[AMC-list] AND ANOTHER THING 195.6 OHV cylinder head cooling problem

[tom jennings <tomj@xxxxxxx>]

OK, I just figured out ANOTHER thing, it's bad, easily fixed and yet another
source of heat stress.

To understand this you'll have to look at a head, or a TSM drawing of one.
I'll make a web page about this whole debacle eventually.

The thermostat is housed in the head, but in a snout that sticks out from #1
cyl 5" or more, sort of "on it's way" to the radiator. The thermostat sits
in in a well, the neck goes up to the hose and radiator.

The problem is, as the head heats up, there is NO WAY FOR HEAT/HOT WATER TO
GET TO THE THERMOSTAT. THe water pump design is too simple. Unlike the 232,
which (1) circulates head water (I think) and (2) has the thermostat coupled
thermally to the #1 cylinder, the 195.6 OHV has zero water flow around the
thermostat when it is closed. None.

This confounded me a number of times when I re-filled the system after
working on it. I fill it then idle the engine with the radiator cap on. I
have a thermostat with a 1/8" hole so air purges OK. What happens is, the
head gets HOT, but the front casting w/thermostat in it stays cold;
eventually casual turbulence wafts some heat over there, it opens and runs
normally.

After initial fill up, the head gets hot enough to boil and I can hear the
"water hammer" of steam bubbles, so I've learned to warm the car up til the
head is just too hot to touch, then turn it off and wait til the thermostat
neck is hot. THen I restart and from then on it seems OK.

But it's clearly a terrible design. There's simply no way for the thermostat
to detect head coolant temp without it being open; once warmed up in never
fully closes (maybe in very cold weather...)


My proposed solution is to drill a 3/16" - 1/4" hole in the thermostat and
put the hole towards the front of the car, so that there is always SOME
water flowing, and it will do so over the temperature button on the bottom
of the thermo. It will at the least make the engine warm up slower, but it
warms up in two blocks, so that hardly matters. It might causer a problem if
the temperature is REALLY COLD (Minnesota, etc), but hey, cardboard the
radiator for that.

I'm gonna drill the HEAD for a temp sensor, probably up near #2 cyl if I
can. THe sensor is in that stupid thermo casting.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://list.amc-list.com/pipermail/amc-list-amc-list.com/attachments/20100204/bbe65e6d/attachment.htm>
_______________________________________________
AMC-list mailing list
AMC-list@xxxxxxxxxxxx
http://list.amc-list.com/listinfo.cgi/amc-list-amc-list.com