I thought I had finally gotten rid of the overheating blues...I flushed my system, bled it of all the air, and it drove nicely. I was pushing 120mph with no overheating problems, running <FONT COLOR="blue">cold as ice</FONT>

I went to pick up my friend and let my car idle with the turbo timer. Upon returning to my car, and turning it on again, I noticed it was pretty hot (maybe 4/5 to H). I popped the hood, and noticed my reservoir was completely full infact overflowing. There were also bubbles of air coming out of th ehose which ran into the reservoir.

Here is my theory, please tell me if it holds water (no pun intended)

I dont think my timer is wired to keep the radiator fan on. So while I was inside my boy's house, for the 1:00 my car was on, the fan wasnt turning. This pressure/heat caused some of my coolant to overflow into the reservoir, and eventually it was too much for the reservoir to hold, and it started leaking out. The lack of coolant made my car temporarily overheat.

When I turned on my heat ful blast, the temp slowly dropped, and it dropped even more once I started to drive (and i guess get the water pump spinning, right?)

does my theory of coolany being lost due to overflowing into the reservoir sound true at all? I am going home again this wednesday to troubleshoot, but I simply didnt have enough time to do it this weekend. I was honestly curious to know if i should be considering a new radiator, or if my cooling system is flawed in any way.

cliff notes:
new thermostat
fan motor good, relay good, fuse good
new thermo switch

car was left without rad fan on for a while after long drive
could this have caused a lot of coolant to overflow into reservoir, and contine to gradually overheat?

 

Start with the radiator fan and make sure it is turning on when the car gets hot. If thats working then bubles in the radiator could mean you have a cracked head/block or a leak in the system. Start with the simple things, maybe even pressure test your radiator cap, if its not holding pressure your car will over heat.

 

My money is on your headbolts or headgasket. I had a similar problem, my headstuds came loose and the EXACT same situation would always occur. My overheating got so severe that i couldnt drive the car, so i pulled the engine. I figured it was a blown headgasket, but when i went to loosen the headstuds they were at 30 ft-lbs of torque when i intially torqued them to 70 ft-lbs. I'd check your compression, it might be your headgasket. If its not the headgasket, its your headstuds/bolts.

 

yep, turns on just fine

cap is new

well i did a sompression test not too long ago, the numbers were fine. I just got the head resurfaced, and i put ARP studs in there...stock gasket. No smoke out of exhaust.

I was driving the car HARD all day long, for a constant 4 hours or so, and only when it was at idle did it overheat. And it only overheated because of the fans not turning on. I guess im asking.....

would this overheating without any fans cause coolant to overflow into the reservoir untill its full, and then leak out the reservoir cap?

 

Did you retorque your headstuds after heat cycling them? I am betting that they have backed off, and are the root of your problem.

As far as the your car overheating and leaking coolant out of the resevior, I dont that it would happen. I have had my car overheat full tilt, and no coolant would leak of the resevior. I had a slight increase in resevior level, but not running out. I only had coolant running out when my headstuds got loose.

 

Check if your fan is turning on during idling, it sounds like that might be, but what boosted says sounds about right to me. Check your coolant system for presure and what presure is your radiator cap?

 

no i didnt...but wouldnt this also make my car overheat while driving, and boosting?

well my reservoir was completely full, and the top of the reservoir where you screw the cap on was wet with coolant, and it was leaking down the side

cap is stock. The fans were NOT turning due to the fact that when I wired up my turbo timer, i didnt wire it so the fans would stay on. (not on purpose)

if my studs were not torqued down, wouldnt it leak even worse while boosting 7psi driving, then just at idle? Before this happened, when I was driving all was well and nothing was wrong...no leaks, no overheating.

SINCE the fans were NOT on, and my car was left to sit and just get hotter....wouldnt this cause coolant to go through the radiator cap, into the overflow? And hypothetically if the reservoir cap wasnt on really tight, could coolant leak out here?

When i looked under there...my reservoir was full, and air bubbles were coming out of the hose which fed the reservoir. Once I started to drive it cooled down (i think because the water pump was spinning faster)

 

I have the EXACT same problem. So far i have swapped radiator, cap, thermoswitch, thermostat, and headgasket. I have not had a chance to try it out yet till i throw on the new tranny tommorow.

BTW
Can you explain to me what "heat cycling" is?????????

 

I just took it to mean after they heated up and possibly backed off a little.

boosted- im not knocking your theory of the studs being loose, i just dont want to retorque them unless i need to.

im confused why they would cause it to overheat at idle but not full boost for like a 10 second spurt

 

maybe your water pump?

 

got it replaced 1000 miles ago

 

If there is a leak anywhere in your coolant system, it will overheat. Go through and make sure everything is snug, if there are air bubbles, then air is in the system and it wasnt bled good enough or is a leak. If it comes to it put dye in your coolant and use a blacklight, it will find the little leaks!

