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Engine Coolant Leak - JB WaterWeld

Coolant leak from the rear of an aluminium head on a V6 engine in a very awkward to get at spot.


First I had to locate the leak using LED torch and an inspection mirror, turned out it was from a core plug that had started to rust through.

I had 2 options, 1) have the engine removed and get a plate made to bolt in place to seal the leak or 2)find another way to repair it

I settled for Water Weld as had used before when working for a maintenance company. The tricky bit was doing all the cleaning and filling one handed in the space between the rear of engine and the bulkhead.

First I drained the coolant into some spare containers. Next I cleaned off the crystallised coolant from the surrounding area with a stanley blade scraper then used P80 grit to roughen the area and also remove loose rust from the core plug finally cleaned the area with a cloth soaked in meths, it has a lovely aroma. Emoji Next cut off a portion of the putty and kneaded it to a uniform colour, took approx 5 mins, then pushed it into the recess of the core plug and spread the rest out to over lap onto the flat area of the head. It states that it is cured in 1 hour however I left it over night before refilling with coolant and starting the engine. I used the torch and mirror to check if the repair was holding.

It has been 1 week in which I have covered approx 150 miles and there has been no coolant loss. Saved approx 1 day of a mechanics labour and the inconvenience of having no car!

Peter Rowlands.

Water Weld putty.jpg
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