I am working on the 3.1 to 3.4 swap. I haven't pulled my 3.1 yet so just disassembling the 3.4 for a rebuild. There is this strange plug just to the left of the timing chain cover that I don't remember seeing on the 3.1 block the last time I worked on it. It is a rubber plug that is pressed into a hole in the water jacket and is about 1.25 inches in diameter. It has a bolt in the middle to cause the rubber plug to expand and seal from the inside with a large washer on the outside. Pretty cheesy way to seal it. I haven't seen this mentioned in any of the swap threads. Does that hole exist in the 3.1 block and get covered by the timing chain cover of the 3.1 or have a freeze plug in it?

Thanks.....

 

Hi Larry ,

The thing you describe is a replacement freeze plug that someone must have put there in response to a leaking one . As you know , the proper , factory ones are the all metal and pressed in type , and the rubber one with the bolt and washer is a "band aid" type intended to hold the coolant in just long enough to get it to a real shop for a real replacement . Those rubber ones are the freeze plug equivalent of the "donut spare" , just marginally good enough to get the car off of the side of the road but not to be used any kinds of long term (like over a day , at most) .

By all means replace it with a proper one during the work you are doing to it .....

 

yup thats an emergency freeze plug repair plug , install a new freeze plug and throw that thing away.

 

Great, thanks... I couldn't believe it actually came from the factory that way... I had already cut it out cause it looked like it was leaking a bit and I want to hot tank the block as part of the rebuild... Planning on having this engine last a while so trying to do it right all the way through... The car is a rolling restoration right now...