How to flush my 1952 blocks coolant passages?

[52Cadillac]

 A search turned up zip on my motor.
My 331 is still heating up at stop and go traffic. I'm going to attempt to flush the block myself. Last year done with radiator.... Long story. Replaced lower hose, etc. So Last year took Radiator to shop where they do their acid? Boil? To remove scale. Reinstalled, and same problem. Basically went onto other things. Now I'm back to it.
Now to the block, how is a scale flush/cleaning done? The car is running. Locate and remove freeze plugs? How easy is it to remove and install new ones, is it recommended?  I've heard back in the day of using baking soda, acids, etc, buddy said use Evapo Rust.
I think my Rad is a two row, can my radiator shop install an extra row or two? So I can keep it looking original.
what is recommended here?
Thanks, Mike

[Richardonly]

Hello Mike,

Other readers can correct me if they have other ideas.

Mine is a 1948, 346ci flathead.  Notorious for running on the hot side.

I used a commercial flush (perhaps Prestone) ran it about 1/2 hour, then opened petcock and continued to run garden hose water until it came out as clear as the water going in.  Did this twice about a week apart.

It helped a LOT!

Depending on the condition of your hoses and heater cores, if they are in good to new condition, you should have no problems with leaks after.  To be on the safe side, you may want to temporarily bypass your heater core/cores.  If the hose/hoses  leak after, they probably need replacing anyway.

After I did mine twice, I was stuck in traffic for an hour with the outside temp at 92-95 degrees and had no problem.

Good luck, Richard

[R Schroeder]

I'm going to assume that this is a original engine that has not been rebuilt.

Most cars will run hot in stop and go traffic. You didn't say if it was puking the coolant out, or just running hot.

These are some other things that will cause a hot running motor in traffic.

Old radiator cap. Wrong poundage reading on cap.

Spark timing. Is it set correctly.

Vacuum advance. This is a big one. A vacuum advance that isn't working will keep the car retarded , causing it to run hotter at idle.

Plugged exhaust system.

Bad heat riser. Stuck shut.

Bad thermostat, or missing thermostat.

Belt slipping.

Bad water pump.

Out of all of them the timing to me is the biggest one , then run down the list from there.
Since I dont know the history of what was done, these would be what I would check.
Roy

[52Cadillac]

I will try the block flush. Look around and see if Preston's still has a flush. Heater core is bypassed.
I dont know engine history prior to my ownership last summer. Just running hot as far as I can tell.
How can I tell if the vac advance is working?
Those are helpful Roy, and I will run em down. Thanks, Guys

[Walter Youshock]

Do you have a copy of the Shop Manual?  There should be 2 brass drains on the sides of the block, one on each side.  To be safe, don't try to remove the plugs if they are in brass fittings.  You should see two 45 degree angled fittings like those used on your fuel and vacuum lines.  Remove the fittings with an open-ended wrench, not the plugs.  I say this because I had a fitting break once because I tried to get the plug out...

Chances are there is so much crud in the block that nothing will come out.  Use a piece of wire, small screwdriver or an awl to carefully break through the clog and open up the drains.  You'll be amazed by what comes out of the block.  Cleaning the radiator is only partially effective.  You don't want all that crap going back in your radiator.

One way to check the advance is with a vacuum pump.  If it holds a vacuum, it should be working.  If not, it needs to be replaced.

[52Cadillac]

Yes I have the shop manual. I will do that as well Walter. Leave em open when flushing should push most of it out of the block and away from Rad. If nothing comes or very little clean out. Gotcha.
No vac gauge. Will find one.

[Walter Youshock]

Do you have a timing light?  You can see the timing change with the advance connected and then disconnected with the vacuum port blocked off.  If the light shows the same level with it connected and disconnected, it's bad.  If it is working, you'll see your timing mark change on the balancer as you increase rpm.  Itill show that it is working but it could still be leaking slightly.  The vacuum test is a better indication.

[R Schroeder]

Walter, is that a ported vacuum on that car.
I ask because you said to increase the rpm to see if it advances. If the vacuum is in the intake it should jump right up, on the timing.
Roy

[52Cadillac]

I do have a timing light somewhere. Will dig her out. So basically if I have movement then vac advance should be good.
I did discover a 1/4" copper line running from rt rear exhaust manifold up to my carb. I'm sure I've read somewhere this should be disconnected?

[R Schroeder]

Mike,
What you want to do is remove the line from the vacuum advance and put some tape over the end of the line to block it off.
Set up your timing light and take a reading of the timing mark.
Then install the vacuum line back on the vacuum advance and take another reading. Timing mark should jump up , BTC.
Sounds like it is a direct connection to the intake manifold , so you should be OK.
Some of the newer cars had the line coming off the carb above the throttle plates. There is no vacuum on these until you open the throttle.

So, you should be fine.
Roy

[Jay Friedman]

I think the line running from rightt rear exhaust manifold up to the carburetor is to provide heat to open the automatic choke when the engine warms up.

[52Cadillac]

Is cylinder #1 front left (driver) side?
Edit: just found in manual. That is #1 front left

[Walter Youshock]

That's #1 cylinder--front driver's side.  As for the vacuum advance--with it disconnected and taped off and using the timing light (which now would be a good time to find your timing marks), the timing will move off your idle slightly.  That's the mechanical/centrifugal advance (the springs on the distributor plates) kicking in.  It'll reach a point and not change any more.  With the vacuum advance connected and, if it's working, the advance will go beyond that mechanical advance point.

[52Cadillac]

With timing light hookup, I get zero changes wether I plug advance itself with my finger or not. Pointer looks to be about an inch above the A line. Appears no change at all. Should I conclude the advance needs replacing? If so, will Napa carry?
Thanks, Mike

[R Schroeder]

Oops, missed the part about the exhaust manifold.

Follow the line back from the vacuum advance to where it connects. Should go to the intake manifold someplace, or if it is on the carb, it should be below the throttle plates to get the reading on it for advance.
If its above the throttle plate then you might not get a reading. Not familiar with the older Cadillac's and there connections.

You also dont want the engine running fast if your checking timing. Weights will swing out and advance the timing on you.
Roy

[R Schroeder]

You dont want to plug the advance unit. You want to plug the line , or you will have a vacuum leak.
Where is it connected to on the other end?
Roy

[R Schroeder]

Your manual should tell you where the timing mark should be set. It should go through the whole procedure for you .
Roy

[52Cadillac]

I tried her both ways. Plugged and unplugged advance itself, then the line, no movement at all.. The advance vac line goes under intake and around into front of carb.

I consulted manual. Should be set at the A mark, but if advance isn't working should I wait until I get it operational?
Also, with electronic ignition should timing still be set by the book?
Thanks, Mike

[R Schroeder]

Again, does it plug in above or below the throttle plates, or the throttle shaft when looking at it.
You may have a plugged line or plugged carb, but I need to know where it plugs in.

You can set the timing on the car, if you have it running at a low rpm.

Then find out if the tube is blocked on the vacuum line.

[52Cadillac]

Roy, It's located on the very bottom of carb, in center, just above the intake manifold.