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Overheating,No Rad fans, HFCs, failed mot


burntorange

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Ok what a day i had yesterday.....

So a bit of background to this story. 

I've recently had a custom dual exhaust done with HFCs.....I'm now overdue an mot! and have heard numerous stories about how hfcs passing emissions tests varies....i read that adding some fuel cleaner can help bring them down, so before heading to mot i bought what they claimed to be the best one and wacked that in the zed.

 

Started a blast down the dually by me and within 5 minutes a CEL telling me my cats were underperforming......guessing from all the cral now being thrown down the nice new exhaust.....didnt think about that...

 

Well obviously couldn't take it to an mot with an engine light on so faffed about getting one of my odb2 connectors to work which never seem to be supplied with the pairing pin...useful that.

 

Anyway thats how i found out what was wrong and cleared them....never returned after more blasts.....

 

Went to mot they said my co2 was off the scale at over 1...they stopped the test rather than fail me....though i did notice that the exhausts were looking quite oily considering they were brand new not so long ago...

 

Anyway drive less than 200 meters from the garage and boom the temp needle sky rockets and i immediately pull over with the sound of what can only be decribed as a large kettle boiling.

 

Looked under the bonnet and out trickles coolant...great....an hour and a half later im towed home...

 

I decided to test what was wrong by turning her over...started fine and idled for about 15 minutes amd the temp readiny was edging up and the reading on torque was 110 degrees c before i turned the engine off.....

 

None of the fans had kicked in? Even when the ac is turned on none of them kicked in. Even with a bit of a push to get em going. 

 

Now i have read a few threads about this and people suggest cleaning up the motors. Now i can certainly give this a try but i do wonder if this is actually the cure as surely both dont just stop working at the same time right??? Bit suspicious.

 

If people do think this is what it is i will go ahead and try clean em up. A quick question about this though as im bit of a novice....when taking out the huge coolant pipe to remove the fans i take it thats gonna spill out coolant everywhere...what do i need to know about filling it back up with coolant??

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Sorry to hear your woes.

 

I'm sure you are not the first to have both fans fail, but iirc they do not always come on together. I'm sure someone will be along to  help out and also with the cats issue, although it is always helpful to get them fully up to working temp before an MOT to stand a chance of passing.

 

One thing you should respect is the procedure for refilling the coolant as the ZEDs are notorious for air locks - see here:

 

Edit:  see Zmanalex's post No.16 on page 2 here showing fan failure reasons

 

Edited by Ebized
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Wow, that sounds like a sub-optimal day :(

 

Mine had a total lack of cooling fans when I first got it - decided it'd be worth having a go at cleaning them. When I got the motors apart, only one (out of 8) brushes could actually move. So it looks like it's possible for them to both die.

 

As for removing the hose, I lost less than half a litre of coolant when I removed it. Did have only the front of the car on axle stands, so that probably helped. I got away with just refilling the top of the radiator with roughly how much came out, and haven't had any problems since. That was about 15 months ago.

 

Suppose the coolant thing depends how much you lost yesterday… :(

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I've got HFC's but the rest of the system is standard, albeit with a little blow in the usual place before the back box and mine failed first,  but once they got really hot they were fine.  The problem is yours won't get hot with your cooling fans not working. If the bore on the tail pipe is too extreme that will effect the result, but nothing popping a couple of rags in the end won't fix, but not every test station is prepared to do that. 

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Thanks Ebized I will take a look at those threads cheers, I did intend to take the car in red hot for Mot and arrived on the dot, but they didnt even put it on the ramps until half hour later as the car before had a steering rack fail whilst at the MOT -  dodgy.......

 

Ben this was a sub optimal day considering the zed hasnt missed a beat since owning and it all happens in one day! I will be giving the motor repair a go tonight and hope for the best. 

 

Jay whats the logic behind the hfcs wont get hot if the fans arent working? and the bore on the tail pipe is 4 inchs but hole that actually comes out of back box attaching to the tail pipe is 2.5 inches. where can i find more information about this as i dont quite understand how this would affect the results

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 You can't warm the engine if you're overheating is what I meant. If the bore is too fat the exhaust pressure isn't high enough and air gets drawn in spiking the co2 reading. If you can fit a reducer for the mot that'd help. 

