A Typical Sequence of Events in Cadillac Northstar Models

  • Often when a Northstar overheats, a mechanic checks the cooling system and finds nothing wrong.
  • With no clear indication as to what’s causing the overheating problem.
  • A mechanic may suggest replacing various cooling system components, like a radiator, water pump, or thermostat.
  • Eventually, coolant starts disappearing again, and the overheating returns.
  • If this sounds familiar, it is time to get a proper diagnosis. An experienced Thermalweld technician can provide the fastest and most cost-effective solution to your problem.
  • Let us help you properly diagnose your Cadillac’s overheating problem and ultimately determine if you have a head gasket problem.
  • To mechanically repair the head bolt problem requires a complete teardown.
  • Drilling out the head bolt threads, installing new sleeves, and replacing the head bolts.
  • Some repair shops refuse to replace a Northstar head gasket.
  • For the ones that will, the starting price is $2,400 up to $4,500.
  • Many suggest “just replace the engine.” Replacing the engine is in the $5,000 to $7,000 range.
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CADILLAC ENGINE HEAD BOLT
CADILLAC ENGINE HEAD BOLT
ALUMINUM FROM THE BLOCK IN THE THREADS
ALUMINUM FROM THE BLOCK IN THE THREADS

The Problem

Here are the facts!

  • Galvanic corrosion damages the head bolt threads on the block. Once the head bolts lose tension, the head gasket allows combustion chamber gases into the cooling system.
  • Combustion gases will form air pockets in the cooling system, causing thermostat malfunction and overheating.
  • The Northstar engine has a constant air purge system to prevent air lock of the thermostat, but this is overwhelmed when the gasket head bolts fail.
  • Under heavy power demands, the head gasket will allow more gases into the cooling system than under light power demands. That is why the engine may be okay while driving on flat streets, but overheats very quickly at freeway speeds or while climbing a steep hill.

The Problem

Here are the facts!

  • Galvanic corrosion damages the head bolt threads on the block. Once the head bolts lose tension, the head gasket allows combustion chamber gases into the cooling system.
  • Combustion gases will form air pockets in the cooling system, causing thermostat malfunction and overheating.
  • The Northstar engine has a constant air purge system to prevent air lock of the thermostat, but this is overwhelmed when the gasket head bolts fail.
  • Under heavy power demands, the head gasket will allow more gases into the cooling system than under light power demands. That is why the engine may be okay while driving on flat streets, but overheats very quickly at freeway speeds or while climbing a steep hill.
CADILLAC ENGINE HEAD BOLT
CADILLAC ENGINE HEAD BOLT
ALUMINUM FROM THE BLOCK IN THE THREADS
ALUMINUM FROM THE BLOCK IN THE THREADS

Easy Repair Instructions

Step #1

Install Thermalweld’s Cooling System Modification Kit
It takes about 15 minutes to install this device in your upper radiator hose. Once installed, it prevents thermostat malfunction and ensures proper coolant flow by minimizing air pocket formation. Follow the easy coolant system flushing instructions.

Step #2

Thermalweld Treatment

  • Shift into 3rd gear, drive 60 mph for 5 miles.

The Chemistry

Reinforced graphite composite

  • Forms a high-strength, flat-surface bond that ensures a tight seal around stretched head bolts
  • New thin-layer deposition technology developed to seal high-volume exhaust leaks
  • Reinforced with aluminum silicate fiber
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Dave’s Cadillac Audio Review

“My car’s been driving like a dream ever since you worked on it.”

Robert’s Cadillac Audio Review

“It worked good. It helped my car run good.”

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Let Thermalweld help you properly diagnose your Cadillac’s overheating problem and ultimately determine if you have a head gasket problem.

Custom Hybrid Formula

Thermalweld has developed a head gasket repair solution for all hybrid engines. The solution has a thinner viscosity for hybrids. Unlike all of the other Thermalweld products, it can be poured directly into the antifreeze. There is no need to go through the flushing process.

A blown head gasket in a Gen. 3 Prius usually is not the result of an overheating problem. The problem comes from what is known as “liner thermal expansion” in layman’s terms the engine is turning on and off multiple times during use. Every time it reaches operating temperature the block and head expand from the heat. Eventually the head gasket gives way due to the multiple thermal cycles.

Gen.3 Prius (2010 to 2015)
Symptoms of a blown head gasket in a Prius 2ZR engine:
Morning engine shakes that eventually clear up after driving a little.
Loss of power.
Loss of coolant.
Check engine light - Code P0301 (misfire)

Other causes of the morning shakes could be fouled spark plugs, dirty injectors, or a carbon clogged EGR valve, BUT if there is coolant loss, it is a blown head gasket.

Continued driving a Prius with a blown head gasket could cause a hydro locked engine, resulting in a bent piston rod.
See the images (below) showing a bent rod, and a rod breaking through the side of the 2ZR engine block.

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To ensure the highest probability of success we include (2) Thermalweld treatments with each order. If you feel the treatment process has failed, contact technical support before using the second treatment. The Hybrid solution comes with the same warranty as all Thermalweld products.