Overheating

Tiny
GSFELTNER
  • MEMBER
  • 2000 CADILLAC DEVILLE
V8 two wheel drive automatic 75,000 miles.

Able to make short trips, ten miles, okay. On longer trips if temperature moves above normal engine overheating message shows on the dash. By then coolant is boiling out the overflow.
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Monday, October 25th, 2010 AT 9:07 AM

7 Replies

Tiny
KHLOW2008
  • EXPERT
Hi gsfeltner,

Thank you for the donation.

If the cooling fans are working correctly, then the most probable cause would be a stuck thermostat.

Start engine and run for five minutes. Feel the upper and lower radiator hoses. If the upper hose is very hot whereas the lower hose is cool to the touch, then the thermostat is most likely stuck.
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Monday, October 25th, 2010 AT 9:20 AM
Tiny
GSFELTNER
  • MEMBER
I have replaced the thermostat, radiator has been rodded out, the cooling fans are working on both high and low speed, the expansion tank vent is open, the radiator cap is new, and used dex-cool coolant and sealant tabs.
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Monday, October 25th, 2010 AT 9:37 AM
Tiny
KHLOW2008
  • EXPERT
New thermostats are known to fail as well. You should check it again.

You have gone through everything so the last thing to check would be the water pump. If the pump is bad, it would not be pushing the collant through the system.
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Monday, October 25th, 2010 AT 10:56 AM
Tiny
GSFELTNER
  • MEMBER
Exposed the water pump and it seems to be in working order. Belt is in good condition. What is the next procedure I should take?
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Wednesday, October 27th, 2010 AT 2:52 PM
Tiny
KHLOW2008
  • EXPERT
Remove the thermostat and run vehicle without it to test if it is the cause of the problem.
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Thursday, October 28th, 2010 AT 9:06 AM
Tiny
FACTORYJACK
  • EXPERT
I am going to add some information, as I have been following the post. Before I would invest anymore time or money, I would have your cooling system checked for the presence of combustion gases. By and large, most Northstar cooling system problems are the result of internal leak, especially if there are no external leaks/low coolant. Often times the higher the load, the more super-heated combustion gases are introduced into the cooling system. What happens is the result of poor design. Through the extreme torque placed on the head bolts, and expansion and contraction of metals, the threads (aluminum) in the block end up failing. The repair involves engine disassembly, and steel thread inserts installed to replace the original aluminum ones. In twelve years, I have yet to see a repeat failure after the repair has been done, and done properly. Hope this helps.
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Thursday, October 28th, 2010 AT 9:51 PM
Tiny
JERRY BARTHALAMEW TATUM
  • MEMBER
My suggestion would be not to take to a mechanic. You can do it yourself and the engine does not have to be removed. It is a little harder without removing the engine but it will save you thousands of dollars. There are lots of videos and tutorials on how to do this. You can buy inserts online on eBay and sites like that for no more than $100.00. You can also buy gaskets sets for $60.00 to $80.00. But trust and believe that it is the gaskets. Challenging, cheap fix.
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Monday, October 17th, 2016 AT 2:15 PM

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