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Discussion Starter · #1 ·
Hey guys, just wanted to see what you guys thought about my situation with my Legend. Now that it is getting colder in my area, I have been noticing that my JDM Type II motor runs cold, quite the opposite of my former USDM Type I with a BHG where the needle always hovered around the red. With the new motor, it warms up and gets to operating temp. as normal, but when I start driving on the highway (speeds over 60mph), the needle goes back down to pretty much the blue. As soon as I come to a stop, the needle goes back to normal operating temp and not long after I start driving again, the needle drops. Is my thermostat stuck or something? I haven't noticed a degredation in gas mileage and the motor runs like a champ. What do you guys think?
 

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Discussion Starter · #3 ·
Did the rad flush in March when I finished installing the motor along with a brand new rad, hoses & Type II honda coolant. Everything's fresh and there is no air in the system.

I'm not worried because last year around this time, I couldn't get my motor to run cold even if I threw bags of ice on it......damn bhg. :****:
 

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It's not the motor, it's the cold air. I too was worried about this on my USDM motor a coupla weeks ago. I drive 90 miles to work in the morning on the freeway, and it was about 40 degrees last week and the week before. Well, I'd let the car warm up to the normal temp, and then I'd get on the freeway and watch the temp start to fall all the way down to the blue. I got worried about it the first time and pulled into a gas station to make sure all was ok. The temp started going back up, hit normal, and then when I got on the freeway again, it bottomed out again. After it happened that night on the way home, I realized that the cool/cold air lowered the temp b/c as soon as I hit stop and go traffic, it hit the normal operating temp.

You're safe, enjoy the new motor.
 

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Sounds like a thermostat stuck open to me. If I'm not mistaken, OEM thermostats are supposed to fail "safe" so the engine has a difficult time warming up.
 

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FlipLegend said:
Glad I'm not the only one. How is your mileage? I've read that when a motor doesn't run at normal operating temp, mileage goes down.
How is my car running? 210k and it's running like a champ. I average just about 330 miles to a tank, and when this was happening, there was no fluctuation in the mileage. Now that the temp is in the 70s-HIGH 80s, there still has been no change in mileage.

For those saying that this isn't normal....I've had the same thing happen in my Acura Legend, my B18C1 del sol, and my D16Z6 CRX. So you're telling me that all of those cars are defective? I'd like to hear from someone that drives for long distances in the cold on a regular basis.

It would seem to me that if you have x amount of cold air moving across a surface (radiator) for an extended period of time, all other variables remaining constant, that surface will cool off, hence the temp should be cooler, as well. Maybe I'm missing something?
 

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nasriaz said:
I still think it's a bad thermostat. I have driven when its snowing outside and head wind is crazy but the engine has always been at normal operating temp. If cold weather was the cause I feel more people would complain about this when winter rolls around.
Thanks for weighing in. But in the conditions in which you describe driving, were they long distances for a long period of time at good clip (75-80 mph)? The reason why I'm asking is because of your part of the post that said that you felt more people would complain when winter rolls around. Most people drive in stop and go, where this particular scenario isn't reproduced.....
 

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whats77inaname said:
Thanks for weighing in. But in the conditions in which you describe driving, were they long distances for a long period of time at good clip (75-80 mph)? Just trying to get some pespective.
I cannot say they were between 75-80 consistently, but I have driven over 60mph for very long distances in severe temps. A trip to colorado in winter from OKC, it's about a 12 hr drive.
The temp consistently dropping like that is not normal if you ask me.
 

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Cool, thanks. I wouldn't say my temp fluctated, per say. The temp gradually decreased as I drove, it wasn't a sudden drop. I would say it took about 30 mins to fall in 40 degree weather doing 75ish or so with minimal traffic to really block the path of the air.

Well, Flip, I guess one of us is going to have to replace our thermostat to see what the outcome is. Since you posted first, I nominate you, so.....keep me posted on how things turn out :)

Seriously, living in S. Tx., we're not going to get another cold snap anytime soon so that I can experiment.
 

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there is a reason it is called operating temp. :eek:


The engine and sensors take in account a wind and 80mph by not opening the thermostat(as much..). Personally i would want mine to run a little colder.

