Draining FE coolant through block plugs

J

JimNNN

Well-known member
I'd like to remove the coolant drain plugs on the 352 block in my '61. The engine is in the car and runs good, so I'm not going to take it out. I've read that some people don't have any luck trying to get the plugs out after all of these years, and I don't want this to turn into a fiasco. Any recommendations on how to do this effectively?

If the plugs won't come out, what are your recommendations for draining all the coolant in the block without removing the plugs? Thanks.
 
The only other way to do it, is to knock out a expansion (Welch) plug, on each side. That's no fun either but, if they are steel plugs, that have been in a long time some, may need replaced anyway.
 
I have never had much luck with getting block drains out. What is the reason for draining? Just curious.
 
I'd like to treat the jacket for rust. It doesn't look real bad, but now would be the time to do it.
 
I don't know about FE's, but to better drain the engine's coolant you have to open the drain plugs on YBlocks and small blocks (289/302). I a;ways do this when changing the coolant. I found a better drain plug, a marine unit as pictured. Works in the radiator too.
 

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frnkeore said:
You could vacuum it out, threw the water pump holes.
Click to expand...




That's what I was thinking, too. A small line going down into the block. I have a gas tank siphoning line...would that work?


Thanks for the heads up on the drain kit, Paul. I flushed my Y block out without draining through the stopped up block petcock, but it took five or more complete flushes and probably 35+ gallons of water to get everything cleaned out. I'd rather not go through that again with the FE.
 
Heating rusty NPT type plugs will usually break the bond between the cast iron and the plug allowing it to come out after it cools down. I do the same thing with studs and bolts that won't budge.
 
I just opted to flush the engine with the distilled water, then run the engine for a while. I repeated that procedure three or four times and the water ended up being pretty much clear and absent of old coolant and residue. Then I put in the antifreeze. It's a hassle, but maybe less of a hassle than messing with the plug.
 
The reason for the drain-***** was that during that period mostly water was used for coolant and a alcohol... :D ...based coolant was used for cold weather. The cooling system was serviced twice a year The drain-***** made it easier to completely drain the system.

With a permanent coolant, the service interval went to two years.

If you think the system has jungle-rot, the best remedy (without specialized equipment) is a HD cleaner followed by a complete forced flush (use a garden hose plumbed into a heater hose outlet on the block - thermostat removed). If she won't come clean or you think there is scale, you would then remove the core plugs and go about it that way.

Permanent coolant solved most of the problems if the system was not previously scaled due to negligence (or hard water) and serviced on a regular basis (IMO).

Now tech is available where the system is completely flushed and filled using compressed air pressure.

Heat would most likely need to be used to remove the old pet-***** but their use does make it easier for a complete flush (again IMO).

And of course, distilled water and a quality coolant for fill.

All of this is IMO and your results and mileage may vary.
 
If the block has a lot of crud in the cooling system, drain and refill with 100 % white vinegar. It is a very mild acid. Run the motor for an hour, then drain and flush well. It will clean things inside very well.
 
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