overheating when crusing.. please help
 

My car keeps overheating even when not boosting, just cruising on the highway at 2500 rpm. I just replaced the rad cap and thermostat and bled system. I noticed that the lower rad hose is usually cold, but sometimes it gets warm. Upper hose is hot. I didn't see any coolant in the oil or oil in coolant. The fan works and sometimes my heat gets cooler and then gets hot again. Also the temp gauge goes full hot and then drops back down sometimes. Will usally cool down if i just put the car in neutral for alittle. I have a cometic headgasket and arp head studs with about 4000 miles on the engine. I boost about 8 psi. Has been overheating for a few weeks. Any help is greatly appreciated.

Re:overheating when crusing.. please help
 

You might have finally lost your water pump. If one hose is cold it sounds like you arn't getting circulation.

Re:overheating when crusing.. please help
 

I would hope its not the pump. Its got less than 5000 miles on it.

Re:overheating when crusing.. please help
 

Have you ever had your system flushed? Maybe you have some blockage? Might want to flush the radiator too.

Re:overheating when crusing.. please help
 

you thermostat is probly goin out on you. just change it and see if it keeps happening

Re:overheating when crusing.. please help
 

crx2fast- I just replaced the thermostat and rad cap before I posted. I thought it was the thermostat, but replacing it didn't help. Do you think this one is bad also?

95RedEX- I've never actually had it flushed with a machine or anything but when I built the engine and installed it about 5000 miles ago I made sure everything was clean but I don't remember flushing the radiator. I'm gonna do that now.

Thanks for the help guys. Keep it coming

Re:overheating when crusing.. please help
 

mgiht be the radiator, check the bottom hose for any leaks, if not, i'd put money on the water pump, maybe the timing is off and its making the pump act weird

Re:overheating when crusing.. please help
 

i got 5 bucks on the headgasket is shot

ive been there a few times

Re:overheating when crusing.. please help
 

would bad rings be another culprit?

I am about to rip apart my b16, and it does the occasional heat up thing.

Re:overheating when crusing.. please help
 

Well I'm gonna cancel out the radiator as being a cause. Just flushed it and it flows great. Took the car out for 10 mins, boosted once for like 3 seconds got off the gas and cruised and it overheated again. Pulled over, lost my heat. Lower rad hose was cold. I let my car cool down, then drove home and didn't boost. The temp was about 3/4 on the gauge by the time I got home. I love it! I'm thinking its the pump, but I don't know how its not pumping.

Re:overheating when crusing.. please help
 

Maybe we need to step back a minute... What all have you done to this car recently? I know you said your replaced the radiator cap and thermostat. You rebuilt the engine so I'll assume that's why you have a new headgasket & ARP studs. I'll assume the coolant is 5,000 miles old too and the correct mixture of water/coolant.

When I said flush the radiator, some oil change places will do it for like $50 or so. They hook up your car to a machine and runs some cleaning ---- through to get everything out of everywhere. What's gets me though is the hot and not cooling pipes. ???

For the life of me, I can never remember which way the cooling system flows. If one pipe isn't getting hot, it means you're not circulating coolant at all. I would almost suspect your thermostat and for the 8 or 9 bucks, I would try another, maybe something with a lower heat rating than the one you swapped in. Beyond that, if one is getting warm and the other is getting hot, I would guess that the thermostat is opening, but the pump is not circulating the water fast enough. I really don't even understand HOW the pump works and how it can fail, but it does happen... :-\

Either that or bleed the system again. For at least 20 minutes. Keep adding and squeezing your pipes until no more air comes out. And make sure your fan works too. See where your temp is at when it kicks on. Let us know what happens. ;)

Re:overheating when crusing.. please help
 

I wonder if taking the thermostat out completely would show whether or not you have any internal blockage?

When you purged your system, did you turn the heat on too?

