tonman83 Posted March 21, 2017 Share Posted March 21, 2017 I took my Zed to a RWYB drag racing event at Smeatharpe, Devon (the real home of motor racing) on Saturday. It was my first go up there; and long story cut short, the car started to over heat as I lined up for my fourth attempt. It went up through the temperature gauge, to the top of the red. As many of you know, when you are in the queue up there you can’t get out. I noticed a bit of steam coming out of the bonnet and so when I arrived at the start I told the marshall I wouldn’t race and drove up the quarter mile and back slowly, and the temperature started to drop down (presumably because of the improved air flow). I put the heater on and returned to the pit area, to unsurprisingly find a lot of luminous green coolant had leaked out and was decorating the inside of the under tray. A lot of the rest of the water was around the header tank and the left hand side of engine bay, presumably because the steam had risen and condensated on the in inside of the bonnet. It seems to me that it must be a split pipe; because there has been no smoke out the exhaust, and there is no water in the oil (as far as I can see from the cap). Furthermore I don’t think that much water could have come out of the header tank lid under pressure. The engine management light came on, which is understandable. I let the car cool down. I topped up the water into the top of the radiator and that which disappeared from the header and drove home, which took about 10 minutes. No temperature excitement. I noticed that only 1 fan was working when the car was stationary. On the brief inspection of the car, I can’t see where the water might be coming from; and I’m not familiar with the coolant system. It doesn’t look like it’s coming from any head gasket type areas or the radiator, more like around the header tank, or where the alternator is. I filled the header tank last night, and it was still full this morning; so maybe only leaking under extreme load? So the questions!: - How badly do people think I have damaged the car? - Where can I locate a coolant pipe diagram? - Whats the easiest way to find the leak? - Does anyone have experience of this type of thing? - What other improvements should I make to the car to prevent this in the future? - Any other advice please! Quote Link to comment Share on other sites More sharing options...
Jez @ H-Dev Posted March 21, 2017 Share Posted March 21, 2017 (edited) Overheating is usually the fan motors failing. You can refurb them, fit new ones or replace the whole lot with Mishimoto. We prefer to replace the motors with OEM or copies: http://h-dev.co.uk/product-category/350z/engine/engine-cooling-and-management/ The coolant leak may have only been while the engine was over temperature and boiling up. You may or may not have caused engine damage. The only real way to find out is to get the fans fixed, bleed the coolant system and top up and see what happens. Fingers crossed you've got away with it. Edited March 21, 2017 by Jez @ H-Dev Quote Link to comment Share on other sites More sharing options...
Randy_Baton Posted March 21, 2017 Share Posted March 21, 2017 (edited) Its probably just a broken fan - common problem. If the air con is on and the cars stationary both fans should be on. However when the fans start to go it can be intermittent so just because both fans come on doesn't mean there isn't a problem. When this happens the coolant gets heated, expands and comes out of the same place you put in. You can either take the fans out and recondition them - cheap Buy a mishimoto fan shroud - next cheapest but can be noisy Buy new OEM fans - Expensive Edited March 21, 2017 by Randy_Baton Quote Link to comment Share on other sites More sharing options...
tonman83 Posted March 21, 2017 Author Share Posted March 21, 2017 Thanks both; I will check the fans in a bit more depth tonight with the air con etc. If neither fan was working at that time that could have been the problem. I am surprised how much affect the fan has. My gut thought is that it isn't too bad; as I noticed reasonably promptly and didn't do anything moronic. Where is the pressure valve relative to the header tank, or maybe there isn't one? Is there a bleed valve to assist topping up? Where are the likely weak spots for me to check? Many thanks guys, really appreciated. ps the car had some work done at Horsham a few years back (plenum, exhaust, re-map etc) still going well! Quote Link to comment Share on other sites More sharing options...
Jez @ H-Dev Posted March 21, 2017 Share Posted March 21, 2017 (edited) The rad cap is the valve between the pressurised system and the header. There is a bleed valve at the back of the engine on the drivers side. Its plastic and in a smallish hose. You must use a screw driver that fits well or you'll strip the centre out and won't be able to bleed the system. You can usually tell if the coolant system is bled properly - if it is, the heaters will blow hot when at idle (temp on max, cabin fans on). If they only blow hot with the revs held up then you've still got air in the system. Edited March 21, 2017 by Jez @ H-Dev Quote Link to comment Share on other sites More sharing options...
tonman83 Posted March 21, 2017 Author Share Posted March 21, 2017 OK, cool. I will have a look. Many thanks Jez Quote Link to comment Share on other sites More sharing options...
tonman83 Posted March 21, 2017 Author Share Posted March 21, 2017 Good evening, I've just been out having a look at the car. Firstly, you guys are right about the fans, they don't seem to engage properly. I turned on the air con with the car stationary and they didn't get going without prompting. With the car idling, and the header tank full of water, I tried to bleed the system using the screw valve at the back but there was little water coming out, in fact I had the screw completely off without much movement without me prompting water by squeezing the pipe at the top of the rad. I'm going to slowly trundle to work tomorrow and see what happens. I think I may need to force more temperature to get it going? Quote Link to comment Share on other sites More sharing options...
