speeder Posted October 13, 2004 Share Posted October 13, 2004 My new 3.0 Turbo motor is driving me crazy with an overheat problem. First: F54 block (Cylinders Copper O-ringed) , P90 head, Factory Turbo Head gasket, massive AZCar Aluminum crossflow radiator, 160* thermostat, CSR Electric Water Pump. I have the water pump being turned on at 140* by my E-motive ECU, Electric fans turned on at 180* by a switch in the thermostat housing. The car overheats sitting at idle and driving around.. While warming up, I can see all events happen on the temp gauge at the correct temp: 1.Water pump comes on at 140, cools enough to turn off momentarily, then turns on and stays on. Temperature starts to climb. 2. Thermostat opens at 160, and temperature hangs there for a few seconds, then starts to climb. 3 Fans come on at 180, Temp goes down to 175 for a few seconds, then climbs to 200 - 210 or so. I then shut off the car to prevent damage. I've ensured that there is no air in the system by jacking up the front of the car, then running the electric pump until no more air bubbles appear in the radiator while filling. The Radiator is very clean inside. Just for good measure, I swapped the radiator witth the identical one from my daily driver. no change. There are no signs of head gasket leakage. Removing the thermostat made no change to operation. Radiator, thermostat, and fan setup was used on my old motor with good success, and all seem to be working well. The electric water pump is different from the old setup, but I know of several people who use this piece with good success. Wideband O2 says AFRs are about 13.8-14 during these times. I plan to double check timing but I saw 20* on the timing light at idle. I'm starting to think water flow problems - But... With the engine at 200* plus, shut off after running for a while, I can manually turn on the fans and pump, and watch the temp plummet on my mechanical temp gauge. Anyone have suggestions? I have about run out of ideas. Quote Link to comment Share on other sites More sharing options...
Doug71zt Posted October 13, 2004 Share Posted October 13, 2004 Is the water pump turning backwards? It almost sounds like the same thing as a SBC with the water pump turning backwards. Apart from that??? Too much or not enough restriction in the system? I would swap in a good old belt-driven pump to troubleshoot, if that was the major change from your old set-up. Good luck - Keep us posted Doug Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted October 13, 2004 Share Posted October 13, 2004 It may run a bit hot until the rings get broken in, depending on your piston-wall clearance. I have seen 2 L motors do that. I like the suggestion of going back to the mechanical pump to troubleshoot though. Atleast you could rule the electric pump out. Hmmm...yep, the pump running backwards would do it too... Quote Link to comment Share on other sites More sharing options...
speeder Posted October 14, 2004 Author Share Posted October 14, 2004 Pretty sure the pump is running "Frontwards" but I'll double check. Going back to mech pump is a step I'll take fairly soon. I'm going to play with pump speed/flow control, too - Mike, I'm running fairly tight piston to wall clearances (.004) for forged pistons - they are TBC coated on the tops and teflon coated on skirts, running .004 piston to wall. This is a little tighter than Mfg. recommendations, but I have used these same Venolia pistons/ coatings / clearances before with good results. How hot is "a bit"? 30* or so? How long you reckon it'll take to wear in and cool down if that's the problem? Man this is frustrating - I'm itching to begin high boost tuning. Every indication is that this motor will be a real beast! Butt Dyno says that it has as much grunt at 7 psi as my old one had at 14. Quote Link to comment Share on other sites More sharing options...
2126 Posted October 14, 2004 Share Posted October 14, 2004 Just a thought....in the process of building the motor, did you have the block boiled out? After years of operation, a thin layer of scale and corrosion build up on the interior walls of the waterways. Even though a visual check shows almost nothing, this layer of stuff acts as an insulation barriers and significantly reduces heat transfer from the block to coolant. Just an added thought. However, it probably like what Z-Gad said. Quote Link to comment Share on other sites More sharing options...
240Z Turbo Posted October 14, 2004 Share Posted October 14, 2004 Rick, a few things I would point out. Is it wise to not run the pump until the temps get to 140F? I would think you would want it on at all times as to not create hot spots. Remember, the temp gauge may not account for an unhomogenous water temp as the water is stagnent in the system. Running a lower thermostat can, in some cases, make the temps run hotter. Try running a 180F thermostat. Burping the system can take some time so make sure the overflow bottle is in use so it can draw water back into the system replacing the air. I would swap back the mechanical pump until you can isolate the problem. BTW, did you have your butt dyno calibrated this year? Quote Link to comment Share on other sites More sharing options...
speeder Posted October 15, 2004 Author Share Posted October 15, 2004 James, I've lowered the pump "on" temp to 100* with no improvement. I've also put some small holes in the thermostat to enable some convective flow before the pump turns on. Pretty sure that there's no air in the system - I ran the pump with the front end jacked up until no more air bubbles appeared in the radiator - and I do have a recovery bottle. The pump is pushing water in the forward direction - I removed the top hose from the radiator, turned on the pump, and was amazed at the rate water was expelled. The block I'm using has been hot tanked. There has been some electrical interference being generated by the pump that is being picked up by my CAS - So far I've only seen this on a hot engine (above the pump on set point) with ignition on and the engine not running. Under this condition the injectors can be heard to fire. I can see very small (10 mv. p-p) pulses with an o'scope on the CAS signal with the engine not cranked, pump running, which are obviously enough to trigger the E-motive. With the engine running, this signal is about 4 volts p-p and very even/normal looking. I would assume that there's some kind of auto gain control in the E-motive? Car seems to run well once started, but now I wonder if this noise could be affecting the timing? I've put extra shielding on the CAS cable and tried several ground points for the shield with no joy. This is very weird as my three electric fans (some closer to the CAS than the water pump) generate no interference at all. Dang, the pump is such a trick piece, but it's got to come out! I'll do that tomorrow, as well as go to a 180 'stat. Hey, I dunno - been so long since the car's been right maybe the butt's out of cal. Quote Link to comment Share on other sites More sharing options...
