I have a 91 hatch with a B18A1 in it. The car runs so cool, I am wondering if it is bad for it? The previous owner took out the fan because it NEVER came on, and the car never got over 1/3 of the way up on the temp gauge. NOW the thermostat must be stuck open because it takes 10 minutes of driving in 90 degree heat for the temp gauge to creep up to the cold line itself, let alone get hot. Is it bad for the motor to run it this way? If I do get a new thermostat, do I need to reinstall the fan if the car continues to stay in the lower half on the temp gauge?
Just wondering,
thanks
-Marc

 

In for similar problem...

 

Well, I suppose running cool is better than overheating!

 

Good question but if that were the case then they would have just eliminated the thermostat entirely. It's there for a reason. Running cooler is definately better than overheating though. The fan is a backup incase you begin to overheat in traffic. I like to have it there just incase.

 

I was under the impression that if it runs too cool,then the ECU will adjust accordingly and cause increased fuel consumption...can anyone else back this up?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by subgeniusdude &raquo;</TD></TR><TR><TD CLASS="quote">I was under the impression that if it runs too cool,then the ECU will adjust accordingly and cause increased fuel consumption...can anyone else back this up?</TD></TR></TABLE>

That is abosoloutly true. If the motor isn't at normal operating temp, then it is in "warm-up" mode. When the ECU is in warm up mode, it runs the motor very rich to reduce thermal shock...

You definently want to be at "normal" temp when driving...

 

wow, i wish i was in this boat. I have a b18a1 in a 90 hatch, and my temp guage reads exactly the same as it did with the stock D series. The guage works, and I actually am still battling a few coolant bubbles here and there. I think I would rather run cooler.

I am running the stock radiator with two fans. I left the condensor fan in there for when i get my a/c working again...

My underhood tempretures seem awfully high, even though the coolant reads ok. Are you guys running different radiators than stock?

As for the ecu question, I am not sure. I know at warm up, the FITV mechanically increases the amount of air sucked in, keeping the idle high until the coolant is up to operating temps. other than that, I'm not sure what the ecu reads and changes...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LShatchboy &raquo;</TD></TR><TR><TD CLASS="quote">I have a 91 hatch with a B18A1 in it. The car runs so cool, I am wondering if it is bad for it? The previous owner took out the fan because it NEVER came on, and the car never got over 1/3 of the way up on the temp gauge. NOW the thermostat must be stuck open because it takes 10 minutes of driving in 90 degree heat for the temp gauge to creep up to the cold line itself, let alone get hot. Is it bad for the motor to run it this way? If I do get a new thermostat, do I need to reinstall the fan if the car continues to stay in the lower half on the temp gauge?
Just wondering,
thanks
-Marc</TD></TR></TABLE>

Are you sure you have a thermostat? I would replace it anyways, and definitely reinstall a fan. If you ever have to sit still after driving for a while, the coolant will be getting close to the point where the fan will kick on anyways. It's a good safeguard at the least.

Also, just because the gauge "stays" in the same spot, doesnt mean the motor is running at the same temperature. The stock gauge basically shows "cold", "operating temp" and "overheating". It was designed to stay in the "operating temp" section for temperatuers anywhere between 185* and 212*.

 

OK, UPDATE!

Put in a new thermostat and radiator hoses just in case, all new coolant as well. Car will start to rise in temp after it sits for awhile, but as soon as I hop in and drive, it goes down past the cold line again. All the way down.

I do however see that there is a spot on the thermostat housing where a plug should connect. I dont have one on there, might this be an issue? It is brownish colored. Not sure if you need it or what.
thanks for the help,
Marc

 

I believe that plug is where the coolant temperature sensor plugs in?

 

overcooling will increase engine wear on your bearings, crank, etc. how many lbs is your radiator cap? additionally how thick is your radiator? if it's too thick too much heat will dissipate resulting in a permanent overcooling condition. just some things to check.


Modified by civickid03 at 1:32 AM 8/6/2006

 

The radiator is a stock STD radiator. The coolant gets hot, the intake manifold feels like a normal B series shoudl, I know the engine is at normal engine operating temps. The gauge doesnt read so though, maybe its the temp sensor? I dont know, its pissing me off! AARRGG!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civickid03 &raquo;</TD></TR><TR><TD CLASS="quote">...how thick is your radiator? if it's too thick too much heat will dissipate resulting in a permanent overcooling condition. </TD></TR></TABLE>

That's kinda silly because if the coolant was over-cooled the thermostat would shut as soon as it hit the prescribed temperature and prevent fluid from even circulating through the radiator. You could have a radiator the size of Chicago and the motor temp still shouldn't drop below the thermostat setting...

The problem is that your radiator cap is stuck open. I think when motor swaps sit for any period of time, the thermostat remains open to the elements (because the hose is unplugged). Without the coolant present to prevent corrosion, it craps out. Just replace it (it's like $12), and be glad it wasn't stuck shut...