Thread: Coolant in cylinders; fresh 400 sbc build

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I recently finished a 400 sb build that someone else started. The heads were machined and ready to go when I got it and the block had yet to be torn apart. I took it apart and inspected and all looked real good as if the engine had very few miles. It didn't even have any ring ridge. So I build it and put it in and fire it up.

First thing I notice is smoke from bank 2. Was blueish white. Second thing is the engine get warm Fast! And the coolant will not stay in radiator as if combustion is getting there. So I turn it off and go do something else as I scratch my head to figure out where I went wrong. Topped off the coolant after it cooled down and walked away again. Came back the next day and the coolant was very low again with no external leaks. Desided to try to start it and it would only turn an inch. So now I pull the spark plugs to see which cylinder is hydro locked. #4 poured water. Turned it over to pump it out and #6 had a little as well as #1 and 8. I think 1 and 8 might be because I forgot to put sealant on the intake and the coolant is getting into the intake ports (I hope). #4 And 6 is definitely a problem.

Heres the question. Before I take it apart, I will check all cylinders with my compression gauge. Is there a way to determine if the block is cracked or just the head gasket could be the problem BEFORE I take it apart? I will also check the head for warp-age.

I just walked back out to look at it after typing this post and #4 was full of water again after just sitting there for a few minutes. This means it is flowing there pretty fast. Turned it over and water pumped out of #4 only. This tells me it is likely a head gasket but I want to be sure before tearing it down again

more likely is a cracked cyl. block or head

lets say its a cracked head. I have a set of 305 heads sitting around. What would be the out come of 305 heads on a 400? The only upgrade is a 0.442 int./0.465 exh. cam.

Just foating some thoughts, but the question was is there a way to tell whats wrong before I take it apart? You know, like if you put oil in the cylinder you can determine bad rings or a valve.

sounds like you got leaks all over---could be wrong head gasket for 400 block and also the 400 blocks crack pretty bad from the steam holes to the bolt holes to the cylinder---400s have 2 small steam holes between the cylinders to feed water from the block to the head---if you have the wrong gaskets or the wrong heads can be a problem---also these blocks are syameez bores and they crack from those steam holes to the bolt holes to the cylinder---cracks may not show up until the bolts are torqued

Should I have put oil or sealant on the head bolts? I put oil as I always have but I just read in Alldata that thread sealant is used. Something just tells me that I did something wrong when putting the heads on. I'm gonna check compression tomorrow, remove the head bolts and clean them and reinstall them (maybe about 5 ft lbs over torque) and recheck compression to see if it changes. I build this in the backyard with now shelter so I dont think I paid as good attention to what I was doing as I would in the shop

Sounds like you should pull the heads and check hole alignment with the block and gaskets. If water is flowing in that fast, there has to almost be something else wrong. I don't think a crack will send water into the cylinders that fast with the motor being cool. Probably no other way to tell except pull the intake and heads.

like Jerry said... .there is a crack or something not line up gasket or water port holes to fill up that fast its big . as for head bolts the threads need sealer on them but even with no sealer they will not fill up the cylinder. last one that fill up one that fast.. that i look at had it bad spot in the ex port ....weak casting

Last one I had do that had a crack in cylinder wall about 2" long half way down.I don't think it would leak that fast even if you left a bolt out.

Did you drill the heads for steam holes?
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No I did not. The block is in stock form

It's not the block that gets drilled, it's the heads. Did you look at the link I provided for you?

Originally Posted by techinspector1

It's not the block that gets drilled, it's the heads. Did you look at the link I provided for you?

No sorry haven't had time. Here are my compression numbers...

#1 = 175 psi, 3 = 150, 5 = 140, 7 = 170

#2 = 142 psi, 4 = 168, 6 = 166, 8 = 157

#4 is the one that water flows out of. 1, 6, and 7 only have a little when I turn it over.

The heads were done by a machine shop before I got this mess. I can only assume that they are fine.

Originally Posted by techinspector1

It's not the block that gets drilled, it's the heads. Did you look at the link I provided for you?

I just skimmed through your post and remembered that they said that they tried to rebuild the stock 350 that came in this truck. (78 K5 Blazer) They found that the 350 block was cracked and then found a 400 to build for it. The heads were already done and I think it could be possible that the heads were off the 350. So, with that in mind and the compression specs I posted, is it possible that my problem is that water is entering the cylinders through these non-existent steam holes??

Originally Posted by Bigbzc

No sorry haven't had time. Here are my compression numbers...

#1 = 175 psi, 3 = 150, 5 = 140, 7 = 170

#2 = 142 psi, 4 = 168, 6 = 166, 8 = 157

#4 is the one that water flows out of. 1, 6, and 7 only have a little when I turn it over.

The heads were done by a machine shop before I got this mess. I can only assume that they are fine.

Not if they don't have steam holes drilled in them.