273 coolant leak

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GJSZ51

GJSZ51

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...understatement...

As some here know, I am nearing the completion of my 65 barracuda. Essentially stock build on a 273 with a factory 4 speed. Had to move out of my shop last October, then got sick (understatement). Anyway, brought her home and fired her up for the first time before illness struck. Ran great, smooth as silk through break in, had an exhaust leak at # 7. Gasket slipped on install, missed the rear bolt hole. No biggie.

Long story short, picked up a new gasket set. Removed rear bolt at # 7 and coolant poured out. Not a leak... shot a stream out as big as your finger until radiator level dropped sufficiently. Is there a water passage behind these bolts that requires sealant or have I a cracked head? No coolant present in the crankcase. I have not pulled plug # 7 to see if it is coolant fouled. I used no sealant on the bolts when installing the manifolds.

Though I would ask here before I started removing the head.

Thanks in advance

GJS

cuda motor.jpg
 

The front and rear bolt holes go into the cooling passage of the heads. Factory stock has studs in these locations. Put bolts or studs back in with some thread sealant and you'll be good to go.
 
Now you know there's water there. You might not have known all 4 corner exhaust mount holes are wet holes back when engine was assembled. Those 4 should have gotten sealant on stud threads.
No time like the present to correct that. Save on coolant cost :)
 
GJSZ51 said:
...understatement...

As some here know, I am nearing the completion of my 65 barracuda. Essentially stock build on a 273 with a factory 4 speed. Had to move out of my shop last October, then got sick (understatement). Anyway, brought her home and fired her up for the first time before illness struck. Ran great, smooth as silk through break in, had an exhaust leak at # 7. Gasket slipped on install, missed the rear bolt hole. No biggie.

Long story short, picked up a new gasket set. Removed rear bolt at # 7 and coolant poured out. Not a leak... shot a stream out as big as your finger until radiator level dropped sufficiently. Is there a water passage behind these bolts that requires sealant or have I a cracked head? No coolant present in the crankcase. I have not pulled plug # 7 to see if it is coolant fouled. I used no sealant on the bolts when installing the manifolds.

Though I would ask here before I started removing the head.

Thanks in advance

GJS

View attachment 1714936248
Click to expand...
Very nice 273. I am partial but I think the HP 273 is one of the coolest looking engines Mopar ever produced.
 
Thank you, everyone. It is a very sweet little motor! Glad to know of the coolant passages. I'll know to drain the radiator if manifolds need to be removed. Thanks Redfish

I must admit, I was near panic mode!

Thank you Rocky_JS and Grimreaper. Time for a test drive...
 
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