ricardin559 Posted June 22, 2014 Report Share Posted June 22, 2014 hello im new on this community. i have a 73 datsun 620 and i have questions about the sensors in the thermostat housing. First of all i know that the one on the left goes to the temperature gauge but what about the one in the right what is it? Does any one know? Quote Link to comment
datzenmike Posted June 22, 2014 Report Share Posted June 22, 2014 Are you in California? Normally, the L16 in the '73 only has a temperature gauge sensor. Later L series motors have EGR (exhaust gas recirculation) to reduce oxide emissions and have a temp controlled air bleed in a vacuum line to the EGR. When cold the air bleed is open and when the motor warms up the bleed is closed and full carb vacuum can be applied to the EGR valve. In simple terms there is no EGR when the engine is cold.... but I digress. It's very likely that someone broke the thermostat housing changing the thermostat and replaced it with a later 4 or 6 cylinder housing with an extra sensor in it.r 1 Quote Link to comment
ricardin559 Posted June 22, 2014 Author Report Share Posted June 22, 2014 yes i am. what about the one im holding and also the blue one that sticks out in the upper right? thank you Quote Link to comment
datzenmike Posted June 22, 2014 Report Share Posted June 22, 2014 Bottom left is the water temp sender. Bottom right is a temp switch. Opens or closes a connection when at operating temp. I have the '73 620 FSM and it's not shown. Possibly it allows the second set of points to be used or, not, depending on engine temp. If there is not a mate to that plug on the harness then the thermostat housing was likely swapped. Top right is a water by pass hose. It should be connected to that metal pipe just below it and go to the lower rad hose. It doesn't appear to be connected and is likely plugged with a bolt or something. Quote Link to comment
ricardin559 Posted June 22, 2014 Author Report Share Posted June 22, 2014 thank you very much, that helped alot. the bottom right cable did not have a connection to the distributor so i really dont know where it goes. so that upper right hose goes to the bolt that is touching my finger? Quote Link to comment
datzenmike Posted June 22, 2014 Report Share Posted June 22, 2014 Top right is a water by pass hose. It should be connected to that metal pipe just below it and go to the lower rad hose. It doesn't appear to be connected and is likely plugged with a bolt or something. Can't sat it any clearer. Take a look at the end of that woven hose. Is there a bolt in it? Or where does it go??? 1 Quote Link to comment
ricardin559 Posted June 22, 2014 Author Report Share Posted June 22, 2014 Yes there is a bolt at the end Quote Link to comment
ricardin559 Posted June 22, 2014 Author Report Share Posted June 22, 2014 so does it go in that bolt i told you? Quote Link to comment
datzenmike Posted June 22, 2014 Report Share Posted June 22, 2014 Well it should be connected to that pipe in the picture, so maybe it was changed also. Quote Link to comment
datsunaholic Posted June 23, 2014 Report Share Posted June 23, 2014 As far as I know, all '73s have that second sensor. It's for the dual-point system. My Mom's '73 has that, though since it was converted to single points it's just plugging the hole. However, oddly I was looking at her truck last week and noticed it's a California-emissions truck per the emissions sticker (which is very odd, being she bought it brand new off the Yonker Datsun lot in Kent, WA in 1973). Quote Link to comment
ricardin559 Posted June 23, 2014 Author Report Share Posted June 23, 2014 As far as I know, all '73s have that second sensor. It's for the dual-point system. My Mom's '73 has that, though since it was converted to single points it's just plugging the hole. However, oddly I was looking at her truck last week and noticed it's a California-emissions truck per the emissions sticker (which is very odd, being she bought it brand new off the Yonker Datsun lot in Kent, WA in 1973). can you show me how your mom's truck connections looks like ? Quote Link to comment
datzenmike Posted June 23, 2014 Report Share Posted June 23, 2014 My FSM shows a temp sensor and electrical switch but it's the same as the 510 and mounted on the drivers kick panel. It senses 50 F temp but why was it in the cab?? Never understood this unless it was assumed you would have the heater on in very cold weather. My '76 710 has that same sensor / switch on the housing, it's a California emissions model and an L20B. Quote Link to comment
MikeRL411 Posted June 23, 2014 Report Share Posted June 23, 2014 yes i am. what about the one im holding and also the blue one that sticks out in the upper right? thank you If you want to replace that corroded thermostat outlet fitting, a KIA Sephia unit will fit. If you have metric fittings, no sweat. If SAE bolts you will have to ream the metric holes to the next larger SAE size. Depending on fan bllade clearance,MOPAR Aluminum V6 thermostat just may have enough clearance between the fan and the hose to be viable. 2 Quote Link to comment
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