Packard Forum Index » V-8 (1955-56)

Will opening the radiator drain cock completely drain the engine (provided the front of engine is lower than the rear), without removing any hoses? 56 PAT.

I doubt it. Note that the water pump lower MANIFOLD arm sets rather high on the block.

PRobably drain completely if u lifted the back of the engine 60 degrees or more. But i don't think that's practicle.

Also be advised that BOTH SIDES of the block need to be drained (as a general rule). Because the left water jacket is independent of the right water jacket of the block.

Disclaimer: I've never actualy chequed a PACKARD V8 to see if they are seperate or not. Rule of thumb is that they would be so i'd drain BOTH sides.

The radiator petcock can only drain the coolant that is able to get to the radiator via gravity. That's fine if you're only working on tha radiator, thermostat or water pump, but it's no guarantee that engine water jacket will be completely emptied of its coolant. It's not necessary, however, to remove a radiator hose or tip the engine to drain it. I have to do exactly that with an inline four in one of my other old cars, and its a lot of extra work.

If you can get the front-end jacked up and safely perched on a pair of sturdy jackstands, examine each side of the block and you should find the drain plugs. They are pipe plugs, but should have a hex head - though I don't recall the size. The plugs that I've removed from my Packard V8s were brass, and came out without much trouble. (My Chevy V8 has iron plugs but will get brass next time.)

Yet, don't be surprised if no coolant comes out after you've removed any of the those plugs, because a lot of "sediment" may have built up at that point. If so, just chip away at it with an awl or similar pick, but be prepared to get splashed when you fianlly breach the dam. (Not good work to do in cold weather.) If I'm also removing the thermostat for replacement, I'll sieze the opportunity to flush the block with some water from a garden hose while those plugs are out.

If those drain plugs have never been removed, you may be surprised at all the crud that comes out, but that's not unusual.

In that case, I'd recommend reinstalling the plugs and closing the petcock, refilling with plain water, and running the engine until the thermostat opens and for a few minutes beyoind that. Then, shut 'er down, and drain the radiator and block again.

While you're at it, you may want to consider backflushing the heater core(s), which would require removing hoses.

When refilling with coolant, I tend to mix the solution slightly stronger than 50/50, run the engine, and then test for freeze point and dilute (or strengthen) the mixture, as needed.

Removing those engine drain plugs the first time is a bit of work, but only the first time. It goes much quicker the next time.

BH. Thanks.
I did see in the manual about the drain plugs but, as many times as I have been under there I can't recall seeing them. Probably four years ago I did look and check out the freeze plugs to make sure they were in good shape.


Packardv8, Thanks, good info.


I'll check it out and let you guys know how I make out.

BOTH drain plugs are about 1 inch above the oil pan flange.
The RITE is at the rear of the block. The left is center of the block.

NOTE that hte oem plugs may have been replaced at one time with recessed allen head type plugs makeing them hard to find, filled up with dirt and so-forth.

Be careful that if replaced with aluminium plugs then a GOOD allen wrench will be needed to keep from rounding out hte allen recess.

BTW. Use a SIX point socket or boxed end wrench to remove them. NOT a 12 point nor open end wrench otherwise the hex head of the plug will round off.

PackardV8,
Thanks again for providing such detailed information. I usually try to use the hex end (drive) of the socket to remove the sq. headed pipe plugs, if the hex on the plug is in good shape, if not then (like you)I use a six point socket. I also like to use brass instead of aluminum or steel. I sure hope they weren't replaced by allen headed plugs, those things are usually a nightmare if installed in dirty locations or where exposed to road grim,salt and whatever.
We are having a winter (snow,sleet,wind) storm today and for the next few days so I won't get to it until there is better weather.

I'll keep you posted on events.

Check Figure 5 in the Engine section of the factory shop manual for a view of the left side of the block. (If you're working from a PDF, be advised that the manual archived here at P'Info was rescanned for improved image quality.) You should be able to see the drain plug right where PackardV8 said it would be.

Then, if you look at Plate No. 27 in the parts book, you'll recognize the drain plug just below the exhaust manifold, to the rear of the the outlet.

I didn't find an illustration of the right side, but once you find the drain on the left side of your engine, it will give you an idea of what to look for on the other side. They're not difficult to get to.

If you have some time, give the plugs a squirt of penetrating oil and wait about 15-20 minutes before you put the socket to them.

I'm not able to find the 'fill mark' on the oil bath air cleaner of my 56 Executive. The manual indicates a fill mark on the air cleaner. In 12 years i've never been able to find it.

Remember some as a single line an inch or so long stamped into inside of bowl approx 1/2 to 3/4 inch from bottom and others had the line with "Fill or Full" also stamped above..

Brian Thanks,
I have been "OFF SITE" so to speak and just saw your post and it is much appreciated, I'll check it out.
The weather here in Hampton Roads has been and remains to be too bad to mess with the car but, I'll get back on it, soon I hope.