Rebuilt TBI 350 coolant in oil

Hello all, recently purchased a remanufactured TBI 350 for my 87 Chevy 1/2 4x4. After initial break in, I noticed coolant in oil on dipstick and some white smoke out of tailpipe, decided to drain oil and saw coolant definitely in the break in oil. So I resealed the intake manifold and torqued the bolts to spec with new felpro gaskets and a good bead on both china walls. The intake manifold is stock but seems fine, no visible cracks. Still having the same freaking problem, water in oil while running. Did a coolant pressure test and it seems to hold fine (aside from small leak at actual tool which I can hear). This does not seem to force any water out of drain plug hole, I was told it would be a steady drip if I had a cracked block or head gasket, I do not get a steady drip with the pressure tester. I am at a loss, I am not completely sure if the machine shop will help me bc I cannot confirm if it is the block or intake manifold. It was a long block build so I did the manifold, I do not see oil in radiator. I am stuck and have lost my motivation, any help greatly appreciated, thank you !

Check the spark plugs and see what they look like. I'd be willing to bet head gasket or cracked head before anything else. Did you dry mock the intake? Have the block and heads been decked?

If your pressure tester is leaking you need to get another one that works. And leave it for a couple of hours or overnight.

Could be a crack in the intake. It would have to be magnafluxed to be sure. I would for sure try an oil change or two to see if it happens again. But you have to check it very frequently. If the oil was like that the whole break in, you might have some issues.

You have a leak in the tranny cooler that's inside the radiator. New radiator time. Ain't worth fixing.

Snoots said:

You have a leak in the tranny cooler that's inside the radiator. New radiator time. Ain't worth fixing.

Click to expand...

Not transmission fluid, it's a throttle body 350 sbc with water in the oil. I'd pull the plugs put a pressure tester on the radiator wait a bit then crank the engine and look for water spray.

Snoots said:

You have a leak in the tranny cooler that's inside the radiator. New radiator time. Ain't worth fixing.

Click to expand...

Radiator is new, Isn't the transmission completely separate from engine ?

Ricko1966 said:

Not transmission fluid, it's a throttle body 350 sbc with water in the oil. I'd pull the plugs put a pressure tester on the radiator wait a bit then crank the engine and look for water spray.

Click to expand...

I did this and didn't see any water out of plug holes

Cdog_96 said:

I did this and didn't see any water out of plug holes

Click to expand...

I quoted snjots to let him know you are talking about a 350 sbc ,not a TH350 transmission,figured you'd pick up on that. It's not the radiator,yes the transmission is separate. How did you let it sit with pressure if the tool is leaking pressure?

Ricko1966 said:

I quoted snjots to let him know you are talking about a 350 sbc ,not a TH350 transmission,figured you'd pick up on that. It's not the radiator,yes the transmission is separate. How did you let it sit with pressure if the tool is leaking pressure?

Click to expand...

Held it for 25 minutes in a certain position so the fitting wouldn't leak

Fix the tool so you can let it pressurize longer, my gut is saying cracked head, I'd ask the machine shop,how they want you to proceed. The reason I have a gut feeling cracked head is a lot of times a crack in a head doesn't open up until it's hot, we used to find them all the time taking them out of the steam cabinet.

Ricko1966 said:

Fix the tool so you can let it pressurize longer, my gut is saying cracked head, I'd ask the machine shop,how they want you to proceed. The reason I have a gut feeling cracked head is a lot of times a crack in a head doesn't open up until it's hot, we used to find them all the time taking them out of the steam cabinet.

Click to expand...

How long and what pressure to set the tool to ?

Ricko1966 said:

I quoted snjots to let him know you are talking about a 350 sbc ,not a TH350 transmission,figured you'd pick up on that. It's not the radiator,yes the transmission is separate. How did you let it sit with pressure if the tool is leaking pressure?

Click to expand...

I gotta call the Evelyn Wood Speed Reading people and get my money back!

Cdog_96 said:

How long and what pressure to set the tool to ?

Click to expand...

15 psi for as long as it takes. You may find something in 10 minutes it might take 12 hours. It would be worth pulling the valve covers and seeing if coolant is seeping from the headbolts.