Vintage Mustang Forums banner

1 - 4 of 4 Posts

·
Registered
Joined
·
73 Posts
Discussion Starter #1
I have turned 200 miles on a newly rebuilt 1971 429 CJ engine and have been taking it easy for the first 500 miles until it is properly broken in. Twice now the temperature has spiked to the far right (pegged the hot side) after 20-30 minutes of driving (25-50 mph). Since I have been driving locally I have garaged it so not to do damage. I thought it was an air bubble in the line but have sinced ruled that out. Water pump et al are new. Generally, it registered slightly above midpoint. Anyone have ideas as to the cause? Thanks.
 

·
Registered
Joined
·
2,392 Posts
Being a fresh rebuild it could be a number of things, all of which would sound pretty simple but anything can easily be overlooked when putting a motor together. Could be timing, could be a gasket partially blocking a water passage, could be scale or mineral build up in the block got dislodged and is clogging the radiator, maybe the carb is lean. This is one of those cases where the K.I.S.S. philosphy usually applies, check all the simple stuff you can think of.
 

·
Registered
Joined
·
9,649 Posts
I would temporarily install an aftermarket mechanical temp gauge to verify that your car is actually getting as hot at the stock gauge indicates. The first thing I would change would be my temp sender and test the thermostat for correct opening temperature.
 
1 - 4 of 4 Posts
Top