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Car is getting hot

2678 Views 17 Replies 5 Participants Last post by  FD Maguire
I have a 4 door 1989 Acura Legend.

The problem I have is that it is running very hot. It got right below the red line on the engine temperature gauge a couple of times. I realize how much one needs to worry about this with an aluminum block.

My mechanic replaced the coolant temperature switch. Now, the car is no longer going up to below the red line but, at times, it is getting up 95% on the temperature gauge at the dash. At other times, it runs just fine down the road. We suspect the electrical fans are turning off when they should not.

Another problem we have is that the fans do not run when you turn the key all the way off on the car even when the car is hot. In the past, you would hear the fan noise when walking away from the car at times. Interestingly, they do run if you put the key in and turn the key forward just prior to starting the engine.

We have a third problem. The AC just seems to go off at times (at least that is what we think versus being low). The AC will run perfectly cool and then just go off. My wife asked me if the problem could be connected but I kept so knowingly telling how those are two different systems. In the last 6 weeks, we had to replace the AC compressor that went bad. I had suspected that I might have a different problem with the AC of potential looming "black death" if the old compressor had fouled up the system (no way did I want to flush the system at that cost and I do not have a kit of my own). I thought maybe a piece of crud was getting caught in the thermal expansion valve causing it to cease working for a bit and then it would work again when it cleared. Like I said, it works great when it is working. Still, I questioned if the pressures would even allow for this kind of clogging.

Thanks to this site, I have access to the manuals for my Legend. In looking at some of the PDF's, I realize now that the Fan Timer Unit and the Fan Control Unit could be the issue here and a link between the AC and the engine coolant system. Once again, I learn to listen more closely to my wife.

I was hoping that people might have had some of the same problems as me and some insights on what is most likely to go wrong of the options I have here. Thanks!!
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Okay, I have done some more testing. The fans will stay on IF the key is in the rotated forward just prior to the location where you would press forward to start the engine.

And, the fans turn off after the engine has cooled down properly with the key rotated forward. However, if you remove the key, the fans turn off even when the car is hot.

And, we have noticed it does tend to start getting hot when going up hill at the times when it is getting hotter (does not always get hot going up hill).

One more thing I should share. My mechanic recently replaced the motor on one of the fans as all part of this. We thought that might be it, but it turned out that the motor on the fan was okay.

We also replaced all the hoses minus the two large one's to the radiator because the first few times it got hot, it boiled over. We could see a small hole in one of the hoses. Once we did this, it never got that hot again and never boiled over again when it did get close to the top of the gauge (never once got to the red line on the temperature gauge. We assumed that the coolant system was not holding temperature so the boiling point was reached.

I am assuming that we did indeed have a problem with a small hose in one of the hoses causing the system to loose pressure. But, I also think we have another problem. Could be that the original over heating problem kind of kicked something over past its break point but just guessing here.
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It sounds to me like you have a head gasket leak. I experienced similar symptoms with my Legend two years ago.
Not pushing back hard on what you are saying, but wouldn't it be using coolant if that was the case?

It is not using any coolant right now.
Not pushing back hard on what you are saying, but wouldn't it be using coolant if that was the case?

It is not using any coolant right now.
Good point but it could be a slow HG leak. If you havnt done so already, read the trouble shooting section of the service manual.

I hope its not the case because its an expensive repair.
I am having the EXACT same issue with my Legend.

Mine is definitely a short in the electrical running to the cooling fans. The TCU is throwing 12 blinks indicating the issue.

I have pulled the car over when the temp needle starts to rise, popped the hood, and found one fan not running. I have also noticed the fans NOT running once I turn the car off...even if the engine is still hot. Also, in the ON position, the fans run for no reason.

I plan to check the cooling fan control board/wiring this week. Probably just some re-soldering to be done.

I would be shocked if your issue is HG-related.
I think I am just going to start with re-soldering the Fan Control Unit and the Fan Timer Unit first no matter what. Tons of people talk about problems with the bad soder joints so I doubt I can loose anyway by doing this. If it is not the problem, I might be nipping in the butt a problem that might have showed up later.

No strong tone here. But, I just do not think it is a blown head gasket either. If it was loosing pressure, it should then still be boiling over when hot and it is not doing this. And, then why would it be getting hot when there is still plenty of coolant in the system.

Likely electrical, I think. Of course, that is me saying this and I am the one asking for help :) Anyway, you got to love electrical problems... sometimes feels like chasing a ghost.
Both fans should be running when it gets to the boiling point when the car is running. When the car is completely off, the fans do not turn on. They only turn on when the Key is in the ON position or when you have the A/C turned on.

Try doing this, bring the car up to it operating temp (fans kicking on), and carefully touch both the top and lower radiator hose. The top hose will normally be hot, so be careful not to burn your hands. The lower hose should be as hot as the top. If it feels cold/warm, the thermostat isn't opening. If both hoses feel hot, make sure your radiator cap is sealing properly. If everything seems fine, you might have air in the system.

Next to the temp sensor on the water passage way by the throttle body, you will see a nipple type bolt. That special bolt will let you bleed the system. When bleeding, make sure heater is all the way to the max and at full on, then carefully open the bleeder. It would be a lot easier to have a clear hose attached to the nipple and run it into the reservoir tank so you don't lose coolant.
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I have no experience with 1gs but armed with what I know from my 2g, if your losing coolant your car should not overheat past 3/4 unless your coolant is ran dry.

Assuming your engine coolant temp sensor, thermostat, fans and radiator are operating properly.

