Holes?

[Jokester]

When I bought this car (33 Chev sedan 327) the previous owner had drilled and tapped holes in the intake manifold that open into the water jacket at the rear of the heads.  He had 3/8" hose plumbed forward and hooked into the upper radiator hose.  He said he had done it because "all those small blocks run hot".  I took all that junk off and plugged the holes and have been running it for 3 years without overheating.  On the highway it just touches the red, but I never lose any water or boil over.  I can idle around the fairgrounds at a 180.

Recently I have noticed that the gauge goes to the hot peg after about a 2 mile drive.  By the time I find a place to pull off the road and check things out, the car is back to 180 degrees.  Then it runs correctly the rest of the day.  It just pegs the gauge on the initial warmup.   I've changed the sender and the thermostat with no change.  I'm assuming the gauge is bad.

This weekend at a car show, I saw an original 50s rod that was right out of the barn.  It had a small block with a blower on it.  It had holes drilled and tapped at the same location as mine, and there were petcocks installed there.  Has anyone ever run into this before?  Are the petcocks to let air out when filling the radiator or what?

Any ideas?

thx,

bjb

[wayne petty]

ok cooling systems//

the thermostat keeps the water circulating inside the block until it reaches operating temp...it circulates through the bypass hose on ford small blocks.. on chevys there is a small hole on the mounting  face of the waterpump.   this circulates a little water from the right side of the motor only....the bypass on chevys is run though the heater core. out the heater hose on intake manifold and back into the water pump side.  without this circulation the engine may overheat as the thermostat does not get the flow of heated water past it...until it gets hot enough to open the stat and allow the cool water in the radiator to get swapped into the motor. this also allows the water in the radiator to cool off .    it will never cool off  if the water does not stop or almost stop. which is why when you take out the stat the cars overheat during long hills... this also puts too much pressure in the top tank.   most pumps can putout many more gallons a minutes than the radiator to flow so it builds up in the top tank and blows the seams out. this effects cars with large top tanks do to the increased tank internal area.

some cars also need to run 192/195F stats to not over heat...205F stats are also available... a 160 stat may open too early and get the water circulating though the rad too fast too early.. big 70's cads had this problem...
ie. big engine, small radiator.


fwd mopars and other cars had overheating problems when the heater cores would clog up and limit the bypass flow through them.. this killed a lot of 2.2/2.5 mopar motors..

[paul5456]

If this just started I would replace (or check out) the thermostat.  It sounds like the engine is heating up because the thermostat is closed and then the stat opens, letting the engine go back to normal operating temperature.  It may be a little slow in opening up.

When I bought this car (33 Chev sedan 327) the previous owner had drilled and tapped holes in the intake manifold that open into the water jacket at the rear of the heads.  He had 3/8" hose plumbed forward and hooked into the upper radiator hose.  He said he had done it because "all those small blocks run hot".  I took all that junk off and plugged the holes and have been running it for 3 years without overheating.  On the highway it just touches the red, but I never lose any water or boil over.  I can idle around the fairgrounds at a 180.

Recently I have noticed that the gauge goes to the hot peg after about a 2 mile drive.  By the time I find a place to pull off the road and check things out, the car is back to 180 degrees.  Then it runs correctly the rest of the day.  It just pegs the gauge on the initial warmup.   I've changed the sender and the thermostat with no change.  I'm assuming the gauge is bad.

This weekend at a car show, I saw an original 50s rod that was right out of the barn.  It had a small block with a blower on it.  It had holes drilled and tapped at the same location as mine, and there were petcocks installed there.  Has anyone ever run into this before?  Are the petcocks to let air out when filling the radiator or what?

Any ideas?

thx,

bjb

[wayne petty]

i was so deep in explaining the cooing system i missed the point...

the question now is do you have a bypass system installed

the coolant flow in most motors goes from the water pump into the block, flowing around the cylinders,  up through the back of the block and forward though the cylinder head, up into the coolant crossover in the intake...the water circulates over the stat. through the bypass and back into the block again...

without any bypass the stat blocks the heat in the blocks and heads...the coolant does not circulate until the stat opens. by the time the heat migrages up to the stat the engine is almost at the point of overheating.. your temp sender is probably in a head. which is a good spot.. it gives the true temp of the engine... on the intake it gives the temp of the circulating coolant... no coolant .. false readings...    many newer cars even use a small bleeder hose to the remote coolant tank. this keeps the smallist amount of coolant flowing past teh stat and removes and trapped air.    air and steam do transfer enough heat to the wax filled bulb that is the temp control in the stat..

the brass bulb at the bottom of the stat has a glob of wax in it...with an oring sealed piston above ... when the coolant comes up to temp the wax expands forcing the piston and rod out. this forces the stat open agenst the return spring..

if the motor overheats the stat may go all the way open and build up enough pressure in the wax to force past the orings and seal and out into the cooling system, (not enough material to notice)  the next time the system comes up to temp there wont be enough wax to force the piston open agenst the spring...


do you have an infrared temp gun...  check the head and the intake whiile its warming up... they should all stay the close to the same temp if the coolant is properly bypassing until it reaches the operating temp tehn the upper hose should get hot as the first hot coolant passes though.. infrared tamp guns are $40 to $50 at harbor freight.. pepboys had a limited range one that fits in a pocket for $20  its range is -5F to 270F so it should work for most cooling systems...i got one from harbor that has the sensor head on a wand  that tops out at 1100F...$39  but i think it was discontinued. i have trouble with it... the box and pouch keep getting under something and it turns it on... so it has dead batterys when ever i need it... krazy glue and a few thick o rings will cure that problem...just not accomplished yet


also some stats can be had with a little ball check valve in them. this lets out any trapped air/steam

if you want you can drill a 1/8 hole somewere in the stat to let a small amount of water circulate.  

this will eliminate the need for a bypass system.. and prevent  most overheating problems..

a drilled hole does not work well with computer controled fans.. or electric fans... but it does work

you can also check for clogged radiators by scanning the fins with the infrared temp gun...

cold spots indicate cloggages..