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Technical Weird Freeze Plug Failure

Discussion in 'The Hokey Ass Message Board' started by justpassinthru, Jan 22, 2020.

  1. justpassinthru
    Joined: Jul 23, 2010
    Posts: 524

    justpassinthru
    Member

    Ran into an issue with a 65 corvette 327 that we are rebuilding the 4 speed transmission on.

    We noticed a slight coolant leak at the right front freeze plug under the motor mount.

    Being extremely difficult to replace with the engine in the car, due to the frame being in the way, and the trans and clutch already being out, we chose to pull the engine and replace all the freeze plugs.

    According to the owner, the engine was rebuilt in 2012 and probably has less than 3,000 miles on it.

    Coolant appeared to be clean looking and bright green in color.

    As you can see from the photos, all the freeze plugs are steel and have some sort of growth on them, some worse than others. They appear to have some sort of sealer slathered on them, that seems to be quite hard on the outside of the plug but kind of rubbery on the inside and a tan/brown color. I can't identify the sealer.

    There was sediment in the water jackets, that was below the level of the freeze plugs, that looked like rust and scale. More than I would think would be in a 8 year old rebuild and that the owner claims was changed twice since being rebuilt. I guessing, probably not cleaned out well during the rebuild.

    Whatever is on these plugs does not seem to appear inside the water jackets.

    I am not a chemist, but this looks to me, like some sort of chemical reaction between whatever sealer they used on the freeze plugs and the coolant actually growing and eating away at the freeze plugs?

    I have cleaned out the water jackets the best I can, scraping with welding rods and flushing with water, and installed new brass freeze plugs.

    Any of you guys have any ideas on what might have caused this?

    Bill

    1.JPG 2.JPG 3.JPG 4.JPG 5.JPG 6.JPG 7.JPG
     
  2. DOCTOR SATAN
    Joined: Mar 21, 2014
    Posts: 710

    DOCTOR SATAN
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    from okc

    Looks bad, I'd go back with brass.....
     
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  3. squirrel
    Joined: Sep 23, 2004
    Posts: 55,942

    squirrel
    Member

    It's likely that the coolant was not changed often enough, I'd suspect that long before suspecting the sealer.

    For a car that doesn't get the maintenance it needs, brass plugs are a great idea.
     
  4. justpassinthru
    Joined: Jul 23, 2010
    Posts: 524

    justpassinthru
    Member

    According to the owner the coolant has been replaced 2 times since being rebuilt
    Bill
     

  5. I agree with Jim ( @squirrel ) here. Let me make brass plugs a 3fer. I always try and go back with brass if I can.

    The sealant may be Permatex number 2. It is not supposed to harden but it will get a hard crust when exposed to air. Permatex number 2 is the go to sealant for soft plugs if you are an older mechanic.

    Here is a trick of you got the engine out of the car, bet yourself some bottle brushes. like those used by a mechanic to clean out oil passages. Run them around as much as possible in the water jacket. Then beg borrow or steal a pressure washer. this is gonna be messy, blow around in the water jacket. last but no least tape of as many holes as possible and jam your shop vac in an open hole. Then block that one and move to another once. You can get one pretty clean that way.
     
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  6. justpassinthru
    Joined: Jul 23, 2010
    Posts: 524

    justpassinthru
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    Also whatever is on the plugs, is kind of soft and rubbery, not hard like rust scale.
    Bill
     
  7. KenC
    Joined: Sep 14, 2006
    Posts: 1,045

    KenC
    Member

    Some silicone sealers/gasket maker type stuff are acidic when curing. I've read that can cause corrosion is some cases. Bathroom sealers under windshield rubber has been blamed for rusting the underlying channels.

    Maybe

    edit to add: Google this 'What metals does silicone corrode'

    edit again: Probably installed plugs/sealer and then let it set for a long time before coolant was installed. So the acid never got diluted until it had done its' thing
     
    Last edited: Jan 22, 2020
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  8. justpassinthru
    Joined: Jul 23, 2010
    Posts: 524

    justpassinthru
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    The sealer is not Permatex #2. That is what I use. It also doesn't seem to be some sort of silicone sealer either.
    Bill
     
  9. squirrel
    Joined: Sep 23, 2004
    Posts: 55,942

    squirrel
    Member

    How long did it sit between changes? Also, if it has a little head gasket seepage, the exhaust in the coolant will really speed up corrosion.
     
    ottoman likes this.
  10. justpassinthru
    Joined: Jul 23, 2010
    Posts: 524

    justpassinthru
    Member

    According to the owner, the coolant was replaced two times since 2012. I don't know if that means including the initial fill on the new engine, and changed once after that or if it means filled initially and 2 two times after that.
    Bill
     
  11. treb11
    Joined: Jan 21, 2006
    Posts: 3,948

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  12. harpo1313
    Joined: Jan 4, 2008
    Posts: 2,584

    harpo1313
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    from wareham,ma

    Looks like that stop leak shit ,weird how it was attracted to the back of the plugs where it would be cooler than the block.
     
  13. squirrel
    Joined: Sep 23, 2004
    Posts: 55,942

    squirrel
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    I like your signature... "THIS ISN'T THE KIND OF ANSWER I WAS LOOKING FOR OUT OF YOU!"

    We can only guess, I suppose.
     
  14. DOCTOR SATAN
    Joined: Mar 21, 2014
    Posts: 710

    DOCTOR SATAN
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    from okc

    I am thinking maybe the previous owners version is wrong......
     
