omerfar23

Help – Civic EX overheating
My 1999 Civic EX (213000) miles is overheating. The car only heats up when driving at 70mph on the highway with AC on.
1. The gauge only goes up slightly and dances if I keep up or each off. Both Radiator hoses are extremely hot. Overall, there seems to be a lot of heat under the hood. Not leaking any coolant.
2. The car gets to normal temperature very fast from cold start. Both main radiator and excess reservoir do not loose coolant
3. No leak or steam. When I popped the radiator cap off, I see bubbles but they are not splashing out. No coolant on the dipstick. Dipstick is usual brown. No white smoke out the exhaust pipes
4. CEL is on for P1337 (crankshaft position sensor), P0153 (Oxy Circuit slow), P0132 (Oxygen high voltage) and P0133 (Oxygen slow response)
5. Heat Shield rattles when accelerating – possibly manifold leak or crack. UNCONFIRMED
6. Timing belt and water pump were replaced about 40,000 miles
7. Checked the fan, it kicks when things get hot. Radiator is old and missing fins.

Thermostat – Car is fine at idle and in traffic, both radiator pipes are warm/hot. So does this indicate the thermostat is good ?

Radiator – Not leaking any coolant, old/missing fins. Not pressured test yet. Should I do a pressure test?

Fan – Kicks in on-time. Not missing any pieces. Good shape overall.

Water pump – relatively new pump, haven’t check pressure? How to test this specifically?

Head Gasket – No coolant in oil but overall under the hood the car is very warm. How to test for this?

Heat from the possbile manifold leak causing issues?

I will do a flush today and pressure test the water pump with hand. Any other ideas.


[RESOLVED] After changing the thermostat, cleaning the old radiator with special coolant, and doing a full flush with new fluid the car is running without any heat issues for last 2k miles (knock on wood).

EJ8mike

Well since ur rad is old/missing fins, i would replace that.

Also, only ur upper rad hose should be hot. The lower one is supposed to take cooler coolant from the rad to the engine.

I would replace rad & bleed system, then go from there.

omerfar23

Will try that. Should I replace the thermostat? I already bought it and my gut says thats the not problem. I guess it can't hurt.

EJ8mike

Yes, do it too....easy.

teamXteg

may seem dumb man but when u take off your radiator cap, look at the little rubber o rings on the inside of the cap. i drive mine for work. lots of miles for work and everytime i would come home it would be steaming. i popped the cap off and half the gaskets/ o ring under the cap were missing. idk if its from just normal wear and tear. but worth a quick look and a quick fix for me

omerfar23

I changed the thermostat but the car still overheats on the highway a little bit.

i slowed down on the highway and turn the AC off and the car cooled down.

Can the car overheat because of leak in the exhaust? The car sounds very loud and seems to have a rattling sound from exhaust?

Any ideas? Change the radiator?

CFiannotti

Since your fan comes on properly,and it is still "overheating,I suspect there is a clog in the radiator. If you are driving high speed = higher RPM,and have less cooling efficiency from an old radiator,I would change that first.

EJ8mike

Yes! Radiator....do it! I said change t-stat only cuz u already had it and thought you were gonna do them at the same time. Your radiator is not efficient enough.

omerfar23

i will do that but I hate throwing parts at it. Can overheating can be connected to exhaust possible leak?

EJ8mike

Not that im aware of.....

omerfar23

is the radiator for auto or manual same for 99 civic? i found one on craigslist in very good condition for $20 but its from an auto tranny car. I have a stick shift.

EJ8mike

Yea, you just plug up the 2 ports on the bottom of the radiator that are used for the auto tranny cooler lines.

