1992 first gen, bought it last week or so, put about 1000 miles on it, yesterday, coming home from town, sprung a bad leak in the freeze plug at the top middle of the passenger side block. At first thought it a house that passes close to the block there, but no, it's the freeze plug. It's a really big freeze plug, and my parts store had no idea the size. Clearly, 1-5/8 not big enough. You guys know what size this is or a diagram of frreeze plugs with the sizes? I saw on a search everyone says use red loc tite for this? I see a billet freeze plug for sale on the internet, does this happen enough for an aftermarket part to be made? In all my years owning Cummins, I have never had a freeze plug go out. Could this be a sign of something more serious?

 

I have replaced freeze plugs that have rusted bad. Any Cummins dealer should be able to get you one based on the ESN and CPL numbers. I also use Red Loctite to install them.

 

If the truck sat for a long time and has had a lot of corrosion in the cooling system then yes freeze plugs can fail. I'd flush your system once you replace the freeze plug, use distilled water mixed with the concentrate anti-freeze. I've wanted to add a coolant filter for a number of years now but just have not found the time to get it done/

 

Okay- update. I pulled freeze plug- corroded right through- prior owner had run water only for last year and a half- I live in Hawaii- so freezing never an issue. It is a washington state truck- still has the water plug in heater for cold weather LOL- I put that plug in, one at the back same side sprung a leak, It had a hole in it too- clearly rusted through. I replaced it, no problem- now, herein lies the rub. I went to replace the "middle" one- under the turbo pretty much- it slid in too easy- did not need to pound it it- I compared it to the old one, clearly the same size- 2-1/4 inch plugs- clearly fits too loose! I just JB welded in the thing for now, hoping it doesn't leak- I am between a rock and a hard place with using/getting the vehicle where it needs to go.

Anyone have this problem before with the freeze plug not being tight enough? I have never had this happen in 40 plus years of wrenching! I don't know of any freeze plug one mm bigger than the one I have (I think it is listed as 57.15mm for stock)

I have to wait about another hour before I fire it up and see if it leaks.