| Freeze Plugs- what do i need to know ? [message #351443] |
Mon, 20 January 2020 08:22  |
hertfordnc
Messages: 1164
Registered: September 2009
Location: East NC
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The Revcon has not been run much for years, it's still not driving (brakes)
I was running it up to temp to set up the controller for the electric fan when steam began coming out of the right rear of the engine.
I was pretty happy to diagnose a freeze plug rather than a head gasket.
So, should i replace as many as i can reach or just the bad one?
Are some more likely to fail than others?
This engine has had mostly just water in it for the last few years
Dave & Ellen Silva
Hertford, NC
76 Birchaven, 1-ton and other stuff
Currently planning the Great american Road Trip Summer 2021
It's gonna take a lot of Adderall to get this thing right.
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| Re: Freeze Plugs- what do i need to know ? [message #351446 is a reply to message #351443] |
Mon, 20 January 2020 09:11  |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Never run just water. CORROSION let alone freeze damage. I'd replace the leaking ones and add coolant for now, until further investigation can happen.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Freeze Plugs- what do i need to know ? [message #351448 is a reply to message #351443] |
Mon, 20 January 2020 09:29 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
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My experience replacing freeze plugs in limited but the few that I have replaced all were rusted through and never blown out from freezing. They also were on installed engines. Many times on instaled engines they are almost impossible to get to. So my recommendation is replace what is broke or easy to get to. If the engine is out of the vehicle then replace them all.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Freeze Plugs- what do i need to know ? [message #351451 is a reply to message #351446] |
Mon, 20 January 2020 10:09 |
hertfordnc
Messages: 1164
Registered: September 2009
Location: East NC
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JohnL455 wrote on Mon, 20 January 2020 09:11Never run just water. CORROSION let alone freeze damage. I'd replace the leaking ones and add coolant for now, until further investigation can happen.
Forgive me for I am a SINNER!
I've had the coach 10 years, for about seven of those years I really wanted it gone. But now i have two boys and they love it so we are diving back in with family support.
Dave & Ellen Silva
Hertford, NC
76 Birchaven, 1-ton and other stuff
Currently planning the Great american Road Trip Summer 2021
It's gonna take a lot of Adderall to get this thing right.
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| Re: Freeze Plugs- what do i need to know ? [message #351452 is a reply to message #351443] |
Mon, 20 January 2020 11:04 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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hertfordnc wrote on Mon, 20 January 2020 09:22The Revcon has not been run much for years, it's still not driving (brakes)
I was running it up to temp to set up the controller for the electric fan when steam began coming out of the right rear of the engine.
I was pretty happy to diagnose a freeze plug rather than a head gasket.
So, should i replace as many as i can reach or just the bad one?
Are some more likely to fail than others?
This engine has had mostly just water in it for the last few years
Dave,
It could be just the one plug, but that is rare. You should be prepared to replace more.
Now, here comes some "good" news. I recently (in the last few years) have had mine and other engines on the shop floor. I always take lots of pictures for two reasons: With modern cameras they are cheap AND They are better than my memory.
So, I pulled up the pictures just to be sure and you are lucky. The 455 has only three core support holes in the outside of both banks and none in the rear of the block, under the timing gear cover or in the valley. You only have to worry about the six plugs that you can see from the sides.
As KenB stated, Anticorrosion protection is one of the larger purposes of modern coolant.
Get used to calling them "Core Plugs" as they never were freeze protection and will never do that. They corrode away in untreated water pretty fast.
Now, in your specific case, I would arrange to replace the failed core plug and be ready to replace others. They are not easy to remove and the hole must be clean before replacement. When you start this operation, have a cooling system pressure tester on hand. When the first is replaced, please pressure test the system to what ever the little pump will do. It has been my experience that there is seldom just one that needs replacing.
I wish you a simple success.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: Freeze Plugs- what do i need to know ? [message #351456 is a reply to message #351452] |
Mon, 20 January 2020 11:47 |
hertfordnc
Messages: 1164
Registered: September 2009
Location: East NC
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Thanks Matt,
Cooling system pressure test ?
What would be a good target PSI? Would it be as simple as putting shop air to a heater hose?
Dave & Ellen Silva
Hertford, NC
76 Birchaven, 1-ton and other stuff
Currently planning the Great american Road Trip Summer 2021
It's gonna take a lot of Adderall to get this thing right.
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| Re: Freeze Plugs- what do i need to know ? [message #351457 is a reply to message #351443] |
Mon, 20 January 2020 11:59 |
6cuda6
Messages: 975
Registered: June 2019
Karma: -6
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As others have said...replace them all if you can. Most of the time they are under the exhaust manifold area on the side of the block and hard to get direct access too.