Re:overheating when crusing.. please help
 

Thanks for the help 95RedEX. I've got a built turbocharged d16a6. I also have a block guard which i believe could cause the car to overheat but my engine was not overheating even on hot days in the summer. It has just been happening recently. When i put the engine in approx. 5000 mi ago I put a new honda oem water pump and thermostat with a 50/50 coolant/water mixture. Since the overheating I was just adding water when the radiator was low. I decided to replace the rad cap because I have no idea when the last time it was replaced. The symptoms I had led me to believe I had a bad thermostat and possible air in the system. So i threw in a new stock temp(I believe 180 degree F.) stant thermostat and tried to bleed the system. I filled the radiator with the bleed screw open until coolant came out and closed the bleed screw. Then I started the car and turned the heat on full hot high blower and added 50/50 mix until the rad was full. I let the car run for at least 40 mins fan never came on. My heat was hot. I took the car out for a drive and it overheated in a few mins. Pulled over overflow full and fan on. Heat got cooler and lower rad hose was cold. I let the car cool down refilled rad and drove home. Car got real hot again on the way home. When I got home the fan was on and the lower hose still cold. Still no circulation. Pump? Blockage in rad? Thermostat? I took the upper and lower hoses off the rad and flushed it with a hose real good. It seemed to flow very well. Refilled cooling system and took it out for a drive. Overheated again- that was my last post. Lower hose still cold. Next day I tested both thermostats. I heated water till 190 degrees and dropped the honda one in. It seemed to open all the way. Removed the stant from my car and tested that also. It also opened. I decided to run with no thermostat. I filled up the cooling system and started the car. I let it run for alittle and the lower hose got pretty warm. I also squeezed the lower hose. I could feel the coolant flowing. Yay!!! Pump seems ok!!! Took the car out for a spin. Got on the highway and boosted a couple times. The temp gauge didn't budge. I gotta get going. I'm gonna post again later and let you know what happens. sorry so long and i hope it makes sense

Re:overheating when crusing.. please help
 

removing the thermostat will just prolong the time until you see the symptoms....

Re:overheating when crusing.. please help
 

you think my symptoms point to headgasket as you stated earlier? what do you think is going on?

Re:overheating when crusing.. please help
 

Aren't block guards notorious for adding heat? ???

Re:overheating when crusing.. please help
 

I was thinking about this again this morning... How are you purging the air? You should set the heater control to hot, open the radiator cap and then start the car. It really doesn't matter if the overflow is filled, but the radiator should be filled to the top. Let it run for awhile and you can try to bleed it with the bleed screw, but IMO, that thing is worthless.

While it's running, grab the radiator hoses and give them some quick squeezes to try and burp any air pockets out. You want to do this for awhile until the thermostat opens and recirculates the water in your engine (hopefully bringing some air with it). The level in your radiator is going to go down or spill over... Just keep adding and squeezing and adding until you're 100% sure that the air is out.

I'm not sure if this addresses why your lower hose is cold, but ---- it, I'm sure you don't want to take Hotrex's advice and tear your head off just yet... ;)

Re:overheating when crusing.. please help
 

yeah, I believe so, but I didn't have any overheating problems for awhile. I don't think the blockguard is my problem. Also, I think it flows sufficiently. -just doesn't cool the top of the cylinder as much. here's a pic
[img height=500 width=650]http://usera.imagecave.com/ahsnowbd/DSCN0855.JPG[/img]

Re:overheating when crusing.. please help
 

You are right on me not wanting to rip the head off yet. It just seems to amaze me that that would be the problem. I've got arp head studs and a cometic head gasket and only running 8 psi boost. I'm sure there are plenty of people here reusing stock gaskets and used head bolts with no problem. Actually i know someone who is reusing headbolts and headgaskets with over 100k. mi and running 15 psi boost. I've tryed to bleed it how you said with the exception of squeezing the hoses. Maybe I still didn't get all the air out yet somehow. I'm gonna try again. thanks for the help

Re:overheating when crusing.. please help
 

If it's not the HG, Hotrex owes you 5 bucks. ;D

Re:overheating when crusing.. please help
 

If it is the HG I'm gonna be pissed. Anybody else using a cometic gasket? I thought they were supposed to be top notch.

Re:overheating when crusing.. please help
 

just do a compression test if you think it's the head gasket. i just replaced the radiator fan switch temp sensor cause my car would overheat after a while. the fans would come on when the car was in idle parked, but when the car got hot, the fan switch would stop working. no problems for 1 week now with the new fan switch sensor. i did a compression test and it was good. before that evyone would say headgasket, pistons, rings.lol did you install the thermostat backwards? just a thought. and i'd change the fan switch sensor if you've never done that.

Re:overheating when crusing.. please help
 

I'm gonna mess with it later today. I am positive I had the thermostat in the correct way. I should recheck the fan and make sure it is coming on when driving. I know it works but I have only seen it on when idling. I'd also like to do a compression test. I wish it was summer. I'm sick of this getting dark at 5:00 ----.
thanks for the advice

Re:overheating when crusing.. please help
 

my car was doing the same thing, then i tested my rad fan, and the fuse/relay was shot. so i rigged it up to a toggle switch and VOILA ! no more over heating :P