I hate to ask this, but.. BHG?

[Supra mn]

Search bar, I know. I've been looking for some good information, but it seems like google and the forums are clogged up with random threads.
I've read through the common symtoms of a BHG, how to test for one, etc.

I guess I'm just wanting some confirmation before I start tearing this thing down.
So here's the story:
87 turbo 5 speed, finally got it running right, with some minor problems.
Went for a short drive to test out the integrity of the engine, didn't beat on it, turned around and stopped at a parking lot maybe a mile from home.
I have electric fans which I just happened to forget to turn on, and as I let it idle in the 95* day while I checked out a few things under the hood, I didn't notice it overheating. Next thing I know, coolant is spewing out the overflow. I shut it off and the needle on my stock and aftermarket gauges are spiked. I let it sit for a few minutes and then turn the key to Ign, aftermarket gauges reads about 210. Not too horrible for just a few minutes of cooling down, definitely not as bad as I expected.
I let it completely cool down and then start it back up, seems to idle fine but running a little rough. A few days later of just letting it sit and idle until warm up, and it starts running really rough, no power when I tried to drive it out of the parking lot, and eventually died. My immediate thought was BHG.

Compression test results before and after the overheating:
1: 185/150
2: 190/155
3: 200/155
4: 190/155
5: 200/155
6: 190/142

I thought that maybe the head bolts had either loosened, or stretched. I torqued them down to 75 lbs, didn't do anything.
My thoughts are still BHG, but with the numbers still in spec and no single cylinder extremely low, the HG didn't bust? Or maybe a warped head?
I have the basics laying around to do the head gasket job if needed, just wanted your thoughts on it before ripping the head off.

 

[hvyman]

Was this a fresh rebuild?

If so there will be a big difference in numbers from fresh rings to broken in rings.

I'd ditch the electric fans if I was you. It's already caused you problems so far and you've barely driven it.

Make sure the cooling system is bled and the radiator cap is good.

Can also block test and leak down test. And coolant pressure test.

 

[Another MkIII]

Speaking from experience, my engine passed every test except for a block test when hot. I tore it down today and it had a very blown head gasket on cylinder 6, with 1, 2, and 5 on the way. After 5 years of owning a Supra, I've joined the BHG club. So my advice, don't waste your time on a compression test or any of that, go straight for a block test and get a straight answer.

-AM3

 

[Supra mn]

Thanks for the advice guys.
As for if it were a fresh rebuild, I have no idea. I bought it not running, trailered it home and eventually got it running.
The motor felt strong and had some upgrades, so im guessing there was a rebuild at some point.
I pressure tested my cooling system and found some leaks a while back. But I fixed them all up to that point. I don't think air in the system would cause a lack of power, almost no throttle response, and a bad idle though.
Ill look into the block test. Seems like my best bet at this point.

 

[Another MkIII]

My local Napa had a nice block test kit for about $45. Worked great.

-AM3