Author Topic: Freeze plug failure and overheating of my 346 engine!! Any thoughts??  (Read 398 times)

Offline z3skybolt

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  • Name: Robert L. Ritchie
Well it never stops,

I have 600 miles on a just completed very expensive professional overhaul.  Coming home from Sat. morning coffee with old airport bums.... after about 15 miles of driving, I noticed the temp. gauge was full hot.  I was about 1/4 mile from a farm driveway so I wheeled in and shut the engine off.  It dieseled for about 45 seconds and it took me that long to realize what was going on. Finally I put it in gear, popped the clutch and of course the engine stopped.  Smoke from hot antifreeze dumping on the engine block poured from beneath the car. I was puzzled that the radiator was not steaming.....but first things first.

I let it sit for about 25 minutes and the temp gauge had dropped to just above middle.  The engine started right back up. I had hoped that it would cool down at idle while I tried to determine the cause and perhaps added water....but the temp gauge began to rise instantly. After running it for a few seconds I shut it back off.

Having scalded my hands and arms when removing the radiator cap on my old tractor last summer.... I was hesitant to remove the radiator cap and so waited another 30 minutes. When I removed the cap I was astounded to find little or no coolant in the radiator.  I walked to the farm house and got a couple gallons of water.

When I poured water into the radiator, a little at a time...it began to run out the left side of the block right behind the crankcase vent/breather (??)tube..  To make a very long story shorter....the freeze plug on that side had pushed out at the bottom and allowed the coolant to pour out.

The car was brought home on a "roll aboard" and is in the garage for the weekend. Monday morning I will have it transported to the mechanic that installed the engine here in MO, the engine was overhauled in Ohio. The local mechanic will install a new freeze plug.

They were all replaced new during the engine overhaul.  The car has been kept in a heated garage, it had proper coolant in it and no way was this an issue of freezing temps.  I have no idea why it pushed out. Anyone have a fail safe method of making sure that this does not happen again?  Is this a common problem with the freeze plugs in the old flat heads? How could it have been improperly installed?

I am hoping against hope that my $12,000.00 overhaul was not ruined by the overheating.  The engine didn't bog down or lose power before I shut it down.   It was cruising smoothly at 50 mph. I don't know how long it was hot before I noticed...but I don't think very long. The oil pressure was normal before, during and after the overheating.  It restarted quickly and easily before the second shut down.  The dieseling and knocking which occurred before I popped it in gear has me concerned.

I am beginning to regret ever getting involved in this whole affair....after having waited a lifetime to own such a beautiful vehicle.

Bob
1937 Buick Special Coupe( owned for 46 yrs.))
1940 LaSalle 5227 Coupe(bought in May 2016)
1974 VW Beetle bought ( in 2000)
1985 Lincoln Town Car Signature Series( bought new)
2000 BMW Z-3(bought new)
Newer cars that don't matter.

Offline Steve Passmore

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  • Name: Steve Passmore
Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #1 on: November 11, 2017, 04:09:49 PM »
I had the same thing happen about 20 years ago. I had fitted the nearest size core plugs I could find. (I know, you guys call them freeze plugs but we won't get into that) The plug I fitted went in the hole just about but was really too tight. It would not flatten. This is no good at all because it must be able to expand and flatten when punched. These would not. I thought it would be OK but after 10 miles the hot water pressure blew one of them out and I lost all the water.
Steve

Offline Jeff Rose CLC #28373

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  • Name: Jeff Rose
Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #2 on: November 11, 2017, 04:20:54 PM »
I am beginning to regret ever getting involved in this whole affair....after having waited a lifetime to own such a beautiful vehicle.
I don't have an answer for you on your problem. I can only offer a little encouragment. I too have had to have my car with a fresh rebuild towed. (Ironically going to an airport in MO--1H0). It is a sickening feeling and I understand. It will get fixed, and you will drive it again.
Best of luck,
Jeff
Jeff
CLC #28373
1970 Coupe DeVille
1955 Series 62

Offline harry s

  • Harry Scott 4195
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Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #3 on: November 11, 2017, 04:40:11 PM »
Bob, Keep the faith and as Jeff said good luck. When your mechanic goes to install a new plug have him check the small ledge  just inside the hole. In some cases this ledge will deteriorate and not give enough support to expand the plug. If this is the case you can use a rubber expandable plug.     Harry
Harry Scott 4195
1937 7529
1941 6733
1948 6267X

Offline gary griffin

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  • Name: Gary Griffin
Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #4 on: November 11, 2017, 07:47:06 PM »
There are repair plugs that have a screw to tighten them and a gasket and they do not fall out. Designed to repair plugs in tight places where you can not swing a hammer but may hold better than factory plugs.  As most of us know we call them freeze plugs but they are actually installed to remove the sand used in the casting process and do not always prevent freeze damage.  Do not count on them to prevent freeze damage!!
Gary Griffin

1940 LaSalle 5029 4 door convertible sedan
1942 Cadillac 6719 restoration almost complete?
1942 Cadillac 6719 (parts car) (Gone)
1957 Cadillac 60-special (Needs a little TLC)

Offline z3skybolt

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  • Name: Robert L. Ritchie
Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #5 on: November 11, 2017, 08:14:56 PM »
Thank you,

And that is why Steve P. called them "core plugs".  Of course he is correct as are you. I appreciate all the suggestions and will follow up with my mechanic after the weekend.  All thoughts and experiences are welcome and appreciated.

