Vibration causing a real main seal leak
 

REAR MAIN SEAL LEAK

Well after all my efforts and replacing entire major car systems, I think I'm having a real main seal leak that is caused by vibration that increases at higher RPM's at freeway speeds. I have a brand new Ram Air V motor along with a brand new Richmond 5 speed trans. Rearend is fresh as well. The only parts that remain in question are the harmonic balancer and the drive shaft, but both are new. The balancer is an original NOS GM part and the drive shaft is supposingly balanced.

Does anyone recommend anything else to look at? Im lost for words and am about to go ape on the engine builder.

The engine has been internally balanced = crank, rods and pistons.

Balancer and drive shaft is in question, but again, any ideas on what else could cause this?

thanks

mike

Are you showing an oil leak after driving at higher speeds rather than just cruising or idling around? Or is it leaking when the engine is running no matter what rpm or speed?

Breaking the motor in without driving it - the motor has no leak. When I drive it at high speeds, it leaks. Driving it period it leaks.

vibration
 

neutral balanced flywheel ?

I hope so, I purchased all the internal parts from Butler Performance.

Draw a chalk line on the damper (balancer), then take it up to where it vibrates. Slow down and get home. If the outter part has moved, it is junk. If the damper is still in the same place as marked (and the movement can be as little as .030") check it for any signs of the bonding seperating. Next, check your flexplate/flywheel for any cracks, especially up close to the center at the crank flange. I am thinking that after all these years the Damper's bonding has deteriorated and it's about to let go. Just because it's NOS does not mean it's good !!!! Age is still the enemy on it.

Functioning PCV?

Thanks for the advice goquick. I will give that a try.

Yes Ron, The PVC is working.

Keep us updated. I will be out of town for the next week, so i may not get to check in.

This is all grabbing at straws. There is no way balance will cause a leak and you in good conscience could drive the car. It is all about crankcase pressure and good sealing techniques. Look closer at the pan seals and there is dye you can buy to trace oil leaks. Personally I would clean it well then hold rpms to cruising rpm while watching it from underneath well supported. Rod

Location of leak and description of vibration have me leaning toward an out-of-balance Driveshaft. Check your u-joints. You can put a run-out gauge on this easily. Is there vibration while stationary? If not, go for a drive on a level road, get to rpm where vibration happens in 1st and note speed. Then depress clutch and coast. Do you still feel the vibration? If so, notice if vibration lessens as speed lessens. Try the same in 2nd and so on up to the same speed. If you have the vibration as the same speed, I'll bet driveshaft over engine balance any day...

NOT suspecting the Front Balancer.
I suspect the Flywheel, or Power-imBalance (dead CYL under load or RPM).

As for the oil leak. STOP! do a compression test on all 8 CYLs, write-it-down and report back. Rather high Positive crankcase pressure is needed to cause a BAD rear seal to leak out of the rear flange. I suspect the Oil Pan seal shifted to cause a gaping gap between the oil-pan & Rear Cap. Use the Cork band wetted with RTV there & watch where is tries to go during oil pan bolt torquing.

Aside from the leak, there's some things here that raise a flag with me. First, you need to make SURE about the balance, and the other items, such as the flywheel and balancer. Period. An OE balancer is not zero-balanced out of the box, and you would KNOW if it was balanced or not (look at the bill if nothing else, but it should have weights/drilled holes). For the most part though, OE replacement balancers are junk, and you should really get an aftermarket one.

Flywheels you can order zero-balanced, but they should still be checked, and usually are when balancing a rotating assembly. There again, you shold be able to tell by looking at the bill/invoice and part number, check and see if it's zero-balanced, and if the rotating assembly was balanced (internal or external).

Driveshaft. Is it a factory one that was in the car before? Did it vibrate before? Driveshafts fail, just as u-joints do, and yokes wear. As inexpensive as a driveshaft is, why not replace it? For the piece of mind if nothing else? How much did you spend on the engine? Can you swing another $250 for new shaft, yokes, joints, and balance?

