Has anyone replaced a blown head gasket on the 4.0 RR engine without doing a block test?

 

same block as a Disco so I will say yes

 

So, it is not necessary to do a block test when changing a blown head gasket. It's a good idea, but not a must do?

 

It's a good idea, but not a must do?

 

I would guess most DIY HGs are without a block test (using shop air pressure, not the $50 chemical test).

Head gaskets give hints - like:

White smoke out exhaust
Overheating
Hoses rock hard
coolant tank boiling
coolant in oil
coolant leaking from gasket external

Cracked block can mimic many of those

The "odds" are that if you have misfires or leaks in the front or rear cylinders it is HG, and inboard cylinders could easily be cracked block leaking behind a sleeve.

The must do is a machine shop check of heads for flatness, 0.002 inch.

After you have done all that, $300 for parts, a couple of weekends with the wrench and breaker bar; and machine shop work; you would be most unhappy if a cracked block was there.

There are also products like KSeal and Irontite to consider. As well as a top hat sleeved block from an engine rebuilder.