ComicArtist Posted October 2, 2012 Share Posted October 2, 2012 My 78 with a bone stock L28 started overheating. Radiator had a big crack, which is probably why it overheated. So I replaced it with a Koyo S13 SR20 radiator, and removed the thermostat because I suspected it being clogged. This was just a temporary solution until I could get to a parts store to get a new thermostat. However, I've driven it to work since then, and it WON'T get above 130 degrees. Driving, it goes right above 120, and goes to about 130 at stoplights. And it doesn't even have a fan shroud. Any opinions why it's doing this, temp sensor is good, plenty of coolant. Quote Link to comment Share on other sites More sharing options...
NewZed Posted October 2, 2012 Share Posted October 2, 2012 The thermostat controls engine heating by restricting coolant flow, to keep heat in the engine block so that it will reach designed operating temperature. You're in a good spot, just put a good thermostat back in, and you should be golden. Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 2, 2012 Share Posted October 2, 2012 Yep, thermostat regulates flow through the radiator to give a desired output temperature from the top of the engine. Without it regulating it, you simply go by heat input and heat rejection. The radiator rejects more heat than running the engine produces, you don't warm up. Minimum you really want to consider is 160F, which will get oil to 180-190, hot enough to 'burn off' water condensate that is a byproduct of combustion. Short trips you may well be advised to go with a 190 thermostat to help with this, especially in the winter. Quote Link to comment Share on other sites More sharing options...
ComicArtist Posted October 2, 2012 Author Share Posted October 2, 2012 Sweeeeeet. Tony, haven't talked with you in a while. I've been too busy building my RX-7 to pay much attention to the Z lately, just been driving it. The stock fan shroud won't fit with the radiator, so I'll probably just get a thermostat and some flexalites when I get the money. I was pretty pleased with the fitment, here's some pics if anyone's interested. And here's a couple pics of my RX-7 if anyone's interested haha Quote Link to comment Share on other sites More sharing options...
78zstyle Posted October 3, 2012 Share Posted October 3, 2012 Did that radiator bolt right in or was any modification done? Quote Link to comment Share on other sites More sharing options...
ComicArtist Posted October 3, 2012 Author Share Posted October 3, 2012 Had to massage the inside of the frame rails with a hammer a bit, the bottom of the rad was about 3/16" too wide. Besides that, it was just drilling new bolt holes and making an upper hose. Quote Link to comment Share on other sites More sharing options...
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