Now, the leak, sometimes it may LOOK like it's the rear main when it's actually something else. Check the filter housing, they sometimes spray under load when hot. Check the filter. I've seen where the rubber ring stuck to the housing after a filter change and the next filter was screwed right on top of it. Look at the distributor area and see if it's puddled up around there, it can trickle down the bellhousing and look like a rear main leak. It can leak on the pan rail too. Wipe it all down, go around the block, and check again until you're sure where it's coming from. If it's the rear main, check your PCV setup, etc.

.

If the valley pan is leaking it will also run down the back and look like the rear main or pan.

I think you have excess crankcase pressure and it's pushing out when at higher rpms.

Ditto on buying an aftermarket balancer.

My balancer came apart during a race weekend, didn't know it at the time that's what it was, the trans pilot bearing came out as well, not sure which came apart first though.
By the end of Saturdays races the rear main was leaking from the vibration, but the vibration was pretty severe.


If everything already mentioned checks out though the next thing to check is the bellhousing alignment.
Also check the clutch assembly. Vibrations can be tough to pin down.

If everything external checks out there's only one place left to go. Don't want to toast a V engine.
V block or just the top end?

As previously stated the leak may not be associated with the oil leak. What kind of seal did you use on the oil pan where it goes around the rear main bearing cap? If you used a rubber seal you may be leaking there and when it leaks there it it very hard to tell if it coming from the back of the pan or the rear main seal. In either case it would require you to pull the engine to repair. I never use the rubber seal on the back of the pan. SD performance sells a special made wide cork seal ($5.00) that is used in lieu of the rubber seal, that seal is the best you can get and mine never leak when I use the SD cork seal. Also it may be remote but if the crank was cracked that would cause a vibration. To rule out the driveshaft, the driveshaft would only cause a vibration while driving and would not be related to engine RPM, so if it does not have the vibration when you rev it in neutral then that would cause me to suspect the driveline.

Tim C

Thanks for all the advice. Let me try and clarify some things.

I just got the drive shaft out and repaired. Threw it back in the car and the condition and leak is still there. The front joint was bad even though the drive shaft only had about a 1000 miles on a rebuild. The joint was out 10K and the limit of play is 2k. The shaft was also out of balance a bit and was brought back into specs.

Unfortunately, the vibration is still there. It's hard to pin down if the vibration is coming from the engine, drive line or rear end. I have tried to rev the engine in neutral and still cant quite verify if it's the engine or not.

The car has NEW everything and this is no bull. The rotating assembly = Kellogg crank, Ross pistons and H beam rods were all neutral balanced by Butler. The General Motors balancer made in Mexico is also GM = but who knows whats up with that. If I rev the engine, it looks true and not wibble wabbling around. The car also has a brand new Richmond 5 speed manual trans. The flywheel and clutch should be neutral balanced, but am uncertain if Butler did the internal balance with the fly wheel parts. They did not do the assembly. The oil pan gasket is a cork gasket but the rear portion is rubber as all Pontiac's are. The rear main seal is a BOP Vitton seal.

Oil filter housing is solid.

It for sure is leaking from the back end of the engine inside of the clutch bell housing. Yes, I had the bell housing check on the block with the trans bolted up to verify alignment. I think the play was 2 or 3 thousands which I believe is way within in spec.

The oil pressure gauge is pegged at 80 PSI when driving the car and the pump was also supplied by Butler. As far as the PVC system, the car is running the original 303 Ram Air V carb that has the extra PVC pipe running off the side of the carb base with new hose and pvc valve. Not sure how this can cause a leak, but that is the info.

As far as what the engine is, it is a NOS 428 SR block 4-bolt main motor. It would be the correct block for a Ram Air VI motor configuration. NOS heads, and intake to boot.

Any more thoughts on where to go from here besides blowing the car apart again?

damn...

It may be that the pressure control valve (PCV) is not keeping up with the crankcase pressure that the engine has when running at higher RPM.

What kind of oil are you running?

Best to do a compression test as HIS suggested.

I agree with Ron here. Excess crankcase pressure that the PCV cannot vent fast enough forcing the oil out of any place it can find.

Not all Pontiacs used the rubber rear seal. A lot of the gasket kits have both the rubber and cork seal. I always use the cork seal, the rubber ones usually leak.

Hmm -

So if you guys suspect a PVC system, what about running without one or an open one? How can I verify this?