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  15. I don't see a number or size on the plugs. Is the owner sure the rebuilder changed plugs? They are also painted....most machine shops paint the block first and then install plugs/cam bearings. Of course that's not a good way to come up with a conclusion, but the no markings on the plugs makes me wonder.
     
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  16. harpo1313
    Joined: Jan 4, 2008
    Posts: 2,584

    harpo1313
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    from wareham,ma

    Are there any signs of an actual rebuild?
     
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  17. Mr48chev
    Joined: Dec 28, 2007
    Posts: 33,861

    Mr48chev
    ALLIANCE MEMBER

    Chris hit on one point, normal parts house freeze plug almost always have the size on them even in the pre-packaged for specific engine sets. Some low buck rebuild kits may have plain ones though.
    On the other hand "rebuilt" has a lot of different meanings depending on who you are talking to. Some will say it actually isn't rebuilt unless it has been hot tanked or otherwise cleaned, run though the whole machine process including boring the block. on the other side, I've had a lot of guys tell me that the engine was completely rebuilt and what it had was a ring and valve job using the 80 buck engine kit with rings, rods, main bearings and gaskets and a quickie valve job. The rings, rods and mains redo is fine if you don't pawn it off as a complete rebuild.
    I'd agree that the black crud might be stop leak. I like a lot of other old farts use #2 Permatex and have for the past 58 years since I was a sophomore in high school auto shop class. Never had an issue with it except cleaning it off my hands.

    The rust, = the plugs are old and wren't replaced or what ever coolant the owner was using didn't have the proper rust preventative in it and that just flat doesn't sound right. I've never heard of coolant that didn't have some sort of rust inhibitor in it. You might ask what antifreeze he used and do some investigating to see if there are comments on the net about that brand not being a great rust inhibitor. That was why we changed to coolant or a very regular basis in the 60's was that it didn't have the long life stuff that is in the top brand stuff we have now.
     
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  18. justpassinthru
    Joined: Jul 23, 2010
    Posts: 524

    justpassinthru
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    There is a number on all the freeze plugs. 1 5/8", 1635C, MADE IN USA. They look like normal Dorman plugs. The freeze plugs in the rear of the block, by the flywheel are not painted and obviously newer than original.. Those look bad on the inside also.
    Bill
     
  19. Welp, that blows my theory out of the water. Hope you get it figured out.
     
  20. Gman0046
    Joined: Jul 24, 2005
    Posts: 6,256

    Gman0046
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    This is not a Weird Freeze Plug Failure. At some time radiator Stop Leak was poured into the cooling system. It will rot feeze plugs every time and look just like the pictures in the OP's original post. The gunk backs up behind the freeze plugs and rots them out. Doubt that Stop Leak is doing much good for the heater cores as well. Radiator Stop Leak is something I'd never consider using. Fix a leaking radiator right or not at all.
     
    Last edited: Jan 22, 2020
  21. manyolcars
    Joined: Mar 30, 2001
    Posts: 9,176

    manyolcars

    Thats what I do but every other rebuilt engine I have seen is painted after assembly, the gaskets, bolts and everything and it looks cheap. A lot of transmission shops coat the entire transmission with paint too.
    I learned to specify, Dont Paint Any of My Parts
     
  22. nochop
    Joined: Nov 13, 2005
    Posts: 3,818

    nochop
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    from norcal

    Looks like they acted like sacrificial anodes
     
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  23. I just wondered that beings they were painted, were they even replaced when the engine was rebuilt
     
  24. BJR
    Joined: Mar 11, 2005
    Posts: 9,817

    BJR
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    I bet the core plugs were not replaced in 2012. They may not be original core plugs, but are probably much older than the rebuild in 2012.
     
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  25. Beanscoot
    Joined: May 14, 2008
    Posts: 3,056

    Beanscoot
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    Almost certainly the block was not cleaned out properly during the "rebuild". I would take all the claims about this engine with a grain of salt.

    A possibility for the corrosion seen: You used to be able to buy Oxalic acid for cleaning out cooling systems. After a certain amount of time it was supposed to be dumped, a neutralizer (sodium carbonate, usually) added and the system flushed again to clean it out.
    If there was lots of sludge in the water jackets, the acid (and every other stop leak junk added over the years) could have been trapped in there to fester.

    Heck, I wonder if it really even is a Corvette engine.
     
  26. 42merc
    Joined: Dec 19, 2010
    Posts: 894

    42merc
    Member

    This is the right answer.
    I used Solder Seal (looked like aluminum powder), just a small container to seal things on a fresh engine with new freeze plugs. Less than a year later while under the car I noticed a dripping freeze plug.
    I drained the water & removed the plug. The plug was eroded thru where the stop leak had accumulated on the casting next to the plug.
    Later, I pulled the motor to change the clutch, & at that time replaced all of the freeze plugs.
    Many of them were paper thin from the stop leak.
     
  27. squirrel
    Joined: Sep 23, 2004
    Posts: 55,942

    squirrel
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    If you were using water instead of antifreeze, that alone might be responsible?

    But anyways, interesting thoughts on the stop leak causing rust. Something to look for.
     
  28. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 6,695

    56sedandelivery
    Member Emeritus

    Never seen peanut butter used to seal freeze plugs. But seriously, I have NO idea what was used, but it would be nice if everyone did know so it could be avoided. Maybe send a sample into one of those companies that does testing on used engine oil? Just a thought. I am Butch/56sedandelivery.
     
  29. Or something corrosive was used in the block to remove rust and scale and not flushed or neutralized.
     

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