Heater Not working
 

Hi guys i have a 2001 Honda civic auto.

This past week my heater has been acting really weird. The heat comes and goes as i drive. It takes about 10minutes for any heat to come on and after it does come on it will go out after 3-5minutes then come back on after 4-5minutes then off then back on and then stays on until i arrive at my destination.

The car warms up as it normally does and reaches just below the half way mark on the gauge. That happens within 2-3minutes of driving. Its about 2/4C(34-37F?) here in toronto.

I even tried remote starting my car for 10minutes inside my garage(with the door open..lol) and my engine was just below half way point on the gauge but still no heat for about 10minutes and then it kept coming on and off 2-3 times then it stayed on. Also when it does come on it comes on at fully temp(super hot)


What could it be?

Thanks for the help guys. Its getting cold up here in canada. lol

Re: Heater Not working
 

you have air pockets in your coolant/rad/heater core....


this is most commonly caused by a blown head gasket,

check the coolant level in your rad and overflow bottle when the engine is COLD....the rad should be full to the top, the coolant bottle/overflow should be between the min and max lines,

if either of these are low, top them up with "blue" OEM coolant from honda, DO NOT USE ANYTHING ELSE!

after you do this drive the car for about 15-20 mins, then stop and check the level in the overflow bottle, it should be slightly higher then it was when cold,

DO NOT OPEN THE RAD when the engine is warm/hot

Re: Heater Not working
 

okay ill check that today after work. how do i check if its caused by a blown head gasket or some other reason. My car seems to run fine.

1.is the head gasket replacement something i can do. I work on my car. Nothing crazy like engine swaps but all the maintenance stuff.
2. approximate cost? for part?

thanks

Re: Heater Not working
 

what you are describing in your original post (air in the cooling system) is the first sign of a blown head gasket,

if your overflow coolant bottle starts to fill up and overflow with coolant, this is another sign of a blown head gasket....you will need to top the system up first to see if this happens,

you can have a compression test done on all 4 cylinders or do it yourself if you like, this is another way of diagnosing a bad head gasket,

a head gasket replacement is a MAJOR job and will cost big $$ if you can not do it yourself,

basically your stripping the engine right down....you will need to remove the exhaust manifold, the intake manifold, the timing belt, the valve cover, and remove the cylider head....this is not a job for your average "oil changer" home mechanic....

i can not say if you are able to do it on your own, only you can decide that for yourself,

Re: Heater Not working
 

thanks so much for the info mikey. I noticed another thing while driving. When my foot is on the gas the hot air comes out of the vents. When i get to a stop light and my foot is on the brake, the air keeps getting colder and colder until the light turns green and i put my foot back on the gas. What does this mean? So i guess my initial comment bout it randomly cycling on and off was wrong. IT is actually on when im driving and off when i get to a stop light or park the car.

any thoughts?

Re: Heater Not working
 

could be a clogged heater core, or air in the system like i said,

check your coolant levels, i cant conclude anything until you do that

Re: Heater Not working
 

oh sorry i forgot to say i checked my levels and it was a bit low. I topped it up.

I am not sure why the heat is only coming while i press on the gas and stopping when i come to a stopped. I got rid of any air in the sytem. but as you said if its the head gasket i am guessing it is continuously getting into the system? would that make sense? as i move forward and press on the gas air is pushed out of the system and then when i get to a stop air is coming back in?

thanks again so much mikey1. I guess if i can figure it out ill take it to a mechanic but i would like try and do it myself especially since its such a odd problem that it only comes on when i push the gas pedal. IF it was not blowing hot air at all that would be a different story.

Re: Heater Not working
 

if it is the headgasket how much would an independent mechanic charge for it? i was reading honda charges almost $3500!! my car is probably only worth 2.5K lol

also what would happen if i drive with a leaky headgasket? would it just be this heating problem? or would it be something else like over heating?

