Miss Diag.

[not2old]

Though I found the answer to my minor overheating problem. Top of radiator was hot to touch and bottom was cool. Found and bought new radiator thinking after sitting for 7yrs was blocked. Well new radiator does same, so believe it must be water pump. temp gauge never so above 200 and radiator temp also rear same, but after shutting down hear thumping at timing cover area for about 2-3 minutes. Anyone confirm/ agree?

Alan L

 

[Nance]

My also has a thumping sound after I shut it down.It has always done it.My temp stays at 190.

 

[72fastback]

Is 190 a good temperature for the 351. When I told that to a chevy guy who races his camaro he thought it was a little high. But with my rough idle cam it seems to idle perfectly at 190 below that I have to double pedal it hahaha.

Guess our cars are hotter than chevy's even the temperature gauge thinks so.lollerz

 

[not2old]

Can someone confirm my findings? Its not running hot But if the waterpump feeds into the bottom of the radiator, which stays cool to touch, and After the T-sat opens, it would send hot coolant to the top of the radiator which does get hot, does this mean the waterpump is defective? It also means that I now have a new all aluminum radiator and the original all copper one is also OK.

Alan L

 

[PAPPY HAROLD]

I MAY BE FULL OF IT, BUT I THINK IF YOU LOOK CLOSER YOU'LL SEE THAT IT CIRCULATES THE OTHER WAY. T STAT HOLDS IT IN THE ENGINE AND THEN RELEASES TO THE RADIATOR. I THINK THE TOP SHOULD BE HOTTER.

 

[OLE PONY]

I agree, the top should be hotter and the hot water flows down through the cooling fins to the bottom.

 

[don29163]

Have you tested the radiator cap? I'm thinking that thumping noise is steam. I also think that your cap should hold 14-16 PSI. I'm going on memory, but doesn't water under pressure have a higher boiling point?

Also, when the engine is not running the pump is not pumping, So, i think you could rule out the pump as the culprit.

 

[OLE PONY]

Have you tested the radiator cap? I'm thinking that thumping noise is steam. I also think that your cap should hold 14-16 PSI. I'm going on memory, but doesn't water under pressure have a higher boiling point?

Also, when the engine is not running the pump is not pumping, So, i think you could rule out the pump as the culprit.

I just bought a Motorcraft reproduction cap for my 73 and it is rated at 13 PSI.

 

[72HCODE]

190 is the normal for these engines. the T-stat would be a 192 degree, sometimes the southern cars got the 180-182 version.

are you getting any water out the overflow hose?

i believe everyone is correct the top of the rad would be hot when the T-stat opens and allows coolant into the radiator, it then flows down and the rad and get picked up by the bottom hose to go back into the water pump.

on your lower radiator hose, make sure the hose isn't collapsing when you rev the engine. there is a Anti collapse spring that should be installed inside the hose, when you drive at highway speeds the lower hose can start to pinch off from the vacuum produced by the coolant getting sucked into the water pump, that can choke off cooling.

if you have a temp gauge, it usually reads halfway for normal.

when you shut the engine down hot the engine will heat soak for like 15 minutes where it will get very hot since the cooling system and fan is not working.

it wouldn't hurt to have a look at the water pump if you suspect it, the impellers could be rusted away and the pumping reduced.

you could reverse flush the cooling system and see how much junk falls out.

you could also go down a heat level in your spark plugs to reduce the engine heat.

change out the fan for a 5 blade flex or just make sure you have the correct fan installed.

just some ideas.

 

[don29163]

Have you tested the radiator cap? I'm thinking that thumping noise is steam. I also think that your cap should hold 14-16 PSI. I'm going on memory, but doesn't water under pressure have a higher boiling point?

Also, when the engine is not running the pump is not pumping, So, i think you could rule out the pump as the culprit.

I just bought a Motorcraft reproduction cap for my 73 and it is rated at 13 PSI.

That is great, I would still get it tested and see what pressure it is holding. I promise you the thumping noise is not normal.