94 Lude running hot after changing thermostat

Fourth Generation Honda Prelude topics

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crizma
Lude Lady
Posts: 55
Joined: Wed Jun 22, 2011 4:27 pm
Prelude Model: 1994 S
Location: texas

94 Lude running hot after changing thermostat

Post by crizma »

Hi,
My 1994 prelude has suddenly started running a bit hot, so I turn my a/c off & turn the heater on and it almost instantly shows to be cooling down. I haven't let it get all the way to HOT but it has gone 3/4 to hot before I noticed, it usually stays at the halfway mark on the gauge.
Checked all the fluids and all good. New thermostat installed yesterday, thought I'd be good to go nahhht. After driving less than 3 miles (at night) with the a/c on full blast the temp started rising past the halfway mark. After I turned off the A/C it ran normal temp, it started inching back up after I drove it for a good ten miles (without a/c on). Any suggestions from my fellow luders?

Thank you .

Rani


I love my car! So happy to have a Prelude again! :D


Oh, I am in Texas and it has been 3 digit weather lately.

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spiffyguido
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Prelude Model: 1991 SE-SR
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Re: 94 Lude running hot after changing thermostat

Post by spiffyguido »

Two questions, did you get the thermostat with the right heat rating and did you install it in the correct direction.

crizma
Lude Lady
Posts: 55
Joined: Wed Jun 22, 2011 4:27 pm
Prelude Model: 1994 S
Location: texas

Re: 94 Lude running hot after changing thermostat

Post by crizma »

My step dad purchased the one that the car parts place said was supposed to go in a 94 prelude S. He did get the wrong one first but went back and got the right one.
I am assuming he put it in the right direction. He did mention that the one that was in my car looked totally different , something bout things sticking out of it . You know I am not real up on the proper mechanic lingo. However making sounds effects has worked pretty good thus far. wink
The previous owner may of been in a money crunch when they decided to rig the thermostat , cause I think My step dad mentioned seeing bailing wire, and other cost cutting materials LOL

Tomorrow, I can check and make sure it is right side up. I did ask if it was right side up and I may of stepped on his feelings . Then again Step Dad couldn't find his keys at all last night only to later discover them in his pocket :shock:

crizma
Lude Lady
Posts: 55
Joined: Wed Jun 22, 2011 4:27 pm
Prelude Model: 1994 S
Location: texas

Re: 94 Lude running hot after changing thermostat

Post by crizma »

Spiffy, not sure if this is of major importance, but when I turned the heater on to make the temp go down is was hard to tell that the Heater was on. Air was blowing but no real "heater" type air.

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spiffyguido
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Re: 94 Lude running hot after changing thermostat

Post by spiffyguido »

You might be having a trouble with your air mixer. Have a look at this thread and see if it sounds related. RedRacer gives a very good description of how to disassemble and check the mixer.

viewtopic.php?f=3&t=629

crizma
Lude Lady
Posts: 55
Joined: Wed Jun 22, 2011 4:27 pm
Prelude Model: 1994 S
Location: texas

Re: 94 Lude running hot after changing thermostat

Post by crizma »

When my thermostat was being changed the other day it was brought to my attention that my car was rigged/fixed to where the thermostat was totally bypassed. I think I know why now, since it still starts to run hot or hotter than the halfway point on the gauge even after the thermostat was replaced, some type of hose or valve was bled, and now there have been two sensors replaced. Does it makes sense the previous owners were bypassing the thermostat because it doesn't signal the fan to come on til the temp gauge is already past boiling at 3/4 to HOT on the dash meter? I can see how that would be a problem Doh!
Stepdad and the mechanic were trying to tell me that it is normal for the meter to hit the 3/4 mark before it starts cooling down BUt.. this is just not true at all is it? The previous Prelude I had and this one never went past the halfway mark on temp gauge unless there was a problem. I am really not wanting to run my car that hot before the fan kicks on since I lost my wonderful 92 SI that way.
What could the problem be now? Any idea at all? Any advice would be greatly appreciated. If I can avoid taking it back to the mechanic for the 2nd time in 4 days it would be better for my $ (or lack the of).
Oh, even with the car hitting the H point twice when was in parking lot waiting to see if the fan kicked on and still the car is not losing any collant or wateer, it's not even making any over heating type sounds or odors. please help : )

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spiffyguido
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Re: 94 Lude running hot after changing thermostat

Post by spiffyguido »

How was the thermostat "bypassed"? By removing it? Why anyone would want to do that is beyond me. The thermostat helps regulate coolant flow during engine warmup. It's not a crucial part, but having it there is a good idea.