Re: Heater Not working
 

the head gasket is continuously letting air into the cooling system,

the heater core is the highest point in the cooling system, so air gets trapped there at idle speed and can not get out because the water pump is turning slow at idle speed,

when you stomp on the gas (engine revs higher) the water pump starts turning faster with the engine speed, so there is now enough pressure/flow to push the air out of the heater core, then the heater core will be filled with warm coolant, hence you now have heat,

when you stop and idle, the whole cycle repeats itself, the air will go back into the heater core,

hard to say what an independent shop would charge as rates vary so drastically....i think $1500 would be at the cheap end of the scale, and increasing from there,

its best to have the problem diagnosed by a shop, dont just walk in and say "i want my head gasket replaced" because if they do that for you and by some odd chance it does not solve the problem, they are just going to say "we did what you asked",

i am just outside toronto, if it wasnt so cold out i would do it for you, LOL

Re: Heater Not working
 

perfect thanks so much mikey. aww man i would have def brought you the car. some cash and a case of 24! :)

i shall get it checked out hopefully tomorrow. thanks again.

Re: Heater Not working
 

let me know what the lowest price is you get, i might make you a better deal :)

Re: Heater Not working
 

I think I have the same issue, just trying to make sure before I sink $1500CDN into the car (quote is for head gasket and timing belt replacement).

Symptoms:
When idling car starts blowing cold air (or non-heated air, can't tell I live in Canada and its -15'C outside right now).

I have replaced the thermometer and did a coolant flush but that only worked for about a day, then the symptoms returned.

Oil reserve appears to be clean, i.e. no coolant is mixing. However, I did notice some oil mixed in the coolant when I changed it.

Car has 305K on it, do I suck it up and pay for the fix or just buy a new (used) car?

Re: Heater Not working
 

Yep, blown.....

How long have you had the car? How well did you maintain the rest of the vehicle? If it's falling apart, get a new one. If you put lots of repairs (non-engine) into this one then keep it!

If the engine has 305k on it, you may as well try for a used engine rather than going the head gasket route, whatever you find is cheaper.... and depends on the state of your current engine.

Did you maintain it well? Changed fluids frequently? Changed replaceables often enough (water pump, timing belt (twice?), valve clearance, air filter, etc... Did it ever overheat?.. If it did, throw the engine away, probably won't be able to machine it for the new gasket anyway.

Re: Heater Not working
 

I have taken very good care of the car, and other than this the car has been great. I put roughly $500-$1500 a year into it for mostly maintenance stuff, brakes, struts, a/c replacement, new tires, ball joint, this is the first real engine issue.

Engine has never overheated.

Since there is no coolant leaking into the engine am I ok to continue to drive the car, or will I damage something?

Re: Heater Not working
 

Wow, well in that case I would definately keep the car. Head gasket "should" be a once in a car-lifetime thing so it's doubtful you will ever see it again, but you never know! Yea, HG is a $900 job and timing belt, etc is about $600 so $1500 seems right. Since the engine has never overheated you should be ok putting a new gasket on it, likely no warping has taken place.

You "can" drive it, probably won't do any harm, but be very very cautious! You never know when the leak will become severe; could happen in an instant and if you don't notice and the engine overheats.. ugh...

If you want to save some money and are relatively technically inclined, you could do the HG and timing belt on your own and save some money. Lots of DIYs in the forums on the topic! If you're not too sure, better leave it to the pros.

Re: Heater Not working
 

Watched a few videos on this, and I don't think I 100% comfortable doing this, lots of areas to make a mistake.

One thing I did notice is that the timing belt comes off when you take off the valvetrain assembly, why would I be charged $500 for this? Am I missing a something?

Re: Heater Not working
 

The timing belt does not have to be removed from the engine to do the head gasket job.
It only has to be slipped off of the camshaft gear.
I can accomplish this with only the upper timing cover removed, I do not need to take apart all the rest of the timing belt area.
Other mechanics may or may not do the same.

You will be paying for the rest of the disassembly required to actually get the timing belt removed from the engine and replaced.....
although I'm not too sure about the price you were quoted (but that's not my area).

If it already has 305k on it, I'd say to replace the tensioner pulley and spring set with dealer parts if it wasn't replaced during the last timing belt service.
Replacing the water pump may be a good idea too, if it hasn't been done recently.


HTH

Re: Heater Not working
 

Replace the Thermostat first...sound exactly like my issue, and cost a million times less than a head gasket inspection

Re: Heater Not working
 

Last year when my HG went, I bought parts(timing belt, water pump, HG, etc) from the dealer, with a total of ~$700. My mechanic charged me $600 for labor. Total cost for the repair was $1300.