No coolant circulation

Tiny
ERIC30
  • MEMBER
  • 2008 MAZDA 626
  • 2.5L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 116,000 MILES
Had a leak in the radiator, so took it to a shop. They replaced the radiator, thermostat, hoses, and water pump. Upper hose gets hot, but lower hose stays cold, so I replaced thermostat two more times and radiator again, same problem each time. They did pressure test, no leak down, so head gasket is good, no water in oil either. When running and warm It builds up pressure, but lower hose still cold. I had no problems at all before. I am no mechanic, but sounds like bad thermostat. But can three be bad? Third one was a Mazda thermostat. Also, burped system numerous times. Both the shop and I are stumped. Any ideas?
Tuesday, January 9th, 2018 AT 4:42 PM

7 Replies

Tiny
STEVE W.
  • MECHANIC
  • 14,187 POSTS
Okay, so the only issue prior to the repairs was the leak in the radiator correct? They replaced the water pump, radiator, hoses and thermostat and then you have this issue. You replaced the thermostat and radiator again. I would check the hoses first, it is not unheard of for one of the caps on the new radiator to be left on by accident and block the flow.
Next check the water pump, first be sure the belt is driving it in the correct direction, if it is, remove it and verify that the impeller is also turning and is the correct direction as well. Also, check the impeller to coolant passage for clearance issues. I have seen more than once that a replacement pump had been assembled wrong and the inlet side had excessive clearance. That basically means the pump just pushes the water around inside itself with very little flow through the system.

Also, could you verify the vehicle year/make and engine please?
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Tuesday, January 9th, 2018 AT 8:27 PM
Tiny
ERIC30
  • MEMBER
  • 6 POSTS
After more time at the shop, they determined that the head is cracked, so I dropped the car off at another shop to get another opinion.
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Wednesday, January 10th, 2018 AT 3:44 PM
Tiny
STEVE W.
  • MECHANIC
  • 14,187 POSTS
If it is getting hot real fast and building pressure a bad head is possible. A combustion gas test would show that.
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Wednesday, January 10th, 2018 AT 5:31 PM
Tiny
ERIC30
  • MEMBER
  • 6 POSTS
First estimate was $3500, an looking for another.
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Saturday, January 13th, 2018 AT 2:40 PM
Tiny
STEVE W.
  • MECHANIC
  • 14,187 POSTS
Is that for just head work or replacing the engine?
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Saturday, January 13th, 2018 AT 8:08 PM
Tiny
ERIC30
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  • 6 POSTS
That is for head gasket, machine work on head, plus timing set and labor.
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Saturday, January 13th, 2018 AT 8:14 PM
Tiny
STEVE W.
  • MECHANIC
  • 14,187 POSTS
You might want to see about getting a rebuilt head, could save you money overall.
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Sunday, January 14th, 2018 AT 7:41 AM

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