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Car Forum / Honda Cars / January 200795 Accord runs hot on freeway
I have a 95 Accord which starts to run hot after about 15 to 20 minutes of driving on the freeway. It runs at normal temperature on surface streets. I know for sure that the fans are working properly. I’ve taken it to 2 mechanics and one says it’s the main fan motor and possibly the thermostat. The other mechanic thinks the radiator needs to be replaced due to a clog, and if not that, then it is most likely the head gasket leaking. I’m really confused here. Any help would be greatly appreciated.  SignaturePosted at author's request, using http://www.AutoBoardz.com interface Articles individually verified to usenet standards. Visit URL to contact author/report abuse Thread archive: http://www.AutoBoardz.com/95-runs-hot-freeway-ftopict203686.html > I have a 95 Accord which starts to run hot after about 15 to 20 > minutes of driving on the freeway. It runs at normal temperature on [quoted text clipped - 5 lines] > the head gasket leaking. I�m really confused here. Any help would be > greatly appreciated. take it for a run on the freeway. when it's hot, open the hood and look in the coolant expansion bottle. if you see bubbles, it's head gasket. if not, you can get it tested to be sure. if it's not head, go for thermostat and radiator, in that order. but before all that, make sure coolant level is ok - both in the radiator and the expansion bottle. >I have a 95 Accord which starts to run hot after about 15 to 20 > minutes of driving on the freeway. It runs at normal temperature on [quoted text clipped - 5 lines] > the head gasket leaking. I'm really confused here. Any help would be > greatly appreciated. Jim beam's advice is solid. I'd add that I suspect the radiator more than the thermostat because the heat builds up, but that assumes it isn't the head gasket. My own head gasket test is more sensitive but has the disadvantage that the leak may not be as obvious when cold. I test with a cold engine by removing the radiator cap and starting the engine. I pinch off the overflow tube and put the palm of my hand over the radiator opening for a few seconds. Steadily rising pressure or (worse) pulsations indicate a head gasket failure. If either jim's test or mine indicate trouble, shops can do chemical tests for hydrocarbons in the coolant to confirm the problem. Mike Thank you for the great and very helpful replies. I am going to try the things recommended here. Also, the mechanic that thinks it’s the radiator, says that since the radiator is plastic, it needs to be replaced. It cannot be flushed. Is this correct? Since I have never had to do so, what would be the best place to start to find a shop that can do the chemical test for hydrocarbons in the coolant > "pinkfloyd" <none@000.com> wrote in message > news:965002_e0d918b8d5f7b207ad5d229ebae4e321@autoboardz.com... [quoted text clipped - 38 lines] > > Mike SignaturePosted at author's request, using http://www.AutoBoardz.com interface Articles individually verified to usenet standards. Visit URL to contact author/report abuse Thread archive: http://www.AutoBoardz.com/95-runs-hot-freeway-ftopict203686.html Today I checked every recommendation posted. First I tried the cold method to check for possibility of bad head gasket. I pinched the reservoir hose, and placed my palm on the radiator opening. I did not feel any pulsating. Second, after a long drive on the freeway, when I stopped, I checked the reservoir, and there were no bubbles. Third, while driving on the freeway back home, when the car started to heat up, I turned on the heater full blast, and the temp cooled down right away. > Thank you for the great and very helpful replies. I am going > to try the things recommended here. Also, the mechanic that [quoted text clipped - 5 lines] > to start to find a shop that can do the chemical test for > hydrocarbons in the coolant? pinkfloyd <none@000.com> wrote in news:965321 _bbd9486094e485fede355cb837e57234@0000.com: > Today I checked every recommendation posted. > [quoted text clipped - 8 lines] > heat up, I turned on the heater full blast, and the temp cooled down > right away. Then your rad is internally blocked (or the fins have fallen off). SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ > pinkfloyd <none@000.com> wrote in news:965321 > _bbd9486094e485fede355cb837e57234@0000.com: [quoted text clipped - 13 lines] > > Then your rad is internally blocked (or the fins have fallen off). First put a new Honda thermostat in it.Not some aftermarket TS,a real Honda TS. SignatureJim Yanik jyanik at kua.net >> pinkfloyd <none@000.com> wrote in news:965321 >> _bbd9486094e485fede355cb837e57234@0000.com: [quoted text clipped - 16 lines] > First put a new Honda thermostat in it.Not some aftermarket TS,a real > Honda TS. It's not his thermostat. I'm sure of that. SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ > >> pinkfloyd <none@000.com> wrote in news:965321 > >> _bbd9486094e485fede355cb837e57234@0000.com: [quoted text clipped - 18 lines] > > It's not his thermostat. I'm sure of that. [snipped] Could be it is not opening all the way causing the temp to run hot. Using the heater as a mini radiator helps to lower the temp. Of course that would also work if the radiator was partially blocked. > "Tegger" <tegger@tegger.c0m> wrote in message >> It's not his thermostat. I'm sure of that. > > Could be it is not opening all the way causing the temp to run hot. > Using the heater as a mini radiator helps to lower the temp. Of > course that would also work if the radiator was partially blocked. Heater core flow is completely independent of the thermostat. Inlet flow is from the head's outlet end, and outlet flow is downstream of the thermostat. In other words, the same circulation feeds the heater core that occurs in the head/block due to the thermostat bypass when the thermostat is closed. SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ >>> pinkfloyd <none@000.com> wrote in news:965321 >>> _bbd9486094e485fede355cb837e57234@0000.com: [quoted text clipped - 18 lines] > > It's not his thermostat. I'm sure of that. at that age,it's certainly suspect. Besides,just how much heat can the heater core dissipate,if it cools down his motor? Maybe he's got a worn water pump too. SignatureJim Yanik jyanik at kua.net > Tegger <tegger@tegger.c0m> wrote in >> It's not his thermostat. I'm sure of that. > > at that age,it's certainly suspect. There's certainly no harm (and lots of good!) in replacing the thermostat while the cooling system is in dry-dock, but the thermostat is not the OP's particular problem here. See my other post. > Besides,just how much heat can the heater core dissipate,if it cools > down his motor? Maybe he's got a worn water pump too. The heater core is an amazingly efficient heat-dump device. You wouldn't think so due to its size, but it is. It can very easily compensate for a rad that can't shed as much heat as it was designed to. SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ > The heater core is an amazingly efficient heat-dump device. You > wouldn't think so due to its size, but it is. It can very easily > compensate for a rad that can't shed as much heat as it was designed > to. But it can't compensate for a thermostat that's stuck shut! SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ >> Tegger <tegger@tegger.c0m> wrote in > [quoted text clipped - 6 lines] > OP's > particular problem here. See my other post. That's my view. The thermostat is a good target because it's inexpensive and probably due for replacement while the coolant is drained, but the symptoms are pretty classic for a plugged radiator. The plastic tanks in the radiator are also plotting to crack, I'm sure. Remember, 'pinkfloyd' - OEM only on the thermostat and be sure the system is properly purged of air when the system is refilled with Honda premix (never add tap water). When you replace the radiator and thermostat, you can Set the Controls for the Heart of the Sun and still stay cool. ;-) Mike >>> Tegger <tegger RemoveThis @tegger.c0m> wrote in >> [quoted text clipped - 28 lines] > >Mike I apologize, but I don’t understand about setting the controls for the ’Heart of the Sun and still stay cool’. Thanks for all your help. It is greatly appreciated. SignaturePosted at author's request, using http://www.AutoBoardz.com interface Articles individually verified to usenet standards. Visit URL to contact author/report abuse Thread archive: http://www.AutoBoardz.com/95-runs-hot-freeway-ftopict203686.html >>When you replace the radiator and thermostat, you can Set the > Controls [quoted