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Guy said he will do emissions first when i go next time after ive give it a good run.  If i remind them about an LSD will they know to test it on the road or will i have to tell them?

 

Is it possible to remove the fan motors with everything still in situe? 

Edited by burntorange
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1 hour ago, burntorange said:

They dont look that big the motors and only held on by what i can tell is 3 bolts.......may have to have a look at this later.  I will certainly ensure mine is not roller tested as i cant be dealing with another thing!! thanks for the advice

See post No.15 on this link about the fitting, dealing with fan motor refurb that might also help you

 

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Thanks very much for that helped a treat..... getting the fan shroud out was so much of a faff.....and getting the metal tabs holding the motor housing together..... both took way longer than i thought it would. 

 

However upon opening them 3 out of 4 brushes were seized in both motors..... bizarre huh. 

 

So freed them sanded them a little added some lubricant.....used a dremel on the electronic contacts on the motors. 

 

All rebuilt and ready to go in..... ran out of sunlight... fingers crossed all worked

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Ok so not good!! put it all back together and after about 5 minutes when the engine was around 70 degrees c i noticed a little smoking coming from somewhere down by where the fans are. left it a little while as i couldnt exactly see where it was coming from and it might have been some coolant i spilt from the day before when removing the top hose of radiator.... smoke was getting stronger and it started to smell like electrical burn, shut off the engine and even though the motors had been spinning, all what in no particular fashion i could tell up to this point, the motors were burning hot to the touch on the back of them, burnt my finger touching em in a split second. 

 

So hasnt worked out in my favour, no idea why!! so where can i buy new motors from or do i have to buy the whole unit?

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Wow, sounds like you're really having a rough time at the moment.

 

Weird, though… they were spinning, and burning out at the same time? °_0

Possibly the low speed contacts were fine, then something slightly shorting out the high speed ones? I take it you removed all the paper clips if you had those to hold the brushes back whilst putting it back together…


For replacements, I believe the stock response is PM Zmanalex :p

Though FWIW, when I was having problems, I basically decided that if I couldn't fix my existing ones, I'd get the Mishimoto shroud and fans for way less than replacement motors seemed to be going for: https://www.torqen.uk/nissan/350z/cooling/radiators-fans/2093-350z-de-mishimoto-aluminium-fan-shroud-kit-mmfs-350z-03.html

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I am having a well rough time lol, i got to get this car sorted and mot'd before next wednesday as my partner who currently is giving me lifts goes away on work duties!! and before the overheating i was having issues with emmisions!!!! everything was going so swimmingly until this last couple of weeks!

 

I have just bought the mishimoto fans from them directly, are these plug and play like they suggest? as i have heard different on this forum, like how you have to wire them up yourself due to the fact they only have two wires rather than 4.

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Interesting… I did not notice that when I was looking - like I say, it was my backup plan if I couldn't get the factory ones going again.

 

The rewiring seems to be taking the two low speed wires from the OEM fans to one of the new fans, and the two high speed ones to the other. So rather than two fans running slowly, or two fans running quickly you just have one at full speed, or two at full speed. Suppose that's what makes those fans cheaper. I can't get to the wiring diagram right now (silly intellectual property laws) but from what I remember of it, whats being said here and on my350z makes sense.

 

Edited by Ben–350Z
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I gave up on the stock fans after mine constantly jammed and my coolant hitting the skies splattering out the bonnet :wacko: 

 

Ended up with mishimoto fans for I think £160 and are perfect. They are loud when sitting still but doesn't bother me. 

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so a quick update, fans were very easy to fit and you can actually fit your hands behind them which makes it so easy to plug/unplug the connectors, and it dont half shift air too which is great. it is definitely louder than the original fans, has a sort of turbine sound to it, but to be honest thats nothing compared to having a better cooling system.

 

now for the MOT lol

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