It seems that the car does not leak at idle once I clean up the mess.

suggestions?

So once I do do a compression check - what should I look for? The engine is aorund 9.75 to 10 to 1 compression.

I am currently running AMSOIL synthetic 10w-40 with an AMSOIL filter.

How do I check or work with too much crank case pressure?

Here is a link to a quick video of the car running. Sorry about the bad lighting, but the car does not seam to leak at idle.

odd....

http://www.flickr.com/photos/31412306@N05/5097482959/


Im wondering if the vibration is actually an issue or is it just how the car runs...

Or try this link

http://s1094.photobucket.com/albums/...t=MVI_8127.mp4

428, the MAIN thing you need to do is determine if your vibration is in the engine, or in the driveline. You need to rev the car in nuetral, with it PARKED, not going tdown the road. If you have a vibration at a specific rpm, you have an engine balance/motor mount/mechanical issue. If your engine feels ok in the driveway at 3000 rpm (or whatever your trouble rpm is) while in neutral, go drive the car. If the car now vibrates at cruise at the specific rpm, put it in neutral and let it coast at the same speed, but with the engine idling. If the vibration is still there, it is in the driveline: tires, drums, rear end, driveshaft, diff, yoke, u-joints, etc. The driveshaft needs to be indexed as well. It could be 180 out. Once you determine whether the vibration is engine or drivetrain, you can start to hunt it down.

Thank you for your insight and I shall apply your logic in determining the problem.

I think we need to back up a bit here and rehash the problem vs. condition.

I have assumed the vibration is causing the oil leak. I need to look into the vibration issue as well as the oil leak.

Some folks are saying to do a compression test and check the PVC system.

I would like to know how do I test, or confirm if the PVC system is the cause of the leak or the vibration.

Please advice forum.

thanks

mike ornellas

If you block the pcv you will have oil blowing out of every gasket on the engine. Not at idle, but while you are driving it for sure.

A cheap way to fix the problem is this: http://www.summitracing.com/parts/SUM-120108/

This setup will have a hose from each valve cover to each header collector and draw a vacuum on the crankcase to get rid of the excess pressure.

Or this way, it's a more expensive way but much more effective and an increase in performance: http://www.gzmotorsports.com/complete-pump-kits.html

A vacuum pump is the best way to go.

You mentioned that your oil pressure is pegged at 80 psi while driving this sounds very unusual. If your oil pressure with a warm engine is pegged at 80 psi while normal driving you have a problem. Your warm oil pressure should not be that high unless you are reving the engine above 4500-5000 RPM. If this is the case your bearing clearances are way too tight or something else is wrong. All Pontiacs do not run the rubber seal at the rear of the pan, only those who don't know better use the rubber seal. As I said in my earlier post, the best seal is the special made extra wide cork seal from SD performance.

Tim C

Tim C

How much time did the engine have prior to putting synthetic oil in?

You could connect an additional line from a valve cover to your air cleaner in addition to the pcv. How big is the port you are connecting the pcv too on the carb?

Perhaps a larger port if using a small one would help pull more vacuum.

Search the forums there is a few guys who have posted ways of increasing the vacuum to the crank case to relieve pressure besides header evacs or vacuum pumps.

The engine has only run AMSOIL.

It has less then 200 miles on it.

Glad to hear about the internal balance, and if you sourced the flywheel and clutch from Butler, it's a good bet it was zero balance stuff (still would check part numbers as to the vibration).

After hearing about the PCV setup, I'm leaning away from that, think you're good in that respect. No way would I go to a pan evac setup, that will only suck oil into the exhaust, and I'm not a fan of vacuum pumps either, think it's overkill for the street. And, just to say, I've seen where they work TOO good, and actually SUCK the rear seal or valley into the pan/engine.

As for the 80 psi, that's probably the pump they gave you, or one with the extra spring and the builder tossed the extra/heavier spring in there. If it's one of their' new blueprinted pumps, it's probably shimmed, and you will see more psi from those, no biggie. Only thing to keep an eye on is the distributor gear, they tend to wear quickly with the higher psi pumps, especially the bronze ones for rollers. (There's a specific one that is hardened for use with higher psi pumps too, fyi).

