Ok Guys, I just picked up a 1957 Cadillac 2 door. It was a barn find that has not run since about 1983 according to the reg and insp. sticker. After cleaning off the years of filth and 2 dead rats (no kidding) laying across the motor, I noticed right away the feeze out plugs were missing on the front of both heads. we got it up on the lift and of the 4 plugs visible on the block, 3 of those were out as well. Obviously the motor had water in it and I am hoping that the plugs performed as designed and the block is not cracked. Does anyone out there know if there is also a plug or plugs behind the flywheel at the rear of the block. I took the inspection plate off the bell housing but it is impossible to see anything and no evidence of any blown out plug in the bottom. I would rather not pull the motor to check. I have a shop manual but I couldn't find any reference to these plugs in it.
When you say, "I am hoping that the plugs performed as designed and the block is not cracked", realize that those plugs were not put there to protect the block from cracking if the coolant freezes. That is a widespread misunderstanding. They are core plugs, not freeze plugs. Although the plugs do tend to be pushed out when the coolant freezes, the purpose of the plugs is to seal holes that were used in the casting process when the block was made. The sand that formed the water jacket cavity needed support. Those holes are where the sand cores were held in position while the iron was poured. Based on what you have said, odds are very high the block has multiple cracks, both visible and not. Point being, be careful about putting much money or effort into the engine, especially until you know exactly how bad it was hurt. At one time I could have told you, but it has been over 30 years since I saw the back of a Cadillac block like yours. What I can tell you is that it is customary to have at least one core hole at the rear of each cylinder bank. So it's pretty much certain there will be at least two water jacket plugs on the back of the block.
Thanks for clearing up the correct reason that these core plugs exist. Now I'm feeling worse than before. It would be ****py if the block is cracked as we just got it running a couple of days ago. I only ran it for a minute and didn't allow it to get hot.
Don't start cursing yet, it may be the reason it was taken off the road in 1983 was to change a leaky core plug...especially if only the plugs which are easy to get to are out. If it has cracked from freezing there should be at least some sign of cracking on the outside of the block.
There are no plugs in the back of my 390 blocks. Pretty sure 365 would be the same.Still 2 more at the rear of the heads though. Roger
put the plugs in that are missing , fill and pressure test. all you have to lose is a few dollars for the plugs and some time.
By the time ice pushes a soft plug out, the block is broken. It's not like squeezing toothpaste out of a tube, you know. Water freezes and expands in all directions, not just in the path of least resistance.
OK, Well putting in new plugs and pressure testing is no longer an option. The water pump is on my bench waiting for a rebuild kit, the radiator is at the shop waiting it's turn to be pressure tested, and the hoses are in the local landfill by now, although I bought new ones. Now that the pump is off the front of the motor most of the plugs are easy to reach, however there is at least one in the block that would require removal of the exhaust pipe at the manifold on the p***senger side. All that considered and the fact that I want to keep the car, as the saying goes, "in for a penny in for a pound", (I really have no idea what that means but it sounds like I am using it correctly) I decided to pull the motor. Oh yeah and a stranger I met gave me a factory dual quad intake for the car, so how cool is that gonna look? (it's true he gave it to me just ask my wife) I'll pull it this week-end and hopefully you won't see any wanted posts from me in the near future.
I am pretty sure I would not pull the motor yet. Maybe yes, but only if I knew I was going to send out the block and heads for testing by pressure. There well could be internal cracks that can't be seen when apart, nor magnafluxed either. So I would wait for the radiator and whatever is needed to get it running again. Can you find one of those aftermarket bolt together freeze plugs that are used for hard to reach areas? Get it together, run it to see if it has water in oil, or oil in the water, and if it does not boil, or get hot, or show bubbles in the coolant.
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