Thanks to all of you.

Bob
1937 Buick Special Coupe( owned for 46 yrs.))
1940 LaSalle 5227 Coupe(bought in May 2016)
1974 VW Beetle bought ( in 2000)
1985 Lincoln Town Car Signature Series( bought new)
2000 BMW Z-3(bought new)
Newer cars that don't matter.

Offline V63

  • Posts: 324
  • Name: W Link
Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #6 on: November 11, 2017, 08:22:20 PM »
I would verify the fan belts are SNUG! It does not take much looseness to make the fan I effective! In theory you should not be able to manually pull the fan and slip the belts!

 Also verify the radiator cap is of sufficient reach to seal!!!

Lien fuel mixtures and retarded timing cause over heating!

Offline Jay Friedman

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Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #7 on: November 11, 2017, 11:07:39 PM »
I agree with gary griffin. 

I also once had a one of these plugs pop out from my 331 not long after a rebuild.  Normally with the motor out of the car, to install one I put the plug in the hole in the motor, place the round end of a ball peen hammer in the center of the plug, and whack the other (flat) end of the ball peen hammer with a 2nd hammer.  This spreads it and it remains in place.  With the motor in the car there wasn't enough room to swing a hammer, so I couldn't install a new steel one this way. 

Instead I bought one of the replacement hard rubber ones Gary mentions that have a screw in middle to tighten them.  A problem was that the holes for them on a 331 motor are 1 31/64" in diameter and the nearest size rubber plugs made are 1" in diameter.  I ground the hard rubber on the plug slightly all around on a bench grinder until it fit in the hole and installed it.  It has been in the motor 10 years and 28,000 miles and does not leak.

1949 Cadillac 6107 Club Coupe
1932 Ford V8 Phaeton (restored, not a rod).  Sold
Decatur, Georgia
CLC # 3210
"If it won't work, get a bigger hammer."

Offline Steve Passmore

  • Posts: 4935
  • Name: Steve Passmore
Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #8 on: November 12, 2017, 03:47:58 AM »
.  As most of us know we call them freeze plugs but they are actually installed to remove the sand used in the casting process and do not always prevent freeze damage.  Do not count on them to prevent freeze damage!!

I can vouch for that first hand, Gary. I found a 37 straight eight Buick on a farm decades ago with the block cracked nearly 30" front to back and right through all three plug holes without removing even one of them.
Steve

Offline The Tassie Devil(le)

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Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #9 on: November 12, 2017, 05:52:09 AM »
I have a feeling that they started to be called Freeze Plugs when block heaters were invented, and inserted into the holes in the blocks.   This was a convenient place to put them.

Down here, we call them Welsh Plugs.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
(Past President Modified Chapter)

Offline Jay Friedman

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Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #10 on: November 12, 2017, 06:18:21 AM »
I've heard them called Welsh plugs here in the US.
1949 Cadillac 6107 Club Coupe
1932 Ford V8 Phaeton (restored, not a rod).  Sold
Decatur, Georgia
CLC # 3210
"If it won't work, get a bigger hammer."

Offline cadillacmike68

  • Posts: 1140
  • Still finishing up this 1968
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  • Name: M Santos
Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #11 on: November 12, 2017, 07:41:21 AM »
I had the same thing happen about 20 years ago. I had fitted the nearest size core plugs I could find. (I know, you guys call them freeze plugs but we won't get into that) The plug I fitted went in the hole just about but was really too tight. It would not flatten. This is no good at all because it must be able to expand and flatten when punched. These would not. I thought it would be OK but after 10 miles the hot water pressure blew one of them out and I lost all the water

We refer to it as coolant here.  :P

Now I'm concerned about my new rebuild.....
« Last Edit: November 12, 2017, 07:45:21 AM by cadillacmike68 »
Regards,
"Cadillac" Mike
Current:
1968 DeVille Convertible
1996 Fleetwood Brougham
2009 STS NorthStar Platinum ed RWD
2011 CTS PRemiun ed Sedan RWD
Past:
2008 CTS Premium ed Sedan AWD
2005 CTS Hi-Feature Sedan RWD
2000 ElDorado ESC Hard Boot Convertible
1995 Fleetwood Brougham
1973 Sedan DeVille
1970 Fleetwood Brougham
1969 DeVille Convertible

Offline jackworstell

  • Posts: 154
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  • Name: J L Worstell CLC #7558
Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #12 on: November 12, 2017, 08:20:07 AM »
My friend has a 1937 Series 60 and he had the engine totally rebuilt by a professional shop maybe 5- 6 years ago

Within  about 3 yrs or so of the rebuild he had two plugs pop out....at different times.     We were able to replace one with metal plug....just barely had room to swing a tool to flatten it.     The second one.... we had to use the expandable rubber type.