 

I have the *exact* same problem, and replacing the radiator cap seems to, ummm, change the problem. I replaced the stock cap with one from Napa. A 1.6bar cap. And now my radiator doesn't boilover anymore (because the new cap is holding pressure, which raises the boiling point).

The problem I have now is that I am burning coolant in the engine, and blowing white smoke out the exhaust on restarts when my motor is hot.

I did a compression check too, and it looked fine. I am going to replace headgasket and see if this is it.. I am LOST as to what it could be if my headgasket isn't bad...

 

my next step is a new radiator and a new cap.


I checked for leaks, all is well

 

If I recall correctly, ARP head studs need to be re-torqued period.
Most peeps dont want to re-torque them, so they over torque on initial install.

I think you have blown headgasket symptons.

 

New headgasket. I was going 120 on the highway at full boost with no overheating problems. If the studs were loose I think I would have found out then, right?

it overheated because of me not leaving my rad fans on while the cat sat. this overheating caused the coolant to go out through the radiator cap into the overflow and continue to do so until the car shut uff. My coolant went into the overflow tank, it overflowed, and i lost coolant.

Air got in my coolant, and therefor got circulated through the system.

 

I don't think air would get into your system unless the car cooled down after you
overheated.. but you said your resevoir was full, so there's no way for it to suck
in air.. Air is getting into your system some other way...

 

Why don't you wire the turbo timer so that the fans do come on?

 

The metal expands and contracts when you heat up the engine and cool the engine down. When doing this you let the metal of the stud "relax" in the threads when it cools down and the studs get looser. I torqued my head studs to 70 ft-lbs with moly lube, and when i went to take my head off they were at 35-38 ft-lbs. When your headstuds get looser you are effectively letting the head come off the block when you are into boost. When your head starts to lift you either blow a headgasket or overheat, or both.

If you are only getting overheating at idle, then its probably not your headstuds. I was experiencing overheating all the time, in sporadic bursts. When i would get into boost i would overheat, when i would let the car idle i would overheat. The headgasket was perfectly fine when i pulled it out. I went over the entire thing with a magnifying glass to make sure i wasnt missing little cracks.

Quick question, how is your idle?

 

hey if u guys wired up the turbo timer wrong your fan will never kick on when u at idle with the turbo timer on....u might have the wrong accesory wire...if your turbo timer is on... u shouldnt be able to hear your radio.. if u do u wire it wrong..hope it helps....

 

EG6, I'm just curious, but in your first post, you ask a question. When you get answers, especially ones you may not want to hear, you say you know why the car overheated. Well, yes, if the car ONLY overheated, then I would say the fans are the problem. But, if you had the overflow resevoir pour some coolant out, then you have air in the system. The posts about the headstuds or headgasket are the most likely symptoms. If you have a sleeved block, it could be a dropped sleeve, but that is remote. The reason it doesn't happen at full boost, you are pressurizing the cylinder, and some of the air is leaking into the cooling system. Once you start to creep, there is now air in the system, and it will eventually prevent coolant from flowing properly. The water pump can't move air, just water. Are your headstuds new? Did you measure them prior to installation? If not, to save yourself possibly massive headaches down the road, buy a new set, measure them, and then install them. Retorque them according to directions and you should be good to go. I say buy new ones if you didn't measure them because you can't be sure they haven't stretched. The manufacturing tolerance is more than the allowable stretch, so you can't guess. You aren't blowing any white smoke because you don't have any coolant getting into the cylinder, its the other way around. I'd bet if you stayed out of boost for a while and just drove it around, it would never happen. Been there, done that. It CAN be a PITA, but it doesn't have to be. Good luck!

 

my idle is beautiful, right around 750 rpms.

i bought brand new arp'sm and did not measure them. I used moly lube and torqued down to 78 ft lbs. You guys really think this is the source of the problem? I guess im still trying to get why my car runs fine at boost... IF I dont hear many more suggestions i guess this is what i will do to try and fix it.

 

If its a bad headgasket, a simple leakdown test will tell you, take off your radiator cap and look for bubbles! I suggest fix your damn fan problem already and see if it helps, then look for alternative solutions if it didnt help.

 

do your fans kick on at all. if not there's a sensor called a thermo sensor when it heats up it provides the ground to kick the fans on. find this sensor its either on the back of the block, in the bottom of the radiator or by the thermostat housing. let it warm and use a jumper wire and jump across the harness plug if the fans kick on bad sensor. start with simple things common honda problems.

 

Leakdown test results were fine. I got all the air bubbles all the air bubbles out of the system by running the car and squeezing the hoses and adding coolant as necessary. Do the hoses only bulge when they overheat, or all the time?

Thanks...the thermo switch is a brand new one from honda. The fan motor is good, I tested it with a cordless drill battery. I also but a voltmeter in the terminals of the fan harness, and it got power from the switch. So the fan does indeed get power.


EDIT: I think its the waterpump, that makes sense huh? low rpms, low flow of the pump.


[Modified by B18EG6, 6:30 PM 3/22/2003]