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1991 Cadillac Deville where is plug located near water pump?


Its been years since I have looked in the area of freeze plugs in the 4.1 4.5 and 4.9, so for me to give you the exact location, I cannot do that, however so you do know what you are looking at, I can describe for you.
My question would be; why are you asking about a freeze plug? They rarely leak and if they blow out like from situations of not having enough anti freeze in the winter, the anti freeze/water will empty the engine in less than a minute.

There are numerous freeze plugs in the engine block and heads. They ill stand out because they appear to be off colored discs located in the block. They should be visible behind the bracketry and are not located behind the water pump. In a general answer, you should see one on each side of the water pump in the front of the engine where the water pump is located. There will be 3 or 4 on each side of the engine block and there will be 2 more in the rear of the engine where the transmission is connected.

The purpose of a freeze plug is to prevent expansion of the fluid inside the engine block which would cause it to crack.

If a freeze plug blows out, you would not be able to drive the vehicle because freeze plugs are about 2" across and fluid would just pour out of the block.

The aluminum engines can be destroyed very quickly from over heating because they actually  melt under heat. If driven at temps over 225 degrees with a 50/50 mix of coolant/anti freeze or the hot light is on, if the engine is not shut down right there, right now, the head gaskets ($1,500.00-$2,000.00 repair) blow and will leak numerous ways. Blown head gaskets are not the cause of over heating, but the result of over heating.

Unless the freeze plug is leaking from rust (rare on vehicles made past 1980 because galvanized plugs are used), one might see seeping, but no leakage.

So, I guess my question is why do you think you need a freeze plug changed?

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Rob Painter


Alarm system questions cannot be answered on this forum. These systems are not what I can answer. Without being physically at the vehicle and not knowing what kind of electrical service has been done on the vehicle, there is no possible way to give an accurate answer over the internet. My expertise is in Ignition/key based anti-theft systems. These issues include GM VATS (resistor chip in key blade) PASSLOCK (MRD)-ignition lock rotation based, no special ignition key and the PKIII Transponder (computer chip in key) systems. These systems are not alarm based and are integral with the starting of the engine. This is why I cannot diagnose alarm problems without physically looking at the vehicle: Alarm systems are a completely different annimal than ignition key/lock based anti-theft system. Many alarm questions come from vehicles 10 years old, and since older, many hands that had been involved over the years.I am an expert in all GM factory (ignition/key based)systems. Alarm system questions pose to many situations beyond my knowledge as to what has been done to the vehicle over the years. Some guy may have actually wired the stereo into the alarm system. Who knows? Over my past 30 years in vehicle wiring repair, I have seen unbelievable wiring disaters done by guys that consider themselves "mechanics." I have seen stereos and alarms intalled using surgical tape. I have seen modules burn up, un-fused circuits, wiring jambed between the doors and even lamp cord used for a starter kill. To answer alarm questions over the internet without examining the vehicle is like asking; What does it take to remove a dent?


Education/Credentials-ASE certified. 11 years with a GM dealer and 17 years with a repair facility dealing with only the repair of theft recovered vehicles.

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