it only leaks while im driving the car under load won't all the oil under the car show the dye when i jack it up and take a look ? or will the dye only show up at the source of the leak?

 

Clean the entire undercarriage area carefully, entire oil pan (in particular the rear near the rear main seal), oil filter housing, torque converter (remove the cover), distributor area (don't forget there is that O-ring seal on the bottom of the distributor which keeps oil from splattering up and out the distributor) & the intake manifold gasket area. Add the dye - allow the car to idle for 10-15 minutes until it reaches operating temperature. Go under the car w/ the UV lamp and look for leaks (I know you said it doesn't leak until you drive it), but that dye is a very tell-tale weapon at your disposal for finding this leak.

Next, increase the RPM of the engine (standing still - not driving) to >2000 RPM for say five minutes. Go back under the car w/ the UV lamp and look for leaks.

Finally, take it for a two to three mile drive and go back under the car and look for leaks.

The leak will be evident at the source. If the dye shows everywhere, you have more than one leak probably. The rear main generally drips down the front side of the torque converter housing and out that little hole at the bottom of the cover - generally. You'll be surprised what you find when you use the UV/fluorescent dye. It is certainly the very first step to take before moving further. You'll at least be able to rule out the distributor, the intake manifold, the oil filter housing and most likely you'll rule out the oil pan gasket. If you can rule these out, you're most likely looking at the rear main seal or elsewhere.

 

Thank you Chief i will follow this by the letter and report back with my findings

 

Was able to find the dye and a cheap uv pen light with glasses at advance auto and ran the test .After the first run of 15 minutes nothing really to speak of .The second time i ran it at 2000 rpms for 15 minutes it got good and hot at 195 degrees ,shut it down and seen a tiny line of oil on the crank but more importantly oil seeping down from the top lip of the oil pan in the rear.The oil pan bolts seemed to be pretty loose so i torqued them all in sequence .Ive always been gun shy about cranking down those bolts because they can easily warp at the rails.I suspect they may have loosened a bit due to all the heat cycles since this just started leaking after lots of run time.After a decent ride i only notice a small amount of oil on the pan now.(certainly not blowing all over as it was ).im holding out hope that this was the cause.Lesson learned here is on a new build its always a good idea to check the torque on ALL your bolts intake ,exhaust, valve cover, oil pan etc.Heres a perfect example of checking the easy stuff first.If my luck goes south i let you guys know.Thanks

 

You probably found the issue. Indeed, heat cycles, old bolts, old bolt holes, type/quality of oil pan gasket & sealer. Small stuff but annoying when it leaks. I always re-torque stuff whenever I have my car on jack stands. Good Luck.

 

Glad you found it, deadeye! I'd try the dye but I'm afraid of what I would find.

 

Hope it is fixed but my ears went up when the OP stated oil pressure was 40 PSI at idle.
My freshly overhauled 455 is about half that at idle, about 40 at power.

 

I was tempted awhile ago when 1st posted regarding oil pressure @ idle. Hopefully he found the issue. Reviewing my own oil pressure after an R&R of the intake manifold gasket, distributor rebuild, new oil pump & take-up & new oil pressure sending unit I measured 20 psi @ idle, 50 psi @ power (stock 350).

 

Yes that it correct 40 psi @idle and about 60psi cruising.This is with vr1 20w50 oil, standard oil pump, and oil restricted push rods.I am considering going to 10w 40 vr1 next summer .

 

deadeye, my pressures are the same, maybe a touch lower after warm-up; 38-40 @ idle, 55-60 at cruise. I'm currently running Rotella 20w40 with an HV oil pump and ~.003 main clearances. Is the high pressure our problem?

 

thats a good question Mac . I would like to hear from the experts .it doesn’t seem too high to me

 

Well it wouldn't make much sense to install a high volume oil pump, like me, if it's going to cause leakage problems. My problem is probably that I'm just not good at sealing these beasts up, lol.