Now, with the higher psi pumps, you will have more of a tendancy for leaks. I've run them on a number of occassions and that's why I was talking about the oil filter housing, because I've seen where the bolts are too long, and the housing doesn't clamp the gasket very well. Under pressure, it will spray past the gasket, idle, no leak. Valley pan as mentioned before, valve covers, have a tendancy to trickle down the parting lines and heads back there and look like a rear main seal leak, have to look hard.

You say you're sure it's coming from WITHIN the bellhousing? Rear main you can see from under the car if the pan has the grooves for the rubber seal. You can see if the teets are in the grooves too, know if it squeezed out. With an inspection mirror you can look past the lip of the pan and see the seal too. It's not in the bellhousing, if you catch my drift. The block plate is in the way, except where the crank register is, so it would leak outside of the plate for the most part. (That's why I suggested looking around the distributor as well for build up).

Do you have a vent on the trans? Is it plugged? Maybe pressure is building up and your seeing trans/gear oil? Blowing out the front bearing cover? It's a thought, easy to check.

Lastly, if it is coming from the rear of the block, I mean it could be a block plug, like the cam galley, or a crack even maybe in one of the oil passages, since they bulge into that area (reaching there, would be rare). For those, to check, you'd have to drop the trans, etc of course, so you want to rule out everything else first.


.

All good postings & responses. Particularly that rear-oil-plug-comment. The external rear valley plug needs teflon tape to go with the hope & change.

Let's re-visit:
""""""The oil pan gasket is a cork gasket but the rear portion is rubber as all Pontiac's are. The rear main seal is a BOP Vitton seal."""""

I just installed a cork band-seal (have a few left) instead of the rubber seal between Oil-pan and Rear Cap to AVOID the oil leak caused by the rubber seal shifting badly out of alignment. The 3-little-holes in the rear of my oil pan could not be trusted to hold the rubber seal in place.
================================================== ===========
I suspect engine-DRIVELINE vibe & oil leakage are separate problems.

Should you include bent rim, wheel imbalance, low tire pressure in the possibility?

Need to get a syrometer to help find out the cause of the vibration. Many lawn mower places sell them as a tach. The leak sounds crankcase pressure related. Perform a leak down test on the cylinders.

:)

Just struck me, do ring manufacturers recommend break-in/ring seat with syn oils? 200 miles, depending on the cyl finish may not be enough for seating. Maybe use a conventional oil for a 1000 or so miles?

.

Thanks for all the replies.

Im most confident that its a rear main seal and not something else dripping from somewhere else. The leak happens only when driving the car and the oil pressure is pegged past 80 PSI. I'm leaning towards crank case pressure myself at this point because I will be very upset if I have to pull the engine to change out the oil pump.

I think your rings have not seated as you are running synthetic oil and have a bunch of blow by causing excessive crankcase pressure.

That could be the case but I dont see blue smoke coming out of the tail pipe anymore.

No reason to change the pump, high pressure wouldn't be a problem in general. High oil psi certainly doesn't cause a rear main leak. You say it's pegged past 80 when driving, like when it's cold? Or fully warmed up? If when warm, try 10-30, and if it still seems high, maybe even 5-30. What kind of gauge is it, is it new, electric or mech, and what's the range on the face?


High crankcase pressure would be due to blow by, and depending on the cyl finish, can take some time to seat. (Some like using a very fine cross-hatch, prolongs seat). Again, regular/conventional oil would be best to use for break-in/seat. Leak-down would tell you, though with 200 miles, I would still give it some time (and expect some blow by for now).


.

This is the 2nd motor that I have experienced this same problem of oil leak. The gauge is the factory rally cluster. the max range of that gauge is 80 psi. At Idle it reads about 40 or so. On the freeway it reads around 65 psi at crusing speeds. It pegs past 80 - I assume past 80 when I rev it and when the car is being driven hard. The pressure is high to me when the engine is warmed up. Running thinner oil I feel will just make it easier for it to get past the seals.

2nd engine with the same leak? Same builder by chance? Hm, maybe the seal was installed incorrectly? And the previous engine, on disassembly, showed it was a rear main seal? Maybe go back to the rope type or something?

