either my radiator or water temp sensor or water temp guage is acting up. it doesn't really matter if it's a hot day or a cool night, it acts up ramdomly. i moved my radiator a bit temporarily to put the ac back in my car, and it hasn't acted the same since. when at a stop light or driving, the guage reads that the water temp is rising very quickly; almost scary quickly. itll go up to 3/4 from half, and then when i start driving again it'll jump back down to normal (half). i flushed out the whole system last week, and the prob didn't happen again till tonight. the same thing happened...i was driving the car a little hard, hitting max boost through two gears. then after i stopped at a light, it started climbing again. one of my friends said that he's never seen a water temp guage jump up so fast before, so he suggested that it's a sensor or guage problem. it's just a little unnerving with the guage moving around like that. any suggestions?? im thinking about getting redline water-wetter tomorrow and putting that in and see if that helps any. someone suggested that it might be the thermostat also. i've also been told that it's probably an air bubble in the system. i dont wanna start changing everything until i have an idea what it is that's wrong. i think i might eventually get a performance radiator with more fins+ better cooling power, but i know plenty of people with boost and no prob with the stock radiator.
any suggestions about how to find out what's wrong or tests i could try??? anyone else have this prob before???
any help is appreciated. thanks!!!

 

Ok, just for verification:

You have a turbo?
You put A/C back in? and that's when the problems started?

 

yes, i have a turbo; no the ac is not back in. sorry for the confusion. it's on a 97 civic ex....i had some heat wrap before on the top ac hose, but i don't think that'd really make a difference.

 

What motor are you using? SOHC od DOHC? Sounds like an air pocket, did you open the coolant bleeder screw? Is the coolant mix 50/50 with water? Water wetter is nice but until you fix the problem I wouldn't add it. You can test your T-stat once you remove it by putting it into a pot of water and heating the water with a thermometer to see when the Tstat opens.

 

It's alright, that's why these kinds of questions get asked before I make suggestions.

You said you moved the radiator, is it one of those half-width ones the civics are notorious for? If it is, do you have the blank-off plate in place beside it? It sounds to me like the radiator fan isn't pulling air across the fan very well, or not enough air is being forced across the radiator. In any event, this is definately a lack of efficiency in your cooling system. Here's what I would check [in order].

• Open the coolant bleed screw and verify there's no air in the system, you'll know because as you fill the radiator, fluid will start leaking from the bleed hole
• Make sure the cooling fan is coming on when the temperature climbs
• Make sure you have a good path for air to go through the radiator, and not around it
• If the above fails, test and/or replace the thermostat if it's faulty. Water Wetter is a cooling aid, not a fix.

 

im using the d16y8 (stock sohc vtec).

the haynes manual said i dont have a bleeder screw (that's only some integras) and that i just needed to idle the car for a few minutes, turn it off, then squeeze the upper radiator hose to get the air out (which i did).

i used pre-diluted radiator fluid (the orange stuff) but it was having this prob before i flushed the system.

the fan is turning on, i've seen it in action.

yea, it's a half-width radiator.
what's a blank-off plate?? the ac is out, so it's getting okay air-flow (im sure my intercooler doesn't help though).

hmmm....it's wierd, because i was racing a gs-r hatchback today, and in the moment i forgot about the prob with my radiator. after i had run him a few times it climbed a bit, then went down, then went up again, then went down again, so i stopped racing. then, on the way home from work this morning, i was driving very conservitively, and it started climbing again, without even hitting boost. probably the thermostat.

about how much is a good deal for a new one??

 

A blank off plate mounts beside the radiator in the space where the radiator doesn't occupy. Air is like any other fluid, follows the path of least resistance.

As for the bleed screw, look where the upper radiator hose connects to the block, and double check that there isn't one. If you do have one, it'll be right beside the upper radiator hose on the block.

Thermostats are under $20 usually.

 

could also be a bad gaguge sensor or bad gauge sending unit, let's not forget.

How about the in-dash thermostat gauge, is that showing the car running hot too?

-PHiZ

 

A bad guage or sending unit usually reads full cold or full hot all the time. It still sounds like poor circulation or an inefficiency issue to me.

 

It could be an air bubble, but where did the bubble come from? I'm hoping you don't have a blown head gasket and air is being pushed from your combustion chamber into the water jackets. If you open yer cap and it smells like gas, start worrying. Then again, I might just be scarin' you for $hits & giggles.

You could always inspect the thermostat. A new gasket would probably cost you $5, and a new thermostat just about the same if it turns out it isn't working. $10 to eliminate one possibility.

Go ahead and do some searching (outside this forum perhaps?) about BHG's and I'm sure you'll find pages filled with symptoms and ways to test from Supra Mark III owners. Those guys deal with blown head gaskets all the time since supra blocks are "defective" from factory as some would say.