Now even when all those are operating properly. A seeping headgasket which will later result in heating upto 3/4 and more commonly past the red mark.

Introducing air into your system is a big problem so make sure to bleed 2 or even 3 times.

Unfortunately in my case I had a major seeping head gasket. To the point where the internal vacuum was forcing air into my coolant system locking my new thermostat. Preventing any flow of coolant through the motor.

Note I didn't lose any coolant during this diagnosis.

So bottom line after replacing my radiator, thermostat, fan relay, and ECT.

I ended up having to tear down my beloved 2g type 1 5 speed down to the block.

Story short, decide whether she's worth keeping and start from the source. Chances are your head gaskets have never been replaced or weren't properly installed on a clean surface or torqued to specs.

Good luck and I hope you can learn from my experiences.
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Good advice on bleeding the radiator. I have done that before and will do it again.

We did check the main hoses off the radiator before and everything was good on them. Both were warm and holding pressure.

On the fans staying on, the manual does say that they will stay on when the car is hot. It should be for a maximum of 30 minutes when it does this. I was going to post a link to the file for downloading from my Dropbox but it tells me I have to have made 15 posts first to do this. If you got the manual files like I got via links from this site, the name of the file with this information is "LG9090A23088A.pdf".


Thanks for the tip. I will bleed the system of air more than once. I appreciate you sharing your experiences. I obviously hope it is not the head gasket. The car is a 1989 but it sat in a garage for years not being used. For its age, it is relatively very low mileage.

I am going to go ahead and resolder everything first just because it is easy relative to things like a leaking head gasket.

By the way, quick question, if the head gasket was leaking, would not the car boil over when it got hot because it was not maintaining pressure?????

I only ask because our car is not boiling over at all when it gets hot now since we replaced all the smaller hoses (everything but the main hoses off the radiator that had already been replace). It is still popping up hot at times and then fine at other times as people have posted.

For me, I am first going to focus on finding out how to fix the issue of the fans not staying on when you turn off the engine and the engine is still hot. That is clearly electrical and/or sensor of some sort because they run fine under other scenarios. If I fix this issue and the car continues to get hot, I will obviously have to dig deeper and hope it is not a leaking head gasket. Replacing the head gasket is not a project I am jumping to take on.
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Quick comments...

When I said I had bled the coolant system of air before, that was on prior work. I have not that since all the recent work was done to replace the old hoses on the coolant system. My mechanic might have done this, but I am not sure. It cannot hurt.

Also, given everything I have read, I think I am just going to go ahead and resolder the main relay while I am underneath the dash already getting the Fan Control Unit. It is not a problem now, but there are so many posts about how this unit goes out on people.
Like I said before, the fans are not suppose to be running with the engine off and no power at all. If the fans do turn on with out the key in the ignition, the fan timer is the culprit. With the fan coming on its own, it can drain the battery life. I know most newer cars have that feature where it stays on when you have the key out, but for the G1 Legends, it never had that feature.
I am spend hours reading the forums at various points over the last 4 years or so. Please read my tone right here because I know what support you give to others.

But, this is a copy out of one of the PDF's on the manual of the text:


Fan Timer System:
When the engine oil temperature is above approx. 105°C (221°F) after the engine is stopped, the condenser fan goes
into operation to cool the engine for a maximum of 30 minutes.
When the temperature falls below approx. 90°C (194°F), the fan is stopped.
The fan motor runs at a low speed to decrease operation noise by using a resistor to the motor voltage.
The oil temperature switch is located on the rear cylinder head cover and the fan timer unit is located under the PGMFl
ECU cover.
If necessary, the fan begins operation 5 seconds after the ignition switch is turned off.


I have not yet hit enough posts to attach the PDF. But, the name of it in my materials is LG9090A23088A.pdf
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A simple test you can do is to warm up the motor to operating temp. Drive it a bit to get her to overheat a bit.

Park and open your hood.

Put on some gloves and squeeze your upper and lower radiator hoses.

If the upper hose is swollen and stiff your thermostat is locked close and it can either be a bad thermostat or worse ( seeping hg )

If your Lower hose is swollen and stiff you may have a plugged radiator.

If you have the time and a spare car you can drain and pull your radiator then with it out run water through it to see if its clogged or in working condition.

As for your fans, check all fuses and I'm not sure if 1gs have a fan relay on the bottom of the radiator but if it does I would replace it.

I troubleshooter a lot of these problems and I was getting false hits because my seeping hg lead me to believe it was other problems. Sly devil.
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I will do just that.

This car is old enough that a new radiator probably could not be a bad thing no matter what as well. Still, we are only at roughly 120,000 miles for a 1989 car. That is not too shabby. But, I know some things get old just by time no matter how much less the mileage is than one would expect on a 1989 car.
By the way, I already replaced the coolant temperature switch and have checked all the fuses.

I was considering replacing all the relays, but think I will just start with what you are recommending here and bleeding the system again in case there is some air in it.

When my mechanic replaced the majority of the hoses (everything on the driver side minus the main radiator hoses that are relatively new), he could have not fully got all the air out. Through reading a ton of older posts, I have come to understand how the G1 can be finicky to get all the air out.
Ah, I see what you mean. I just found it in the manual:

The fans run when the oil in the engine block gets too hot at 221°F. Thats something I didn't know lol. Do you have a thermometer gun to see how hot the engine block is?
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Ah... I wish I did have a thermometer gun. Might get one. Always looking for good excuses to buy new tools.
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