 

In our cases it doesn’t seem to matter yours is hv and mine is stock and our oil pressure is basically the same . I used the reinforced oil pan gasket with a thin film of rtv on both sides and it held well up til the bolts loosened up . After a 40 mile drive I’m noticing just a few drips . I don’t think any amount of tightening will seal completely once the oil gets by the gasket . Oh well got something to do this winter

 

The oil pressure at idle should be read at normal engine operating temperature - e.g. enough time for all of the oil & the engine to achieve normal operating/running temperature. Any oil pressure measured before achieving normal engine/running operating temperature would be expected to result in a higher oil pressure reading.

You can have either or both types of oil pumps - high volume (gears are larger and push more volume of oil; but not at a higher pressure using the standard bypass valve or pressure release spring); - high pressure (standard bypass valve spring or pressure release spring replaced w/ a stiffer bypass valve or stiffer release valve spring to achieve a higher pressure at the same volume if using the standard oil pump); and, you could (of course) use a high volume/high pressure oil pump. The OEM standard oil pump for a typical Oldsmobile V-8 engine is defined on page 6B-3 Fig. 6B-101A of the 1971 CSM:

ENGINE OIL PRESSURE TEST

1. ENGINE AT OPERATING TEMPERATURE
2. TRANSMISSION IN "NEUTRAL" POSITION
3. OIL PRESSURE SHOULD BE:
AT SLOW IDLE - 7 PSI MINIMUM
1500 - 3000 RPM - 35 PSI MINIMUM

 

My numbers were taken after engine was up to temp ,car idling in park

 

I'm was just providing an expert 'reference' point for comparison since it was developed by Oldsmobile engineers & the difference between a high volume and a high pressure oil pump.

 

Yes chief and thank you . It makes perfect sense that the hv doesn’t necessarily mean higher oil pressure .do you think that 40 psi at idle is a problem ? Could it be harder on the gaskets?at this point I’m not going to sweat it, just run it

 

I'm not an expert, even having replaced numerous oil pumps and oil pan gaskets over the many years on several vehicles I'm basically a person who thinks outside the box but knows enough to follow what the specifications are for such items so I can best address them on my own.
I don't believe 40 psi is any issue whatsoever. It "might" be harder on the gaskets...can't really say. Personally, I don't have any problems going outside the boundaries of the torque values a tad on these older engines when it comes to oil pan gaskets and transmission gaskets. They're old holes, they're old bolts, thousands of heat cycles. It's not like they rolled off the assembly line. I replaced all my oil pan bolts, cleaned the holes liberally, and when I installed the bolts, I put just a very ever so slight amount of blue Loktite on each bolt as they went in. Even then, whenever I have the car on jacks I snug up bolts to torque value or a tad nudge snugger. You'd really have to crank down on those small bolts to worry about warping the oil pan, IMO. Hey, all-in-all, you found your leak, you're golden!

 

Operating temperature. Idle 25-30 PSI, above idle closer to 60 PSI. I don't look at the oil pressure gauge when I'm going fast than cruising ;-) It's a "cutlassefi" build.

 

Its probably the oil pan. When the oil gets hot it gets slick. when it sloshes back or around it hits the pan rails and finds its way out. Mine wont leak on short drives after I clean it. I have to drive it for a while then I will see a small drip here and there. The rear main seal tends to go flying as it finds its way to the flex plate.


IN typical me fashion I read the first post and went to answer. I just realized you found the leak and it was the same problem I got but I didn't really fix it . on my 350. I didn't feel like pulling the engine out mid summer so I installed an engine diaper ( which is cheap insurance since I spin that small block to 7k rpm) . Pulling it this winter. I did how ever stop the leak( for now) by re tightening and using window urethane around the back of the oil pan. The window urethane is super high solids so it seals topical leaks but it sucks to remove lol.

 

Geez dude, $150 for an engine diaper? Can I just buy some Pampers or something?

 

Well the diaper catches the oil and the rods if that happens lol. For the kind of use i do. Its cheaper then slipping on my own oil and wrecking. If it happens.

 

No, I get it. Makes complete sense for you. I really should pull my engine back out and seal it up again. I think this 455 was pretty beat up, oil pan and front cover-wise. Or maybe the rear of the crank is tearing up the seal but I did have it polished. I used rtv on the seal mating surfaces and offset them.