Cooling water drain plugs

[Rob M.]

Dear fellow restorers,

Could someone send me a picture of the cooling fluid drainholes of a V-8 because I don't want to unscrew the wrong bolt (e.g. oil plug) to get rid of the last bit of cooling water.

thanks,
Rob Musquetier
The Netherlands.




The C1 1959 Corvette Restoration Project

[Dennis C.]

Re: Cooling water drain plugs

Rob, On each side of the block you should easily be able to find a 9/16" hex pipe plug. From the factory, the spark plug wires (at their lowest point) go right by this plug. Each side will hold about 1 gallon of fluid, so have something larger than your coffee cup to catch it. Sometimes, after removing plug, nothing will come out - area plugged with rust and crap. Usually a screwdriver will loosen this up. I know this isn't a picture, but don't think you'll have any trouble locating pipe plugs. Best, Dennis

[Mike M.]

Re: Cooling water drain plugs

on both sides of the block about half way down and half way back, you'll find a hex-head pipe plug(assuming the plugs are original and its a V-8, not 235 6 cyl). they're the ones that'll spit anti-freeze when removed/. there are no oil plugs anywhere near the coolant drain plugs. good luck, mike

[Brian Monticello]

Re: Cooling water drain plugs

Passenger side is shown below

and here's the driver's side (notice the dispstick bump-out on the oil pan). I don't think this is supposed to be a hex head


I got lucky and these came out super easy. On the passenger side the coolant was dribbling out so I moved the bucket - Poked a small screw driver in the hole and coolant spewed out like a waterfall - missed the bucket and got my light wet. A whole bunch of garbage came out with the coolant.

Brian

[Mike Sasser]

you have mail *NM*

[Rob M.]

Re: Cooling water drain plugs

Thanks all, good reply. I'm going to my garage now to get the last stuff out of it !

[Rob M.]

Re: Cooling water drain plugs

Well, that didn't work out yet. One bolt is so tight that I can get it loose and the other is a round headed bolt so I'll need different tooling (and all the shops are closed now in the Netherlands) to get it removed. Better order a proper bolt for this one so next time this will be an easier job...

I'll keep you all posted on my progress...

greetings,
Rob.




The C1 1959 Corvette Restoration Project

[Roberto L.]

Re: Cooling water drain plugs

Checked your site, is very well done and detailed. The kind of images we all eat with devotion. Congratulations.

Roberto, NCRS #30019, RMC

[Patrick H.]

Re: Cooling water drain plugs

Rob,

On my 71, I had to use heat from a hand-held propane torch to remove one side. I replaced each plug with brass ones, available at my local auto parts store. Brass won't rust in place, so next time will be easier.

Patrick

[Dick W.]

Re: Cooling water drain plugs

If you use a thread sealant like Loctice Pipe Sealant with teflon, the plug will not seize in the block. Works wonders anywhere you have tapered threads. Excess can be wiped off. Is not as visible as tape.

[Patrick H.]

Re: Cooling water drain plugs

Dick,

I used that, too. It should never be a problem while I own the car.

Patrick

[Rob M.]

Re: Cooling water drain plugs

All,

Still haven't been able to get them loose and I dont want to mollest. I've tried special untiding fluid to loosen them but they won't move at all. I'm afraid I will have to drain the lot by loosening the lower radiator hose and draining the radiator. ;-(

greetings and thanks for your help,
Rob.

[Dick W.]

Re: Cooling water drain plugs

You will still have some water in the lower water jackets. You cannot totally drain a block unless you remove the plugs.

[Joe L.]

Re: Cooling water drain plugs

Rob----

What you have encountered is the norm for these block drain plugs; they are usually rusted in place and are "solid". If you use too much torque to loosen them, you might end up cracking the block. It's not worth the risk.

In this case, though, there is an alternative that will allow you to fully clean the block and let the plugs stay put. Use a Prestone Flush-And-Fill kit. This allows you to install a fitting in one of the heater hose lines and an "overflow" device in the fill opening of the supply tank or radiator. Using this set-up with a garden hose, you can completely flush the cooling system.

When you're done flushing, you open the radiator petcock and allow the water to drain out of the system. Then, close the petcock. Add enough anti-freeze right out of the jug to give you, considering the capacity of the cooling system, the 50-60% mix that you're after. You might have to start the engine to allow the system to fill completely so that you can get it all in. Finally, after the system has come up to operating temperature, add enough water to bring the system up to full. You're done! A completely clean system with no necessity to open the block drains.

If you wish, you can change the heater hose with the fitting installed in it in order to have a "correct" appearing hose. Otherwise, just install the cap that comes with the kit and you're ready for the next time. If you change hoses at coolant change time, make sure that you do this BEFORE you change hoses so that you cut the old heater hose for the fitting; then install the new heater hose without the fitting.