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Overheating at Idle #4569613
11/10/17 09:26 AM
11/10/17 09:26 AM
Joined: Feb 2017
Posts: 314
NC
fenixguy Offline OP
fenixguy  Offline OP
Joined: Feb 2017
Posts: 314
NC
2000 Civic LX, Automatic, 220,000 miles. On the way home from work Monday, I noticed the temp gauge was creeping up to H while sitting at a red light. Started moving and it dropped. I drove about a half mile until I could pull over. Popped the hood and the electric fan came on. Temp was creeping up again. No visible leaks that I could tell (road was damp so almost impossible). I gave the car some gas and revved to about 3,500 RPM and in just a few seconds, the gauge dropped to normal. I mean dropped, like you flipped a switch. The rest of the way home, it stayed at the normal position and the fan was off. I popped the hood at home and before I could get it open, the fan came on again and the temp started creeping up. I revved it up again and held it and the same thing; temp dropped like flipping a switch. I turned the car off and had supper and then plugged in my OBDII bluetooth adapter. I wanted to rule out a faulty gauge. The car got to 215ish and the fan came on. It kept creeping up to 235. I gave it gas and it immediately dropped back to 215ish, within 10 seconds and stayed there as long as I kept the revs up.

I haven't had time to look at it anymore but I'm taking a half day at work and going to look into it. I'm starting with the thermostat. I'll remove it and check it on the stove to see if it's opening. Meanwhile, I thought I'd run the car to see if it overheats with the thermostat out. It's due for a timing belt/water pump in the next 10,000 miles (last one was at 135,000). If it overheats with the thermostat out, it almost has to be the water pump or a head gasket failure right? Is there anything else anyone would recommend looking at while I'm checking?

To add: I had a heater hose fail about 20,000 miles ago and while I had the system drained I replaced the thermostat (Advance Auto, could be the problem) and flushed the system with distilled water until it was clear, then added 1/2 the total capacity of full concentrate. If it is more than just a thermostat, I'm probably not going to fix it. I have 4 vehicles and this one is just my beater/spare. The wife will cry, as it's her "baby" (but she drives the CR-V, go figure) but we really don't need it. Any advice is appreciated.


'16 Frontier SV 4x4-PP/Nissan OEM
'08 CR-V EX AWD-Valvoline Syn MaxLife/Fram TG
'01 Civic EX-Valvoline Syn MaxLife/Fram UG
'00 Civic LX-PYB/Fram UG
Re: Overheating at Idle [Re: fenixguy] #4569616
11/10/17 09:32 AM
11/10/17 09:32 AM
Joined: Sep 2015
Posts: 1,528
USA
mk378 Online content
mk378  Online Content
Joined: Sep 2015
Posts: 1,528
USA
The first check you should make is to confirm the cooling system is full. Park on level ground and wait until completely cold. Remove the radiator cap the radiator should be full to the top. Also if there is air in the cooling system, the heater usually doesn't work very well even though the engine is hot.

Very likely, something related to the radiator fan has stopped working. One common problem is that the thermal switch does not always start it when it should. The fan is really only needed when the car is idling for a long time or in slow traffic. At speed, the motion of the car forces air through the radiator anyway.

The fan is controlled by a switch on the thermostat housing. When the coolant leaving the radiator (and entering the thermostat) heats up to 160 F, the fan is supposed to start. The ECU does not control the fan. Unplug the switch and put a jumper wire in the harness plug. The fan should now start immediately when you turn the key on. If it does not, check the fan motor, fuse, and relay (the latter two are in the box near the battery). If the fan does run, test drive with it running all the time and confirm no overheating. Replace the switch in that case. If it does overheat with the fan running all the time, then you would look for other problems in the cooling system.

Last edited by mk378; 11/10/17 09:39 AM.
Re: Overheating at Idle [Re: fenixguy] #4569619
11/10/17 09:37 AM
11/10/17 09:37 AM
Joined: Feb 2017
Posts: 314
NC
fenixguy Offline OP
fenixguy  Offline OP
Joined: Feb 2017
Posts: 314
NC
As stated, the fan is working. It almost never has came on while we've had the car (neither does my '01), but it does come on now that it's overheating while idling. I can rev it up and once the temp drops back to normal, the fan stops.


'16 Frontier SV 4x4-PP/Nissan OEM
'08 CR-V EX AWD-Valvoline Syn MaxLife/Fram TG
'01 Civic EX-Valvoline Syn MaxLife/Fram UG
'00 Civic LX-PYB/Fram UG
Re: Overheating at Idle [Re: fenixguy] #4569622
11/10/17 09:40 AM
11/10/17 09:40 AM
Joined: Sep 2015
Posts: 1,528
USA
mk378 Online content
mk378  Online Content
Joined: Sep 2015
Posts: 1,528
USA
Have you checked the coolant level? Both in the tank and in the radiator.

