(10/11/2009)
A few weeks ago, I got my car back from the body shop with a Shine Amuse bumper and a new Koyo Radiator with Koyo Radiator cap. The car ran perfectly fine for 2 weeks then in the past few days, I've noticed the water temp going out of control on normal 20 minute freeway drives.

Instances:
1. During a regular 20 minute freeway drive on a chilly day, I noticed the water temp gauge at 2 bars past normal, so 1 bar past the middle (normal is 1 bar below middle).

2. On a chilly 63 degree night drive in the city, I noticed the water was 1 bar below normal, which has never happened in the past 3 years of ownership even in 40 degree weather.

3. I WOT on the freeway for about 30 seconds on a chilly 62 degree night, then noticed the water temp gauge was 1 bar before reaching H. I pulled over and turned the engine off to let it cool. After about 15 minutes, the water temp gauge was in the middle. I have only done economy driving since then.

On all freeway drives now, the water temp gauge generally resides in the 2 bars past normal range. The body shop is highly recommended and reputable, so I'm assuming it wasn't mechanic error or damage. Hopefully, it's just a small issue like a faulty thermostat, or even a faulty radiator that I could just replace. I'm going to call the bodyshop on Monday, but I'd like to get an idea of what the possible issues are beforehand. Thank you.

Below is a picture of the AP2 dash to paint a better picture of what I mean by bars, the middle, and H. The picture does not reflect normal water temp.


UPDATE after fix (12/28/2009):

I had my coolant flushed and replaced the thermostat along with the parts related to it. The temperature is now running normal during normal driving but if I VTEC, the temperature still rises out of control. My mechanic said it could be one of 2 things. The fan could be malfunctioning, or I have a leak in my head gasket (which would suck horribly).

I'm going to go with the fan malfunctioning for now. What do you guys think it is? Get a new fan or could it be some other issue? I pulled over after testing out the car to extreme water temperatures and it seemed like the fan turned on quite some time after. As soon as the fan turns on, the temp drops to normal very quickly. I can't tell if the fan's on while driving because it's too loud, but I'm assuming it's not. This seems like more than a malfunctioning fan. Any help would be greatly appreciated.

 

I know you understand how it works based on what you're saying, but you're calling it wrong - the gauge on the dash is not oil temp, it's only water temp.

That said, with radiator work, the first thing I'd personally check for is air in the system.

 

Yea...Im pretty sure thats just a temp gauge for water.

Bleed the system, turn on the heater, might have air bubble somewhere.

 

*Edited original post to reflect said correction

 

im assuming the shop did not bleed the cooling system properly,


there are 2 bleeder ports, one on the intake manifold side and one on the rear heater line on the firewall.



i would say re-bleed the system then go from there.

 

So the problem went away for a while, so I didn't take it to get the radiator bled. Today I turned on the heater while on the freeway and the water temp increased to H within 3 minutes. It happened again a few hours later after I let the engine cool. Also, there was barely any heat coming out of the vents. It'd be lukewarm if anything. Is this still a radiator bleeding issue or a thermostat issue?

Just for reference from my original post, these occurrences happened after I had a shop install a Koyo radiator.

 

check your ect sensor. thats engine coolant temperature sensor. it could be giving you false readings if its cracked or going out.

 

But that wouldn't explain why the heater doesn't blow hot air when the heat is on anymore, and instead, raises the water temp bar to an extreme, right? I'm just trying to figure out the exact issue so the shop won't take my car for 5 days looking for the issue.

 

air lock in the heat exhanger is probably it. Sometimes it takes a while to get all of the air out of the system and takes a few burps to get it right. I doubt anything is related to the radiator other than the fact that it was installed with too much air in the system. Autobody shops can be reputable but they don't necesarily know about bleeding cooling systems. Rather than risk engine damage start burping the system asap. Burp it with the heating system on hot, lots of detailed posts on how to do this on this site.

Other issues could be a bad thermostat but that is rare, also make sure the connector for the fan switch is properly conntected and they didn't leave it off by accident.

 

Thanks a lot! I'll schedule an appointment today.