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Old 11-17-2005, 09:40 PM
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Excessive oil under valve covers in SBC?

Still looking where this burnt oil smell and oil consumation problem with the 383! Today my in line filter tapped into the PCV showed a lot of oil after only few minutes run..something like 4-5 onces after ten minutes.That is a lot of oil that would gone into the intake if not intercepted by the filter.

The baffle I installed into the valve cover has its base about one inch higher the mating point of the cover and head.For having picked up so much oil within such a short drive tells me the baffle had to have its base right into some solid oil or being really close to it so the oil was just getting lifted right into the baffle and up to the carb base.that is about a good two inches of oil under the cover floating on top the head's base! Is this a normal oil volume or is there something wrong? I've checked the brodix heads have two oil draining holes of about 3/8" at each end of the head but when inserting a piece of wire further in I can feel a much disminishing diameter into the block itself..the engine has a milling 55 pump should this block had seen the oil draining passages enlarged? If not can I think that my oil burning problem comes from there as the valves stems are always submerged and my pcv can't work properly?
thanks,
Ronald.

P.S. I since writing this have changed pcv oil baffle to something lower profile and have picked-up far less oil but still too much.

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Old 11-17-2005, 10:53 PM
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Hi Ronald.

Since you are getting such a large amount in your seperator, the baffle is the most logical culprit of your oil usage. I doubt that the valve cover is filling up with oil. What I suspect is the baffle is doing a very poor job of keeping the oil that is being tossed off the rockers, out of the PCV suction. Seen it happen many many times. When the engine is spinning up, the rockers are tossing oil everywhere inside the cover. If the baffle is not doing the job, the PCV will suck it up big time.

What kind of rockers are you running, stock or roller?
What kind of covers are you using, stock, after market, or tall ones for rollers rocker clearance?

If you can put a stock set of covers on it, I suspect that your oil usage will drop down to normal. The baffles in the aftermarket covers leave lots to be desired. From what i've seen, stock baffles are about all that really does the job.

Mark
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Old 11-17-2005, 11:13 PM
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Try taking the valvecover off, and brazing in another baffle. Make sure the oil has to make a long zig zag journey to get to the PCV valve grommet. I have had much sucess with this whenever an engine sucks oil in through the PCV system, whether it's blowby problems or just no baffle.
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Old 11-18-2005, 12:30 AM
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this thing has just had run-in time on it? I would take it out and put the rings through their paces before u try to troubleshoot. Motors generally burn more oil than normal for the first few miles-

K
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Old 11-18-2005, 03:46 AM
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Stock baffles and breathers worked ok to 7 grand on LT1s and Z28s way back. Are you running a high volume oil pump and a hydraulic cam?
A high volume pump should only be used with solids and either a restrictor kit or edge orifice(still available) lifters or you'll fill the covers and starve the crank. If it is street driven, a stock pump should be enough.
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Old 11-18-2005, 05:14 AM
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I`m not sure if this will help or not, but it did help me with the same problem.
If you look at how the factory ran the PCV filter to the air cleaner you`ll see the filter it uses in the air cleaner box, this system also acts as a restrictor.
I`m running a open element air cleaner and a push in breather with 1 pcv valve, when the push in breather`s filter goes bad and falls apart, the engine starts using oil via the pcv valve, I replace the push in breather and it stops.
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Old 11-18-2005, 08:35 AM
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I don't know why GM had to place the crank vent right on top of the rockers.

You can move the crannkcase vent to the middle between the center cylinders. That will help some as well.
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Old 11-18-2005, 08:47 AM
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I will try all the ideas suggested here but as the oil pump itsel being a high volume or pressure I don't know...and cannot replace this now..but its a milling for sure and I suspect it to be rather high volume or pressure and yes I have hydraulic lifters. I have to eliminate the lousy baffle..and will just put in a new breather since I suspect my actual one having its foam oil saturated thus not allowing enough air in.

Nobody mentionned anything about the "should-be-enlarged" or not oil return passages into a high performance modified block...as I said I tried pushing in a straightened coat hanger wire into the said passage and could feel it is pretty much smaller that what the holes are right into the heads hence possibly seing the oil level so high as having the valves stems completly and always submerged into solid oil..noone ever ran clear see-through valve covers (do they exist?).

