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Had My Coolant Flushed. Now My Radiator Fans Won’t Turn Off.
2002 Nissan Maxima GLE with factory nav and integrated climate controls.
Had a local shop flush the coolant, replace the upper and lower radiator hoses and swap out the thermostat (and housing) one or two Fridays ago. After filling the system with fresh coolant, the shop owner said he had issues sorting out the cooling system: The fans were turning on when they weren’t needed and after about five to ten minutes of driving.
He initially thought he wasn’t fully purging the system of air, which was leading to the radiator fans turning on, but he eventually ruled that out as he spent several hours trying to diagnose and purge the system to no avail. The fans turn on after about five minutes of light driving and before the system reaches the adequate temperature required for them to activate. He emphasized that the car was NOT overheating and that the fans were turning on BEFORE they should have, which I believe he said is 205 or 215 degrees Fahrenheit. Just to clarify, this is with the AC system OFF and after purging the system with the heater at full blast.
He wasn’t able to figure out what was causing the problem and ended up refunding me for the service (minus the coolant cost) since he left me with an issue that wasn’t there before. Yay! 😑 At least I’m not overheating, but the car sounds pretty nasty at stop lights, etc. and I’d really like to fix whatever is causing the fans to stay on.
The mad scientist next door thought the shop may not have purged the system correctly so he tried purging it himself in his driveway, but the fans turned on again the next morning after about five mins of driving.
I narrowed down the problem to possibly being a bad relay so I replaced the relay in the RAD FAN 1 slot hoping that it would solve the issue. It didn’t. I read in another thread here that the RAD FAN 1 relay controlled the speed of both fans, but further reading of that thread told me that this only applied to 4th gen Maximas. Can anyone clarify? And is it possible that the problem I’m having is being caused by bad fan motors instead or an improperly installed or faulty thermostat?
I have a suspicion that it may be the coolant temperature sensor, but I’ve also read that this will usually lead to overheating, not overcooling, and I don’t want to keep throwing relays and sensors at the car without knowing what exactly is wrong or broken. Anyone here have any ideas? I’m about fresh out. 🍄
This post leads me to believe it’s a bad thermostat:
And since you are going to have to re-burp the system of air, either have the front end on ramps or have it jacked up in the front to ensure it's purged of air properly.
And since you are going to have to re-burp the system of air, either have the front end on ramps or have it jacked up in the front to ensure it's purged of air properly.
Did the "mad scientist" have the front of the car on an incline as mentioned by The Wizard? I have the Lisle Funnel which I have used on my Maxima and it worked great with the car on an incline.
Did the "mad scientist" have the front of the car on an incline as mentioned by The Wizard? I have the Lisle Funnel which I have used on my Maxima and it worked great with the car on an incline.
Yes, he’s a professional, my guy. Don’t ever disrespect the mad scientist like that.
Last edited by 2DAMAX-4DSC; Nov 13, 2020 at 11:48 AM.
If you buy an Autozone thermostat and use the OEM housing, it can be installed incorrectly.
Are you on drugs? It is an assembly, a housing, built-in, with a bolt pattern that cannot be incorrectly installed, there is no possibility of purchasing a new thermostat in any other form, no matter where it is purchased. OP has an electrical problem.
Are you on drugs? It is an assembly, a housing, built-in, with a bolt pattern that cannot be incorrectly installed, there is no possibility of purchasing a new thermostat in any other form, no matter where it is purchased. OP has an electrical problem.
I don't think we're talking apples to apples here.....You can buy any aftermarket thermostat and install it into the OEM housing. Look at the picture you posted. See those two screws? The thermostat comes out.
Why would the OP have an electrical problem? He didn't have these issues before the work was done, so common sense should tell us his new issue is most likely related to the recent work that was done.
No way dude, you're still drunk from last night and think you're modding the Lexus forum. I'll wait for your link to the thermostat only, with no housing.
Go to bed lol. Then when you wake up, tell IB to add dark mode to this place already will ya? Sheesh
Just realized OP has a 2002 so my info may be bad. I thought he had a 2001. All my experience is with 95 through 2001 Maximas. The picture you posted I believe is for the 95-2001 though.
Last edited by The Wizard; Nov 14, 2020 at 02:04 AM.
"Common sense" would tell me he is fail-safe-ing for some reason. But I need more info. Too much focus on non-issues like purging and not enough focus on whatever that grease monkey mechanic jacked up.
A note on "purging"; It's not necessary. Fill up the radiator, start the engine, use your radiator funnel, rev it a few times til no more bubbles come out, and you're done. No need for ramps, there's no special magic or valve that opens when you turn the heater on, so you don't need to do that either, just fill it up, fill up the overflow tank, and drive the damn thing. None of that crap is even listed in the FSM for bleeding the coolant system. In 20 miles your radiator cap will have done it's job and purged air and/or opened to suck in coolant and the system will be in equilibrium.
Like I said, I have no experience with the VQ35 engine, but that picture looks just like the VQ30 thermostat housing. I believe you that it's a VQ35 thermostat housing. Appearance wise, they are awfully similar.