***ALways check radiator cap pressure!!!! Most of the time it is the radiator cap......no lie!!!!!!!

Get a new one
 

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swift said:
there is a reason it is called operating temp. :eek:

The engine and sensors take in account a wind and 80mph by not opening the thermostat(as much..). Personally i would want mine to run a little colder.

***ALways check radiator cap pressure!!!! Most of the time it is the radiator cap......no lie!!!!!!!

Get a new one
I don't think the radiator cap has anything to do with it. This past week, the temp has been in the high 80s, and the needle never moves past the second tick mark, regardless of what kind of traffic I drive in.
 
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On absolutely every Honda/Acura I have driven, the temp needle stays put in the same location regardless of even the most extreme heat or cold. It never moves. If it is moving, there is a problem.

I'm going with replace the thermostat too. Cheap and simple. Plus if you haven't done it in a while you are being proactive. When water temp drops, the thermo should close. It doesn't sound like that is happening. It can't be the water pump because you say it runs normal temp at idle. The cold air through the radiator when up to speed is your variable here.

Although some people like to run without a thermostat for performance reasons, you will be doing so at the expense of gas and plugs. A cold engine uses more fuel and a rich mixture will foul plugs much sooner. For comparison purposes, I had a short in a wire for the temp sensor on my Accord and I saw an 18% increase in gas mileage after I fixed it.

Good luck.
 

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Discussion Starter · #16 ·
My radiator is brand new all metal CSF installed in March this year with a brand new cap. I guess I will test my thermostat in boiling water to see if it is working right. The thing that gets me is that my engine runs great and I get at least 350 miles a tank, sometimes 370 when I'm stretching it (needle on red or below), just by that, I would think my car is operating normally.

And on that note, do they make performance thermos for our cars that open at a lower temp. I had one on my B18C1 made by Mugen but I do not see a Legend application.
 

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FlipLegend said:
My radiator is brand new all metal CSF installed in March this year with a brand new cap. I guess I will test my thermostat in boiling water to see if it is working right. The thing that gets me is that my engine runs great and I get at least 350 miles a tank, sometimes 370 when I'm stretching it (needle on red or below), just by that, I would think my car is operating normally.

And on that note, do they make performance thermos for our cars that open at a lower temp. I had one on my B18C1 made by Mugen but I do not see a Legend application.
Damn, man, 350 to a tank? Do you do a lot of stop/go driving, or open road? And does the JDM Type II get better gas mileage than the USDM did? The part about the engine running great....yeah, same thing with me. And unlike the previous poster before you, I'm not experiencing a drop in mileage or performance, either.
 

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Discussion Starter · #18 ·
I do about 90% of my driving on highways. I rarely do stop and go driving since I live right off the highway and the airport I work at is also right off the highway 20 miles south of where I live. I thought I would get less gas mileage out of my alpha touring because the extra ponies but that is not the case.

As for performance, I don't really have a way of measuring that with my setup. Since I still use a Type I tranny and Type I ecu, I already know that I am not fully utilizing my Type II motor, therefore, performance was degraded the day I installed the jdm heart.

Could I remove the thermo without having to drain the cooling system? Assuming I let the car sit for a day without driving. I was just going to keep the upper rad hose propped up while I removed the thermo and check/replace it.
 
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FlipLegend said:
Could I remove the thermo without having to drain the cooling system? Assuming I let the car sit for a day without driving. I was just going to keep the upper rad hose propped up while I removed the thermo and check/replace it.
You don't have to drain the entire system, but you will spill some coolant if you don't at least drain *some*. Hell, you'll make a mess regardless, but I'd drain some into a clean bucket and just pour it back in when finished. You will need to add some coolant because of spillage, and bleed when you are done.
 

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Discussion Starter · #20 ·
Searchin4acoupe said:
You don't have to drain the entire system, but you will spill some coolant if you don't at least drain *some*. Hell, you'll make a mess regardless, but I'd drain some into a clean bucket and just pour it back in when finished. You will need to add some coolant because of spillage, and bleed when you are done.
Dually noted. Thanks!
 
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