The engine has close to 1000 miles since rebuilt now and before concluding it needs to be reopened I am testing every possible minor possible issues!
thanks,Ronald.
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Old 11-19-2005, 02:45 AM
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If it's a Melling 55 it's a stock replacement pump, if it's a 55HV it's high volume. The stock oiling system in a SBC is better than most other pushrod V8s. The stock breathers sit BETWEEN cyls 1-3 and 6-8, not over the rockers.
The stock oil returns are fine for street use - just make sure your head gaskets don't restrict the holes too much.
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Old 11-19-2005, 08:04 AM
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Quote:
Originally Posted by IanRiordan
If it's a Melling 55 it's a stock replacement pump, if it's a 55HV it's high volume. The stock oiling system in a SBC is better than most other pushrod V8s. The stock breathers sit BETWEEN cyls 1-3 and 6-8, not over the rockers.
The stock oil returns are fine for street use - just make sure your head gaskets don't restrict the holes too much.


My invoice says Melling 55A just to get me confused even more! I have a 60 PSI once all warmed up at cruising 2400RPM. I've checked the returning oil passages both sides: when I look into the 3/8 " diam or so holes into the heads themselves its evident they are not in line with the passages opening into the block itself...a wire will makes its way at the upper part of the holes drilled into the heads but its thight...its like there is an offset between the two holes and of course this result in a slowed down oil flow ...I can imagine about the holes the pushrods gets through allowing the oil to drain at some point taking over the draining holes.
Is this type of offset/restricted oil passages between the heads and block peculiar to my set up or all aftermarket heads will do this?
thanks,Ronald.
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Old 11-20-2005, 01:25 AM
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A 55a is not a high volume pump. 60 psi at cruise is ok, pressure relief cuts in @ 80 psi. You should have 3/8 drain holes at each end, I can't see it so I can't offer a firm fix.
The pushrod holes are higher than the valvev guides, so drain back is not viable. It could be return holes, it could be a blocked oil gallery, hard to say, can you send pictures of oil return holes?
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Old 11-20-2005, 09:15 AM
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Quote:
Originally Posted by IanRiordan
A 55a is not a high volume pump. 60 psi at cruise is ok, pressure relief cuts in @ 80 psi. You should have 3/8 drain holes at each end, I can't see it so I can't offer a firm fix.
The pushrod holes are higher than the valvev guides, so drain back is not viable. It could be return holes, it could be a blocked oil gallery, hard to say, can you send pictures of oil return holes?
Ian, thanks for your answering.


I will try getting pictures soon and post them. But as I said initially there is one 3/8 hole at each extremities of the brodix alum. heads..they keep their 3/8" diameter steady for all the head's depth that is maybe 4-5 inches but these holes definitly don't align with a similar size and shape hole into the block itself..if I shed a flashlight into the holes I rather see a kind of blockage at the bottom where the bock itself is...there is a small passage left but it is angled upwards and a steel wire will make its way through this restrictions but I can feel it is much smaller than the hole into the heads..and there is no screwed restrictions inserts that can be seen in there..it is like the holes into the heads are just lower ,rather aligned with the block's own passages.

thanks,Ronald.

P.S. If I can't post the pictures here I'll try e-mail them directly to you.
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Old 11-20-2005, 12:24 PM
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Quote:
Originally Posted by IanRiordan
Stock baffles and breathers worked ok to 7 grand on LT1s and Z28s way back. Are you running a high volume oil pump and a hydraulic cam?
A high volume pump should only be used with solids and either a restrictor kit or edge orifice(still available) lifters or you'll fill the covers and starve the crank. If it is street driven, a stock pump should be enough.

Doesn't a high volume oil pump just bypass-the-oil when the engine galleries get all the oil they can pass?

Isn't the oil filled top end problem just a drain-back problem that is being crutched by restricting the oil to the top end???
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Old 11-21-2005, 01:48 AM
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No, a high PRESSURE pump will bypass. Perhaps I worded my post poorly, an HV pump should only be used with solids, roller rockers and a restrictor (gallery plugs or lifter type).
I know many have used HV pumps with hydraulics, myself included, but most of us have learned from this. I ask these questions because it is hard to diagnose half a world away. The problem could be one or the sum of many. I suspect it is merely head gasket overlap or poor block to head symetery, but without seeing it I can't say for sure so I like to ask to clear up any unknowns.
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