Quote:
Originally Posted by olddog
If the torque on the other head never changed, why was the gasket leaking. Too high a pressure on the pressure test? Maybe.
I think you said that you put the heads on, but someone else assembled the short block. I have had builders claim they have never seen a new block that everything was in spec. Were the decks checked? I think I would give them a good look over. Straight edge and feeler gauges plus a look for scratches and what not.
You said you would have a kiss cut on the heads. Won't hurt anything and may help.
On the head studs, it would be interesting to screw a few in by finger and make sure they don't stop at the point where the bolts ended. If they go right in, the bolts never damaged them. I would still run the tap through them as recommended.
PS
If there is a big step where the bolts ended, you might want to run a regular tap past that point first to blend the step. Then run the bottom tap.
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Quite honestly, under normal operation, I don't think the other head gasket would have been leaking. It was pressure tested to 30 psi, double max operating pressure. (the other head gasket started leaking at less tha 5 psi) At the point of that head's pressure test I'd already made my mind up to pull that head too, due to the head 000bolt issue. I just wanted to see what it did at various pressures. The leak was tiny with nitrogen. With water and it's larger molecular size it might not have leaked at 30 psi. When the engine experiences higher coolant system pressures it's typically already warm so the clamp on the gasket is a tiny bit greater. I do believe this is what pulled that head bolt loose. After seeing all this I've made up my mind that I'm going to put a small bead of RTV around all of the block to head coolant ports though...
As far as the short block, it was run through one of the finest FE builder's CNC block machine. It was also assembled by them.
In talking with Barry R I do have an item in the short block to check. It seems that Pond aluminum blocks have pressed in ductile iron sleeves. Barry has seen several blocks after a problematic tear-down where the sleeves weren't entirely seated on the bottom stepped groove. What happens is under operation and the clamp of the head gasket's compression ring the liner finally comes to rest. The problem is, now you have a liner below deck height and a head gasket compression ring that's no longer compressed. You end up having to re-deck the block (complete tear-down)
The positive side is, it does happen v-e-r-y infrequently and it's typically found after a leak from the compression side of the head gasket. I don't have any compression leaks, that I know of. Rest assured there will be a close inspection.
I will only have the heads cut if they show any signs of warping. I'm getting hold of a machinist's straight edge and I've got my feeler gauges in hand. The manifold's been cut to give me perfect port/block alignment so I really don't want to change things unless I have to. I will clean them up nicely though.
I will do a close inspect and test fit on the existing threads. They will be chased regardless.
I will make a 2 x 4 wood jig for the initial helicoil bore job. It will allow be to be 100% perpendicular to the deck surface when I hand drill it. Barry stressed this, big time. I'll be using my trusty 14.4 DeWalt for the drilling duties...
I would rather have the drill stall then grab 'n twist at an odd angle. I'll use plenty of drill/tap/thread cutting fluid during the operation, along with a operational wet/dry vac with it's nozzle duct taped at the drill site. After the helicoil's in I'll set a head on the block and run a test fit on the hole's new stud.