Nominal Posted November 26, 2013 Share Posted November 26, 2013 In anticipation of summitting the Takaka Hill while towing a trailer of camping gear, I'm doing a bit of maintenance on the Holden's cooling system. Radiator was recored about 10 years ago, might need doing again. I also pulled the water pump and thermostat. It has a coolant flow to the inlet manifold via a couple of hoses routed from the lower thermostat housing. I pulled these to check them, and found a lot of grungy rusty water, despite all my flushing. So, here is the lower thermostat housing. The inlet manifold attaches to the two ports on the left of the pic. The top port joins the main flow below the thermostat. The bottom port goes to the channel at the bottom of the housing. Fine and good. Here is the where the housing attaches to the head. Main flow is fine, into the head. However there is no connection for the channel. WTF. I don't know the history of this motor - it came in a car I wrecked. I'm ass-u-ming that the head is for a different application. Anyone know if this can be sorted by a bit of drilling? If not I'll just block the lower port somehow and do without the manifold coolant flow. Quote Link to comment Share on other sites More sharing options...
Threeonthetree Posted November 26, 2013 Share Posted November 26, 2013 The thermostat housing that you have is the correct part for that particular head. That's assuming that it's a pre 1976 cylinder head. This type of setup meant that coolant only flowed when the thermostat opened. The later style as found in the HX Holden (1976) onwards allows coolant to flow continuously and therefore looks different. Your setup is fine. Give it a good clean and flush. Quote Link to comment Share on other sites More sharing options...
Nominal Posted November 26, 2013 Author Share Posted November 26, 2013 There's nowhere for the flow to flow though - the lower hose port goes nowhere as the channel is completely sealed off by the head face. Am I missing something Quote Link to comment Share on other sites More sharing options...
Nominal Posted November 27, 2013 Author Share Posted November 27, 2013 OK, so much googling later (how can it be so tricky to find holden head photos?), a typical 186 head looks like the pic below. The hole that I have missing goes down through the head gasket surface to meet the small hole on the water pump face, which is the low pressure side. I'll have to see what can be done about it. Quote Link to comment Share on other sites More sharing options...
kurtis1791 Posted November 28, 2013 Share Posted November 28, 2013 Is it causing a problem? its obviously been like that for ages. Personally id leave it if was all working efficiently as is. Quote Link to comment Share on other sites More sharing options...
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