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Options for a block heater on 2006 3.3 Sonata?

These two show up as compatible on the companies websites but they have different size threads. Also the Kats shows compatible on one retailer website but not compatible on Amazon. The Zero Start shows compatible on OReillys but not compatible on EBay and Amazon.

Kats 11479 24MM
Zero start 3100113 25MM

I also read the US Sonata engine block has some type of protrusion not allowing a block heater. Is this true?

Both companies shows plug is located center back (towards dash) on engine block. Is this plug only accessed from underneath? Would anything have to be removed to get to it?

May I ask, "Why a block heater?"
Is this for assured starting in very/extreme cold or for quicker heat/defrost in the car’s interior?

I lived and worked for many decades above the 45th parallel and never used heaters, etcetera. Temperatures hit as low as -30F to -40F and we never had problems starting a vehicle. These were all GM vehicles, but most modern vehicles are designed to operate in the cold.

Perhaps your weather is more severe?

I’d definitely recommend full-synthetic motor oil of the specified viscosity for better oil flow at start-up in cold weather.


Instead of driving yourself nuts looking at all the online sites just get the block heater from your local parts store. That way if it does not fit you can return it and possibly get the correct one .
Other that a dealer parts counter the chance of finding someone who actually has put one on a 13 year old Sonata is slim.

Loud screeching engine noise that lasts 2 seconds. Only does it in the teens or lower. Figured a block heater could not hurt, plus will be plugged in at work. Read it could be valve issues or timing tensioner. If it is one of those two is damage still being done when it is warm weather and no noise? Is the cold causing it or exacerbating it?

OReillys has to order one and can take up to 2 weeks. Napa can not even give me a timeframe of when they would get it.

That noise could be caused by a loose or old belt or bad belt tensioner.

I’m not understanding how it could be a valve issue, but agree with @texases, “That noise could be caused by a loose or old belt or bad belt tensioner.”

I can tell you that on my coldest cold starts (probably below -15*F) I had my cars make awful, frightening, loud death knell squealing and screeching noises, and even a dribble or two of coolant from where hose clamps secured lower radiator hoses.

I thought, “Oh, great, what’s wrong with my car? I have to drive to work!” and after this happened many times only in extreme cold soaks, and all symptoms went away after the engine ran a bit, and never resulted in a problem, I quit stressing over it. It goes with living where people should not live in winter.

I’m not saying that you don’t have a problem, like one with a worn pulley or belt, but a block heater may or may not help.

Have you ever replaced any belts and are any adjustable or are they self-tensioning?


If William Carrier had not invented a practical Air Conditioner while working in Buffalo, nobody would be living all year in Florida.

By the way, the belt that is squealing is probably the serpentine belt or tensioner, the timing belt is toothed and if that was squealing, I doubt if your car would be running. A block heater will not likely have much effect on your serpentine belt or tensioner and if you coldest temp is around -15F, you don’t need one. I once bought a car from Canada that was seized by US Customs that was equipped with a block heater but I never used it.

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