Is the pressure cap on the radiator or on the overflow?
Is the pressure cap on the radiator or on the overflow?
Meaning "broken"? That would be the problem, then.Originally Posted by CudaMan
No virtual cars, I reckon?
acket.
I also would suggest a pressure tester. My semi tame mechanic has found some really tiny water leaks on my race car over the years with his pressure tester.
Yeah sorry, my train of thought tends to jump around a lot. The metal pressure cap is on the rad. This off-white plastic reservoir off to the side just has what is essentially a plastic bottle cap that is split open as if it was screwed down way too hard.
I wouldn't know.
Yeah I get spoiled daily driving on "200TW" race tires with tread.
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The coolant in the 350Z disappears not after a drive, but after sitting. I've been checking regularly. Leads me to believe the evaporation theory is the culprit. I've temporarily duct-taped the cap to try to form a better seal. See if that does anything.
Hmm. New cap installed yesterday afternoon right after topping up the reservoir with distilled water. Ran a few errands last night. This morning, checked the level before starting the car and it was halfway down to LOW. Drove to a couple places, returned home and the level was right at the FULL mark again. Ok so maybe hot/cold makes a difference to the level (I would think there would be markers on the reservoir if that was the case - I've seen this on P/S reservoirs for example). So I'm checking it every so often now today. Still full after 30 minutes...
Hot and cold will affect the level of the fluid.
There will be instructions on how to check the level of the coolant - either cold or hot. With configurations as I understand the Z has, usually there is a level indicator on the overflow which is checked hot, maybe even running. Assuming it's a full-pressure system (like most modern cars - the radiator cap always holds pressure) overflow exists to catch whenever is expelled when pressure is exceeded due to fluid expansion. As it cools, the contents of the overflow are sucked back into the radiator. For this reason, these systems are usually checked hot as there needs to be a certain minimum level of coolant in the overflow at max pressure to ensure air isn't sucked back in when it cools. For some cars (my Jag is an example) you overfill the radiator, that overfill is expelled into the overflow and that creates the minimum level. For others (the Fiero is an example) the system is filled, run to hot, and then the level in the overflow is checked and some amount added until the HOT FULL line is reached. You can't really damage the system by overfilling it - anything truly extra will end up on the ground - but you can hurt the system by underfilling it since, again, you can end up with air in the system and that's bad. It's important to know how to check the system to avoid that latter scenario.
While it's possible to lose coolant only when cold (things contract, leaks are created) it's far more likely that you're losing it when hot (contents under pressure, being forced out). You're probably observing a hot/expanded system looking full, but when cool/contracted looks low. It might be fine - you gotta see how/when to check the level. A system that has been infiltrated with air may look more full than it actually is - air expands a lot when hot, so if it's been trapped in the system somewhere (either being sucked in from the overflow or through a leak) you can have a system that's *really* full when hot, and *really* empty when cold. Some cars (the Jag) are *really* problematic to get air out, others (the Saab) are really easy. Something someone who knows Zs would be able to comment on... but it's important there is no air in the system for this reason (and others, cavitation is bad, air is a poor conductor of heat, air will wear coolant faster).
It's pretty unlikely evap would result in effective loss. Although coolant might be expelled into the overflow at 210+ degrees, it'll cool quickly and loss from boiling would be minimal if any. Once under boiling point (which is... 230 degrees with coolant?) loss from evap would be negligible, even over a long period. The old Trans Am didn't even have a cap on the reservoir and steam would come billowing out from the hood when it was shut down and it still didn't lose much.
If it's a leak, check the easy obvious places like thermostat housings, upper radiator hoses, heater core hoses and then move onto the harder stuff like the water pump. Hopefully it's one of those things, and not some impossible to find mystery leak like the Aero... losing a cup a month sucks ass.
Last edited by thesameguy; July 25th, 2017 at 12:22 PM.
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