Guest szlash280z Posted December 4, 2003 Share Posted December 4, 2003 I had an Efan for my 78 with turbo conversion. I got tired of it running hotter on the gauge than I was comfy with so I went back to the stock fan. Even though I need some viscous fluid in my stock fan it cools so much better. However, my engine still seems to want to overheat when I shut the engine down! Today I went to Lowe's in my Z. I bought the part I needed and was back out to the car within 20mins. when I started it back up my temp gauge was almost pegged to the HOT side. The engine ran like crap, the valves and stuff were tapping like mad even though I had oil pressure (P90A Hydrohead) When I touch the valve cover I get burned, when I touch my intake I get burned. No intercooler installed yet. Everything gets so damn hot under there after shut down. I just don't understand it. My gauge says normal temp when I park it! I even have the '78 Vented hood too. I keep thinking the head will warp or my head gasket is going to blow while the engine is OFF! (that wouldn't really happen right?) Does anyone else have this problem? It sucks! Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 4, 2003 Share Posted December 4, 2003 If you get an electric fan and hot wire it on a temp switch it will come on even if the key is out. Mine comes on after I've shut the car off pretty often. I've got a 240SX lower hose with the temp switch in it, and it will run for a while before the coolant temp in the hose cools off. Works for me. I don't think it's really all that big a deal, though. Every car heat soaks when the engine stops. You may want to take temps with something other than a stock temp gauge (guessing that you're still using the stock gauge). I found that my temps were WAY different and much lower than what the stock gauge showed when I switched to an Autometer with a temp probe in the thermostat housing. Jon Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted December 4, 2003 Share Posted December 4, 2003 I originally had my efan wired that way on my NA motor, I kept thinking it would kill the battery so I changed the power to ignition switched. I was going to go that route again when I got my new efan setup from the ford car that lots of people seem to be going with. the reason I think it's a problem is that my valves start tapping LOUD when this occurs. They did that once when my efan died in traffic too. So I know the head has to be getting too hot. I can't seem to get any good readings with my digi meat thermo either. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 4, 2003 Share Posted December 4, 2003 I dont think it would matter much if the fan stayed on with the car off... the water pump isnt working anymore so the water is not circulating... sure the radiator water will cool, but the water in the motor? That is really strange szlash... are you letting the car cool before shutting it off? I'd think this would be a really good reason to get a turbo timer... you could set it to let the car idle as long as 5 or 10 minutes after you are already out... it should cool off by then, and that way water is still circulating. However this is just a bandaid... the car shouldnt be doing that. I'd be more interested in searching out problems with the cooling system... something strange like bubbles trapped in the system, a radiator that is too full or not full enough, or a partially sticking thermostat. Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted December 4, 2003 Share Posted December 4, 2003 when the motor is running the temperature stays normal. I always run it slow before parking and even let it idle a minute or more before shutting it off. I have enough coolant in the system. Could the problem be too much coolant and not enough water in the mixture? I can't see it being the thermostat since the temp is fine while it's running. Maybe the intercooler will help it... Could it be too much engine block paint or something? I have a couple of coats on it... that sounds retarded! Quote Link to comment Share on other sites More sharing options...
yo2001 Posted December 4, 2003 Share Posted December 4, 2003 water does have a better heat transfer than anti-freeze. But you got to run anti-freeze in the winter time. I wouldn't worry too much if your car heat soak. as long as the temp goes back when you ar edriving it. Quote Link to comment Share on other sites More sharing options...
innerware Posted December 6, 2003 Share Posted December 6, 2003 szlash, have you figured it out yet? I have a non turboed Z (280) and have the same problem. If I rid e for while and go to the store and come back in 20 minutes or so, the car is heat soaked and after restarting it will run like crap until it cools a little. It will start up and then rpm reall low and rpm bounce too. I don't think that I have any pinging though. It concerns me too. This happened after putting in a new radiator for me. Anyway I was hoping you had figured something out. Quote Link to comment Share on other sites More sharing options...
