ABAC compressor still playing up!

[lotus_esprit_s1]

Tried to use my Abac compressor today after replacing the head gasket last week and the pressure relief valve in the pipe from the low pressure side to the high pressure side is still constantly cracking off. I presumed this was due to head gasket failure / loose head bolts but it now has a new genuine head gasket and correctly torqued bolts. The head appeared in perfect condition when removed, along with bores / pistons etc (compressor has only been used occasionally)

The valve is rated to 4.5bar. The receiver is only reaching 4.5bar on it’s dial.

Any ideas?

Thanks!

 

[mtt.tr]

That's only pops of if your valves are leaking backwards

 

[lotus_esprit_s1]

Removed head and found that a tiny part of the blown head gasket (which blew between the high and low side) had made its way into the low pressure side, then been blown down the low to high feed pipe and finally jammed itself in the high pressure inlet valve, preventing it from closing all the way.

Thanks!