Hey guys, Ive been searching and trying everything and cannot figure out my overheating problem. The engine is a sleeved and built b18c1 in my 1993 Integra. The problem is that the temp gauge is going crazy and saying my car is overheating. The thing is that it is not steady at all, it will fluctuate up and down, wildly at times, anywhere icluding and between normal temp and almost all the way up. As soon as I turn the heating fan on, it will slowly go back down, which makes me think it IS overheating, but if that were the case, it would STAY hot and not fluctuate, right?

I have bled the system over and over, heater on full blast with front end of car jacked up for over 45 minutes at times, no air. No coolant in oil/oil in coolant. Compression and leakdown good. No bubbling or overflowing coolant reservoir. Brand new OEM thermostat, brand new PWR radiator, no visible leaks.

When I bleed the system, for the most part, it seems to not really overheat until I put the cap on, and when I go for a ride it will, for the msot part, stay at normal temp as long as I am moving.

I keep thinking that it really may not be overheating and it may be the temp gauge sender, but the fact that when i turn the heater on full blast that it comes down is really throwing me off.

Any input would be MUCH appreciated, I am very aggravated and upset here, and if someone can help me out they would be my savior and really make me happy!!!

 

Have you replaced the water pump? Do you have good flow? if you look in the radiator can you see the coolant moving?

Having the cap off or on shouldn't matter.

Is your fan coming on?

 

OK, sorry, I totally forgot to mention that it has a brand new OEM water pump, and that I also have the fan wired to run all the time. In case it comes up, yes, it is wired correctly and is set-up as a puller and is functioning perfectly.

With the cap off, the coolant appears to be circulating, although I honestly I do not know EXACTLY what it should look like, it appears to be whooshing (for lack of a better word) and pulsating and moving, and since it is not pushing out of the radiator nor are any of the hoses swelling, I am assuming it is moving correctly. Also, the bottom hose is hot as it should be, so that right there signifies functionality as far as I know.

Im totally stumped here.

 

Yea I asked about the pump and flow because I have had the pumps fin's/rotating assembly come off on the inside. looked normal from the outside(Not a honda)

Have you flushed the system? you might have a passage blocked or partially blocked.

I can't think of anything else.. I'm stumped too.

 

Red Line Water Weter!!! Do you have a deck brace?

 

No I have not flushed, I didnt bother and I know thats not the problem because the block and head were hot-tanked.

No, I do not have a block brace, just sleeves. Water wetter will not help here, but thank you for the idea.

Anyone have any ideas?

 

I would be so grateful if someone could help me out soon...I know you guys know how it is... I can barely sleep or function because I am so upset about this and its killing me

 

HHHHEEELPPP!!

 

it could be just a bad temp sensor........did you try replacing that?

 

No, I havent, but for some reason I dont think thats it, because of the fluctuation and the fact that it stops when the heater is on full blast.

Also, with the car off and cooled down, Ive noticed that the coolant level keeps dropping very slowly, even though it is NOT leaking internally/externally or into the overflow...strange...

 

Tire temp gun aimed at the radiator will get you a pretty accurate water temp reading.Any local stock car guy will probably have one.Do you have a wide band o2 ? Recheck The ignition timing.If your overheating with a stock radiator cap you should be pushing some coolant into the overflow.I have seen some sleeved blocks with alot of RTV (silicone) in them.This can block the rad. or thermostat.I have seen pump impellers spin on the shafts , but those just got hotter and hotter until they boiled over.

 

Thank you for the input...I actually went out today and bought a cheap water temp gauge. It could not fit in the stock location, so what I did was run the car with the cap off and the sender in the neck of the radiator. I ran the car at operating temp for over 20 min and it stayed solid at 190. I couldnt try any longer because the car died (another problem, as if I dont have enough), but the needle did not fluctuate as it normally does, last time it actually did not fluctate at all until I put the radiator cap back on, it did it almost immediately after????? I dont know why but it wouldnt "overheat" until the system was pressurized after the cap was on. There is some extra coolant in the overflow, but I think most of it is because I voerfilled the radiator.

Also, why would the level slowly keep sinking with the car cold and cap off? I keep adding and it keeps doing it, I know there is no air and the system is full? Wierd...

 

It still sounds like trapped air to me.The coolant your adding is :
1: Filling the air pocket
2: Filling the oil pan
3: Leaking on the ground
4: Leaking on the carpet from the heater core.

Thats pretty much your options

 

Thanks for the input, guys. The cap is a brand new one that came with PWR so that is good. I actually tried one that I know is good and that had no effect.

There is no coolant going anywhere so there must be some huge air pocket or something like you said...but when the coolant is slowly going down there is absolutely no bubbles coming up (as I described when the car is NOT running). Like I said, I also ran the car with the heater on full blast, rad cap off, and car jacked up as high as possible for like 45 minutes so there couldnt possibly be any air in the system. I also used the bleed screw. I thought maybe it was the coolant lines for my turbo (its installed but Im not boosting yet, everything is running as stock now), but they are low in the system and they are getting hot so they are working. Im very stumped here...