text clipped - 7 lines] > > Thanks for all your help. It is greatly appreciated. "Set the Controls for the Heart of the Sun" is from 'Umma Gumma' - my fave Pink Floyd album ;-) Mike <snip> > Maybe he's got a worn water pump too. pump can't wear in a way that reduces flow - there's no parts that touch. jim beam <spamvortex@bad.example.net> wrote in news:L9-dnexQr- 2Ppy3YnZ2dnUVZ_vrinZ2d@speakeasy.net: ><snip> >> Maybe he's got a worn water pump too. > > pump can't wear in a way that reduces flow - there's no parts that touch. is the impeller plastic or metal? IMO,plastic can degrade,even immersed in the coolant. SignatureJim Yanik jyanik at kua.net > jim beam <spamvortex@bad.example.net> wrote in news:L9-dnexQr- > 2Ppy3YnZ2dnUVZ_vrinZ2d@speakeasy.net: [quoted text clipped - 5 lines] > is the impeller plastic or metal? > IMO,plastic can degrade,even immersed in the coolant. metal. you're right, it can corrode, but rarely does. i wouldn't call degradation wear, but yes, that's possible. >> jim beam <spamvortex@bad.example.net> wrote in news:L9-dnexQr- >> 2Ppy3YnZ2dnUVZ_vrinZ2d@speakeasy.net: [quoted text clipped - 9 lines] > metal. you're right, it can corrode, but rarely does. i wouldn't > call degradation wear, but yes, that's possible. ISTR reading somewhere about a water pump impeller that had worn away.It didn't say whether the impeller was plastic or metal. also,I believe an old thermostat could open only part way,and pass -some- coolant,but not enough,explaining why the heater core could dump enough heat to keep the motor cool. I really do not believe a heater core can dump enough heat -by itself- to keep a motor cool. Otherwise,there would be no need for such a large radiator at the front. SignatureJim Yanik jyanik at kua.net <snip> > also,I believe an old thermostat could open only part way,and pass -some- > coolant,but not enough,explaining why the heater core could dump enough > heat to keep the motor cool. I really do not believe a heater core can dump > enough heat -by itself- to keep a motor cool. Otherwise,there would be no > need for such a large radiator at the front. it depends. it's all a matter of the energy that can be transferred per degree of air temp difference. if the energy coming out of the coolant is less than that which can be dumped through the heater matrix, then it definitely can. you'd need to know the numbers to be sure. >>> jim beam <spamvortex@bad.example.net> wrote in news:L9-dnexQr- >>> 2Ppy3YnZ2dnUVZ_vrinZ2d@speakeasy.net: [quoted text clipped - 12 lines] > ISTR reading somewhere about a water pump impeller that had worn away.It > didn't say whether the impeller was plastic or metal. Some Fords have had problems with eroded impeller pumps. It isn't clear whether the impellers are steel or aluminum, magnesium, or other metal, but the picture I saw was clearly of metal. IIRC dissimilar metals in inadequate coolant were involved. Mike pinkfloyd <none@000.com> wrote in news:965002 _e0d918b8d5f7b207ad5d229ebae4e321@autoboardz.com: > I have a 95 Accord which starts to run hot after about 15 to 20 > minutes of driving on the freeway. It runs at normal temperature on [quoted text clipped - 5 lines] > the head gasket leaking. I’m really confused here. Any help would be > greatly appreciated. If it runs fine on city street but not on the highway, it's most likely a clogged rad. A test: Next time it starts to overheat, turn the car's interior heater on full-hot, along with the fan on full-blast. Does this make the needle go down? If so, the rad isn't cooling properly. One thing to check is the fins at the bottom of the rad. If they corrode and turn to dust, the rad will be unable to shed heat efficiently. SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ Anybody check to lower hose on the radiator,I have heard of a lower hose that would collapse at high RPM from the water pump. The lower hose contains a stint when new to prevent this from happening. That stint maybe rusted away allowing this action to take place. > pinkfloyd <none@000.com> wrote in news:965002 > _e0d918b8d5f7b207ad5d229ebae4e321@autoboardz.com: [quoted text clipped - 18 lines] > One thing to check is the fins at the bottom of the rad. If they corrode > and turn to dust, the rad will be unable to shed heat efficiently. |
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