freeze plug


Old 12-22-04, 09:00 PM
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freeze plug

My 1999 Jeep Cherokee 4.0 litre is leaking from corrosion at the freeze plug (2nd from front of block). Can this be replaced without removal of the intake and exhaust (from underneath)?
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Old 12-23-04, 04:16 AM
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batcat, Yes you can do it from underneath.

BUT first, I just want to Hello to everyone, I'm new to this forum. I was looking for Home remodeling tips, which I know nothing about. however I think I can help with car stuff. Kinda in trade.

Now back to the Freeze Plug. I don't know of that exact location. I'm not there, but if there isn't anything obstructioning access it's farly easy to do. If you can see it and get a hand on it, this is how I would do it in 7 steps:

1) First drain the cooling system (Cold engine).

2) You can jump to step 3 but you'll probably get soaked with antifreeze I do.
I take a long pointy bar and hammer to punch a hole thru the plug at the lowwest point in the bad plug to drain the coolant left in the engine block. (I use a long punch, but a long srewdriver may do or there are special tools you can buy to remove and install the plug, but they do the same thing) Also,You can drain the block by removeing the block drain plug, but I find it more work and they are usually corroded in and not worth the time. Be carefull when punching a hole in it cause coolant will come shooting out That's why I use a long punch, and you will need something to catch it in.

Break time!

3) After it's pretty well drained I take dull/blunt bar (a old srewdriver with the end ground off) and a hammer to punch out the old plug. (Actually, you punch it into the block!) I place my blunt bar near the edge of the plung that looks strongest (less corroded) Please Don't place the bar between the plug and the block, you cound damage the block, place it on the inside edge of the plug, No Problemo! One good whack, maybe two and It'll pop into the block Some more coolant will probably dribble out. The plug will be laying loose inside the hole.

4) I take my finger or a magnet and fish it up into the opening of the hole and take a pair of needle nose ViseGripe's and latch onto the lip of the old plug and pull it sideways out of the block. It usually comes out easily.

5) I take some sand paper and lightly clean the edge of the hole in the block to get any rust off of it.

6) NOW, comes choices. Actually, you need to decide before starting the job or you'll have to make a run to the parts store. You can put in the same OEM (Original Equipment Manufacturer) type which takes some skill and a cup and bar for that size to get in correctly, straight and flush! (the special tool for freeze plugs or I find a bearing race driver works well too.) OR you can use a Aftermarket rubber one that's much easier. There are pros and cons for both types and I'm sure everyone has thier opinion on 'em. But I find they work great and hold up well. So the next step will be to install the rubber plug. By the way, the come in differant sizes, so make sure you get the correct one. (Could be an 1 5/8", 1 1/4" etc) Any parts store should have listings for your vehicle.

7) To install the new rubber plug I take a rag and soak up as much of the coolant left in the hole in the block as I get the coolant left below the opening in the block. I take some brake/parts cleaner on the rag and wipe the rim of the opening to get the residual coolant off off the block and take a new / clean piece of sandpaper and lightly clean it again and repeat with the cleaner on rag (Link free rag of coarse) Then I take the new rubber plug (which is really rubber and metel with a stud and nut on it.)
Insert it in the hole. Don't use any sealer of any kind. You want it as clean and dry as possible on the plug and the block. then you tieghten the nut while holding the plug to keep it from turning with the nut. The Aftermarket ones come with directions on how to tieghten it. Don't over tieghten it, Tieghter is NOT better!!!

That's it!
Of coarse this would be a good time to change any other plugs that look bad, especialy the ones that like to hide behind the starter & motor mounts, the t-stat if it hasn't been done in a few years and any hoses the need changing before you refill the cooling system.
Old 12-23-04, 08:59 AM
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Thanks David

Thanks a bunch David! Your step by step instructions have certainly eased my anxiety. I was particulary glad to find that the rubber plugs work because I don't think I could get anything in there to install the OE type without removal of the intake and exhaust. Thanks again.
Old 12-24-04, 07:08 PM
Join Date: Aug 2003
Posts: 478
For your information. Usually the bottom of the freeze plug will be rusted. This is due to a mud like mixture of rust etc. that builds up at the bottom of the water jacket. I will bet if you stick your finger in the bottom of the opening you will feel it or it may well be built up above the opening where you will see it. This stuff was likely touching the freeze plug and made it rust through.

Depending if the coolant is flowing from front to back or from back to front the next freeze plug in line will usually have a little less mud but it will be rusting out next.

The freeze plugs almost never rust from the outside in. While you have the coolant out take a small tack hammer or anything similar and tap all the freeze plugs you can get to. You may poke a hole in 1 or more. If so it would have rusted out soon so change it now so you don't have to do this all over again soon.

If you plan to keep the car replace any that don't sound solid beacuse they are rusting out too. When done flush the cooling system to get as much crud out as you can and put in a fresh mix of 50% antifreeze & 50% distilled water.
Old 12-24-04, 08:25 PM
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Thanks Car Nut. Now living in Florida, we tend to not check the coolant as we did where there was a threat of freezing. This vehicle was wrecked a couple of years ago and apparently the dealer put water only in the radiator. This has resulted in corrosion problems, including the loss of the water pump impeller blades. We are weighing our options.
Old 12-24-04, 08:53 PM
Join Date: Oct 2004
Location: USA
Posts: 719
I haven't change a freeze plug in a long time.
at that time, I found some all brass freeze plugs that have a brass nut you turn to secure the plug.
you may need to ask around.
They may call them expansion freeze plugs (all brass no rubber).

May need to use a sealer. ask the person at the parts counter.

If the plug is close to the exhaust the rubber plugs may not last.
Old 12-25-04, 10:12 AM
Join Date: Aug 2003
Posts: 478
Originally Posted by batcat
Thanks Car Nut. Now living in Florida, we tend to not check the coolant as we did where there was a threat of freezing. This vehicle was wrecked a couple of years ago and apparently the dealer put water only in the radiator. This has resulted in corrosion problems, including the loss of the water pump impeller blades. We are weighing our options.
Unfortunatly some people do not know that not having a 50-50 mix of antifreeze & water can lead to costly corrosion related problems later as you have found out. I have also seen the all brass or copper expanding freeze plugs. That might be a good choice where you can't get room to drive a regular one straight in. The rubber ones seem to work ok if not over tightened, but if it is close to the exhaust as GWIZ said it may fail. Another problem with the rubber ones is they will deterioriate if you have an oil leak and they get coated with oil.

If you live where it never freezes you can skip the anti freeze if you want. You can use anti-rust and water pump lube instead. Follow the directions for the proper mix, use distilled water to mix and change it regularly just like you would with antifreeze.

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