Hi everyone, I am hoping someone can help me... My Zed is overheating when driving but not when on idle. I have recently changed every single water hose and got a new radiator as well. When testing it in the garage I had it running for a full hour and it was all ok. I took it out this week and after 5 min it got really hot. I just got thermostat out, as I thought that may be a problem, but it got hot again. I checked all spark plugs and there is no water coming out there, so I don't think it is a blown headgasket. Is it possible that I got a bad radiator or there could be something else? Any advise is much appreciated!
check that your ac radiator isnt blocked up with gunk, check your fan clutch hub(the metal hub bit inbetween your white plastic radiator fan and water pump/pulley) check the belt, and also the hub when the engine is hot(with it turned off of course) check how easy it is to turn the fan. may not be catching enough when heated, so under load is not drawing in enough air. and also, get your water pump checked.
Did you flush fresh water through the system When you pulled all the pipes etc off? these if neglected for years can completely block up in places and stop the flow. Hows the impellor on the water pump itself?
Thanks! Thank you both for quick reply... I have checked the water pump and it is fine. Fins are also good. I did do the full flush when I changed the hoses. My car has electric fan. I am about to put the old radiator back in... Don't know what else to do... Thanks again
If the system is not bled of all air, then you will get periodic 'overheat' temps when steam pockets pass by the temp sensor in the top radiator hardpipe. I experienced spikes of up to 100 degrees, but this was using ecu talk. Usually a few good revs and topping the system up when cold a few times will expel all air. Otherwise park facing up a hill, idle and top off system as needed with the thermostat open. Probably the most likely cause right now, see how that goes and report back if it has not resolved itself.
Thanks Mitch I have tried that last week and it did not solve the problem. That is why I resorted to drastic measure of putting the old radiator back in today. Old radiator was working fine I just changed it for a bigger thinking it would be better.... Now I have a major headache. I didn't think it was a head gasket as there was no milky residue on the oil cap, but that looks to be the problem now. Thermostat is good, there are no air pockets (car was jacked up right in the air), radiator is good, all hoses are good, there are no leaks, I have checked all spark plugs and there are no traces of coolant on them or coming out from there. Is there another way of checking if it is head gasket? I just want to try everything possible before getting the engine out, again!:help:
oil resembling diarrhea in the coolant, milky looking oil when checking the dipstick - hope for your sake its not the HG...
Two thoughts. My experince with head gaskets is like a hose coming out of the exhaust. Thought 2, had similar problem with Z31- radiator cap. Replaced original, newby did not hold pressure.
Check in front of the radiator that you didn't drop a rag down there and it blows up across the radiator when driving then when you stop to check it falls back behind the bumper out of site. It happened to me years ago and was very hard to find it. Cheers Dave.
TT or NA? If TT, ditch the Thermo and go back to OEM clutch fan assembly. Admittedly, some have had success with TT's and thermos, but most haven't. CFM of your thermo is a major determining factor as well. Personally found a 3630cfm wasnt up to the task, but contributing factors were FMIC and direct mount (no shroud to draw through the entire radiator).
Thanks everyone I checked the dipstick and it is not milky. Having said that, I didn't like the water coming out of the radiator, it did resemble to brown milky liquid, and the cap was brownish... There is nothing coming out of the exhaust... Cap on the radiator seems fine. That is on both of them. So, my next step is doing a pressure test for the head gasket. I have to find someone that has one. Hopefully I can get that organised this week. Thanks again everyone. I will post the progress...
have you checked the temp through the ecu to make sure it is definately overheating? my temp guage in the dash has always reads a little over half way for quite a while now (looks like its a little hotter then it should be) but with consult and nissan datascan, the temp always reads fine, as it should be. and also as twin terror mentioned and i think i did also, check infront of your radiator for anything blocking air flow from the front. could be leaves, dirt, rag, plastic bag, or just years of built up gunk blocking the AC radiator at the front, which could be stopping air flow from making it through. only other thing I could possibly think of is a blockage in the engine some where, or possibly a loose/split hose some where, which may be drawing air into the cooling system.
have you checked the temp through the ecu to make sure it is definately overheating? my temp guage in the dash always sits a little over half way, has done for quite a while now, even with a new temp sensor (looks like its a little hotter then it should be) but with consult and nissan datascan, the temp always reads fine, as it should be, the guage is just a little drunk. and also as twin terror mentioned and i think i did also, check infront of your radiator for anything blocking air flow from the front. There could be leaves, dirt, rag, plastic bag, or just years of built up gunk blocking the AC radiator at the front, which could be stopping air flow from making it through. Check your coolant temp sensor plug, when dirty or not on properly, they will read incorrectly. Check your radiator cap, the radiator caps from supercheap, peps, repco etc, usually dont fit very well, they don't seat properly down in the top tank, the zed's cap is deeper. This would cause your cooling system to not pressurise and overheat. Check your overflow hose is on properly, if your overflow is not connected or leaking, this can cause overheating once the system reaches enough pressure to open the cap. Check your hoses are done up properly, and have no splits, they could be drawing air into cooling system, which would cause overheating. (very possible since you mentioned hoses were changed when you replaced the radiator) if there is a split or loose hose in the right place, you wont always get a coolant leak, it will just draw air into the system. check your lower radiator hose isnt collapsing in. And the only other thing I could possibly think of is a blockage in the engine some where. but don't panic too much thinking your engine has had it, fairly sure its just something little, going off what you have explained so far.
I would wager that this is your problem. See if you can buy/borrow a clutch fan setup and see if the problem sorts itself. As previously described, most electric fans just don't have the ability to generate the airflow to adequately cool the system.
I disagree, but I do understand how it's easier to blame the hardware than the people setting them up. To the OP, does the fan actually come on? And you do have 2 electric thermo fans yes? One attached to the radiator, and one sitting in front of the AC condensor?
I should perhaps update my post to say that most SETUPS of electric fans are incapable of providing the airflow? Either way, I don't think it can hurt to check whether the fan is the issue, given the track record of these setups causing issues. Particularly given that he's considering pulling the engine!
its your fan go back to the oem fan, thermos are shit all day , ( unless working properlly , ) sorry thermo guys >
Thats ok, I fogive you. Like I said previously, don't blame the fan, people have no concept of which ones to buy and how to set them up, so they're doomed to fail on 9/10 zeds. I however wouldn't go back to a clutch fan now, i get much better efficiency with the thermos.
Overheating by head-gasket is caused by hot combustion gases entering the coolant under high pressure. The resultant pressure now transferred to your cooling system expels your coolant through the cap into your overflow bottle. When enough of your coolant is replaced with gas you will quickly overheat as the water pump can't pump air. If/next time your car overheats, once the pressure in the cooling system normalises (once you can squeeze the top hose with little to no resistance), remove the cap carefully(ie . without scalding yourself), check your coolant level. If you can see clean coolant, you likely don't have a HG problem
In addition to what pexzed said, head gaskets usually bring on a very quick over heat when accelerating and cool back down when decelerating. You say you "just got the thermostat out". Does this mean you took it out altogether and reassembled without it or did you replace it with a new one? They will overheat very quickly without a thermostat fitted.
