New rebuild has water in oil during break in start up

[Mach S Code]

Hi I am hoping that someone has an idea to help, I just spent $4000 on my engine, I put in M L S head gaskets, good intake gaskets and all the good parts including A R P hardware. I put in Lucas break in oil and fired it up and broke it in correctly and after 20 minutes I shut it off, checked the oil and it was a little foamy. It did not look like pudding but after pulling the valve cover there was condensation in the covers and a little foamy oil in the top of the head. I drained the oil and it had a little water mixed in. I don't think the multi layer steel head gaskets would have blown with only 20 minutes of running or the intake gaskets failed. If anyone has any ideas please let me know before I start tearing it apart.Thanks, Bill

[GerryP]

Do not start tearing anything down until you do a cooling system pressure test.  You want to make sure you actually have a leak.  If the system won't hold pressure, then get yourself an endoscope.  You can get them for around 40 bucks and they use your phone for the images.  Get one with a 5mm head.  Here's one that includes the viewer:  https://www.amazon.com/Industrial-SKYBASIC-Waterproof-Inspection-Semi-Rigid/dp/B07ZH9P8QH/ref=sr_1_1_sspa?dchild=1&keywords=endoscope+5mm&qid=1611266202

You can use this camera to inspect the guts of the engine without having to tear it down.  You would pressurize the system, then look for evidence of water drops or streaming water.

It's usually a problem with the intake gasket.  Not always, but that's a good place to start.  It could be a head gasket.  In that case, you'd pull plugs and look for evidence of steam cleaning on the plugs or in the chamber.  It could be a casting failure through a crack or porosity or a casting mismatch.  The worst case would be a crack in the block or head.

You can usually find water leaks in the teardown process.  You have to be very careful and move slow in inspecting the parts and sealing surfaces.

[1968galaxie]

Oil feed passage in block to cylinder head?
These sometimes are an issue on 40+ year old blocks.

[C6AE]

Oil feed passage in block to cylinder head?
These sometimes are an issue on 40+ year old blocks.

This causes oil in the water, a different problem. The pressure difference between oil system and water system makes that one a pretty easy diagnosis.
I'm betting on the water passages at the intake to head. But... as mentioned it would be a good idea to pull the plugs and pressure test the cooling system while it is still assembled.

[My427stang]

Did you cut the decks and heads for the MLS? They like a very smooth and flat surface. However I agree with Gerry, pressure test and troubleshoot first

[Mach S Code]

Hi,the block and heads were tanked, magnafluxed and decked, I will get back to everybody after I check it all. Thanks, Bill

[Barry_R]

Double check and maybe retorque before getting too far into it.  The MLS gaskets can be a little sketchy on fluid sealing at times.  I know a couple builders who smear them with silicone or spray sealant on them (although I do not).

[RougeRiverForeman]

 All good advice. Run a re-torque on the head and intake bolts.
 
 Pull the distributor and get a borescope down into the valley, pressure test the cooling system, if you do not see a pressure
 drop or leaks right away let it sit for a while under pressure and re-check.
 
 If the block and heads were shaved during the rebuild you may have an angle misalignment issue with the head to intake
 surfaces, and causing the gaskets to seep.

[TJ]

Silly question...How warm did you get the engine?  If it stayed cool enough, I can see some condensation forming inside the valve covers.  Burning gas makes water and it needs someplace to go...some will get past the rings.

A cold night followed by warm, sweaty day will make a lot of moisture that will linger if you don't get the engine warm enough.

Definitely pressurize the coolant and watch it for a while before taking anything apart.