440 Advice

I need advice regarding a 440 left had rotation recent rebuild about 10 hours of run time. It is leaking oil at the rear oil seal about a pint every 3 hours of running time. I have had to put a high pressure spring in the oil pump to get 40 lbs. oil pressure which drops to 20 lbs. at 1000 rpm. I am faced with pulling the engine or living with it. The oil pressure has been checked at sender port so the issue is not with oil gage or wiring. The oil for the first 6 hours was Brad Penn 10-40. I changed to 15-40 Rotella for the last 3 hours with only minimal change in oil pressure. Any advice would be greatly appreciated.

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KavaKava said:

I need advice regarding a 440 left had rotation recent rebuild about 10 hours of run time.
FYI.... a LH Rotation engine is Standard Rotation. (rotation is viewed from the flywheel end an engine)

It is leaking oil at the rear oil seal about a pint every 3 hours of running time.
If by chance this is a REV RH Rotation engine, and if the incorrect rear main seal was installed, it may explain your oil leak.

I have had to put a high pressure spring in the oil pump to get 40 lbs. oil pressure which drops to 20 lbs. at 1000 rpm.
20 psi @ 1k rpm is low.
Is this a reading from the electric oil pressure gauge, or a reading from a mechanical gauge?
If from an electrical gauge, you may want to verify the reading by temporarily installing a mechanical gauge.

I am faced with pulling the engine or living with it. The oil pressure has been checked at sender port so the issue is not with oil gauge or wiring.
OK.... that answers my above question.

The oil for the first 6 hours was Brad Penn 10-40. I changed to 15-40 Rotella for the last 3 hours with only minimal change in oil pressure. Any advice would be greatly appreciated.
If the oil pump is working correctly, and if the oil viscosity is correct, low oil pressure is typically a result of excessive clearance at several or more forced-lubrication areas..... such as main bearings, connecting rod journals, cam bearings, etc.

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Loosing a pint of oil every 3 hours sounds like a real messy bilge. That's pretty low pressure to loose so much oil. Are you sure that it isn't just leaking out? Fresh rebuild, with issues like this??? You should not be questioning clearances 10 hours after a rebuild. That information should be in the engines log book.

Pull the engine and find the problem? It will not magically fix itself the next time you turn the key. You certainly don't want to be stranded at sea, risking life. Pull the engine and find the problem(s). b As for your choices of oil. I'm not sure if putting good money into boutique oil will solve your problems. Engine calls for straight 30W.

Good luck, Noel.

Agreed..... pull this engine and find out what is wrong!

I'm inclined to ask for the details of "recent rebuild"....??

It does sound like your rear seal may be compromised or possibly installed backwards if it's not a rope.
The 440 crank likely has slinger grooves around it. Small slashes in the seal area ////// one way or the other \\\\\\, depending on the intended crank rotation direction that are meant to direct oil back toward the engine and away from the seal.
What you don't want is a left rotation crank in a right rotating engine or a either which would tend to pull oil into the seal.

Do you have a PCV operational on this engine? If not, you may be pressurizing the crankcase.

A leak down test before you pull it might provide some insight.
Is the oil pump new, or a used one that was "fine" on another engine? Either way you should check the pump to SM specs.
Are you seeing any air bubbles in the oil. A crack in the oil pickup tube threads can pull air into the oil.
Cut open the oil filter and inspect it for excessive metallic particles.
You might zip a valve cover off and make sure the rocker shafts are on correctly. Oiling holes should be pointing downward and toward the valve.

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daves69 said:

It does sound like your rear seal may be compromised or possibly installed backwards if it's not a rope.
The 440 crank likely has slinger grooves around it. Small slashes in the seal area ////// one way or the other \\\\\\, depending on the intended crank rotation direction that are meant to direct oil back toward the engine and away from the seal.
What you don't want is a left rotation crank in a right rotating engine or a

right rotation crank in a left rotating engine,​

either which would tend to pull oil into the seal.
I am not familiar with the 440 crankshaft and the small slashes being a part of the crankshaft.
On the GM engines, the seal surface is smooth and the "slashes" are within the seal.
As Dave says, they are there to wick oil towards the crankcase area.

Do you have a PCV operational on this engine? If not, you may be pressurizing the crankcase.

A leak down test before you pull it might provide some insight.
Yes..... a cylinder leak-down-test (not a cylinder pressure test... aka compression test) would be informative, but must be done prior to pulling the engine down.
Once torn down, this test can no longer be performed.


Is the oil pump new, or a used one that was "fine" on another engine? Either way you should check the pump to SM specs.
Are you seeing any air bubbles in the oil. A crack in the oil pickup tube threads can pull air into the oil.
Good point.
Again.... not familiar with the 440...... but over-filling the oil pan to the point of the crankshaft dipping into it may cause aerated oil, of which would lower the oil pressure reading.

Cut open the oil filter and inspect it for excessive metallic particles.
You might zip a valve cover off and make sure the rocker shafts are on correctly. Oiling holes should be pointing downward and toward the valve.

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Thank you all for your replies. I have removed the reverse rotation engine and now have to order new seals. Felpro only recommends a rope seal. Dvorak machine recommends their red seal which has a silicone elastomer side rail seal and a polacrylate crank shaft seal which requires removal of the slashes in the seal area. Never an easy decision!! Any advice would be very much appreciated.

Once you polish the "slashes" smooth you'll surely need the recommended seal. A rope would likely leak. I'm sure
FWIW, I prefer the rope. In the automotive world, folks have had a lot of issues with newer seals replacing leaking rope seals. of these folks don't smooth out the "slashes", or they've installed the seal backwards, or apply sealer where it's not necessary. An engine, oor is it a motor Rick) with a lot of blow by pressure can hurt a seal too. So make sure your PCV is functioning.

daves69 said:

An engine, oor is it a motor Rick) with a lot of blow by pressure can hurt a seal too. So make sure your PCV is functioning.

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Hey.... are you making fun of me????


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Any resolution on this??!! I’m sweating the rear main seal issues on my two rebuilds...

Sorry for my late reply. I had to pull the engine and send it to a different re-builder. The low oil pressure was due to a lifter shaft installed upside down and the new rebuilder installed a rope seal. He also found leakage in the small hydraulic tube that goes to the oil pressure sender. He also indicated that the engine should be using Brad-penn and not multi viscosity oil. If there is no oil dripping off of the timing inspection cover, which would be oil slinging off of the fly wheel, the oil could be coming from a poor valve cover seal. He said this leak is “sneaky”, and due to over tightening the valve cover bolts which will crack a cork gasket and dimple the cover. He said to only use an expensive silicon rubber seal. Another issue are the side seals on the gasket carrier. A Chyrselor repair manual recommended soakin