sturgis81

My wife's 69 with 351 windsor has an issue. Even after engine flush oil appears in the rad, however there is NO water in the oil when i drain it. It is not milky but black. It almost seems like there may be a hair line crack in the water jacket somewhere but i can't think of where they would intersect to do this, at first i was hoping it was transmission fluid but it definatley appears to be oil. I really don't want to pull the motor but i think i may have no choice, any ideas would be appreciated.

1970

do a leak test on the rad and see were air is getting out

Starfury

+1

You can "rent" a coolant system pressure checker at many auto parts chain stores (you buy it, then get your money back when you return it).

A leakdown test would be a good thing as well, but understandably more difficult.

guitarman376

I have same yr/motor. When my head gasket blew I had milky coolant but no water in the oil. Check radiator 1st, otherwise you might have bigger problems.

sturgis81

When the wife went in 2009 on the mustangs across america the tranny fluid was diverted to an external cooler as she thought that was the problem, however, the problem was still there, the water pump gasket was replaced,that didnt work. If it were a head gasket would there not be water in the oil??? Don't get me wrong , changing the head gasket is way easier than pulling motor , thanks for the input, does anyone second the motion for head gasket replacment???

5.0pntydrpr

Well, it could be a head gasket, but I also vote for a leak-down test. It can be difficult, but requires much less time and money than a head gasket swap, which may or may not be the cause of your problem. The leak down test could you provide you (which you can then provide to us) more information.

sturgis81

ok, I will do leak down test. I'll get back to you guys soon, thank you for your input!!

sturgis81

Leak test done at 15 lbs, it passed. I put dye in the oil and used a black light, I got the motor hot , added dye then ran it for 5 mins, turned it off and let it sit for 1/2 hour or so then ran it for 5 more mins. There is no dye in the rad at this point, I guess my next thing is to do a thorough flush unless anyone has any ideas before i flush it.