saikou

Now, before anyone suggests, I've bled my car's coolant many times since I've owned the car and I've never had an overheating problem short of a bad ground when I swapped the motor. I'm just stumped on what's causing this... well, here's an overview:

Been running the same 1/2 size Mishimoto radiator for a year without problems. Maybe about a month or so ago, I replaced my upper radiator hose and bled the coolant as usual. Couple weeks go by and I notice it overheating when I was stuck in traffic, shut it off and coasted into the shoulder of the highway to let it cool. Well, ended up that my crap Autozone thermostat was stuck closed and not allowing coolant to flow through the motor. Replaced with OEM thermo and now I notice my fan kicking on while I'm bleeding the coolant. By this time I'm f'king shitting my pants in joy because I thought I fixed my car. I was wrong - damn thing still overheated. I work at a Lexus dealership so I just had a tech I trust take a look at it. Told him the situation and he was lead to believe that it was the ECT switch after the thermo. Replaced with another one I had laying around and it hadn't overheated for about 2 weeks. Now, I was confused about this, since the fan kicked on before we swapped sensors. He thought that perhaps it was working intermittently. Eh...

Run to a friend's apartment last night and I pull into a spot and notice the temp gauge over normal by 1 bar. Pop the hood and run out to see if the fan was even running - it sure was. Went out tonight to just drive around to try and diagnose and it wanted to overheat again... just by one bar. I've noticed that whenever I'm constantly driving, it doesn't overheat... that's the obvious part, it shouldn't when I'm moving fast enough. But when I come into a parking lot, drive around and try and find a spot to park, it'll start to overheat. I'll take notice of it and get back on the road and it'll cool back down.

Now, I'm not running a block off plate for the other half of open space from the Civic radiator, but it's been like that for over a year without problems until now. 50/50 coolant/water mixture and I'm not leaking anything. About 10-15,000 miles on new water pump. Both upper & lower hoses are hot. Have bled coolant many times, have any ideas guys? I'm just about ready to throw parts at it.

Saosinx

why did you change just the upper house, and not the lower? preludes are known to have bad temp gauges so try a pyrometer. get the car to start "overheating" and use the pyrometer to see if it is really overheating. i believe it shouldn't go any higher than 190 which is around when the fan should be kicking on. you could also get a water temp gauge and hook that up and we all know that is mad JDM. and did you also make sure that the hose going in the coolant reservoir is attached, and has not fallen inside it? that's all i can think of right now.

saikou

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Saosinx &raquo;</TD></TR><TR><TD CLASS="quote">why did you change just the upper house, and not the lower? preludes are known to have bad temp gauges so try a pyrometer. get the car to start "overheating" and use the pyrometer to see if it is really overheating. i believe it shouldn't go any higher than 190 which is around when the fan should be kicking on. you could also get a water temp gauge and hook that up and we all know that is mad JDM. and did you also make sure that the hose going in the coolant reservoir is attached, and has not fallen inside it? that's all i can think of right now. </TD></TR></TABLE>

Haha, I was thinking about getting a water temp gauge. Just went out and checked to see if the hose going into the coolant reservoir was still attached and it is. What exactly is a pyrometer and how would I use it?

Also, I forgot to mention... when I bleed the coolant, I'll leave the radiator cap off and I can let it sit for a whole day and the damn thing wont overheat. Could a bad radiator cap cause a car to overheat?

Saosinx

it can. having a bad seal on the radiator cap can let air get in and cause air bubbles. you can pick up a stan from any LPS and it might fix the problem. and also some parts stores can do a pressure test on yours so call around and see if any can do it, and just take yours there and have them test it before you go buy a new one. and if it is the problem, then pick up a new one. you know what i'm saying?

saikou

Sure do, thanks. I'll take it to a parts store and have them pressure test it. Hopefully that's all it can be, because it sure has been stressing me out.

Saosinx

good luck.

m00nr0ck Si

Thats what my overheating problem resulted in ......effin radiator cap

Hawkze_2.3

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by saikou &raquo;</TD></TR><TR><TD CLASS="quote">Sure do, thanks. I'll take it to a parts store and have them pressure test it. Hopefully that's all it can be, because it sure has been stressing me out.</TD></TR></TABLE>

You still have that Mishimoto radiator right? Might have come with a cheap-o cap...does it look worn or anything?

saikou

Yup, still have the mishimoto radiator. You know, I'm not sure... I've honestly never really looked at the cap closely. Just never thought it could ever cause a problem. I'll check it out in the morning. Also, if it is actually bad, I have no idea what cap will fit, as an OEM Civic cap does not work to my knowledge.

KILLAB17VTEC

it can be another faulty thermo or check the caps for wear.

dartonh22

do your hoses even get tight or swell a little when its getting hot, i had this same problem when i bought my fluidyne, i didnt replace the cap and i ended up blowing my headgasket tryin to diagnose it, so please dont make the car heat up to see if the gauge is faulty, go buy the 7 dollar cap, and see if it fixes it, thats probably it.

saikou

Yup, radiator cap is worn. Ran around town today to see if any auto parts stores had a cap similar, but no luck. Now I gotta wait on Mishimoto to send me another cap. Thanks for the help guys.

Hawkze_2.3

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by saikou &raquo;</TD></TR><TR><TD CLASS="quote">Yup, radiator cap is worn. Ran around town today to see if any auto parts stores had a cap similar, but no luck. Now I gotta wait on Mishimoto to send me another cap. Thanks for the help guys.</TD></TR></TABLE>



I have some extra caps in the garage

m00nr0ck Si

mugen cap will fit it.....

saikou

Nah, that's too much money for a radiator cap IMO.

Saosinx

i got my spoon for like 30 bucks shipped. works great for me.

saikou

Well, don't have to wait on Mishimoto to send another replacement. Turns out, there are radiator caps that can fit, despite what I've read online. For future reference, anyone needing to replace their cap on their Mishimoto radiator - item number 7516 (Murray Ultra radiator cap) from O'Reilly Auto Parts will work. Not sure of the model car this cap works for, but should help; same 1.1 16lb cap. A replacement cap for this radiator was $30 shipped, outrageous. I only spent $7.57 at the auto parts store.

Drove the car pretty hard afterwards for about an hour and Brandon knows how freaking hot it was this afternoon. So far, I haven't gotten it to overheat *knocks on wood*

Hawkze_2.3

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by saikou &raquo;</TD></TR><TR><TD CLASS="quote">Drove the car pretty hard afterwards for about an hour and Brandon knows how freaking hot it was this afternoon. So far, I haven't gotten it to overheat *knocks on wood*</TD></TR></TABLE>

It was a hot b!tch!! Glad that cap worked for you.

Another odd thing was the old cap had no real signs of wear, none that I could see anyway. Maybe the spring was weak or something....

Token Blk Guy

I was just about to make a thread about my overheating issues on my 99 lude good thing i searched. Well today was really strange I was driving around on the highway and my needle shot up to aleast 2 bars over the thermo sign on the temp guage in the car (its never been tht high). I turned off the AC pulled over in a parking lot, turned off the car waited 10 min, turned on the car got back on the road and turned the AC on, Needle shoots up... same level..

About 1 month ago when I was commuting 100 miles to work all highway I would notice the needle creeping up to the middle to top of the termo sign but never over it like it was today.. I figured it was because it was like 100 degree and i was drivign with the AC on.

I just had all my hoses, coolant, rad cap and I believe my thermo replaced in Aug all from the original parts. So I am not sure what could be causing this...