Freshly Rebuilt 350-Crankcase full of coolant

[honkon]

I rebuilt the 5.7 in my Yukon and started it up for the first time a couple weeks ago. Started it up and let it run a couple separate times, for no more than 30 minutes collectively. Then I pulled the oil cap and saw this.

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Son of a *****.
There wasn't any mixing of the oil and coolant before the rebuild, and it looks like there still isn't any oil in the coolant now. I didn't notice any sort of excess smoke coming from the exhaust either.
I sorta placed my bets on the intake gaskets being screwed up somehow, so I took the intake off without doing a compression test or anything, but it doesn't really look to me like anything is getting past the intake gaskets.

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So I don't know what's up. And why would the coolant passages be so rusty already? They definitely weren't like that when I put it back together.
The bare block went to a machine shop to get cleaned up, and I sure hope they would have noticed if it was cracked. I completely disassembled the heads, and cleaned the mating surfaces well. I didn't notice anything amiss with them, and I didn't drop em on the floor either. I took time to ensure I had the correct head gaskets, and that I installed them correctly. I followed the head bolt torque procedures to a tee.
The radiator looks relatively new, but you'd think that if it was the oil cooler leaking, there'd be oil in the coolant, wouldn't there?
I don't know. I'm at a loss. I guess I got the wrong head gaskets or installed them wrong, or somethings cracked. I guess the next step is a compression test.
About to give up on this damn thing.

 

[RichLo]

Dont give up yet, you may be over thinking the situation!

Has it been humid lately where the truck is parked? That really just looks like the engine never got warm enough to evaporate the condensation inside the engine.

A compression test would be a good idea. Also since your already obviously paranoid, run a cooling system pressure test also, its just a pressure gauge that goes on the radiator cap opening and pressurizes it to check for leaking or a loss in pressure with no leaks could be a cracked oil cooler in the radiator. Your intake has to go back on first obviously though.

 

[Markgyver]

Some of the head bolts are in the water passages and need sealant.

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[Jay33089]

Dont give up yet, you may be over thinking the situation!

Has it been humid lately where the truck is parked? That really just looks like the engine never got warm enough to evaporate the condensation inside the engine.

A compression test would be a good idea. Also since your already obviously paranoid, run a cooling system pressure test also, its just a pressure gauge that goes on the radiator cap opening and pressurizes it to check for leaking or a loss in pressure with no leaks could be a cracked oil cooler in the radiator. Your intake has to go back on first obviously though.

I'm with @RichLo. The oil laying in the valley doesn't appear to be milky. And looks really clean in there! As for the rust in your coolant passages. Your passages were probably rusty before the rebuild. Residual rust inside the water jackets is always gonna be there. Virtually impossible to get it all out. They look pretty good to me.

 

[evilunclegrimace]

You stated that the crankcase was full of coolant. Did you drain the oil and see if it was over full?. As far as the rust issue do you have the correct coolant/water mix?

 

[honkon]

Some of the head bolts are in the water passages and need sealant.

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I'm reading that all 17 head bolts go into water jackets. I somehow didn't see anything about having to seal them while building it.
God.
I appreciate everyone's input.

 

[evilunclegrimace]

I'm reading that all 17 head bolts go into water jackets. I somehow didn't see anything about having to seal them while building it.
God.
I appreciate everyone's input.

The Factory service manual specifies Loctite # 592 thread sealer.

 

[honkon]

I took a valve cover off today to look for signs of coolant seeping out around the head bolts.

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Looks a little milky down there to me. It makes sense that the leak would be around the head bolts. I didn't put any sealant on the damn things. Don't know how I missed that. I'm good at learning stuff the hard way.

Dont give up yet, you may be over thinking the situation!

Has it been humid lately where the truck is parked? That really just looks like the engine never got warm enough to evaporate the condensation inside the engine.

A compression test would be a good idea. Also since your already obviously paranoid, run a cooling system pressure test also, its just a pressure gauge that goes on the radiator cap opening and pressurizes it to check for leaking or a loss in pressure with no leaks could be a cracked oil cooler in the radiator. Your intake has to go back on first obviously though.

Truck and engine have been inside for the whole rebuild. I'd like for humidity to be the issue, but I don't think it is.
I'll keep your other suggestions in mind. Thanks.

You stated that the crankcase was full of coolant. Did you drain the oil and see if it was over full?. As far as the rust issue do you have the correct coolant/water mix?

I drained it but I haven't looked to see if it was overfull. Definitely looked a little milky and didn't smell right though. Coolant/water mix is a little on the water heavy side of 50/50. I guess the rust is normall, I'm not too worried about it.
I guess I'll seal those bolts up and we'll see how it goes. Thanks everyone.

 

[phantom 309]

You can remove them 1 at a time, seal it then retorque then move onto the next one.
Run the motor at 1500 for 20 mins to check your cooling system and heat the oil up good, then change oil and filter.

 

[retorq]

Someone say retorq?