cooling issues

[johnboy]

So, I finally had some time to get back out and do some work on the car. I installed my rebuild (gaugemarks) gauge cluster and new temp sending unit and was hoping that my cooling nightmares were a bad gauge, but it seems this is not the case. Even with the new gauge, my temp readings are still jumping up to 250. I installed a new radiator cap with a temp gauge built in, and it is not reading anywhere near what the gauge in the dash is reading. A couple things that I have noticed: The upper radiator hose gets hard as a rock once the engine warms up (not hot, just hard like it is full of air), the cap gauge only reads about 80 degrees when the temp gauge says 210. When I try to fill the system with the radiator cap off, it just overflows, it doesn't burb and flow. I have considered flushing the whole system and starting over, but I do not have a heater or a/c, so I have no where to t into for the flush kit. One of my other problems is that I have no choke, so it takes forever just to get it to idle from a cold start. I am at wits end with this thing. The motor only has about 30 miles on it since the build and I know it will run hot until broken in, but at this point, I don't even know if it is running hot or just bad readings. The hoses do not feel hot enough for it to be 250 IMO, but i don't know for sure. I am going to try to drain it as much as I can, drill holes in my t-stat (yes it works, I tested it), fill the block up to housing, and get a thermal temp gun and check the heads. If you guys have any other recommendations or tricks that I can try, please feel free to shoot. I have never had this problem with any other SBC I have build, they are usually pretty good at purging themselves of air, so I am almost at the point of scrapping this motor and starting over. The build is as follows: Gen I 4 bolt main 350 .30 over, TRW flat tops, balanced crank, stock rods, ARP bolts throughout, 230/230 @ 50 112 LSA hydraulic cam, 64cc Brodix IK200 w/ 550 springs, Fel-Pro .039 head gaskets, Edelbrock RPM intake, Holley 650 DP, Summit hi-output HEI, 1 7/8 ceramic coated long tube headers, new water pump, 180 t-stat, MKvii fan. As far as running is concerned, it runs great, she is a fun little street screamer, but the damn cooling issues are driving me nuts. Sorry to rant on, but I am just looking for advice. Also, if any one knows how to flush this thing without a heater hose, please let me know. Thanks guys.

 

[High Country Z]

Sounds like you're getting pressure build up in the cooling system. Maybe a leaking head gasket or a cracked cylinder head. I would suggest testing the cooling system with a pressure tester to see if it can hold pressure.

 

[johnboy]

Sounds like you're getting pressure build up in the cooling system. Maybe a leaking head gasket or a cracked cylinder head. I would suggest testing the cooling system with a pressure tester to see if it can hold pressure.

Thanks, I will pick up a pressure tester today and give that a shot. I have noticed occasionally I will get a small amount of coolant pooling up at the right front of the motor where the intake meets the head (the first intake bolt area on the drivers side), I assumed it was coming from the water neck (aluminum swivel head; pain to keep tight) running down, but now i dont know. I really hope it is not the head, they are brand new

 

[COPO]

A new block wouldn't need a flush. You didn't tell us how old the rad is? If old, is it caked with white calcium on the inside cores and are the outside fins brittle?

Got one of these to test the water when you drain a bit?

 

[johnboy]

A new block wouldn't need a flush. You didn't tell us how old the rad is? If old, is it caked with white calcium on the inside cores and are the outside fins brittle?

Got one of these to test the water when you drain a bit?

COPO, they radiator is brand new as well. It is an aluminum two row from advance.

 

[COPO]

You didn't install a high flow water pump by chance, did you?

 

[johnboy]

You didn't install a high flow water pump by chance, did you?

Yes, I did. Its a Weiand I believe.

 

[COPO]

Swap it with an OEM and I bet your over heating issues will be gone. Hopefully you have the correct rotation too on the pump.
The high volume pump is moving the water too fast to be able to cool the system.

 

[Fbird]

ding ding ding....i think we have a winner!

double...no...make that triple check the ROTATION of the pump impeller.
You Chevy guys have pumps going both ways (all PONCHO here).
Second really big advice is to calibrate your SENDING unit:

This is by far the simplest method to determine what YOUR temp is on YOUR gauge in YOUR car.

tools:
1 pot (2qt)
2 pieces of wire 6' each (any gauge)

Process:
remove sending unit from car. With 6' wire extend sending unit's connection. Use other 6' wire to connect to a ground ON THE CAR. Now connect the sending unit ( be sure to completely cover the gauge wire's connection) per the gauge wire and the GROUND wire.
Fill pot with water. Go boil the water. WITH the car's IGNITION ON.........place sending unit in pot of water. Watch gauge should read 212 F but we'll settle for 210. lol

Now regardless of what gauges, wires, location, motor, any of the above....you now know what YOUR gauge reads with that sending unit @ 212 F

good luck

 

[johnboy]

Just got done doing the pressure check. Took the tester up to 10 lbs and inspected everything for leaks, left connected for about 10 mins and pressure held dead on at 10lbs, no letdown. Next, I am going to go try and find the reciept for the water pump, so i can see what it is. I will let you know what I find out. i hope it is as easy as the water pump, cause this is getting old.