On the Preludes I've owned (2nd and 3rd gens), the fans seem to kick in as the temp gauge approaches about 5/8. This is a pretty loose thing to go off though, because all gauges are not going to read exactly the same.

If you are worried about cooling and your fans, you need to make sure of a few things.

-Are you coolant temperature sensors working well? In the case of fan control, I believe the one in the bottom of the radiator is the most important.
-Is there sufficient coolant in the engine? Has the cooling system had the air bled out of it? Is the coolant appropriately mixed? Some people think that running just water is okay....bad idea!
-Is the water pump working as it should? Bad water pump = no/low water circulation.

crizma
Lude Lady
Posts: 55
Joined: Wed Jun 22, 2011 4:27 pm
Prelude Model: 1994 S
Location: texas

Re: 94 Lude running hot after changing thermostat

Post by crizma »

For whatever reason those people were bypassing the thermostat it was working like that, Before they 'fixed" the bypassing problem it was working fine and not running hot. So , if you do not know why they would do it then we will never know LOL was hoping you knew.
Yes, there is and has been coolant and water mixed in the radiator, and it is full and so is the reservoir bottle. The air hose was bled by the mechanic Friday and we thought the problem was solved. Not solved cause on my way home I turned the a/c on high and within 3 miles my temp gauge was already at 3/4 to Hot. The next day my step day changed out two sensors and I am assuming these are the ones you spoke of.
I will take it back to the mechanics today or tomorrow morning and I will mention the things you have told me could be the problem. Hopefully I can get this fixed asap. A lot going on this week that requires me driving more than 4-5 miles. If I do not use my a/c my car doesn't get hot or not nowhere near as fast. Sitting at a redlight also triggers the temp to rise.

crizma
Lude Lady
Posts: 55
Joined: Wed Jun 22, 2011 4:27 pm
Prelude Model: 1994 S
Location: texas

Re: 94 Lude running hot after changing thermostat

Post by crizma »

Oh, The other day I kind of ran up on the median that I didn't see in the middle of the intersection, I wonder if that could of knocked something loose?

crizma
Lude Lady
Posts: 55
Joined: Wed Jun 22, 2011 4:27 pm
Prelude Model: 1994 S
Location: texas

Re: 94 Lude running hot after changing thermostat

Post by crizma »

To answer your question about the thermostat being by passed... Stedpdad said that there were wires bypassing it.
Thank you for your quick response. Thanks for always helping : )

crizma
Lude Lady
Posts: 55
Joined: Wed Jun 22, 2011 4:27 pm
Prelude Model: 1994 S
Location: texas

Re: 94 Lude running hot after changing thermostat

Post by crizma »

One more thing.... My car still gets great gas milage!! 300-335 miles a tank.

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spiffyguido
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Re: 94 Lude running hot after changing thermostat

Post by spiffyguido »

I think we need to clarify what part you're talking about. The thermostat has no wires and sits inside the main coolant line on the front of the engine. I'm guessing you must be talking about a sensor. Perhaps the coolant temperature sensor.

crizma
Lude Lady
Posts: 55
Joined: Wed Jun 22, 2011 4:27 pm
Prelude Model: 1994 S
Location: texas

Re: 94 Lude running hot after changing thermostat

Post by crizma »

sorry Spiffy I did not see for myself but I am certain that it was the thermo cause when my step dad went to pep boys that is what he purchased and replaced. He told me it was just like the shell of a thermostat in my car, he even got a long magnet and checked to see if part had fallen off somewhere but found nothing.

Took it back to the mechanic just now so this afternoon hopefully we can have this mystery solved. I will let you know what the verdict is.

crizma
Lude Lady
Posts: 55
Joined: Wed Jun 22, 2011 4:27 pm
Prelude Model: 1994 S
Location: texas

Re: 94 Lude running hot after changing thermostat

Post by crizma »

have you ever had a car that shows HOT on the temp gauge but the car really isn't over heated at all?

crizma
Lude Lady
Posts: 55
Joined: Wed Jun 22, 2011 4:27 pm
Prelude Model: 1994 S
Location: texas

Re: 94 Lude running hot after changing thermostat

Post by crizma »

on this mission we have replaced the Radiator, thermostat, temp sensor switch, fan switch and added juice to the a/c. After getting it back from the mechanics today I didn't even turn the a/c on and my car ran with the temp gauge at the halfway mark the entire time. The mechanic said that he thinks there is still a problem with something because when he was letting it sit and run with the a/c on to see if it was getting hot, the gauge moved to hot on the dashboard but under the hood he said it was not hot at all and the fan wasn't blowing hot air when he put his hand up to it.
Any ideas?



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