Olly350z Posted March 21, 2017 Share Posted March 21, 2017 Possible your water pump mightve died, have seen it before. Odd that when fully unscrewed you wernt getting much flow Quote Link to comment Share on other sites More sharing options...
tonman83 Posted March 22, 2017 Author Share Posted March 22, 2017 Good morning All, A quick update; I drove the car to work today and stopped every 15 minutes to bleed the coolant and it's looking like it's working quite well. The water is dropping towards max in the header tank, the temperature is stable, the water seems to be filling the pipes more. The fans are still not working. I'm driving sedately. Quote Link to comment Share on other sites More sharing options...
-Bradders- Posted March 22, 2017 Share Posted March 22, 2017 Im currently in the process of bleeding mine.. its a massive ballache, as at the moment i only get hot air when im moving, and cold air when stationary lol. i had a simialr issue with the overheating but it was down to an airlock in the system. Quote Link to comment Share on other sites More sharing options...
Jez @ H-Dev Posted March 24, 2017 Share Posted March 24, 2017 I'm driving sedately. If the engine is ok you can drive normally - just don't let the engine run while the car is stationary for too long - this is when the fans are needed as there no airflow through the rad. Quote Link to comment Share on other sites More sharing options...
tonman83 Posted March 24, 2017 Author Share Posted March 24, 2017 Thanks Jez, I'm going to look into the fans in due course. All seems fine at present. Quote Link to comment Share on other sites More sharing options...
tonman83 Posted March 27, 2017 Author Share Posted March 27, 2017 Quick update, I think the fan motors have had it. I've seen a video of someone trying to repair them. I'm going to give it a go. Quote Link to comment Share on other sites More sharing options...
tonman83 Posted April 4, 2017 Author Share Posted April 4, 2017 Update, cleaned / repaired the fans and it's working well with the ac. Just need to get the car up to temp to check the coolant element works. Quote Link to comment Share on other sites More sharing options...
lct Posted January 8, 2020 Share Posted January 8, 2020 (edited) Hi I need help. I've just dropped my nan off for a hospital appointment and when I was crawling around the carpark practically at idle speed, loads of steam started coming from the bonnet. Pulled over, coolant boiling making a lot of noise and a bit has spilled out. It's thrown a EML on as well. I'm now stuck. Should I just let it cool down, top it up with water and risk driving it home or will I risk making things worse? Edited January 8, 2020 by lct Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted January 8, 2020 Share Posted January 8, 2020 It will be a fan motor issue so let it cool down, top up the coolant and bleed if required. Once you increase the air flow the temps should stay normal unless you have a faulty stat or a permanent coolant leak. Quote Link to comment Share on other sites More sharing options...
lct Posted January 8, 2020 Share Posted January 8, 2020 (edited) Double post Edited January 8, 2020 by lct Quote Link to comment Share on other sites More sharing options...
lct Posted January 8, 2020 Share Posted January 8, 2020 (edited) 42 minutes ago, ZMANALEX said: It will be a fan motor issue so let it cool down, top up the coolant and bleed if required. Once you increase the air flow the temps should stay normal unless you have a faulty stat or a permanent coolant leak. I topped it up with water. Hit some traffic getting out of town, started moving and the temperature was hitting high again. Looks like the coolant level may have dropped. I'm pulled over waiting to cool down again. Argh. I don't even know how to bleed ha Edited January 8, 2020 by lct Quote Link to comment Share on other sites More sharing options...
lct Posted January 8, 2020 Share Posted January 8, 2020 So I managed to get it home, temperature stayed normal. Sitting outside house now idling to see if the temp creeps up again and it hasn't? Would that be normal? Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted January 8, 2020 Share Posted January 8, 2020 That would be normal if both fan motors are kicking in. Quote Link to comment Share on other sites More sharing options...
cs2000 Posted January 8, 2020 Share Posted January 8, 2020 As Alex said, it will be your rad fan failed/failing. Once the car gets hot, one of the two fans should fire up, cant remember which side. If you want a quick test, put the air-con on, Both fans should immediately fire up. If one doesnt, that's your faulty/failing one. Sounds like its an intermittent fan, which will fail at some point. Quote Link to comment Share on other sites More sharing options...
lct Posted January 8, 2020 Share Posted January 8, 2020 (edited) Cheers lads, best get it looked at. It's been bulletproof for 3 years and the week after I get made redundant this happens Should I avoid driving in the meantime or will it be okay providing I keep an eye for the temp rising? Edited January 8, 2020 by lct Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted January 8, 2020 Share Posted January 8, 2020 Fan motors, thermostats and radiators all in stock and good to go same/next day. Quote Link to comment Share on other sites More sharing options...
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