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Help with chasing an oil leak

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Dan Orgill

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Discussion starter · #1 ·
Since finishing my '69, I've dealt with leaks from just about everywhere, tranny, power steering, rear end, and of course, engine oil.

I still seem to have an oil leak that is occurring somewhere on the driver's side of the block ( 396 ). The oil seems to wind up in a drip that collects on an area of the block just above the oil filter, below the rear spark plug. Of course, it makes it's way down the flexplate cover and makes a mess.

I've checked around the valve cover gaskets and around the back edge of the intake, and everything seems to feel dry. There also doesn't appear to be any leaks from the oil pressure sending unit or it's brass fitting in the block. The rear main appears dry as well.

When feeling around the motor, there is some oil of the bottom corner of the cylinder head where it overhangs the block on near the firewall.

Any suggestions, it's really annoying having to jack up the car all the time to clean:sad:.
 
#2 ·
You could try some of that additive they use at dealerships - pour it in and run the engine. It shows up florescent green when you shine a black light on it; shows exactly where the leak is.
 
#3 ·
davewho1 said:
You could try some of that additive they use at dealerships - pour it in and run the engine. It shows up florescent green when you shine a black light on it; shows exactly where the leak is.
Click to expand...
X2.We use it here at my dealership and its a great tool.Its an oil dye that you put directly into the oil.Clean the entire area with brake cleaner and then run engine.The dye will leave a trail from where it came from when exposed to black light.Works best if you can do it without driving the vehicle.
 
#5 ·
Dan Orgill said:
Where would I get a " black light " ?
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I have a dedicated unit at work from Snapon .It also came with a pair of yellow safty glasses which I alco find help.The safty glasses can be got alot of places.The black light,you can get a regular black light bulb and put it into a drop light.Mine is led on a flexable shaft,perhaps they make a bulb for a minimag flaslight.That would work great,but the droplight would work fine.It is a must to have an inspection mirror to see those tight spots,especially behind the intake.
Almost forgot,I think Home Depot,or Lowes for the bulb.Spensors carried them too,or so I remember.
 
#6 ·
I had the same problem on a '69 Z/28 a few months ago. The oil was coming from between the head and block. I know many have said that can't happen and I would agree with them if I hadn't seen this with my own eyes. I could clearly see the leak was come from the bottom corner of the head. I replaced the head gasket. It still leaks but not near as bad .
Good luck
 
Discussion starter · #7 ·
y72ss said:
I had the same problem on a '69 Z/28 a few months ago. The oil was coming from between the head and block. I know many have said that can't happen and I would agree with them if I hadn't seen this with my own eyes. I could clearly see the leak was come from the bottom corner of the head. I replaced the head gasket. It still leaks but not near as bad .
Good luck
Click to expand...
Not liking the sound of that :(
 
#9 ·
Heres this from a while back.


Here you go, its messy but it will find the leak the first shot out, guaranteed.

Warm up the motor, shut it off so the fan isn't blowing any air around it.

Take a plastic bottle of baby powder, spray it all over where theres oil or a chance of a leak.

Let it set for a while, then don't touch it but take a light and look real good and you will see where the oil will run through the powder leaving a distinct brown line.

And you guys, no comments about the diaper business and the brown streaks.:D

Rob
 
Discussion starter · #14 ·
LS7 said:
:thumbsup: Are you taking the car out to Autofest next weekend?
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Doubtful. Don't know how long the car will be tied up for if it's something major. Also, I still haven't gotten my passenger fender/door adjusted to my satisfaction, so it's pretty much a guarantee that someone will look at my car and say " Hey, did you know your door isn't lined up right.."
 
#15 ·
Dan; Here is a tip that another TCer passed on to me a couple years ago. Works like a charm and no special tools are needed. All you need is a willing assistant. Remove your dipstick for your oil. Take your compressor ( or borrow a friends ) and turn the pressure down to approx 15 PSI. Place a pointed fitting on the compressor hose that is approx the same diameter as the dipstick tube. Have your assistant apply a constant stream of 15 PSI down the dipstick tube. You crawl underneath armed with a spray bottle of soapy water. Spray any areas that you suspect to be leaking. When you see bubbles in your soapy solution you have found your leak. The only thing is your block would have to be relatively clean to find a leak. In other words it can't have a half inch of gease caked on it.
 
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#16 ·
Let me make a suggestion here. I have a 1070 Elco with a 402. Same exact situation as you. Check the distributor mounting gasket. I think that is where mine is leaking. Gonna change it Monday night with a friend. Gasket is 99 cents and not that hard to do. Check that.
 
Discussion starter · #17 ·
blm said:
Dan; Here is a tip that another TCer passed on to me a couple years ago. Works like a charm and no special tools are needed. All you need is a willing assistant. Remove your dipstick for your oil. Take your compressor ( or borrow a friends ) and turn the pressure down to approx 15 PSI. Place a pointed fitting on the compressor hose that is approx the same diameter as the dipstick tube. Have your assistant apply a constant stream of 15 PSI down the dipstick tube. You crawl underneath armed with a spray bottle of soapy water. Spray any areas that you suspect to be leaking. When you see bubbles in your soapy solution you have found your leak. The only thing is your block would have to be relatively clean to find a leak. In other words it can't have a half inch of gease caked on it.
Click to expand...
Freash frame off resto, so cleanliness isn't a problem. That is one of the things ticking me off so much, all the constant cleaning:eek:

JeffN said:
Let me make a suggestion here. I have a 1070 Elco with a 402. Same exact situation as you. Check the distributor mounting gasket. I think that is where mine is leaking. Gonna change it Monday night with a friend. Gasket is 99 cents and not that hard to do. Check that.
Click to expand...
Will do. Already checked around the rear of the intake and valve covers, and both are dry. I'm more than a little concerned:(.
 
Discussion starter · #18 ·
JeffN said:
Let me make a suggestion here. I have a 1070 Elco with a 402. Same exact situation as you. Check the distributor mounting gasket. I think that is where mine is leaking. Gonna change it Monday night with a friend. Gasket is 99 cents and not that hard to do. Check that.
Click to expand...
Checked the gasket today, dry as a bone, nothing on the back shelf of the block or the bellhousing of the tranny
 
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Dan Orgill
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