Once again.......... BHG issue

[suprastroker88]

So I got an initial blown headgasket. How? I dont know. But it didnt overheat, so I went the lazy way. It already had an hks 2mm stopper on it, so I just lifted the head and swapped out the gaskets. Started it up, and instant ::bhg:: So I took the head off, stripped it down, had it pressure tested and machined, put it back on. Torqued it down to 90lbs with the grey arp lube in 4 passes (40,60,80,90). Put everything back together........................ instant ::bhg:: once again. Wierd thing is, the first time, all the coolant went from the radiator to the oil system. This time, it's mixed in both the radiator AND oil system. WTF. So I did a compression test and here were the results #1-140 #2-130 #3-120 #4-120 #5-120 #6-120.

Can someone tell me what the f*** is going on please?

 

[xzeror]

did u have the block machined when u put the hks stopper on?

 

[suprastroker88]

It was a new build, so yes. Everything was machined and all. It blew, so I machined the head and put a cometic on, and it still blew

 

[xzeror]

annealed head or damaged block after it blew the first time?

 

[suprastroker88]

i dont know what annealed is, but i had it pressure tested and everything and it checked out fine. I dont think there was any damage to the block at all.


would adding rtv gasket maker in between the layers of the headgasket help it seal, or does it get too hot for rtv?

 

[BrandonW]

im running a hks stopper gasket

was the rear timing case machined with the block? how smooth was the finish?

 

[suprastroker88]

EVERYTHING was machined and prepped for a metal headgasket


there was a little over 3000 miles on the engine when the headgasket blew the first time. now its doing it again

 

[suprarx7nut]

If you're getting instant BHG, you are failing to prep the surfaces correctly. As above, the rear timing cover needs to machined with the block. We need more info on this, but I'd guess you have a bad block or head if you're getting instant BHG. Either that or you are just doing really sloppy work. :dunno:

 

[suprastroker88]

I bought this car from thedave925. go read the build thread and then come back and tell me sloppy work was done. I've personally built 5 7mgte's and never had an issue until this one, which is why I'm asking for help. I can't figure out the issue

 

[suprarx7nut]

I bought this car from thedave925. go read the build thread and then come back and tell me sloppy work was done. I've personally built 5 7mgte's and never had an issue until this one, which is why I'm asking for help. I can't figure out the issue

I'm not inferring you're doing sloppy work, sorry if it sounded that way. I'm just saying if it is blowing immediately then either the surfaces aren't flat, the head or block have major flaws or the assembly is poor. The gasket is continuing to blow for a reason.

For a mhg to seal some things have to happen:
Perfectly flat, imperfection free surface on block and head
Head of proper hardness - Nearly no machine shops check this and they absolutely should
Head and block must be freshly machined - surface RA of ~20 or better (plenty machine shops will not be able to or take the care required to get it this smooth...)
No cracks in head or block
Rear timing cover machined with block
Torque plate should be used during block machining

There are more as well, but that's a starting checklist. Can you verify each of those items? One by one?

 

[CyFi6]

Is it possible the machine shop or person assembling the engine forgot to put the front core plug into the block? If that is missing you will drain coolant right into the crankcase. With the oil drain plug off, does coolant pour out as fast as it goes in? How sure are you that it is the head gasket itself causing the issue?

 

[suprastroker88]

Well it sealed and was perfectly fine for a little over 3000 miles. Then all the sudden it just took a shit.