Loud squealing and excessive coolant pressure

Tiny
RLC3ISME
  • MEMBER
  • 2003 MAZDA PROTEGE
  • 80,000 MILES
Starts after much effort, runs rough and at high rpms, then dies. The squealing sound is coming from the throttle body area (not specifically the throttle body). I just replaced the head gasket, head bolts, and all gaskets nessesary when reassembling.

Deck and head surfaces were withing flatness specifications. Timing was reset to factory. Ignition is a little weak but sufficient and fuel delivery is good. This problem completely baffles me and is disappointing with the experience I have and a run performance certification. I know its difficult to diagnosis without seeing the car, but all help is appreciated.
Friday, September 7th, 2012 AT 1:23 AM

9 Replies

Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
First you need to do is to locate the source of the noise. Throttle body can only be air noise which would squeal if an air passage has a leak or there are restrictions to it.

Ensure the cooling system has been bled of air trapped in system and if the high pressure continues, it would mean the head job has a problem somewhere.

If the reason for replacing the head gasket was due to overheating, the head seems to be the one at fault, or at least it is related to it.

Were the valve clearances checked/adjusted?
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Friday, September 7th, 2012 AT 1:32 AM
Tiny
RLC3ISME
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Thank you for the quick response. The original problem was coolant leakage into cylinder but once it warms up it went away. Also cylinder to cylinder leakage. Valve clearances and actuation was fine when the head was off. Definitely did not check for the air in the coolant system, too busy over thinking everything I guess. Now that I think about it the throttle body gasket had slits covering (maybe) vacuum passages.
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Friday, September 7th, 2012 AT 1:55 AM
Tiny
KHLOW2008
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Ok, go through them and see what you come up with.
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Friday, September 7th, 2012 AT 2:03 AM
Tiny
RLC3ISME
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  • 5 POSTS
Coolant reservoir hose is completely clogged.
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Friday, September 7th, 2012 AT 2:05 AM
Tiny
KHLOW2008
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That can cause the high pressure. Excessive air noise can be due to high idling speed due to the IAC opened too much caused by coolant faults.
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Friday, September 7th, 2012 AT 2:24 AM
Tiny
RLC3ISME
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Ok unclogged the reservoir hose. Fixed the problem but need a new radiator cap I had to put it on half way to allow it to flow to reservoir, because it is stuck closed. The car is still dying and throwing a code for the MAF and o2 sensors.
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Friday, September 7th, 2012 AT 2:44 AM
Tiny
KHLOW2008
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Check for vacuum leakages between throttle body and MAF. Seems the squealing noise has something to do with it.
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Friday, September 7th, 2012 AT 2:48 AM
Tiny
RLC3ISME
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Alright. Thank you for all of your help!
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Friday, September 7th, 2012 AT 2:52 AM
Tiny
KHLOW2008
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  • 41,814 POSTS
You're welcome.
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Friday, September 7th, 2012 AT 3:00 AM

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