I'm doing a BHG rebuild and noticed that the water jacket in the rear of my head is...not there. The block has an outlet, the gasket as well. In the head there is just a corroded aluminum area where the jacket should be. Anyone know why?
Water jacket in back of head?
- Thread starter TEMPEST
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yeah i think zooloo started that craze. i was even thinking about doing it...johnathan1 said:
edit. wth i am doing it.
nick, on the head, it is just a flat surface, but the stock headgasket has the copper and gasket hole for it at the back. i could go out and take a pic of my block as well, because on the block there is a gaping hole that has coolant running through it but just gets blocked off from the head. if you drill it out, there will be more coolant going through the back of the head and recirculating it more so that even piston number 6 will get better cooling, and not just the head.Nick M said:
its really weird why toyota decided at last minute to not include the hole in the head... maybe the real 6m's have had that coolant passage because from what i understand its the same block.
But anyway for the drawback, all i can see is that you will lose a bit of heat going into the heater core because the pipe that directly goes over the location of the hidden passage, but for most of us that really isn't an issue...
edit. does anyone want me to take pictures? lol.
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Thats very back yard engineering. I have to imagine they blocked it off to promote flow a certain way, and drilling it out will make it cool worse then it did to begin with.
? i don't get it. and that may be crude, but how do you think machine shops do it? anyway, toyota did a lot of weird stuff with this motor, and looking through the coolant flow chart, this would make coolant flow better.Nick M said:
-Thomas
oh, well that is obvious, but the point of that picture was to show the spot where you would need to drill.Nick M said:
the one at the left is the random hole.
Well, I'm glad I asked! Just for the record, I'll have to drill the passage out. It's alsmost through the block as it is! The aluminum is just gone with some serious pitting corrosion. Good to know it's not altogether a bad thing. More people should probably be aware to look for this as this head gasket was replaced by the previous owner who probably knew nothing about it. Oh, at less than 20k ago on a motor with less than 100k presently. I'll be hand machining the head myself, trust no-one!
I would suggest that unless you actually model the coolant flow with a 3D FEM fluid flow simulator (like Toyota did when they designed it) you should leave it alone because they did it for a reason. Note also that the intake side block coolant ports are partially blocked off by the head gasket holes (look at the pic above). Again, done presumably to balance coolant flow to get more flowing on the hotter exhaust side.
There is a finite volume of coolant from the pump, and you need to balance the flow so that hot spots get enough and cool spots don't get too much. If you unblock the port, some other part is now getting less coolant. Screw around with it a your peril.
There is a finite volume of coolant from the pump, and you need to balance the flow so that hot spots get enough and cool spots don't get too much. If you unblock the port, some other part is now getting less coolant. Screw around with it a your peril.
yet again i stress that you will lose flow to the heater core. it's the only logical thing that it will lose flow to.
There was something similar to this on the 2.8litre Cologne V6 engine ford put out over here - there were gasket passages for the water, but not in the head. Drilling two holes 1.5cm into the head solved a massive problem with overheating, as the valves were in an odd config due to the siamesed exhaust passages.
Head went something like this
I---E---I---E-*-E---I
* is where you drilled the two cooling passages.
Head went something like this
I---E---I---E-*-E---I
* is where you drilled the two cooling passages.
3p141592654 said:
when a 7m blows a head gasket it tends to be the #6 cylinder this is why. it was put there to keep the egr cavity a certain temp I drilled mine out and have had no problems and I checked points on my block with a laser temp gauge and have only seen good results from this. Truthfully I think I should have made the wholes I drilled bigger