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Hardblok Filler Crumbling Apart in Block

4K views 19 replies 14 participants last post by  octanehuffer 
#1 ·
The guys at Kammer and kammer's machine shop filled my block with Hardblok Filler 2 years ago but earlier this summer i noticed my car was not staying as cool as it should. So i popped the radiator cap and saw "gravel" looking chunks in my radiator...i pulled the rad out, flushed it, and put it back in and thought not much more of it. Then the next week out, same cooling issues after 2 runs....i got home and popped the cap again and sure enough, more chunks. Come to find out, the hardblok was crumbling. I now have the motor apart and my water jackets look like a rock quarry. What is going on and how do i stop it? I CANT, CANT afford to just chuck the block. Any help would be greatly appreciated!

Thanks
BP
 
#11 ·
No issues with Hardblok, it goes in every GM block we do. Prep is the key and mixing. I have 6 tall fill units in the shop. Never had an issue and there are gains with it!
 
#10 ·
I would clean it out before doing anything.

I did a short fill on my block with Embecco 885. Supposed to be somewhat superior to hard block...No issues yet after one season.

I have heard that you can get block fill out of the water jackets using muriatic acid (which is the same stuff I used to thoroughly clean my water jackets before pouring the stuff).

I would be a bit leary though of pouring more fill on top of an already crumbling foundation in there, even if you cleaned all the flaked stuff out...What says the other stuff isn't going to come apart anytime soon?
 
#19 ·
Muratic acid may help clean out much of the old loose stuff to give you a good solid base to seal in. Stuff stinks. I think you need to try to get out as much of the loose stuff as possible then clean it with muratic acid, let it dry good and put more hardblock or something on top to seal it in.
 
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