Guest 240zt Posted October 15, 2004 Share Posted October 15, 2004 This may sound obvious but could it be the gauge is wrong ...... Quote Link to comment Share on other sites More sharing options...
speeder Posted October 15, 2004 Author Share Posted October 15, 2004 I wish it could be the gauge - but its readings are backed up by the PC monitor program's readout of the coolant temp and by observations of the temps that things (pump, fans) are switched on. Quote Link to comment Share on other sites More sharing options...
quicker240 Posted October 15, 2004 Share Posted October 15, 2004 Just wondering what temp you want to really run at.Obviously the lower the better but the reason I ask is that many,most,fuel injected cars according to manufacturers anyway,should run over 200 degrees.Many only activate fans at these relatively high temps.Promotes better combustion,emissions,blah blah blah......Also the place where you are reading temps may also be contributing.Are you picking up at the thermostat housing as a stock setup? What I dont like is that even when you kick on pumps fans and all,it continues to heat up.Not a good sign.I hope the mech pump isolates the problem for you.With your setup,you should be able to control temps at will.The only time I encountered a problem like this,I had wired my electric fan backwards,It was blowing through the radiator instead of pulling air.Soon as I started moving good,the car slowly overheated,when I stopped,It would cool down some,but not enough.I felt so stupid..... Good luck with it.May the problem be something simple and stupid like mine was Quote Link to comment Share on other sites More sharing options...
Guest 240zt Posted October 15, 2004 Share Posted October 15, 2004 wow hmmmm uhh . blame it on some one else Quote Link to comment Share on other sites More sharing options...
TimZ Posted October 16, 2004 Share Posted October 16, 2004 Just wondering what temp you want to really run at.Obviously the lower the better but the reason I ask is that many,most,fuel injected cars according to manufacturers anyway,should run over 200 degrees.Many only activate fans at these relatively high temps.Promotes better combustion,emissions,blah blah blah I've been thinking along these lines lately, too. Mine seems to run the best with coolant temps around 195 degF. I've also noticed that many manufacturers are letting the coolant temps run considerably higher than 210. I don't really think that running temps at 200 to 210 is going to hurt anything as long as you don't boil over - meaning the system must maintain adequate pressure, and you must use some amount of anti-freeze in the mix (probably the minimum required for these temps). That said, my coolant temps have been running over 200 and sometimes as high as 210 after a hard run on a warm day, and I still cringe a bit when it does it. I'm still trying to get it to stay down around 195 more reliably. It doesn't have much problem staying cool at idle, though. Also, I'm with James - I've never much liked the idea of not running the pump when cold, and for all the reasons he already stated. It doesn't take that long for it to warm up with the pump running, so why risk things with the added complexity? Have you checked the voltage at the pump? If the pump isn't getting full voltage, this could be contributing to the problem... ...BTW, this is the thermostat that I've been using - I'm pretty sure it was the #301. Here is a bit more detailed description. Quote Link to comment Share on other sites More sharing options...
hanomon Posted October 16, 2004 Share Posted October 16, 2004 I've heard of this additive called water-wetter. Don't know fore sure cause I personaly have not used the stuff. I know guys that have and are satisfied with the results. Any of the speed shops cary it. Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted October 16, 2004 Share Posted October 16, 2004 Curious as to what your oil temps are doing while the car is heating up? Is the oil getting hot and then heating up the water? Quote Link to comment Share on other sites More sharing options...
speeder Posted October 16, 2004 Author Share Posted October 16, 2004 Well, If the temp looked like it was going to stop at 200 or so, I think I wouldn't have been too excited, but it acted like it wanted to keep climbing. I have seen 220 and climbing before getting freaked out and shutting down. I'm reading temp with an autometer gauge in the stock T-stat housing. What really puzzles me was that it didn't start to cool down at highway speeds. That's a clue... Voltage at the pump was good, and when I checked for pumping direction I was amazed at the volume of water that thing moves! When it got hot I could feel no temperature differential between inlet and outlet sides of the radiator, yet for sure the pump and fans were running. I tried a 180* Nissan thermostat (big passage when open) with no help - Tried wiring the pump to come on with ignition - no difference. I don't have an oil temp gauge but wish I did. Oil Temp's my next thing to check if there's still a problem tomorrow. This morning I changed to the mechanical pump and only had time to let it warm up idling - temp stabilized at 180*. I didn't get a chance to test drive, but I'm cautiously optimistic. I probably would have stayed with the electric pump longer if there were no electrical interference issues - but it seemed like there were too many things to deal with at once. Quote Link to comment Share on other sites More sharing options...
speeder Posted October 17, 2004 Author Share Posted October 17, 2004 Took a drive today and everything is good - temp stays at 180. Mech pump and 180 stat did it. Very strange episode with that CSR pump.... Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted October 17, 2004 Share Posted October 17, 2004 Very strange episode with that CSR pump.... Funny, I wouldn't have thought that. Quote Link to comment Share on other sites More sharing options...
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