Antifreeze in oil??

[another69]

I just ran my SBC today to warm it up before I change the oil. When I went to change the oil, it came out very foamy. I checked the antifreeze and it is low but CLEAR- no signs of oil in the antifreeze. The only thing I can come up with is a manifold leak, leaking antifreeze into the oil but not the other way around. Any ideas??

[Mingus]

Probably a manifold leak. Could also be a cracked block. Have you tested the antifreeze? When's the last time you ran it?

[another69]

I'm hoping its a manifold leak. Last time I ran it was 6 months ago. I pulled it apart last night and it looks like it may have leaked past the drivers front manifold bolts, draining the upper radiator hose while it sat- but i'm not sure. I didn't find a "smoking gun". When I drained the antifreeze it had no signs of oil. I'm thinking of reassembly with printoseal gaskets and thread sealer on the bolts if I can't find anything else.

[Kenova]

I've had a manifold gasket leak at the water passages. There wasn't much of the gasket left.
As for the possibility of a cracked block it has been my experience that it only happens if your anti-freeze isn't up to snuff or you are making an insane amount of power.

Ken

[another69]

Never froze the block, and 425ish is hardly an insane amount of hp. I just can't think of another spot where it could leak over from, and I was hoping to find an obvious tear in the gasket

[61ragtop]

Hope you don't have the same issue as me...... I had a new build and it seemed to run fine, then all of a sudden on the 3rd year I had it running the oil was flu of coolant! Thankfully I had not started it before changing the oil. Long story short it turned out to be a porous casting of one of my heads.

Good luck and pressure test the cooling system after the reassembly.

[Mingus]

Was the block decked or heads shaved? I had an engine years ago that was decked enough that the intake should have been milled also. The machine shop never said anything and being a dumb kid I didn't know any better. Put it together during the Summer and all was well. As soon as the weather turned cold and everything shrank I dumped about a gallon of antifreeze into the lifter valley.

[another69]

Hmm... The heads were shaved to clean them up- they are older Dart Pro1 aluminum heads. They were only shaved a few thousands though. I WAS using the cork end seals- maybe that was enough to keep the manifold from sealing complete? I don't know, but a cooling system pressure check, like some of you suggest, seems like a great idea. Is there an affordable pressure tester that any of you recommend, or should I just rent one?

[ehummelman]

When you go to reassemble, use a healthy amount of RTV (I like the Right Stuff brand) around all of the cooling ports as well as the usual front and rear walls. You might want to also check your head gaskets, I've heard of others having coolant leak into the oil from a blown out head gasket. It hasn't happened to me (yet) but others have said it was a problem. More work and money for the gaskets, but it could be good insurance.

[MarkM66]

Pressure check it, and listen for a leak.

[kochevy67]

Pull the plugs also and check for antifreeze on the plugs.

[TheJDMan]

Permatex makes a special Black RTV that is designed specifically to withstand oil exposure and is available from any parts store. I do not use any end gaskets on the SBC intake manifold I just run a big bead of Black RTV and I have never had an intake leak even with drastically milled heads. I also run the .125 thick intake gaskets due to my milled heads.

[another69]

Weird update- I replaced the manifold gaskets with felpro printoseal and used the rightstuff sealer instead of end gaskets. Put it all together, topped off the coolant, and pressurized to 20psi. The gauge held steady with a very slow drop, which I thought was a weeping freeze plug. I never added oil, so to check if my repair worked I pulled the drain plug and out came a few ounces of antifreeze. Crap. After taking a break I decided to pull the valve covers to try and decide which head to pull first. Everything looked clean except for a small bit of antifreeze near one bolt on the driver's rear. I cleaned it off and pressurized again. There was a small but steady leak around the ARP head bolt! I used the ARP thread sealer on all of the bolts when I first assembled it in '07 because it is a factory 400 block and the head bolt threads end up in the cooling jacket. Anyway, I pulled the bolt, cleaned it up, resealed, and retorqued.

Did I just get lucky or is it possible that I have a bad head gasket? It is hard to tell with the design of the SBC, and I hate to pull the heads "just in case". I will pull plugs next and cross my fingers. This ever happen to anyone else?

[another69]

Well, I pulled the plugs and found nothing out of the ordinary. I still seem to be leaking antifreeze into my oil pan though, I get about one drip every 10 seconds. Is there a good way to tell if it is a block or head gasket problem?? Head gasket would seem most likely, but how do you tell which one? I don't want to do both if I don't have to. This is starting to get old...