EJ8mike

Before u buy that used radiator, test for leaks by Putting a garden hose into the upper inlet and running water thru it.

black97civic

Just pull the readiator out and run a hose through it. If a bunch of **** comes out it probably clogged. Use common sense on the radiator fins. They are there because of surface area. The more surface area the better it will cool. If there all smashed its not gonna cool. An exhaust leak may cause your oxygen CELs if its before the o2 sensor but I'm not for sure. If it sounds like its leaking then its leaking. Also your radiator cap plays an important role so if the oring is messed up then replace it. The cap has to hold pressure to raise the boiling temperature of the coolant. A bad cap can cause overheat. I can't say I've seen it on a Honda but I've seen that on other vehicles. When you took the cap off and it was bubbling do you think it was bubbling because it was Boiling? Did you take the cap off when it was hot? Or do you think they were air bubbles?

omerfar23

Good idea about running water through the radiator. I will do that today before i get a new radaitor.

The cooland was boiling when i took off the radiator cap. I took off the cap when the car and radiator was hot.

HondaPartsHero

Do both your fans come on or just your cooling fan?

black97civic

Ok you don't want to take the radiator cap off if the engine is hot. They can explode I've personally had that happen. Burned my arm and face pretty good. If the water was boiling when you took the cap off and it didn't explode then. 1. The cap is not holding pressure or 2. You coolant is really low. So you may want to change the cap.

black97civic

Good question

omerfar23

The radiator fans turns ON when it is getting hot. the other fan, I believe is for the AC condenser. The AC condenser fan turns on righ away when I push the AC button in the cabin.

elton 4302

meu honda estava com problemas iguais ao seu, troquei varios componentes, valvula, mangueiras bomba dagua, entre outros itens tampa do radiador e todas as peças originais, e o problema persistia, quando percebi uma diferença na tmpa do radiador notei que tinha um espaço pra chegar até o final ou seja so vedava a parte de cima do radiador a parte de baixo ou aquela mais no fundo a tampa não alcançava, isto fazia com que o honda esquentasse demais,a ponto de esplodir mangueiras ok tente verificar a tampa faça medidas de uma e outra

jay19

I had the same problem and changing radiator resolved it.

black97civic

YEH!! What he said.

omerfar23

According to Google translate from portuguese:

My honda had problems similar to yours, I changed various components, valve, hoses, water pump, among other items radiator cap and all original parts, and the problem persisted when I noticed a difference in mtpy noticed that the radiator had a space to get to the end that is so prohibited the top of the radiator to the bottom or that the cover over the bottom not reached, this meant that the honda warmed too much, to the point of esplodir hoses ok try to check the cover to make measurements of a and another

I don't really understand what you mean by the placement of the radiator? Do you mean the feet of the radiator weren't settled down all the way?

Also general update:

A. Replaced the thermostat and no change in the condition. I am still drivnig my usual400 miles weekly and the car does't overheat unless I tax the car with AC and over 3000rpm. So i just drive at 60 which keeps the temperature at normal for 1 hour drive in the morning and afternoon.

B. Flushed the radiator and have a special blend of coolant that is supposed to clean the gunk. I got this from advance auto parts. Today, I will flush the coolant, run a garden hose directly to the radiator and clean (with car off), run the hose directly to the engine in place of the upper radiator hose (with car on) and replace the coolant with full-strength anti-freeeze. If this doesn't fix the problem I have already purchased a new radiator and I will that in that next week.

Will keep everyone updated. thanks.

omerfar23

Update - 7/25/2013: Last week I flushed the entire cooling system.

1)I remove the special blue coolant blend that I got from Advance Auto parts. I drove about 300 miles/6 hours of driving with the special coolant blend. When I remove the special blend I didn't see major gunk or particles from the radiator.

2) I topped up with new full strength coolant (mix with 50% water).

At this point, I have driven over 200 miles and no overheating yet. I have started to tax the car more gradually (70 mph and AC on 80 mile round trip daily) and still no overheating, but the weather is less severe (80’s vs 90’s degrees) than before. I will report back after 1500 miles with an update. I have already purchased a new radiator. If the car doesn’t overheat for next 3000 miles I will chalk this up as “fixed” otherwise I will continue throwing time and money at this car. 

elton 4302

good night my 93 honda turned warm, I do not know it masi omque change someone has gone through this problem give me a hint, I changed pump hoses lid and sensors