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What is this growing on my engine?


Aarin Packard

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1949 Plymouth Spec Dlx, have had an intermittent leak for a week. I could see the shine around the bottom of the engine but could not find where it was coming from.

First  thought it was the fuel pump for various reasons,  but the clear liquid did not smell like gas, while checking the oil I just found this clump of yellow crystal-like residue “growing” on the freeze plug. 

Most likely the source of my leak but what on earth is the build up on the engine?? 

do I have to pull the engine to replace the plug?

more info: I installed a new (modern) 3 core radiator earlier this summer as I was constantly overheating, it solved the  problem but my buddy thinks it may be putting too much pressure on the cooling system. Could that be the reason for the leaky freeze plug and the residue?

 

 

 

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Edited by Aarin Packard
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I would suggest flushing the engine with vinegar.  Pretty cheap by the gallon and wont be caustic like some acids.

I would say fill it up with vinegar and drive it around a few miles for a couple days, you may need to add antifreeze right away, do not know your location. so maybe just all day then drain it.

I should add, I like the idea of using vinegar, is a lot easier on the old original radiators, since you have a new one already ....

 

If you can reach it to work on it, you can change the freeze plug. maybe put a sheetmetal screw in the center and use a pry bar to pop it out. Or you might need to punch a hole in it with a screw driver and pry it out. clean up the surface and drive the new one back in.

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2 hours ago, greg g said:

Are you running a pressure cap on the radiator???  Don't know when they switched to pressurized system but early 49's were not pressurized.  Find a non pressure cap or  maybe 3 psi max.

In the meantiime,just don't tighten your radiator cap past the first "stage" to keep it from building up pressure.

You may have to  jack your car up, put it on jack stands,and remove a tire to be able to gain enough "straight-line" access to be able to pull or drive the new freeze plug in. You might have to remove the inner fender panel to gain enough access to do a proper job of cleaning the holes in in the block and seating the new freeze plugs in  place.

Do yourself a favor and replace them all while you are at it. They aren't very expensive,and if one is old and rusty enough to leak,so are the others. Even if they aren't leaking right at the moment.

Keep in mind that once you replace all the freeze plugs that your heater core probably won't be able to handle the pressure from a modern radiator pressure cap,so replace the cap you have now with a new one that will hold maybe 4 psi at the most. If you can't find one,just run your current cap only tightened to the first "stage".

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...and that crud is oxidation and chemicals in the coolant crystalizing/solidifying.  Unknown what additives you or a PO may have put in the coolant, but additives to stop leaks tend to do that, especially if it has been in there a while. It's also a good sign that the system needs to be flushed, as noted above. 

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If you don't already have one you may want to consider an overflow tank for the radiator. I made one up out of black PVC. I have my original no pressure radiator cap but agree you should be good running low pressure cap at just the 1rst lock position. 

Likely the engine was flushed with some chemicals and those were not removed or not completedly removed and are reacting with the plug.

Good Luck 

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So, you have crud around the freeze plug.  That indicates its leaking and its likely to let go soon.  Before messing around with tanks and caps, it'd be Best to pull all the frost plugs, clean up and bang in new replacements.   I believe there is one on the back too....might also be a rear cam plug back there so check your manual before pulling plugs out back.

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