billybronco1

I have had this 2005 Nissan (37K miles) for about two years now. Since day one I smell what I thought was an anti freeze leak but the fluid never goes down. Seems the engine runs supper hot (gauge shows normal) and the smell is from the hoses being so hot. Car has never over heated until yesterday. Its was about 85 degrees and I was driving slow around town, stop & go up a few small hills. I pulled over and heard all this noise and saw the temp gauge was red lined. It was pissing out antifreeze from the expansion tank that which was over flowing. We let the car sit for about 45 minutes drove home on the highwayall was fine. Expansion tank was empty when I got home.

I'm wondering why it runs so hot, is this normal?
Because we were not driving fast I assume there is an electric fan that should come on and off, any way to check?
Maybe I should put in a cooler thermostat?
Does this car use regular old antifreeze, nothing special?

Thanks for your help

billybronco1

Okay doing a test got it hot and let it idle in the driveway. One fan came on the other did not, should they always both come on at the same time?

dkmura

iTrader: (64)

When was the antifreeze last changed? The radiator fans should come on when it gets hot- have you checked the connections? The Z uses regular antifreeze, but you should mix with distilled water to prevent deposits in the radiator.

billybronco1

Thanks, I have no idea when antifreeze was changed if ever. So as it was idling this hot day, the one fan came on for a while then shut off. I put the car in forward and held it stationary while accelerating with brake on to get it real hot, that same fan came on again, the other one not. The temp gauge has stayed normal though all this.

JTeeAre

iTrader: (1)

Well i'm pretty damn sure both fans need to come on, that would not cool the radiator enough while you're not moving fast enough for the wind to cool it off. I think it would also be a good idea to change the coolant out, get some fresh new coolant in there. The recommended fluid which is stated in the FSM is "Genuine NISSAN Long Life Antifreeze/ Coolant or equivalent".

The Genuine NISSAN Antifreeze is 50/50 with water so that's what should go back in. You will need 9 1/4 quarts for the radiator and 7/8 quarts for the reservoir tank.

billybronco1

Yes defiantly want to change that fluid but want to figure out the fan situation first, maybe some else will chime in. I'm going to see if I can switch the wires from one fan to the other and see if the other fan comes on when hot - thanks

icer5160

iTrader: (4)

I'm almost certain both fans should be running with the engine hot or above normal operating temperature. You can easily check to see if the fan motor is shot by turning on your AC to max cold. If both fans kick on, then at least you know the fan motor(s) is good. This would indicate you may have a sensor or relay issue preventing the second fan from kicking on when the engine starts creeping above normal operating temps.

These engines like to run hot, most modern cars do to maximize fuel efficiency and decrease emissions. Since you did get the needle pegged in the red, even for a very brief period of time, I would recommend getting a head gasket leak test done before replacing the coolant.

Good Luck!
-Icer

bad boyz

iTrader: (1)

Almost had the same problem a few years ago, changed thermostat put in new aluminum radiator changed hoses and everything to find out it was a broken water pump which was located inside the engine which was quite expensive to fix.If you do change the antifreeze take into consideration the time and patience it takes to bleed the radiator it's totally a PITA!!!

bad boyz

iTrader: (1)

billybronco1

Update - pulled fan assembly out yesterday and laid on ground, ran till fan came on, switched wires and passenger side fan still did not come on. New fan motor is on order.

billybronco1

Update - got fan motor today installed it and yeah all fixed, both fans come on when you put on the AC and also come on periodically with no AC and high temps. Also I noticed they are multi speed, car seems to run much cooler.

Now what is the best way to drain out as much anti freeze as possible so I can replace it? Although it looks spotless clean, I have no idea how old it is. Someone mentioned pulling the lower radiator hose????

icer5160

iTrader: (4)

Glad to hear it was just a fan motor! I would just pull the drain petcock on the radiator and let it all drain out. That is the lowest point of the cooling system. It should be located on the driver's side of the radiator, look for an oversized philips plastic screw. Be careful with this as it is plastic and can break/strip easily.
-Icer

billybronco1

Well I thought I was out of the woods. Yesterday "before" I changed the anti freeze the fans worked fine and temp gauge stayed in a normal position even when I pushed the car hard. Today I pulled the radiator drain and pumped out the overflow tank. I refilled the radiator with new anti freeze 50/50 and the overflow tank. As soon as I got on the road the temp gauge started to climb to the top (both fans running) What could have happened? Some kind of air pocket or something?

icer5160

iTrader: (4)

Yes, these cars require a very specific bleeding process to burp out all the air. simply refilling and driving away won't cut it. You need to bleed out all the air bubbles which can be a real pain if not done right. There are other threads available going over this topic in detail.
-Icer

billybronco1

Well I was hoping to report good news. I found the bleed directions and followed exactly. Took car out maybe 15 miles all was good, temp gauge stayed perfect, heat came out nice and warm, fans came on as needed. Then I was about home and the temp needle started to peg, so I creeped home stopping and coasting with motor off. With the gauge pegged heat was gone and only blew cool air. Seems I still have air in the system or my second thought is thermostat is sticking or faulty. Also when I got home expansion tank was almost full. What are your thoughts?

icer5160

iTrader: (4)

Based on your details about the heater air blowing cold, further bleeding is required, but for peace of mind, I would still get the coolant tested for a head gasket leak.

Something like .

I would also recommend replacing the thermostat for peace of mind. It's a cheap part and not too difficult to access on the Z.

Aluminum heads and block, make it very easy to get a warped head resulting in combustion gas leak(s). If the overflow tank is getting a lot of air bubbles, you could have a leak/crack in one or both of your head gaskets. However this could also be caused by a simple overheat due to the coolant boiling from air pockets still being trapped in the block and heater core.

Sorry to hear about all the troubles. My friend had something similar happen to his Pontiac Grand Prix. Initially a short overheat occurred because of cheap plastic coolant elbows which crack those GM 3.8L V6 engines used. I told him to park the car and get it towed until we could assess the damage and get it fixed.

Of course he didn't listen and tried to limp it home after adding water at a gas station. The coolant leak was severe, to this day I believe had he not done this, the overheat fix would have been cheap/easy. In the end, the entire cooling system was replaced (hoses, thermostat, radiator, water pump, new aluminum elbows, new coolant temp sensor), both head gaskets were wasted. Both heads needed to be completely redone (shaved, valve job, etc). What would have been a $20.0 fix and a tow truck bill, turned into thousands of dollars for parts and labor to rebuild the entire top end of the engine. The bottom end probably suffered as well since I discovered coolant leaking into the oil. No rod knock though.

WKU350z

billybronco1

I don't think one fan is separate to the other, they both run sustainability. When you put the AC on both fans should come on, also when the temp get up high both fans should come on. I just bought a fan motor for $28 from Rock Auto that did the trick for me.

Now for the air bubble issue I bought a spill free funnel and ran the car for about 45 minutes with some antifreeze in it and watched the bubbles come out. Tonight we took a long cruise and had no over heating issues, I think I might be out of the woods, time will tell.

dkmura

iTrader: (64)

The Lisle spill free funnel you pictured should burp the system well. Did you notice all the bubbles that came out as you ran the car during those 45 minutes? It also allows quick refilling with fresh mixture and is a must tool IMO.

tmdz

As dkmura said.


Also, you need to shut off the engine and leave the funnel (about 1/3 full) in place for for about an hour after you run in. While the engine is cooling it will continue to burp out the air bubbles and replace that air with coolant.


Sounds like you have a case of vapor-lock. Until you get that thing bled completely you will likely continue to have problems with it.