Diagnose This 3.0SC Leak

[2jmotorsports]

Hi Guys,

I have 1,125 break in miles on my rebuilt 3.0L and as I had the rear in the air to adjust the valves I noticed this tiny leak that looks like its between the head and cylinder on #4. The remainder of the bottom of the engine is dry.

I have only seen a single drop of oil on the ground as of maybe 2 weeks ago so its not bad. Do you guys concur on the source of the leak (head/cyl joint)?







Secondly, I re-torqued the heads at 500 miles to 23.5 ft-lbs per Wayne's rebuild book. Im going to do it again but I wanted to double check the torque sequence. I found this sequence for torquing ARP head studs and I imagine it should be the same regardless of what studs are in there. I have the stock steel ones on top and bottom.



Is this an ok torque sequence to use? Is 23.5 ft-lbs ok or should I go higher?

Thanks in advance.

[da Vinci Dan]

Do you see any oil on the top? I don't know the torque spec.

[john walker's workshop]

A retorque would be good. Were the heads flycut and new cylinders?

[2jmotorsports]

Originally Posted by da Vinci Dan

Do you see any oil on the top? I don't know the torque spec.

At this time no, however I have goofed in the past and dumped oil from a new bottle onto the area directly below the filler. I quickly cleaned it up but its possible some may have ran under the tin before I caught it. Ill probably clean the "leak" area and keep an eye on it.

Originally Posted by john walker's workshop

A retorque would be good. Were the heads flycut and new cylinders?

Yes on flycut heads, no on new cylinders. Re-plated originals.

[john walker's workshop]

Perfect head to cylinder interface + no seepage. Used cylinders, take yer chances. Did the cylinders get dressed/machined back to perfection on their top surface in the replating process?

[2jmotorsports]

I dug back through my records and could not find that explicitly stated. They were replated/honed by EBS Racing per their standard process. Ill reach out to them and find out.

Edit: EBS just got back to me and they do not touch the cylinder/head mating surfaces. I guess I have my answer now. Fingers crossed a re-torque helps.

Thanks for your input John!

[proporsche]

let`s hope that will solved your leak..When i do engine or valve job i always use valve grinding paste on the cyl heads where they meet the cylinder..give a 10x twist....so they nicely match..

Ivan

[2jmotorsports]

Ivan,

Thank you for reminding me! I documented my entire rebuild in a notebook because I knew I could never remember details like this. After flipping through it I found that I actually did do the cylinder/head valve grinding compound lapping procedure before putting them together.

I also checked my head stud torque on all cylinders and found no changes. The more I think about it the more I am leaning towards a bonehead oil spill at the oil tank filler being the culprit. In any case Ill clean it up and report back next time if the leak re-appears.

Thanks for the input guys!

[AndrewCologne]

I had exact the same problem. Put pressure of about 7 Bar / 100 PSI on that cylinder using a leak down test device.
With the pressure in the combustion chamber do spray on that area some dish soap. If bubbles do occur you got the gulty as the 3.0 enine comes with sealing rings between the head and the cylinder, here that specific one could be flawed.