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Premium Member
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Discussion Starter · #1 ·
I have 3K miles on it now. Has not missed a beat, and runs like a top. Sunday, I changed oil, filling it up with synthetic.

Put about 60 miles on it since then. Just a moment ago I was checking things as I was planning to drive the Cobra to a meeting tomorrow. (app 200 miles round trip)

When I opened the coolant filler, there was oil in the water. Not a lot, about 3 or 4 ounces that was in the filler neck. I sucked that out and cranked the engine for a moment, observing the water flow. No sign of anymore oil, but I am letting it cool right now to see if any perculates to the opening.

Do I have a head gasket going, or perhaps something less serious, maybe even related to the oil change???
 

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Oil pressure is higher than the pressure in your cooling system.

There's no pressurized oil passages through the headgasket.

I don't have any good news for you on this one.
 

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The Never-Ending Builder
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I don't have any good news for you on this one.
What Randy is trying not to say is, Cracked Block!
:mad:

Hank
 

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Discussion Starter · #6 ·
Ok, that does not sound good.

This may be a dumb question, but, what should I do? It runs fine. Could this be somethiing that will leak a little oil into the coolant? Is it something that I can pull the heads off and see the issue?

Should I not drive it? Or will that help me troubleshoot by watching the oil and coolant levels and content of the other?
 

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On the odd chance that the oil you have seen was leftover from the assembly process - I'd just keep an eye on it for a short while.
If it returns, you probably need to talk with your engine builder or shop that did the machine work on the block.
 

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FFCobra Fanatic
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Head gaskets usually do the opposite with putting coolant into the oil not the other way around. Do you have a pressure checker to check the cooling system? May show something. Are you useing an old radiator from the donor? May have been contaminated before you used it?
 

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Discussion Starter · #9 ·
Non donor build. All new parts. The engine was freshly built by Southern Automotive, who I know will take care of me if there is an issue.

What can make a block crack?

By the way, I decided to go ahead and drive it this morning. Just got to the meeting. (2 hours) It ran fine, and when the meeting is over, the radiator will have cooled, and I will take a look at the coolant.

I have been all pumped up over the spring mountain cruise in two weeks that Mr Barry is planning. That may be in jeporday.
 

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FFCobra Fanatic
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Rick hopefully you will find nothing in the coolant when you look after cool down. Common causes of cracked blocks are overheating or they were allowed to freeze at some time cracking internally instead of a welch/freeze plug popping out. This could have put a small crack in the block that went unoticed at the rebuild or maybe weakend it enough that once bored and machined,along with the added stress opened the crack to where it now leaks. Also possible it could be in the casting as well where there was a void of material that got exposed during the machineing or under stress or shifting while being run. About the most common way to find during the rebuild stages are a pressure test or sonic test of the block and heads.
 

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I agree with HS..

I've also paid the additional $100-$150 to have blocks magnafluxed as well as Sonic tested to ensure both the thickness and concentricity of the cylinder walls.

Mostly block magnafluxing is geared toward observation of the main bearing webs and deck..
Not sure if they could have seen or found a fissure into an oil galley from the water jackets..
 

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iBuild
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Randy,

Would you recommend flushing the coolant, and seeing if it reappears? I had the same thought, new block, possibly some oil left from assembly.

-Scott
 

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1st RFM/FFR Legacy Winner
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That engine was dynoed before delivery so oil in the coolant passages would probably be drained out when it came off the dyno, especially 3-4 ounces.

Hope it was a one time thing Rick.

Greg
 

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Premium Member
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Discussion Starter · #14 ·
Randy,

It was magnafluxed by the builder, and run in as well.

After a lot of driving today, the coolant looks Ok, with just a bubble of oil. I could not get it all out last night, so I duuno.

I Was thinking of flushing it and keeping an eye on it too.
 

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Senior Charter Member
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Flush it, otherwise you'll always be thinking about it.
 
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