Re: Overheating at Idle [Re: fenixguy] #4569623
11/10/17 09:41 AM
11/10/17 09:41 AM
Joined: May 2009
Posts: 12,192
N.H, U.S.A.
ARCOgraphite Offline
ARCOgraphite  Offline
Joined: May 2009
Posts: 12,192
N.H, U.S.A.
Sounds like water pump impeller erosion.

Fan is working so, NP there unless its real late.

Make sure you have no soft radiator hose collapse when you rev it with T stat open.

Also lok at the rad fins and clear off, hose off debris; spary on some dilute some dish detergent to help clean. Don't hit it too hard with the water spray or youll push out the fins.

Good luck.. Up here in the N.E. even old civics are like gold.


2014 Nissan Rogue S CVT, OC#9 41392mi-QSUD10W30 + M110A CHAMP Filter; 2017 Subaru Crosstrek CVT OC#2 ?? mi-SOA/Idemitsu 0w20 + SOA Filter
Re: Overheating at Idle [Re: mk378] #4569625
11/10/17 09:44 AM
11/10/17 09:44 AM
Joined: May 2009
Posts: 12,192
N.H, U.S.A.
ARCOgraphite Offline
ARCOgraphite  Offline
Joined: May 2009
Posts: 12,192
N.H, U.S.A.
Originally Posted By: mk378
Have you checked the coolant level? Both in the tank and in the radiator.
Good idea. Basics first.
I assumed he did this right, but you could have an air pocket that isn't moving.
- Keep rad cap off and let that thing heat up and then fill the rad to top and cap it after it burps a few times. - - Make sure your overflow hose is god and the tank is at the full hot line.

have fun

Last edited by ARCOgraphite; 11/10/17 09:45 AM.

2014 Nissan Rogue S CVT, OC#9 41392mi-QSUD10W30 + M110A CHAMP Filter; 2017 Subaru Crosstrek CVT OC#2 ?? mi-SOA/Idemitsu 0w20 + SOA Filter
Re: Overheating at Idle [Re: ARCOgraphite] #4569626
11/10/17 09:44 AM
11/10/17 09:44 AM
Joined: Sep 2015
Posts: 1,528
USA
mk378 Online content
mk378  Online Content
Joined: Sep 2015
Posts: 1,528
USA
Originally Posted By: ARCOgraphite
Don't hit it too hard with the water spray or youll push out the fins.

If radiator is falling apart like that, it isn't going to work properly, but that manifests itself more as overheating on the highway.

Re: Overheating at Idle [Re: fenixguy] #4569629
11/10/17 09:48 AM
11/10/17 09:48 AM
Joined: Sep 2007
Posts: 968
TX, USA
JMJNet Offline
JMJNet  Offline
Joined: Sep 2007
Posts: 968
TX, USA
Try to find dried up coolant along the coolant hose.
There will be no drip to the ground since the coolant dried up before dripping to the ground.

Of course, if coolant is empty, then you will not see anything.

If there is really no leak and coolant is empty, then the coolant goes into the engine aka head gasket failure.


  • 2017 Toyota Sienna
  • 1995 GMC Suburban 6.5L Turbo Diesel


Re: Overheating at Idle [Re: fenixguy] #4569637
11/10/17 09:56 AM
11/10/17 09:56 AM
Joined: Aug 2008
Posts: 18,541
Ontario, Canada
StevieC Offline
StevieC  Offline
Joined: Aug 2008
Posts: 18,541
Ontario, Canada
Check that the radiator is full of fluid (not the overflow bottle). If that is fine I would be inclined to think the water pump is toast. A bad thermostat would either cause a full cold condition all the time or an overheat condition all the time. It's rare for a thermostat to be stuck in-between which could also create this problem.

Last edited by StevieC; 11/10/17 09:57 AM.

'18 Highlander - AMSOIL SS 0w20 / ATF / Severe Gear
'06 Santa Fe - 535,000km AMSOIL SS 0w30 / ATF (R.I.P)
Re: Overheating at Idle [Re: fenixguy] #4569638
11/10/17 10:00 AM
11/10/17 10:00 AM
Joined: Jun 2015
Posts: 4,225
New England
Virtus_Probi Offline
Virtus_Probi  Offline
Joined: Jun 2015
Posts: 4,225
New England
Does your car have only one fan?
My Outback had dual fans and I wasn't aware that only one of them was working until I got stuck in horrible traffic heading to Maine on a hot summer day. Car started to overheat and I pulled to the shoulder and the extremely rude New England drivers who were already driving down the shoulder due to the jam beeped and cursed at me as they drove in the grass to my right. The people here are just SO choice! No chance of actually getting any help in this scenario and I was able to keep the overheating down by turning the passenger compartment heat up all the way, THAT was super fun! Once we got going again, the car was fine at speed.

