I was on my way to a car show last weekend with my 1952 XK120 OTS when I suddenly was engulfed in smoke. I shut down the car and called AAA. Once the car was trailered home I found that the core plug at the back of the block had fallen out. I am running Evans waterless coolant, and when this dumped on the hot exhaust pipes it created the smoke.
There is not enough room between the rear of the block and the firewall to replace the core plug so I just got done pulling the engine. I found the missing core plug sitting on top of the transmission. This core plug has been in place for over 20 years. I do NOT want to go through this again. What is the best way to make sure this core plug never comes out again? Do I use a particular type of sealant to help lock the plug in place? Inspecting the old core plug it looks like RTV type silicone was used. Someone suggested I use JB Weld when I install the new plug. Is this a reasonable approach?
SNG has a strap kit C 315FK but it seems a bit pricey at $159 for a complete kit of 7 plugs and straps and small bolts.
You could make up something similar, but you have to drill and tap into the block and make a small strap, probably out of stainles.
Sad to hear, esp after 20 yrs.
Was the original idea behind the core plugs to save the block from cracking in the event of the coolant freezing in cold clinates, or have I got it wrong?
If yes, why cant we weld them, or the plugs, as we dont let this happen with modern coolant and non freezing environment in general?
That’s wrong: they were for getting the sand cores and wires out, after the casting process.
They do bupkis to protect against freezing.
Later on, in older engines, to be able to remove the plugs facilitates being able to get out rust sludge: to weld them on would make that process immeasurably more difficult.
I’ve been trying to figure out why The core plug in the rear of the block on my XK engine fell out. The core plug that fell out was not corroded and was hammered so it was basically flat. I was considering replacing this core plug with a Dorman copper expanding core plug with the acorn nut to expand it. When I went to order a 1 3/4” plug it said the max expansion is 1.780”. This caused me to check the diameter of the counterbore in the rear of the block. It measured 1.804”. The diameter of the plug that fell out was 1.815. I checked the counterbores on the side of the block just outside the installed core plugs. These holes measured 1.750”. I have no idea why the counterbore at the rear of the block is larger.
Given this situation what would be the best approach to fix this problem so it doesn’t fail again?
Paul - do a search for Dsnaduo B06P192S19 - 1-7/8" to 2" plug - may work for you if no clearance problem with tightening nut space - just a suggestion - Tex.