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Weird place for a oil leak, Built a Scat 408 engine for a bu

Posted By: 727builder

Weird place for a oil leak, Built a Scat 408 engine for a bu - 03/07/18 08:14 PM

Am I the only one to run into this? A friend bought a Scat rotating assembly from Jegs for a 408 street engine. I assembeled it. Got it together on the stand and primed it. No leaks. Put it in car and fired it up and looked. No leaks. While breaking in the cam for about 20 mins. We shut off the car and raised the lift and noticed oil on the ground. Was coming from bellhousing. Pulled trans. And primed engine again while looking at the back of the block. Cam plug and the 3 pipe plugs all in place and tight with no leaks anywhere. Then I noticed oil from the pilot hole in the back of the crankshaft. frown Video--->> https://youtu.be/lOLVuJM0uJs
Posted By: Bad340fish

Re: Weird place for a oil leak, Built a Scat 408 engine for a bu - 03/07/18 08:20 PM

Yikes, they drilled that one a little deep it looks like.

The right thing to do is replace the crank of course, but if it were mine I would be trying to put a freeze plug or something in there if it is an automatic car and doesn't need the pilot hole.
Posted By: Porter67

Re: Weird place for a oil leak, Built a Scat 408 engine for a bu - 03/07/18 08:49 PM

If it were bought through jegs id get with them, or scat directly Thats beyond the end uses expectations of cleaning and inspecting new parts.

Sucks to pull it down but id not expect to have to be out more then labor in the whole mix, since it was a kit you should have the card or they already should know what your bob weight is.

Id just not put a plug in it, for many reasons but thats just me.
Posted By: madscientist

Re: Weird place for a oil leak, Built a Scat 408 engine for a bu - 03/07/18 09:55 PM

That's junk. I can't tell if it's too deep or the crank has porosity in it.

I'd be replacing that in a hurry. Unacceptable.


On top of all that, the finish machine work looks like it was done by a drunken retarded ham fisted polar bear using dull tools.


Sucks bad but I wouldn't fix it. And if it's a cast crank I'd upgrade to a forged one.
Posted By: Cab_Burge

Re: Weird place for a oil leak, Built a Scat 408 engine for a bu - 03/08/18 03:53 AM

Originally Posted By 727builder
Am I the only one to run into this? A friend bought a Scat rotating assembly from Jegs for a 408 street engine. I assembeled it. Got it together on the stand and primed it. No leaks. Put it in car and fired it up and looked. No leaks. While breaking in the cam for about 20 mins. We shut off the car and raised the lift and noticed oil on the ground. Was coming from bellhousing. Pulled trans. And primed engine again while looking at the back of the block. Cam plug and the 3 pipe plugs all in place and tight with no leaks anywhere. Then I noticed oil from the pilot hole in the back of the crankshaft. frown Video--->> https://youtu.be/lOLVuJM0uJs
shock puke
Don't we hate Murphy whiney
Sorry for your issues runaway
Posted By: 727builder

Re: Weird place for a oil leak, Built a Scat 408 engine for a bu - 03/08/18 07:00 PM

Showed video to guys at local race shop. They said the same thing. Porosity of the cast crank. They said the if the owner doesn't want to spend the extra money to replace it with a better steel crank? Put a freeze plug in to stop the leak and let it go. They showed me several cranks that was drilled to remove weight with freeze plugs put in the back. If anyone ever runs into crap like this? Only a Dorman 555-117 28mm freeze plug will fit.
And it's also Made in China
Posted By: dezduster

Re: Weird place for a oil leak, Built a Scat 408 engine for a bu - 03/09/18 04:34 AM

I have a nagging leak at the back of my scat cast crank 408 2 pans 3 gaskets and I'm on the second rear main seal and still is leaking. Ill know where to look next!
Posted By: Racer33

Re: Weird place for a oil leak, Built a Scat 408 engine for a bu - 03/09/18 04:19 PM

Aww crap. I was planning on ordering a rotating assembly from them. Now I'm nervous. Guess if I pull the trigger I now know the first thing to check
Posted By: 727builder

Re: Weird place for a oil leak, Built a Scat 408 engine for a bu - 03/09/18 06:26 PM

Glad I could help, Or warn others... Was a first for me. Never thought I would ever have to look in the pilot hole while priming a new engine.
Posted By: jbc426

Re: Weird place for a oil leak, Built a Scat 408 engine for a bu - 03/09/18 08:44 PM

I believe Chevy LS motors have a freeze plug style plug in the back pilot hole from the factory. I saw several write-ups about fixing the oil leaks there, while searching for a mystery oil leak on an RB.
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