Oil Filter Leaking at First Prime of Oil Pump

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canadian duster

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Hi Everyone,

I finally got time (after 3 moves in 3 years) to prime my new build (408 LA) and I found a significant oil leak that i believe is from the oil filter (not the plate). Using a drill to circulate a HV melling oil pump. I tried 2 filters just to confirm, and both leaked. After a bunch of research and reading, I've come up with a few items i think may cause it but definitely needing some help:
  • oil filter plate was painted by builder (could this cause a leak at the oil filter gasket)?
  • possible leaking oil filter plate (i plan to crawl underneath while having the wife run the drill to see where first leak is)
  • cold weather causing viscous oil over pressure as it pushed through the filter (highly unlikely)
Its the same plate that was used prior to rebuild (stock plate) and i had no leaks there previously.

Any help would be much appreciated.
 
bit more information. I have to purchase a new oil pressure gauge (current one isn't reading) so i don't have the pressure available. it is the stock style plate (not angled adapter) and i haven't pulled the plate off to confirm gasket yet (was fighting with it late last night and i didn't want to break it). its the same plate that was on prior to rebuild and i had no leaks at that time.
 
with a hi volume pump it is good to drill extra holes in plate. clean area well and use adhesive on a new gasket. on an initial break in of a new engine , especially in cold temps preheat oil
 
I was having problem with leak in same area.Mine ended up being the back of the valve cover couldn't see it running down on the filter just something to check good luck.
 
Check back of valve cover, nice and dry. Trying to decide if I reuse this plate with new gaskets or try the Canton.

Hopefully watch it tomorrow to see where oil leaks from. It sure looks like the filter itself and not the mount, but hard to say until I can see. Could the paint on the plate cause an issue?
 
Well if the paint has some bubbly drips on it, that certainly would not help the filter gasket seal.

If you pull the plate off, then place the plate and the outer gasket against the block and look into the center hole. There should be some gap between the center of the plate and the block. The center flow-through bolt presses on the plate as the bolt is thread in, and closes that gap and thus puts pressure on the outer gasket. Makes sure the plate wants to seat evenly around the outer edges, and that the center area is parallel with the outer edges.

If the plate was not removed at the shop, I gotta wonder if the gasket was not renewed.
 
I had this problem also, what year is your block? I am running an 89 roller block. There was a difference on the plate, and the stud/nut that threads into block after 90/91. Of course initially I used the wrong year stuff on my block and had a significant leak. I have since ditched the 90 degree adapter also.
 
Every time I start the 360 oil pours all over the ground, replaced filter, replaced gasket under block plate with sealant, no 45 degree adapter, no paint on anything. This time a cured it up instead of pouring all over the exhaust it simply blew all over my front passenger wheel. Can not keep oil in this thing. It is a 79 360 out of a truck. Of course replaced pan to a car pan, new oil pick up and gaskets there also. Car sounds amazing but can’t move forward to time it properly because oil just simply will not stay in the darn thing. Super frustrated here, ready to run it till she blows!!!! HELP
 
a 1979 truck 360 should not leak. are u useing the plate and hollow hold down that is the early style? get everything super clean and use a gasket with adhesive-and let it cure for a day. what filter and oil? drill more holes in plate
 
a 1979 truck 360 should not leak. are u useing the plate and hollow hold down that is the early style? get everything super clean and use a gasket with adhesive-and let it cure for a day. what filter and oil? drill more holes in plate
It was the plate that came with the engine already installed and when I removed it, it looked like they’re wasn’t much of a gasket there at all. Ph43 filter and generic 10w30 oil from Lordco
 
It was the plate that came with the engine already installed and when I removed it, it looked like they’re wasn’t much of a gasket there at all. Ph43 filter and generic 10w30 oil from Lordco
The plate looked to be the original one and been there quite some time
 
I’ve heard about drilling holes but have not done that as it was already installed and yes I waited 24 hrs before firing it up
 
The biggest thing I found is to not over tighten the bolt. I torqued it to what was printed and posted on here several times and it leaked. Finally just tightened it just over snug, enough that it won't rotate, and it sealed. Almost like tightening an oil pan or valve covers. Don't kill it. Tighter is not better in this case. Ha!
Also the center boss on mine, it's a 92' 360, was shorter than any of the 340's I've had. I stacked some machine washers the same diameter of the inner gasket to take up the difference. Could probably make your own though. I read where the oil doesn't get fully filtered if you don't fill the gap?

Carl
 
Refer back to post 9 for a check on the plate.

Any chance this engine was a mix of parts? The later Magnum plates will not seal on an LA 360 like your '79.
 
Ok what I’ll do is order a 79 plate from the dealer, see if it’s different than mine, drill out more holes and try again, just snugging it up. If I buy an angled filter will this solve my problem being that the header is 1/16 away from the filter. Or are these angled adapters a pain to seal as well?
 
If you are getting another one, there are aftermarket plates. IIRC Canton makes one. There are other threads here that discuss that, as well as the angled adapters, and remote mount filters and adapters. (My son and I used a Canton remote mount adapter and lines to get the filter away from the header, and make it easy change filters.)


This is readily solvable, so start planning you shows!
 
1991+ 318 360 blocks-the boss that the holddown screws into is 1/4" shorter. new plate - 53009219 - has six holes
 
Different plates for diff expectations.
Low rpm 318, 4 small holes.
Higher rpm 340, more holes
Racing, more holes yet added.

7531630-OilPlates.jpg
 
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