Guest subdermal Posted July 19, 2004 Share Posted July 19, 2004 After waiting a year and a half for my motor to be ready (400 sbc), I get the car and drive it for a week and a half, somehow resisting the urge to open it flat out and giving the motor some time to break in. All is well. The motor kicks ass even at half throttle, I love the feeling of driving it, it's a great conversation starter, and I can tell I'm going to enjoy this car for a very long time. Then one night after taking it on the highway for the first time, I notice a wisp of smoke from the valve cover vents. That's not right. But its still running good, all guages readings are ok, etc. So I drive it home and try to figure out what has happened. A bunch of poeple on various boards tell me that its a normal part of new engine behaviour, but I'm thinking that it didn't do that for the first week, and the motor had been run several times on the dyno before it even went in the car so it should be at least broken in a bit. Friday I drove it to work with the intention of taking it at lunch to the shop I used to get all my work done at. Lunchtime rolls around slower than ever I think, and I hit the road. It has to be at least 35 degrees out (95F) and I'm in dowtown stop and go. 10 minutes to get to the shop, and I find the windows all boarded up and nobody home. That's the only shop downtown. As I turn around to head back to work I notice the temp guage has crept past 190 and is well on its way to 215, and I start to panic. 5 minutes later I'm pulling into the parkade, my temp guage is at nearly 260, oil pressure is fluctuating between normal and none, and my heart is in my throat. I go upstairs defeated and call the place that built the engine... Today I dropped the car off there. Turns out I burned through the rings in two cylinders, which explains the smoke coming out the vents. However, I also now need to get the block and heads resurfaced. Another $1400 and at least another week's delay. Here's the kicker - the reason it was running hot in the first place? The fan is on a manual switch. I did not know this and expected the fan to come on when it was needed, like in every other vehicle I've ever driven. I saw the switch, flipped it, saw the lights dim in the guages and thought "its a dimmer switch for the guages.. wierd but OK". I ran an almost 500hp engine with NO FAN for a week and half, and for at least 15 minutes in 90+ temperatures in stop and go traffic. I am such a moron... plus it looks like my ghetto signals fix is somehow draining the battery. Anyways, just had to vent. Anyone else done something really stupid to their Z they can tell me about so at least I'm not the only one feeling dumb? Quote Link to comment Share on other sites More sharing options...
Tim240z Posted July 19, 2004 Share Posted July 19, 2004 If you want to do some "cooling overkill" on that 400 block..... While it is out, tap threads into the freeze plug holes on the side of the block and run some external coolant piping. It gives some extra insurance against hotspots...... Quote Link to comment Share on other sites More sharing options...
Guest zfan Posted July 19, 2004 Share Posted July 19, 2004 You are not the first and you will not be the last to do something dumb I forgot to turn on the manual switch for my Taurus fan and when my numb brain finallly did look it was hovering around 230-235...ouch! I got lucky and no damage was done I hope all works out ok! Hang in there. Mike Quote Link to comment Share on other sites More sharing options...
Guest subdermal Posted July 20, 2004 Share Posted July 20, 2004 well I burned two rings to ash, and have to get my deck and heads resurfaced... could have been worse. could have been better though hehe. there are already coolant channels custom milled between the center cylinders, fed by an external line... is that what you're talking about, or is this something different? Quote Link to comment Share on other sites More sharing options...
Tim240z Posted July 20, 2004 Share Posted July 20, 2004 there are already coolant channels custom milled between the center cylinders' date=' fed by an external line... is that what you're talking about, or is this something different?[/quote'] That ought to take care of any hot spots 8) Quote Link to comment Share on other sites More sharing options...
Doug71zt Posted July 20, 2004 Share Posted July 20, 2004 I've got a fix for you - Jet (company that makes performance chips) has a temperature switch for fan control, turns on at 195 deg. I used to have my fan wired with a manual switch that turned on the relay, along with the Jet temperature sensor. Then - if I didn't turn the fan on, it would come on at 195 all by itself. Easy installation, 3/8 NPT with a one wire hookup. It is wired to ground the fan relay, turning it on. My last update to my SDS computer added fan relay control, so the computer does it now, but the sensor is still there, just in case. Sorry to hear about the amount of work it required to get it back together - I've done lots of stupid stuff to my Z, but I prefer to call them 'learning experiences' Good luck - Doug Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 20, 2004 Share Posted July 20, 2004 Or you can get a 240SX lower rad hose out of a jy and use the fan switch out of it, turns the fan on at 205 and off at 195. EDIT--just realized this might be a bad idea as your rad hoses might be a different size than the Nissan hoses. Works great for L6 cars though... Quote Link to comment Share on other sites More sharing options...
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