Fortunately both times the car was in his driveway when the plug popped out....we knew immediately what had happened.
He has a very long and very steep driveway...the engine always get a little hot by the time the car gets to the top.  Plus it took us a while to come up with the right radiator cap we should have been using....since corrected.

It's been about 2 yrs now and no further problems.  No other plugs have popped and the two replacement plugs have held.   The engine runs fine ( except it doesn't like to re-start when hot....the curse of the 346 )

We now keep a couple of rubber expandable plugs ( and a wrench) with us when we are out driving the car

QUESTION....exactly what size/type plug should be used with the 346  ??    There may be more to this question than meets the eye
because there are some odd sizes out there....for example 1.792"    Apparently plug sizing has to be done very accurately....maybe within 1/64"    ??

Jack Worstell

Offline Steve Passmore

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  • Name: Steve Passmore
Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #13 on: November 12, 2017, 08:34:29 AM »
We refer to it as coolant here.  :P

I think that's because in modern cars its no longer just water. In my case, it WAS just water. >:D
Steve

Offline Steve Passmore

  • Posts: 4935
  • Name: Steve Passmore
Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #14 on: November 12, 2017, 08:54:16 AM »
My friend has a 1937 Series 60 and he had the engine totally rebuilt by a professional shop maybe 5- 6 years ago

QUESTION....exactly what size/type plug should be used with the 346  ??    There may be more to this question than meets the eye
because there are some odd sizes out there....for example 1.792"    Apparently plug sizing has to be done very accurately....maybe within 1/64"    ??

Jack Worstell

Plug sizes for the 346 block are 1 3/4". There will be discrepancies with a micrometer because these parts are not machined up but punched out.
Steve

Offline Bobby B

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  • Mendham, New Jersey
  • Name: Bob Bender
Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #15 on: November 12, 2017, 09:16:58 AM »
Plug sizes for the 346 block are 1 3/4". There will be discrepancies with a micrometer because these parts are not machined up but punched out.

Steve is correct. They sell two sizes for the 346, 1-47/64" and 1-3/4". Why...I don't know ???  If you try to punch them and they don't hold, go to the larger size.                   

1-3/4" Dorman Part #550-025.                                                                                                             
Bobby
1947 Cadillac Series 62 Convertible Coupe
1968 Mustang Convertible
1973 Mustang Convertible
1969 Jaguar E-Type Roadster
1971 Datsun 240Z
1979 H-D FLH

Offline cadillacmike68

  • Posts: 1140
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  • Name: M Santos
Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #16 on: November 12, 2017, 09:29:33 AM »
I think that's because in modern cars its no longer just water. In my case, it WAS just water. >:D

And you Still run just plain water? Why???
Regards,
"Cadillac" Mike
Current:
1968 DeVille Convertible
1996 Fleetwood Brougham
2009 STS NorthStar Platinum ed RWD
2011 CTS PRemiun ed Sedan RWD
Past:
2008 CTS Premium ed Sedan AWD
2005 CTS Hi-Feature Sedan RWD
2000 ElDorado ESC Hard Boot Convertible
1995 Fleetwood Brougham
1973 Sedan DeVille
1970 Fleetwood Brougham
1969 DeVille Convertible

Offline Steve Passmore

  • Posts: 4935
  • Name: Steve Passmore
Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #17 on: November 12, 2017, 09:37:38 AM »
It was the height of summer and the very first run out after a 6-year restoration. In case of issues, I didn't want to lose expensive coolant as you call it and in my case, as I lost it all it was a wise move.
 We still call it water here anyway even with antifreeze added. We are still and always will be separated by a common language ::)
Steve

Offline jackworstell

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Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #18 on: November 12, 2017, 10:11:36 AM »
"We are still and always will be separated by a common
 language"

    Love it.

Jack Worstell

Offline Bobby B

  • Posts: 1602
  • Mendham, New Jersey
  • Name: Bob Bender
Re: Freeze plug failure and overheating of my 346 engine!! Any thoughts??
« Reply #19 on: November 12, 2017, 11:37:32 AM »
It was the height of summer and the very first run out after a 6-year restoration. In case of issues, I didn't want to lose expensive coolant as you call it and in my case, as I lost it all it was a wise move.
 

Steve,
 I do the same here after every rebuild. No problem running on water, as we all know that water has better heat transfer than coolant or coolant/mix. Problem is protection in freezing weather, pump lubricant, anti-corrosives, etc. I've saved many a dollar on engine break-in due to a small leak or problem. Plus it's a good first flush for a fresh rebuild anyway before you add your final mix. Distilled water is less than a dollar per gallon here. Way cheaper than coolant on the ground. Plus I really hate cleaning that slippery slimy mess up.....;)
                                                                                                                                              Bobby
1947 Cadillac Series 62 Convertible Coupe
1968 Mustang Convertible
1973 Mustang Convertible
1969 Jaguar E-Type Roadster
1971 Datsun 240Z
1979 H-D FLH