Off topic(ish) and kind of semi use less information as I doubt anyone will end up in the same situation BUT it does hint at some important information: When I built my Blue TT slicktop I had every intention of fitting the AC back to it so had the pump on the motor BUT no condensor as I didn't have a good one for the TT. While mucking about testing thermo fans I tested the results from removing the AC compressor, removing that big lump of crap out of the way & opening up extra air flow made a SIGNIFICANT difference is temperatures. Useless information if you want to keep the AC BUT it does show what might seem like not much can make a lot of difference.
I'm goin say its your hub on the fan. My current cooling setup is AMS rad, new oem water pump and thermostat. No shroud or undertrays - only as I'm continuously working on it thought they will all go back on. Also have a plazmaman FMIC and full AC. Temps stay on 83 cruising, 85 while giving it some, 79 downhill and 90 is the highest I have seen coming up quite steep inclines. Figures are from ecu talk.
It can't be the hub on the fan. If it only overheats at highway speeds, then it's something else. The whole reason for a viscous coupled radiator fan is to have the fan running as fast as it can (ie basically a locked viscous hub) at low engine speeds (which usually corresponds top low vehicle speeds, ie low airflow through the radiator), but at higher engine speeds, for the viscous coupling to slip, giving a lower fan speed (and also much less noise). When any car is moving above around 40kph, it's better off having no fan at all, as it just gets in the way of airflow through the radiator.
Are you really suggesting that putting a thicker radiator (requiring more airflow), behind a front mount intercooler, in an extremely tight engine bay may REDUCE cooling efficiency??? And that perhaps Nissan got it right?? Your attitude won't fly here Glenn....
That's just not right. My fan hub was shagged and the car only got too hot on the motorway, where the temperature would slowly climb until I pulled over. Works just fine if you don't modify the car to and fit a considerably weaker fan that said I wouldn't change the stock radiator again.
Haha well reducing the airflow doesn't help either. Have a look at what Nissan did with later model "supercars" (so I'm thinking S15 turbo, R34, R35), all thin and wide radiators. I don't know for sure but I'd just about bet my car (broken tailshaft and all) that you won't find any 56mm radiators in late model Nissans... Anyway we are getting a little off topic. Kawasaki either your radiator is blocked, head gasket is ****ed, or not getting enough air. You've ruled out head gasket, so either swap the radiator out or the fan and clutch...
Not your fan hub then. At highway speeds, without any fan at all, air will flow straight through a radiator, and cool it well. Put an engine driven fan behind the radiator which is spinning at high speed, and the fan itself acts as an impediment to air flow through the radiator. At highway speeds, a fan just gets in the way. Not that I expect you to try, but if you were to pull off the fan altogether and go for a drive on a highway, you'll notice two things. Same or lower engine temps, and less noise.
seeing the usual culprits have been suggested (fan shroud / underbody trays / fan hub etc....) Has the engine received a few casual teardowns and rebuilds ???? reason I ask is I recently saw a V6 that had the exact same symptons you've described, even down to a mechanicle guage fittament :rofl: What we found was the actual block was full of cast off silicon from the various removal/replacements of heads/waterpump/etc etc etc..... the excess silicon was torn from the mating surfaces and washed into the cavities of the block and over the years of backyard mechanicing this built up n up n up till it became a major overheating issue..... with the same symptons you've got :rofl: I used paint thinners to break the silicon down into a gluggy mess and from there was able to (under a LOT of pressure) flush it out easy way to check for full flow other than staring helplessly into the radiator cap hole is to ....... cut the top radiator hose into 3 sections and junk the centre section insert a clear hose ( available from ClarkRubber / Bunnings etc) I actually fitted some short stainless bits and 4 hose clamps to a couple of old top radiator hoses to make my "viewing tube" Its been a helpfull tool over the years and has often supprised me the rubbish one see's even tho you may belive how "clean" the system is said to be cheers
Sorry Dangerous but Rob's really hit the nail on the head with this one, my whole cooling system was new bar the clutch fan and it was cooking, swapped in a new clutch fan and the temps don't go past 83 now. The fan pulls a hell of a lot more air through the radiator than highway speeds do.
I thought the whole point of the clutch fan was to stop spinning at higher speeds so that it didn't drag on the motor, it would only engage at lower speeds to drag air through the radiator??
2.5k rpm isn't what I would call at speed. I bet robs car that a new hub will fix it. Played this game before and won a couple of times.
Well Theo (Anti) has very generously offered to post me up his almost brand new clutch fan to trial, so I'll be fitting it when it gets here and hopefully it will put an end to this mystery. BadZX, the engine has been subject to backyard mechanics but I doubt it's full of silicone. I may be wrong, but I hope not