If you can get at them replacement it is fairly easy....grab a big flat blade screw driver, place it in the lower bevel area of the plug [were the flat part starts to climb up the side of the plug] and give the screw driver a good whack with the hammer....the goal here is to spin the plug sideways in the bore and NOT drive it into the block....once spun you can grab it with vicegrips and wrestle it out or pop it out with a prybar.....pay attention to which way you spin it as sometimes its easier to remove in certain position then others.
As for installing new ones.....couple ways...there is a tool that one can buy to install but the average Joe wont really ever use it again so find a socket or something of the like that fits inside the bore of the freeze plug [preferably a deep socket....if not an extension on the socket may be needed] and carefully drive them into the block paying attention to finish with the plug in as deep and as square as the original. DO NOT put anything on the outside of the plug like silicone etc its really not needed and can cause more harm then good.
Now you say "what happens if i mess up the first one and it goes inside the block?" grab a magnet and fish it out...you will be able to get at it as it will be deformed just remove as above.....next question is "what happens if i cant find it with magnet no matter how hard i try?"....no big deal just forget about it all together as it wont hurt anything if its left in the block but DO NOT just whack all the frost plugs into the block and call it good because then you will have problems [one left behind is not usually a big deal....6 on the other hand would be].
The rotten one...try to spin it like above...if not just get your big screwdriver or prybar behind whats left of the rim, spin and remove.
Just my way of doing these for 30 years but others probably have suggestions as well.....YMMV....
Rich Mondor,
Brockville, ON
77 Hughes 2600
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| Re: Freeze Plugs- what do i need to know ? [message #351458 is a reply to message #351456] |
Mon, 20 January 2020 12:03 |
6cuda6
Messages: 975
Registered: June 2019
Karma: -6
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hertfordnc wrote on Mon, 20 January 2020 12:47Thanks Matt,
Cooling system pressure test ?
What would be a good target PSI? Would it be as simple as putting shop air to a heater hose?
Usually the pressure cap on the radiator is rated for 16 to 18psi.....with the cap off and a Stant pressure tester affixed you limit the test pressure to 25psi.
DO NOT put shop air to a heater hose as its way to high and you risk blowing out something else.....my suggestion is just go down to the your local parts store like AutoZone, NAPA etc as they usually have a tool loan program and borrow the pressure test kit.
Rich Mondor,
Brockville, ON
77 Hughes 2600
[Updated on: Mon, 20 January 2020 12:04] Report message to a moderator |
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| Re: Freeze Plugs- what do i need to know ? [message #351464 is a reply to message #351443] |
Mon, 20 January 2020 12:35 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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The few times I ever replaced core plugs I used a slide hammer with a screw on the end in a hole drilled in the plug. Put the replacement in with a piece of about 1 inch round stock against the center of the plug and lay a lick on it with a dead-blow hammer. I've no idea if that';s a good bad or indifferent way to do it, it's been decades since I did one. P'raps the guru(s) will comment.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Freeze Plugs- what do i need to know ? [message #351473 is a reply to message #351471] |
Mon, 20 January 2020 18:41 |
6cuda6
Messages: 975
Registered: June 2019
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Could be correct....i just went with the most common in the transportation and auto field.
RF_Burns wrote on Mon, 20 January 2020 18:27You can correct me if I'm wrong, and I probably am wrong... but isn't the rad cap of the GMC rated for 9 PSI and over 12PSI can balloon the radiator...
So I would not test it over 9 or 10 PSI.
Just my farmboy shade-tree mechanic way of seeing things.
Rich Mondor,
Brockville, ON
77 Hughes 2600
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| Re: Freeze Plugs- what do i need to know ? [message #351567 is a reply to message #351443] |
Sat, 25 January 2020 07:06 |
hertfordnc
Messages: 1164
Registered: September 2009
Location: East NC
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Update on the expansion plug problem:
It is not one of the six plugs on the block. Its one of the four plugs on the head. Specifically, the one over the exhaust manifold on the right side.
I dropped the manifold and poked a hole in it. Then i managed to get a bite on it with pliers and i pulled out the whole center, it was like i used a can opener.
So now i have this steel ring fused to the head.
I need some advice on technique.
Dave & Ellen Silva
Hertford, NC
76 Birchaven, 1-ton and other stuff
Currently planning the Great american Road Trip Summer 2021
It's gonna take a lot of Adderall to get this thing right.
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| Re: Freeze Plugs- what do i need to know ? [message #351568 is a reply to message #351443] |
Sat, 25 January 2020 07:59 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Chisel the ring out without nicking the edge of the hole? Or a trip to the Men's Mall and ask about a J head. Maybe you could take a hand grinder (Dremel) and get it into a piece you can drive an awl under and peel it.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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So now I use the Indian Head shellac or Permatex #2 on them to avoid that possible scenario.