Had been in an accident and the body shop thought the fans were OK because one of them was spinning, they apologized to me when I got back home and took care of the frozen fan for free.

I'm not sure if this matches your symptoms at all, but I thought I'd share my experience just in case. I'd guess you have something else going on if revving the engine helps cool it down...


2014 Forester XT, 86000 miles
Last Change;
M1 5W30 d1G2
Tokyo Roki 15208AA170 filter
Re: Overheating at Idle [Re: fenixguy] #4569643
11/10/17 10:06 AM
11/10/17 10:06 AM
Joined: Sep 2015
Posts: 1,528
USA
mk378 Online content
mk378  Online Content
Joined: Sep 2015
Posts: 1,528
USA
That model has one radiator fan. The radiator is only half the width of the grille and unlike most cars, is independent of the A/C condenser (which, if equipped with A/C, occupies the other half of the grille and has its own fan).

Re: Overheating at Idle [Re: fenixguy] #4569647
11/10/17 10:08 AM
11/10/17 10:08 AM
Joined: Feb 2017
Posts: 314
NC
fenixguy Offline OP
fenixguy  Offline OP
Joined: Feb 2017
Posts: 314
NC
Thanks everyone. I forgot to mention that I did replace the radiator at ~160,000 due to the plastic cracking and leaking on the original one. I haven't seen any visible leaks (ie: dried coolant/pooling on the splash guard) lately and I'm OCD about looking under the hood regularly (I am a member here right? grin). I know all about bleeding air out of the system so I'll for sure be doing that too. Like I said, I haven't had a chance to look at it anymore while it's cool (it's way past dark by the time I get home now) so I have no idea where the level is in the rad. The reservoir was to the full line the other day while checking.

Regarding the water pump erosion: that occurred to me too almost immediately but isn't that extremely rare and generally in neglected cars with mixed antifreeze? This one has been very well maintained (water pump replaced 90k ago) and never mixed coolants. We're talking about a pretty high mileage car so anything's possible. Also of note: This car doesn't get driven as often as it used to. It has set for about a month without moving and this past weekend I decided to drive it some before winter (it has snow tires on it) to make sure everything is up to par. I changed the oil and drove it some Saturday with no issues and didn't notice any overheating on the drive to work.

Regarding the fan(s): This car's radiator takes up only half the grill (does that make sense?). One side is the A/C condenser with a fan and the other side is the tiny radiator with a fan. The A/C hasn't worked in this car for several years and that fan does not come on ever. Edit: mk378 beat me to it.

Again thanks everyone for the suggestions; keep them coming! I'm not going to spend much $$ fixing it if it's not something simple.

Last edited by fenixguy; 11/10/17 10:09 AM.

'16 Frontier SV 4x4-PP/Nissan OEM
'08 CR-V EX AWD-Valvoline Syn MaxLife/Fram TG
'01 Civic EX-Valvoline Syn MaxLife/Fram UG
'00 Civic LX-PYB/Fram UG
Re: Overheating at Idle [Re: fenixguy] #4569655
11/10/17 10:18 AM
11/10/17 10:18 AM
Joined: Aug 2008
Posts: 18,541
Ontario, Canada
StevieC Offline
StevieC  Offline
Joined: Aug 2008
Posts: 18,541
Ontario, Canada
Do a follow-up once you figure it out! thumbsup


'18 Highlander - AMSOIL SS 0w20 / ATF / Severe Gear
'06 Santa Fe - 535,000km AMSOIL SS 0w30 / ATF (R.I.P)
Re: Overheating at Idle [Re: fenixguy] #4569664
11/10/17 10:26 AM
11/10/17 10:26 AM
Joined: Jun 2003
Posts: 5,921
Illinois
SHOZ Offline
SHOZ  Offline
Joined: Jun 2003
Posts: 5,921
Illinois
Maybe the t-stat sticking?


2008 Hyundai Accent 1.6L 5 sp manual hatchback
2010 Hyundai Genesis Coupe Track 2L Turbo 6sp manual
Re: Overheating at Idle [Re: StevieC] #4569679
11/10/17 10:37 AM
11/10/17 10:37 AM
Joined: Feb 2017
Posts: 314
NC
fenixguy Offline OP
fenixguy  Offline OP
Joined: Feb 2017
Posts: 314
NC
Originally Posted By: StevieC
Do a follow-up once you figure it out! thumbsup


Will do!


'16 Frontier SV 4x4-PP/Nissan OEM
'08 CR-V EX AWD-Valvoline Syn MaxLife/Fram TG
'01 Civic EX-Valvoline Syn MaxLife/Fram UG
'00 Civic LX-PYB/Fram UG
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