You were also saying the coolant can boil off...can this occur with the cap off? Even so, I just dont see how I can keep adding so much coolant and where it is all going???

 

1.) Does you overheating go away when you are moving?

2.) What kind of fan are you using? Is it an aftermarket (can you put a stock fan back on)

3.) Have you checked the ground for your water temp sender (have you replaced this sender?)

4.) have you tried to hook up an alternate temp gauge?

5.) Have your pressure tested your cooling system?

 

1. If I am moving, yes it does pretty much go away, the needle will fluctuate a tad still, though, at times, but for the most part will be pretty steady as long as Im going a decent speed.

2. Yes, it is an aftermarket 10" slim fan, I actually had the blade on backwards (It can be pusher or puller) and thought that was the problem but it is all fixed and made no difference.

3. There is no ground for the temp sender, it is one wire, and it is definitely working because as soon as I unplug it the gauge stops registering. I know it must also be good because if it were malfunctioning, when I turned the heater on it would still be fluctuating.

4. No I have not, but I tried the book test and it shot RIGHT to H, so it appears to be working.

5. No, I tried to do it yesterday, but the system I got did not have the correct attachment.

I keep thinking it is headgasket, that there is air getting in there, but if that were the case wouldnt the gauge still be fluctuating with or without the heater on and car moving because of the air getting into the system?

Also, as SOON as I turn the heater on (almost every time, but not always) the gauge will drop to normal temp instantly or very quickly..


All this stuff is confusing the crap out of me...the car NEVER had a problem before it was built.

 

maybe the o-ring in the water pipe thats on the back of the motor is bad...it's happend to me and i've had that pipe corrode and crack...you said you replaced the water pump did you look at that?

 

do you have a multi meter? if so, i can get some resistance specs for you, and you can ohm the sensor out. tell me if you need them

 

If that o-ring were bad I would be leaking coolant correct? I have absolutely no coolant dripping anywhere i can see, no spots on the ground whatsoever. I did have that pipe on and off a few times, but the o-rings looked decent. The pipe itself was perfect.

As for the resistance specs, I did check them and they were way off, but I was grounding it on a bolt on the valve cover and just assumed it was not a good ground. I know the gauge is good, because if I turn the heater on, or start driving at a decent clip, the gauge stops fluctuating and stays normal. If it were the gauge, Im assuming it would be doing it no matter what. Anyways, the resistance read 60-odd ohms I believe at oper. temp, but the rad cap was off and the gauge was not fluctuating so it wasnt overheating then.

 

Id also like to thank you guys so much for your help thus far...I really appreciate you guys taking the time to help me out here.

 

Bump for the fourth!

 

I would try to hook up an OEM fan.

My thought is that since your overheating goes away when you are moving, that you are not getting suffiencient airflow throught the radiator.

Therefore you may have one or both of the following problems

1.) The aftermarket fan is not drawing enough air through the radiator ( replace with OEM FAN aftermarket is NOT always better. Also if the aftermarket fan is not shrouded ok, it will NOT work like it's supposed to (see below)

2.) The Radiator has issues (replace the radiator)


My fan shroud story:

We had a race car that kept overheating, we could not figure it out.
we did the following steps:

1.) replaced Cap
2.) Replaced radiator
3.) added Water wetter
4.) Adjusted jettting (carburated engine)
5.) Adjusted Timing
6.) Pressure tested cooling systems & compression tested the motor
7.) Changed from an electric fan to a mechanical fan (Chevy 350 motor)

All of the air that went to the radiator went throught this mouth-like channel.
We decided to tape of all the little 1/4" cracks between the channel and the radiator with aluminum tape.

After doing this the temps dropped by over 20 degrees!

What was happening was that the air was flowing around the radiator through these cracks instead of through the radiator.


Like I said these were NOT huge Gaping holes, they appeared to be small, but it did the trick.


We were then able to put the timing and jetting back to where it was supposed to be

 

Bumpity!

 

Sending units can work some times and not others and cause the problem you are having even the gauge cluster can cause this. However it is time to stop being an idiot and find out where the coolant is going! As posted before you have a few things to check.
1) did yo uhave coolant coming out of the bleed screw?

2) HAVE YOU PRESSURE TESTED THE COOLING SYSTEM?

3)Did you look for leaks in the areas that other people listed.

4) If the system is free of air and the coolant level is still dropping YOU HAVE A LEEK SOME WHERE.

 

1. Yes, I did when I was bleeding the system.

2. Not yet, I cannot find an adapter for the Autozone unit.

3. I cannot see any leaks at all, there are no drops at all on the ground either.

4. It stopped dropping after a bit, I checked it today. The car is not running now so I cant run it to check if it drops more, but it should be up and running again tomorrow.