Frost Plug Hi I have a 1998 tj and I am losing radiator fluid from the frost plug, now my motor has a block heater in it I was wondering when I order a new frost plug if there is two kinds of them or do I order just a frost plug and then put the block heater plug into the new one?

Hi William:
3 possible sources I can throw at you:
1) Broken heater hose (not likely but possible.
2) Bad head gasket - use mirror to try to see source between head and block
3) Bad frost plug - Use mirror to try to see frost plug location at back of block.
Hope it's the heater hose. That's easiest to repair.

the main ones are on the sides of the motor between the cylinders, 2 on each side. they are a little more than 1" in diameter. these are the ones that usually rot and leak. if you have a block heater it replaces a frost plug. follow the wire from the pug to the engine this will show the area the frost plug is in and the normal plug is beside it but between the next cylinder beside it. the same position on the other side of motor but you will not have a block heater on that side.

The frost plugs that block heaters go in are along the sides of the engine block. About midway up from the bottom of block where the oil pan mates to the top block deck. 3 or 4 on each side, 1 to 2 inch diameter round metal plugs just slightly recessed in the block. Look below the exhaust manifold, behind the exhaust pipe on the block. Frost plugs are easy to punch out as long as you can get to them.
Punch in one side, and the other side will start to come out-then grab with pliers or vice grips to remove the plug.

When you buy a block heater for your Tahoe, it will come with an instruction sheet, and a diagram of the preferred or recommended frost plug hole to use the heater in. It will also usually show the positioning of the heater element in the block-how to orient the heater into the opening so the element does not touch the block anywhere, but is placed in so the element is exposed in the water jacket of the engine. That make sense? You do not need a sealer, as the block heater has its own O-ring rubber seal. When inserted and tightened down (small wrench or socket, about 3/8 inch or smaller size, do not over tighten-follow sheet instructions), the o-ring should not leak. Be sure and clean that recess well that frost plug was in- get all the rust and scale off with rags or emery cloth (sandpaper).
Not hard at all to install a block heater once the frost plug is removed. Getting access to the frost plug is the devil to deal with. If you are unsure, have it installed for you.

Hi and welcome to FixYa!

You may have worn out hose which can cause the coolant leak. I strongly suggest that you replace the hose to resolve the issue. The hose is surely secured by clams so you will need pliers to squeeze the **** then move it to let loose.

Hope this helps and thank you for using FixYa! Have a good one!

They can be gotten at any auto parts store.There are 2 types. For one you have to remove a frost plug in the side of your block and it screws in easily. I have seen them in 2 sizes, 500 watt and 1000 watt. Just be sure you don't knock the plug into the engine water jacket. The other type is an in-line heater. It splices into a rad hose. Personally I prefer the in-line but it's a matter of preference and budget. The in-line is generally more expensive. You will need to know the diameter of the frost plug or radiator hose when you go to get one. Hope this helps.

The location of your block heater depends on which motor you have. If you have a 4.7L motor it is on the rear frost plug location on the right side of the engine (passenger side).


If you are installing a new one notice the direction the block heater points when it goes into the block (upwards).

If you have a 3.7L engine it looks like it is on the same side of the engine except that is is in the first frost plug location. Here is a picture of it.



Now if I understood your question wrong and you are just looking for the block hearts cord, open the hood and check inside the engine compartment or look agound your grill and front bumper area.

Good Luck

I had the same problem.The leak was from the block heater.I did not notice any leaks on the ground,but was always low on anti freeze.The block heater came apart on the highway and blew all the fluid out of the car,luckly i shut the car off and had it towed to the shop.They replaced the block heater with a rubber frost plug to get me back on the road.Have your block heater checked,they maybe your problem has well.

you have to drain the antifreeze find a suitable frost plug and knock it out, install block heater"follow instructions" run the plug to the front avoiding the exhaut manifole and any moving parts , or you can get an inline that just splices in the heater hose, good luck

None on the block, other than freeze plugs...
The only drain is on the bottom of the radiator (you knew that)...

I installed a Prestone motor flush kit and it flushes just fine, but does not "empty" the engine cavities. This is better, anyway.

You have to splice a "Tee" fitting into a convenient heater hose (highest one).

Hope this helps..

the block heater goes in the firewall side of the engine. There is what is called a frost plug there (actually there is more then one) locate the one next to the ac compressor that is the plug u must remove to install the block heater ( the frost plug is the second one from the front of the engine)