Where Is Block Drain on 1986 951
 

I'm changing coolant and thermostat. I would like to drain the block. I have located a bolt on the block near the firewall in a recess of the block almost under the rear exhaust header. Trouble is that it doesn't turn like other drain plugs I have removed on other cars. This one when first turned, still offers resistance. No coolant came out but only turned it about 10 degrees. Can't imagine any other reason for a bolt to be in block.

Am I loosening the correct bolt? Thanks.

The bolt's UNDER the manifold? If you mean over, this is the correct bolt...

However I didn't remove mine for the same reason, but I don't think removal is totally necessary. Just take out the thermostat, pour water in from the top of the block (where the bleed screw is, keep pouring until water starts coming somewhat clear from the waterpump) reconnect the hose, fill the system up with clear water. Drain again, and all old coolant should be out of the system by then. This'll take some time, as you really should let the engine cool down before you drain the coolant.

I wouldn't want to take that block antifreeze drain bolt out, but mine felt quite similar to yours when I did finally take it out.

Hope this helps,
Ahmet

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It's all the driver...