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Discussion Starter · #1 ·
95 SS 214,000 one owner miles. Car has sat for a couple of years due to opti issues. New water pump and opti and it’s back running but I do have a coolant leak somewhere. The coolant is dripping off the center crossmember but my first inspection hasn’t revealed the source. The water pump installation doesn’t seem to be the culprit as I find no coolant there. It seems most of the coolant is more to the drivers side of the crossmember. Car has headers that I installed years ago and there have been no drilling or tapping done on any of the manifold bolts. I had a couple of broken bolts on the drivers side but was able to remove them by welding on a nut and just backing them out and that was 15 or so years ago.

I know I’m going to have to get back under the car and do more inspecting but looking for most likely culprits for a leak in this location. Any ideas???
 

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At least one bolt (I recall on the DS) for the WP goes into the coolant and requires thread sealant. To trace the leak I find success in just warming up the engine a bit and spraying the whole block with 'too much' cleaner (anything with oxalic acid does fine), leave 10 minutes and spray down with a hose. After enough times that the engine is completely clean and bonedry, just run it and check frequently. Any fluids leaking in the engine bay will find their way aftward from the source just from the airflow.
Reference to 'center' cxmember threw me off, and thought you were referring to the tranny cxmember, you know the one in the center of the car. You do mean the engine one, right? If you mean the tranny location then it's likely a leaking steam pipe grommet or rusted tube.

Your early stable looks (or looked) interesting.
 

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Discussion Starter · #3 ·
Frame crossmember running under the oil pan. Thanks for the reply, I’m going to keep driving and keep checking, I was just wondering if there were any typical leak sources that were not water pump related where the coolant would end up running off the backside of said crossmember and be relatively dry on the front side. I have somewhat eliminated leaks around any of the water pump bolts.

I am concerned that it could be the freeze plug/ plugs. Not that it would be the end of the world but could be outside the scope of my 70 year old body.

my early stable???
 

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my early stable???
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As Ken mentions, ya never hear of freeze plugs letting go on our engines. Numerous leaky WP bolts over the decades though. Of course the v. common leaky weephole when the WP wears out.
 
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Discussion Starter · #6 ·
AFAIK the LT-1engines have brass freeze plugs which are less susceptible to corrosion. Does your car have the optional block heater on the driver side toward the rear of the engine?
No block heater. I guess I hope it’s not the freeze plugs as they look like they would be problematic to replace in car.
 

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Discussion Starter · #7 ·
View attachment 207535

As Ken mentions, ya never hear of freeze plugs letting go on our engines. Numerous leaky WP bolts over the decades though. Of course the v. common leaky weephole when the WP wears out.
I need to update that list! The Mercury and the Barracuda are now in the hands of my wife’s brother. I moved from a 20 acre homestead with a 30x40 garage to a home in the suburbs and only two acres and a homeowners association. Just don’t hav enough space here for everything. Had to sell a fairly low mileage 85 Silverado that was my Dad’s too, such is life. I did add a 99 FRC Corvette some years back .
 

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You could just take bolts out until one leaks and cram a dollop of sealant (?PTFE?) in and run the bolt home = maybe leak magically disappears !
 

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Discussion Starter · #9 ·
You could just take bolts out until one leaks and cram a dollop of sealant (?PTFE?) in and run the bolt home = maybe leak magically disappears !
which bolts are you referring to?
 

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The water pump. You said you just replaced it. My best success with mystery leaks has always been getting the engine perfectly clean and bone dry as I described.

At least one bolt (I recall on the DS) for the WP goes into the coolant and requires thread sealant. .....
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.. Any fluids leaking in the engine bay will find their way aftward from the source just from the airflow.
. .
 
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Discussion Starter · #11 ·
I’m back, I did remove all four water pump bolts, one at a time and put sealer on the threads. Coolant did run out of the lower driver side bolt when I took it out buts not any of the others. I had not noticed any leaks from the lower driver side bolt, but a possible small amount on the ledge of the water pump where the upper passenger side bolt goes in. But in all my inspections I have never found a path where any coolant from the pump was running down to the crossmember.

At any rate after sealing up the pump bolts I drove the car and upon return parked in the garage and gave it an hour or so, jacked the car up and coolant is still dripping off the engine crossmember in the center under the oil pan. I can see coolant on the driver side engine mount, the clamshell portion that faces the block under the 1-3 cylinder spark plugs but I can’t see how or where it’s getting there??????

Any new thoughts?
 

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Discussion Starter · #12 · (Edited)
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These pics show the coolant dripping off the frame cross member and one shot of coolant on the motor mount on the drivers side.
Hood Automotive tire Automotive lighting Automotive design Automotive exterior

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One of the pics is the front side of the motor mount and from all appearances it is completely dry. The only thing I can‘t get a clear view of is the freeze plug that is facing the motor mount. It is the only thing that appears would be possible to get the motor mount wet while everything around and above is dry.
 

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the water pump bolts are 35ft lbs.... #1 torque 15 ft lbs ... then #2 35 ft lbs ..
the INTAKE MANIFOLD the bolts 35ft lbs ... #1 torque 15 ft lbs then #2 torque 35 ft lbs ..
I bought my GM OEM manual nov 1995 ...
I also torqued the engine bolts ....in the GM manual spec/torques ...

the KS sensor under the engine block behind the exhaust manifold ... I did the KS sensors and I used a liquid paste on the threads ....................................iron bock and the different metal KS corrosion

..on top of the engine front and then in the rear engine .. the upper engine assy #210 pipe engine coolant air bleed . some of us did the coolant leaks ..on that pipe engine coolant air bleed ..
 

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I’m back, I did remove all four water pump bolts, one at a time and put sealer on the threads. Coolant did run out of the lower driver side bolt when I took it out buts not any of the others. I had not noticed any leaks from the lower driver side bolt, but a possible small amount on the ledge of the water pump where the upper passenger side bolt goes in. But in all my inspections I have never found a path where any coolant from the pump was running down to the crossmember.

At any rate after sealing up the pump bolts I drove the car and upon return parked in the garage and gave it an hour or so, jacked the car up and coolant is still dripping off the engine crossmember in the center under the oil pan. I can see coolant on the driver side engine mount, the clamshell portion that faces the block under the 1-3 cylinder spark plugs but I can’t see how or where it’s getting there??????

Any new thoughts?
There are six bolts holding the water pump..
 

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Discussion Starter · #16 ·
Thanks, guys I’ll have another look!
 

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Discussion Starter · #17 ·
Took the other two bolts out and applied thread sealant but there was no evidence of previous leaking. But upon inspection I found the upper left bolt had some coolant around the bolt head which didn’t seem possible as I had previously removed and added sealant. I took the intake tube off and may have found the culprit. There was coolant around the bleed bolt on the thermostat housing and when I completely removed it a little coolant ran out and ended up on that bolt. I applied new sealant and reinstalled, we’ll see what happens.
 
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