I wouldn't trust the gauge. I sugguest trying another gauge, even just temp to get an idea of what your other gauge is reading, off or what. 40 idle and 65 cruise sounds right, might just peg once past a certain rpm, not really a bad thing. And yeah, thinner could leak more, but it's not that big of a difference, so shouldn't be that much more. Still say try a diff gauge.

.

FWIW BOP seal doesnt mean it cant leak. Lots of possibilities there. Agree on cork cap/pan gasket being better but the rubber ones have worked ok for me when I didnt have a cork one available. I glue either type on with weather stripping adhesive. Cap and pan rail must be oil free for adhesive to work. A mis trimmed/installed seal, BOP OR rope will leak and maybe not appear to leak at idle because less volume of oil would be present. I would be double checking this area.

BTW high crankcase pressure tends to show up as dipstick raised after a short high rpm burst.

HWYSTR455 posted some valid points. Especially leaking filter housing. I've seen that. Also I once had a near microscopic hole in an oil gauge line that took a long time to track. Oil was found a long way from the line and near zero near the hole. A ford escort I once owned had a fuel pump with an internal leak allowing oil out the vent, spraying oil to opposite end of the engine and there was no sign of oil on the pump. Dont rule out anything till you are certain.

High oil pressure is not the cause of your leak but crankcase pressure can affect oil pressure. Curious what your oil pressure is at idle with a very hot heat soak( idle in front of a wall for a while and push your temps to the higher side of where you run maybe a tid hotter. try to get the oil temp up)

Also high oil pressure can cause more volume of oil to an area where you COULD leak, BUT if its sealed properly your not going to leak. Obviously high crankcase pressures could FORCE seals to leak.

Oh a vibration from engine imbalance will occur at same rpm point in or out of gear and it wont change. It will be there with the vehicle stationary. Severe enough to cause an oil leak you would have big issues.

Another thing Hwystr455 mentioned trying a rope seal. There HAVE been reports of some blocks that just wont seal with the BOP seal. Those blocks were cured of leaks with a "Best"(iirc) rope seal. I used a Mr Gasket rope seal several years back and it lasted for about 12k-15k miles before it started dripping. (a few years driving)

So I here some guys speak of an all cork oil pan gasket. Anyone have a name or link to a site that has this product?

The Felpro pan sets I've gotten in the past always had both, the 2 rubber types and the cork. I just looked on RockAuto and saw the one set, and the pic shows the one rubber and cork, which would work. Napa carries them too, part number 1814. There's also the 'hi performance' set, would have to look that one up, but that's the one I always get.

A number of places carry the braided teflon rear main seal, which I recall many have good luck with. Know Butler carries them. I also recall some had issues with the BOP seal due to the finish on the crank, like the slash/grooves were too deep or something, but would leak. There's a fix for that, could search it here.

.

Could this be a rear pan leak, not a rear main leak?

This one:

http://www.summitracing.com/parts/FPP-1814/?rtype=10

There's also one piece pan gaskets from BOP that some swear by, but I've never used one:

http://www.bopengineering.com

Here's the brainded teflon rear main seal:

http://www.jbp-pontiac.com/products/...ain_seals.html


.

It could be a pan leak but something has to be causing the leak and not just a part failure.

Anyone here use the single piece oil pan gasket before?

What about Viton's new teflon and graphite rear seal?

thanks

Have a leak down done to see how much pressure is bleeding into the crankcase past the rings.

Where are you getting the oil pressure signal from? The oil filter housing or the top of the block by the distributor? If you add another gauge, put the sensor on the top of the block.

The oil pressure sending unit is tapped into the factory oil filter housing. I just drove the car today and there is a slight hint of blue smoke coming out of the tail pipe. Like I said, the car has less then 200 miles on it and now the leak is happening at idle. I tried to tighten up the oil pan gaskets - it helped very little.

The weird thing is that when I drive the car, at idle the gauge is around 40 psi, but as soon as I gently hit the gas pedal, the gauge shoots to 80 and beyond.

It is most likely because of the synthetic oil.

I would change that out with some 10/30 dyno oil and run it for 500 miles and see what it is like then after the rings seat. What cam are you running? If a roller any oil is fine. If a flat tappet cam run some STP oil treatment with the oil to ensure it has enough ZDDP in it.