53 cadillac fresh rebuild overheating on break in.......help!

[mooman929]

Hi I finally started my 53 Cadillac and was breaking it in amd within minutes the car started boiling! Bubbling out the radiator.  This was just at a little more than idle.  I got the radiator checked, water pump rebuilt, tested the thermostat.  The radiator seems hot on the top hose and the bottom pan of the radiator seems cold.  What I doubt its a blown head gasket since the car only ran 10 minutes on a complete rebuild any suggestions.  I'm basically sick over this after all the time and money.....

[dplotkin]

If the top hose is hot and the bottom one not than the radiator is plugged. Did this happen within minutes of a cold start?

Dan

[mooman929]

Yes.  Not even 10 minutes running.  It kinda makes me mad cuz I just paid 150 bucks to have my radiator sent out and tested and pressure checked

[walt chomosh #23510]

radiator shops simply run water thru the radiator to check for flow. You can do this yourself. Did you set the timing so the motor is happy?(did it start right up?) A retarded spark will cause a lot of heat.(spark advance OK?)...how did it run while doing your cam/lifter break in?(smooth/rough?) (timing chain indexed properly?)Air pockets when filling the cooling system? Blockage in the exhaust system?(mouse nest?) I've been there more times then I care to remember!....good luck!...walt...tulsa,ok

[Frank Solano]

The first thing that comes to mind is that you coolant is not flowing properly for some reason. I am having similar issues and i think it all comes downt to water flow. My 56 is still an issue in this area and I am making progress throuh this forum. Is there any good water movement from the water pump thru the top rad hose. If not there is a blockage or the waterpump is not working. In have experienced the impeller on the pump being installed backwards. How did the car run before you rebuilt the motor. If the pump is working then i think the head gaskets intalled upside down could be a factor. When the rad rad was tested , what was the flow rate. I think we are having similar issues and i hope a solution for both of us is close
Frank Solano

[mooman929]

I dk how it ran.  This car has been in my apps shed since 1964.  He gave it to me to restore.  I had a professional rebuild the water pump.  Which doesn't mean that it could be installed wrong.  It only runs a few minutes and shoots out like a geyser when I shut it off

[D.Yaros]

The radiator seems hot on the top hose and the bottom pan of the radiator seems cold.

For reasons that need to be determined, the water is not circulating in the cooling system.  That is why the top hose is hot and the bottom one cold.

[signart]

Test thermostat or remove it for a run test.

[mooman929]

My temp gauge seems to be reading fine but the car just get boiling hot.  The impeller is working and the belt is tight.  I bled the air out of the radiator.  My heater is leaking.  Is there a way to bypass the heater and just circulate the water back thru the block?  Should I just hook the small hose from the water pump to the fitting on the head
  Will that work?

[Jon S]

If you have an infrared temperature gauge get readings of radiator from top to bottom. You have a downflow radiator and bottom should be cooler than top but need readings to better see whats going on.

[Glen]

Moonman are you filling the radiator to the top?  If so this maybe normal, as the engine warms up the water will expand and flow out the overflow. 

Normal operation for these cars is to not fill it the top but leave some space at the top of the radiator for expansion.  Or you can fill it to the top and let it overflow, but do not refill it.  The coolant will find its own level. 

[mooman929]

I don't think that is the reason.  That shouldnt make it that hot.   Does anyone know if I can bypass the heater?  Hooking the small hose on the pump to the head fitting?

[Smedly]

Yes that will work to bypass the heater.
Sheldon hay

[Richardonly]

Heater bypass should have nothing to do with your problem.  Try it if you like, though.

Everything others have said is dead on. 

1st, remove thermostate, try running.

2nd, check water flow after removal to verify pump is doing its job.

3rd, get readings of temp with laser gun  and post.

REMEMBER, a rebuilt engine WILL run hotter until it is broken in .

Best of luck, Richard

[mooman929]

Well I have a leak in the heater somewhere and don't want bother with it right now that's why I wanna bypass it.  By I took the thermostat out and let it run a few minutes and it seems to be a little cooler.  Plus my top hose is Hal pinchedboff now I noticed.  Its such a hard bend it pinched it off. 

[Richardonly]

Sounds like you found your problem.   A bent hose will not let water flow, as you know and thus NOT cool the engine.

Good luck, once again.

[Jon S]

Well I have a leak in the heater somewhere and don't want bother with it right now that's why I wanna bypass it.  By I took the thermostat out and let it run a few minutes and it seems to be a little cooler.  Plus my top hose is Hal pinchedboff now I noticed.  Its such a hard bend it pinched it off.

Either you have the wrong hose (flexible) and need a pre-formed hose.  If you have a pre-formed hose, is there a spring inside it to keep it from collapsing?  If not, see if you can add one.

[txturbo]

You shouldn't be letting a new motor run just above idle the first time you start it. It should be run at about 2k rpms for about 20 minutes to break-in the cam...otherwise you will end up with a flat cam. Have that radiator rodded out, replace with a new one or hook up a known good radiator temporarily for the cam break-in.

[mooman929]

Ok guys.  Still overheating.  I took the thermostat out, washed out the radiator which was completely brown with like a muddy scum in it.  Could this be my overheating issue?  The block was tanked and thought I had most of the rust out of it but apparently not.  Should I just keep flushing it?  I bypassed the heater hoses too because I'm thinking I sucked and bunch of old crud through the cooling system from the car sitting for 50 years.  The fan is on the right direction and the water pump is rebuilt.   Within 5 mins of idling the gauge climbs all the way to hot.  I just replaced the temp sensor as well....

[Dan LeBlanc]

Did you break in the cam yet as everyone else has indicated?  Idling on a fresh rebuild with a new cam will only hurt things.