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Engine New Oil Leak Help.

  • Thread starter Thread starter Slo5Oh89
  • Start date Start date Mar 14, 2025

Slo5Oh89

Member
Oct 8, 2009
226
3
19
Washington, IL
Mar 14, 2025
#1
  • Mar 14, 2025
  • #1
Hi all,

I have a '89 71K miles, I changed the oil the other day now I have random oil leak. Its near the rear of the engine on the passenger side, it is leaking without the engine running for days now. Pan and gasket are newer around 9 years or so they were replaced with no problems till now. Also for some reason dip stick seems to be over the full line, was there oil trapped due to me jacking the front end of the car up? Thinking of dropping the oil in the front sump seeing if that helps...

My thoughts are rear main seal but hat would just leak mostly when running or I could be wrong.

Sure its unrelated but I have a loud exhaust noise on the passenger side too and header bolts are tight.
 

gkomo

now i can hopefully expect to receive the shaft
Aug 2, 2024
2,162
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San Diego, CA
Mar 14, 2025
#2
  • Mar 14, 2025
  • #2
Just to be sure, I’d clean everything up as best I could then watch for the leak so you could be more sure exactly where it’s coming from.
 
Reactions: Slo5Oh89 and General karthief

AeroCoupe

lube between the nut and the face. I know my lubes
Founding Member
Oct 28, 2001
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Claremore, OK
Mar 14, 2025
#3
  • Mar 14, 2025
  • #3
The motor sits in the car at an angle to the rear of the car so if the oil leak is one of the valve cover gaskets the oil can migrate along the intake valley and drip down the back and sides of the block.

Did you pull the front and rear sump plugs when you changed the oil? You could have trapped some oil jacking the front end up but would not think it would be a lot. Its just a five quart system so if you added to the filter and then put 5 quarts in it will be overfull.

Can you post up a picture of the oil level on the dip stick?
 
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Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
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Box behind Walmart
Mar 14, 2025
#4
  • Mar 14, 2025
  • #4
Check very carefully, the areas at and [outboard] of where the cork intake gasket runs into the bottom of the heads.

It's a sneaky fooker!

With aftermarket, there's a gap that you can slide a credit card into. With stock heads, there's no gap but oil can seep at the corners.
 
Reactions: Slo5Oh89 and General karthief

Slo5Oh89

Member
Oct 8, 2009
226
3
19
Washington, IL
Mar 19, 2025
#5
  • Mar 19, 2025
  • #5
So I did determine somehow there was too much oil, so I lowered it to the middle of the safe marker on the dipstick. I was hoping that would resolve it, however there is still oil dripping from the rear passenger side. I will need to jack it up and get under there to see up there but just so strange has not leaked, change the oil now its leaking. Not a ton leaking out but enough and now consistently.

Other odd development I mentioned was the exhaust is loud under the hood on passenger side, headers, downpipe flange, h-pipe all tight. It does appear the back of engine/top of the transmission/housing does appear to have some oil that has leaked there as its dirty. The trans itself is dirty with oil residue. I replaced the valve cover gaskets in like 2009 so I would hope its not them.

But based on this it would not be the rear main seal likely(but yes its from 1989), oil pan gasket, or oil pan as they are both newer around 2016.
 

gkomo

now i can hopefully expect to receive the shaft
Aug 2, 2024
2,162
1,410
133
San Diego, CA
Mar 19, 2025
#6
  • Mar 19, 2025
  • #6
Did you change oil viscosity on your last oil change?
 
Reactions: Slo5Oh89

Slo5Oh89

Member
Oct 8, 2009
226
3
19
Washington, IL
Mar 19, 2025
#7
  • Mar 19, 2025
  • #7
Well that may have occurred yes, last change was done at the Ford Dealer last year. I used 5W-30 Full Syn for this oil change. In no way does it make 3K miles a year so I change the oil 1-2x year.
 
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M

Monkeybutt2000

Mustang Master
Aug 11, 2019
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133
Lafayette,IN
Mar 19, 2025
#8
  • Mar 19, 2025
  • #8
Get yourself a bottle of the green dye from Autozone or wherever and a UV flashlight. Put that in the oil and I guarantee you'll find the leak.
 
Reactions: Slo5Oh89

Slo5Oh89

Member
Oct 8, 2009
226
3
19
Washington, IL
Mar 19, 2025
#9
  • Mar 19, 2025
  • #9
Monkeybutt2000 said:
Get yourself a bottle of the green dye from Autozone or wherever and a UV flashlight. Put that in the oil and I guarantee you'll find the leak.
Click to expand...
Now that's a interesting idea!
 
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