If you undo the two screws, the thermostat can be removed, correct? What if the mechanic bought brand X thermostat w/housing, but used Brand X thermostat and swapped it into the OEM housing? Certainly that is a possibility, correct? And therefore, the thermostat could have been installed upside down?
And I suppose if the assembly guy at the assembly plant was hungover or having a bad day, the thermostat could have been installed upside down. Or maybe it's simply just faulty. Sometimes brand new parts are bad right of the box.
And I went and checked for ****s and giggles, you can indeed buy a thermostat separately for the 95-01 Maxima. I thought I was going crazy there for a second. LOL
Last edited by The Wizard; Nov 14, 2020 at 03:07 AM.
"Common sense" would tell me he is fail-safe-ing for some reason. But I need more info. Too much focus on non-issues like purging and not enough focus on whatever that grease monkey mechanic jacked up.
A note on "purging"; It's not necessary. Fill up the radiator, start the engine, use your radiator funnel, rev it a few times til no more bubbles come out, and you're done. No need for ramps, there's no special magic or valve that opens when you turn the heater on, so you don't need to do that either, just fill it up, fill up the overflow tank, and drive the damn thing. None of that crap is even listed in the FSM for bleeding the coolant system. In 20 miles your radiator cap will have done it's job and purged air and/or opened to suck in coolant and the system will be in equilibrium.
Well, in the 4th gen world, a lot of people have trouble purging air for some reason or another. Jacking the front of the car up seems to do the trick.
And yes, it would be nice to know exactly what the mechanic did do or touched. All we can do is visualize what he should have done and touched and retrace said steps.
How do you mod a forum focused on the VQ35 for 20 years and not be familiar with it
Who said I'm a moderator specifically for the 5th gen forum? I post across all generations and try to help others when possible. I also haven't been a moderator for 20 years...not even close. Now who's on drugs? LOL. Go to sleep son.
Who said I'm a moderator specifically for the 5th gen forum? I post across all generations and try to help others when possible. I also haven't been a moderator for 20 years...not even close. Now who's on drugs? LOL. Go to sleep son.
I'm just giving you a hard time like I always do, man
Will wait for OP to elaborate on his electrical situation and history...
Will wait for OP to elaborate on his electrical situation and history...
Electrical system hasn’t been touched.
Car was running incredibly cool since the day I bought it. Still is.
Originally Posted by The Wizard
If you buy an Autozone thermostat and use the OEM housing, it can be installed incorrectly (same goes for OEM thermostat).
Should have clarified in the OP, it was a Murray Plus OE thermostat AND thermostat housing from Oreilly.
Shop recommended I swap the thermostat. Something in the back of my mind was telling me I shouldn’t, since the entire cooling system was working just fine before which means the thermostat was presumably doing it’s job. Should have listened.
Last edited by 2DAMAX-4DSC; Nov 14, 2020 at 01:19 PM.
I would check thermostat opening temperature (F) since murray brand has so many variants: 160, 180, 185, 187, 195, 203.
If OP got wrong unit, he needs to reimburse the shop service since he provided all the parts.
I would check thermostat opening temperature (F) since murray brand has so many variants: 160, 180, 185, 187, 195, 203.
If OP got wrong unit, he needs to reimburse the shop service since he provided all the parts.
Good call, did not know so many temps were available for aftermarket T-stats. Not sure why there would be, but ok. Why I stick to OEM with critical components.
T-stat specs will accompany whatever model number variant OP bought, if that's the case. If there's a 160 in it, then yeah, fans gonna run a lot Lol
Good call, did not know so many temps were available for aftermarket T-stats. Not sure why there would be, but ok. Why I stick to OEM with critical components.
T-stat specs will accompany whatever model number variant OP bought, if that's the case. If there's a 160 in it, then yeah, fans gonna run a lot Lol
I think OP may've had 203F unit. It opens late. It's for those who want to get heat quickly and is more suitable for frequent short trips.
I'd pick OEM unit too for convenience, peace of minds, no price difference.
I think OP may've had 203F unit. It opens late. It's for those who want to get heat quickly and is more suitable for frequent short trips.
I'd pick OEM unit too for convenience, peace of minds, no price difference.
Nope, 203 is correct. Aluminum blocks like a specific temp, and the engineers of the all-aluminum VQ35 like it to be around 200. To my knowledge, you don't get to pick your T-stat temp parameters for VQ stats. I am not aware of any options such as you suggested, even with aftermarket.
I finally had a chance to look around online. 180 seems to be the common value for aftermarket T-stats, and is inline with the FSM opening temp. I couldn't find any other temp values for T-stats from AutoZone or other branded names.
Going to post this as a reference until I get back. Again, all my references are sourced from my 2003 SE FSM. 5th gen FSM's will all read the same. This is the definitive guide to proper fan operation.
I got three bad motorad t-stats in a row for RWD VQs. They wouldn't open until 212 despite all being 170-180 spec. I gave up, they don't work and are what you buy under any brand name.
OEM is the easiest option, but I used an inline housing on the upper hose on G35. Problem solved and it opens/bleeds instantly!
Check the coolant temp. The fans are working fine.
Last edited by Child_uv_KoRn; Nov 18, 2020 at 09:31 PM.
