360 oil leak at back of intake manifold

-
Texas Red

Texas Red

Old Flunky
FABO Gold Member
Joined
Mar 25, 2020
Messages
103
Reaction score
119
Location
Lake Corpus Christi
On a freshly rebuild 360/410 stroker I have this annoying oil leak that I believe is coming from the distributor hole in the block.....
New Melling oil pump M-72HV pump that I have run for years.....I had 80 PSI at start up (Valvoline 10-30 High Zink VR-1), Had changed all old oil pressure port blocks with new brass 1/8 inch pipe distribution block, nipples
all the normal look at for problem... even made a gasket for my MSD distributor (high tacked to one side of distributor base), new O-ring. I used Permatex right stuff the block front and rear of the intake sealing on a brake cleaned rag wipe for all greases on the block etc..prior to putting down a bead for sealing! inspected intake prior to installing .....all OK or seemed that way........went to great pains for this not to be a problem child while it was still on the engine stand.....Real pain in the boat because the engine sits so close to the firewall in my 72 Duster (Formally slant 6 car) block. The oil pressure at idle is 55 PSI after an extended run time and 180 degrees ....... I have seen 80 PSI on my gauge at start up ......
I have reviewed the oil diagrams/Drawings (1972 repair manual ) .....and the oil port out of the filter feeds the mains, cam bearings and the ,oil pressure port. The only thing that comes to mind is oil is being thrown up somehow towards the distributor in some magical way that could only happen to me.

I am open to ideas ....Throw them at me. Thank you Gary
 
If you have an electric oil sending unit back there next to the distributor, they have been known to leak and make a mess. Oil wicks to other parts and runs downhill. Also check oil pressure copper lines and fittings if you are using a gauge.
 
George I have thought about the sending unit as they are crimped over but a clean paper towel plus the wipe test... New oil pressure 1/8 copper line, new compression fittings at oil pressure block that feeds a 100 # gauge inside the car.........so nothing found there.
Aluminum valve covers/Neoprene gasket (High tacked to the valve cover) really cant feel (swipe test) clean paper towel test........
That is a good thought.....
You are right sir about it can make a big mess as oil can wick/move to an area that is hard to really see where its actually coming from.

I am almost at the point of pulling the intake back , reclean, check, loo for defects in the Intake................. Time and intake gaskets are cheap compared to
not seeing the obvious. Just trying all the simple stuff first....... Signed still frustrated in Texas
 
Sorry there Trailbeast...Dont understand CCV? How? Need more info Thanks................ Please advise
 
From the manufacturer there is a gasket on the dist where it seats on the block.

Most are gone from the years.

Iirc it is a very thin gasket.
 
Dart......I have slept since then ..... I actually have a new spare in the box that was going on another project...Im going to have take a break and go look ...
I swear I m just like a little kid sometimes when is comes to taking parts out the box NOT noticing a gasket other than the O-ring but it makes sense . See that Line
about i have slept since then.... It always cost me money to go to school.....I never get away from it.....
Kind of like one of those times where I put something up so I could remember where I put it at.............

Yes very thin ....You are right
 
If all else fails, double check your valve covers.
The lip around many aftermarket valve covers actually comes in contact with the top of the intake manifold above the runners, preventing the valve covers from tightening down properly and rendering the gaskets ineffective.
The common solution is to make note of where the interference is and grind the valve cover lip at the offending locations. Yeah, it's tough to think about taking a grinder to those nice shiny new expensive valve covers- but sometimes ya gotta do what ya gotta do.
 
abdywgn said:
ir indeed it is from the dist. hold down bolt, wrap it in teflon tape?
Click to expand...
I really think you are on to something here. I knew someone had been down that road already. Because the threads are not tapered its a bolt thread. Merry Christmas
 
Be carefull that is where the oil is comming from. I spent quite a time trying to find the source of an oil leak comming from the back of the engine. I eventually found that the oil pressure switch has a tapered thread and previous owner had over tightened that switch cracking the block.
After taking the engine out I cleaned the area and veed out the area and used JB weld in the crack and haven't had an issue since!
 
I had a distributor years ago that oil would make its way up the shaft and drip out of the vent holes on the bottom of the housing. Something else to look at prior to removing the manifold.
 
Did you mock up the intake and see how much gap you had between the intake and the block china wall? Does it leak most when or after a drive?

Did your block have the roll pin for the intake still there, these can keep some intakes from setting down.

Valve covers (stock or aftermarket) are known to not clear aftermarket intakes very well or at all.
 
Dano...roll pin has been remove.... no I did not mock up the intake but do know a buddy of mine was trying the cork pieces (dry) on the front & back of the china wall and it did not
make up to the heads....so I knew that was not going to work as I used Permatex right stuff when putting it together. I have been busy doing the things I have to
(still work some for $$$) to get to do the things I want to. I am sure I am singing to the choir as Hotrod money somehow keeps depleting.....and we know how this happens. So I will be back on the Duster this weekend.
I sure do appreciate all the input from everyone. I will take a look at the distributor as well. I know I will find it but grabbing some been there done that from a group of old pro's is a great start.
 
do you have a functioning PCV system on the engine? I just can't figure out how you have so much positive pressure inside the block to blow anything out through the distributor hole or the rear china wall seal. Theoretically there should be negative pressure inside the block from the PCV system. My money is still on the oil pressure port back there... now there's some positive pressure where it's supposed to be and just full of oil.
 
You have a very valid point..... I have recently purchased a dual circuit PCV valve from ME Wagner. Trying to get through startup & yes this has been discussed with ME Wagner and the valve is currently set as ME Wagner suggests for startup. What little testing I was able to do on my Holly HP 750 PCV valve port has shown I have 10 inches vacuum at idle and 19 inches at cruise speed (using 2500-3000 RPM as target) I will be back on it this weekend so i should have some updates as the weekend closes out.
 
You must log in or register to reply here.
-

Back
Top