240zprace Posted December 6, 2003 Share Posted December 6, 2003 i could only think of some possibilities a car would overheat... 1. thermostat is no good 2. water pump is no good 3. too much coolant over water 4. fan clutch is no good 5. radiator is clogging up have you checked all these Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted December 6, 2003 Share Posted December 6, 2003 There is some merit to looking into the water pump. Rumor has it the cast steel inpellered ones cool better, but I can neither confirm nor deny that. Also when is the last time you flushed the radiator? Might be worth a shot. Quote Link to comment Share on other sites More sharing options...
Guest Nic-Rebel450CA Posted December 7, 2003 Share Posted December 7, 2003 The only explanation for such overheating is that there is heat somewhere that is being held in, and then has a chance to dissipate when the car is sitting. It is not likely to be the coolant itself as the temp gauge is showing that the coolant is holding plenty of heat. (although I agree that too much antifreeze is bad). Other sources of heat are cylinders (running too lean), air (air in cooling system causing heat pockets while car is sitting), oil (not cooling off because of lack of turbo timer), transmission (transmission trouble causing transmission to get extremely hot and heat is transferring from transmission to engine while it sits). The last item is something that I had trouble with in my truck when my automatic transmission was going out. Quote Link to comment Share on other sites More sharing options...
rags Posted December 7, 2003 Share Posted December 7, 2003 Are you using an oil cooler? Do you know what thw oil temp is? I would put an oil temp gauge in to see if the oil temp is getting too hot. You didn't specify how long the car was running before you shut it down. Rags Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted December 11, 2003 Share Posted December 11, 2003 I still haven't figured it out. it's been about 2 or 3k miles since I FLUSHED the radiator, but I have drained it on many occasions doing this turbo swap. My water pump is new. I am using an oil cooler, it's not the stock one though so it might not work very well. I have the sending unit for the oil temperature in the pan, but no gauge to hook it up to. I am thinking the primary cause of the extra heat comes from the turbo as the intake is very very hot while it's running. so hopefully the intercooler will help. My fan clutch is bad, when I shut it off I can move the fan easily by hand. I hear that you shouldn't be able to move it at all at op temp. and it still cools better than my e-fan did. I will try idling it longer when I stop I guess. Quote Link to comment Share on other sites More sharing options...
Guest Want aZ Posted December 11, 2003 Share Posted December 11, 2003 Have you ever used a product called Water Wetter. It is an additive that you add to the coolant/water. It is supposed to reduce coolant temps by as much as 25*, Have never had the need to use it as all of my vehicles run a little on the cool side anyway. I've seen it at Auto Zone, but Advance, Pep Boys, or NAPA probably has it as well. Damon Quote Link to comment Share on other sites More sharing options...
Tim240z Posted December 11, 2003 Share Posted December 11, 2003 Try cracking open the hood when you park. I bet all that heat from the turbo is just soaking into the engine because it has nowhere else to go. Or try running without the vents bolted to the hood and see if that helps. I don't think that the oem plastic vents are all that effective. Also, do a search, there was a mod mentioned that used little fans installed in the wheel wells to suck the hot air out. Tim Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 12, 2003 Share Posted December 12, 2003 I have a 280 vented hood on my 240... one of the vents (driver side) has a metal pan bolted underneath it... should I remove this? I've been thinking about that... I mean it's on the 'hot side' of the engine bay... but I'm worried about rain... can cold water getting thru there do something crazy like crack a hot manifold? Can it mess with any of the electronics? If you guys say it's safe I'd like to remove that and let it do it's job the way it should Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted December 14, 2003 Share Posted December 14, 2003 Ok, I have some hard numbers now. I put my digi thermometer into screw holes in the intake and on the valve cover, while running they were both only 150*F or so. I put the thermo into my radiator with the motor running and I confirmed that the engine is being cooled just fine and idles at 175*F to 180*F. I didn't really have much time to conduct my time delay test though. I waited about 5 mins, then tested the temps of the intake and valve cover again and they stayed about the same. The reason I tested these are because they felt extrememly hot. My test was a success, however I think it disproved my theory on the heat soak. Next thing to check is the oil. I will change the oil and see if that helps. I have my break-in straight weight 30 oil in there. Maybe multi oil will not perform so bad. Quote Link to comment Share on other sites More sharing options...
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