EricL

Here is thermo specs (it's under the Prelude):

"This thermostat has the operating temperature set lower than normal. It prevents engine power loss by minimizing rapid water-temperature rises under harsh conditions such as during circuit driving. The use of a flow-control-type valve prevents hunting, thereby achieving rapid stabilization of the water temperature (the engine warms up within a short period).

Operating temperature: 68°C (STD.: 76~80°C)

Full-throttle acceleration temperature: 83°C (STD.: 90°C)

PIC:


I was told that this was "one" of the 80-degree C thermostats for the Accord. (Someone else said this should fit the CLS, but...)



AND

HELMS (2001 CL/CLS Service Manual) page 10-6:

Thermostat Test

....
....

STANDARD THERMOSTAT
Lift height: above 10.0 mm
Starts opening 169 - 176F (76-80C)
Fully open: 194F (90C)

Mugen fully open is 83C (181F)

EricL

I'd just like to get a verification on the 2001 CLS (auto) to make sure that 19301-XGMR-0000 (described above) will actualy fit in the 2001? 2002? and/or 2003? (Archive material perhaps?)

http://www.kingmotorsports.com/produ...de/engine.html

(Yeah, I know it says Prelude...)

OUCH!!!!

I don't remember paying as much down here, and try to stick with the factory stuff, distilled water, & Water Wetter ...


[b]

SECOND REQUEST:

IF anyone puts the Mugen thermo and/or switch in, can you report back on the fan switch and thermo part #s?

TIA

Juker008

OK here is my question. And this would pertain to u too TypeR (sell-out u should have bee at Moroso that Fri. night....j/k). Well if it is good to lower the temp in the thermostat. Then what were to happen for us people, down here in the South, where it never freezes. To remove the thermostat all together, throw in a Mugen radiator cap, and Red Line WW. Sure we would have to also do something about the fans. So how bout having the fans run at 160oF. Or if possible all the time? Maybe that might be too much for the fans to do, operate all the time, but would this type of setup work?

Also can u guys make a list of parts for the people here in the south and for people who live up north with climate changes throught the year.


Juker008

Wires

You can remove the thermostat all together. On the CL though, there isn't a gasket. It's a rubber ring that snaps over the outer lip of the thermostat. You'd have to make a gasket, or gut an old thermostat.

For fuel economy reasons, you're probably going to want to run at least a 160 F thermostat though.

As for the fans, the less they run the better. When their spinning, they're sucking HP from the engine (via the alternator). Normally, the fans won't be running when cruising on the highway. The airflow through the rad should be better than the fans. They are needed when idling at the lights....

caddyman

ifthe engine temp isnt normal temp your moisture in the oil wil NOT burn off as quickly, synthetic or dino.

Wires

The 2000 Prelude uses the same thermostat as the Accord V6 and the 2001+ CL-S.

Ok, so the deal is the Mugen opens faster. Hmmm... Kind of wish I dunked the OEM in hot water to see how slow it was.

:P

Wires

I agree with the Titanium thermostat! Wow!

The fans do run independantly. One sensor mounts into the thermostat housing (low temp), and the other into the head (high temp).

Normally A/C forces both fans on....

EricL

there's actually THREE temp switches on the CLS...

Juker008

Why is that? How would fuel economy affect this?


Juker008

Wires

Hot fuel atomizes and burns better than cold fuel. If the engine is too cold, then the fuel doesn't atomize right, and ends up pooling in the intake manifold.

Also, I don't know how Acura does it, but in order to "choke" a fuel injected motor, they spray in more fuel when cold. If you are running at a temperature below what the computer thinks is warmed up, then it'll always be running rich = shitty fuel economy, and poor power.

EricL

Hot fuel does atomize better in some situations. High-pressure direct fuel injection would not care, due to the high temperatures in the cylinder during compression. I would be seriously doubt that you could see or detect any change in the droplet size with a reasonable temperature drop in the coolant (IMO, there are extremes that would validate your position.)

The fuel, in our cars, will not pool in the intake manifold during "normal" operation. The injectors are spraying into the ports, so unless there was a catastrophic/major failure that caused the injectors to stick open, there would not be any fuel pooling/collecting in the manifolds and/or plenum. Your assertion is correct with regards to earlier carburetor and fuel injection systems that didn't use port injection (some FI systems had an injector or two in a hollowed-out carb. body..

Acura adjusts the fuel-air mix depending on the intake air temperature (IAT), coolant/water temp (ECT), throttle position (TP), manifold vacuum (MAP), and the O2 sensor if the PGM-FI signals the system to go into closed loop mode (warm-up over).

Before the car is warm, the thermostat may have some influence on how the car warms up (if it has holes drilled in it or it is of a different design that prevents it from closing off the radiator as well as the stock thermostat).

The service manual notes that it looks at the ECT and IAT and if they are the same, it presumes that the engine is cold.

If a thermostat had a low-enough temperature (during normal closed loop operation) to cause the engine to see a temp well below it’s normal operating temp, I’m pretty sure you would see the engine light come on. I put a note in (earlier) that refers to an engine code associated with “out of range” engine coolant temperatures (ECT).

The largest impact could be in emissions (colder cylinder wall temps) that could cause “quenching”. It is also possible that the higher air density could result in lower gas mileage, lower fuel economy, but higher power output!

The fuel-air trim tables will compensate for the intake air temp and coolant air temp to insure that the mixture has the correct fuel-air mixture (the O2 sensor has a very narrow range of operation and would turn on the engine light if it could not get the mixture in range.

Wires

I stuck the old Fluke temperature probe on the thermostat housing last night. I have a bottle of water wetter in it, so I don't know if that helps or not, but this is what I found:

The thermostat housing would reach 175 F, the cooling fan would kick in, the housing dropped to 165 F, the fan stuff off. The temperature oscillated between 165F and 175F (depending if the rad fan was running or not). Garage was about 65 F.

That's with the OEM thermostat, idling in the garage after driving around town (the thermostat was open - rad hoses were under pressure).

EricL

The Fluke's Type-K thermocouples are pretty accurate... As to how much temperature loss there is -- who knows...

I'm starting to wonder about moving the temp too much lower (re: the Helms OBD II diagnostic notes/codes).

I'm starting to think that a "fan override" switch might be the best solution for "forced" cool downs of the car...

Helms info again:


Helms 11-56 (DTC Troubleshooting):

Note: ECT == Engine Coolant Temperature sensor.

There is a reference to a DTC P0116 OBDII code: "Range Performance Problems in ECT Sensor Circuit"

1. Start the engine. Hold the engine at 3,000 rpm with no load (in Park or neutral) until the radiator fan comes on, then let it idle.

2. Check the ECT with the scan tool

is 176 - 200F (80 - 93C) or 0.4 - 0.7 V indicated?

YES -- Intermittent failure, system is OK at this time. Check the thermostat and the cooling system

NO -- Check the thermostat and the cooling system. IF they are OK, replace the ECT sensor.



I'd sure hate to drag around an OBD II tool to keep resetting the computer...

Wires

I just ordered up a ODB-II tool for the Palm Pilots. When I get it, I'll hook it up and use it to monitor the temperature. One of those curiousity things. From what I saw, mine is running at 165F to 175F (it's probably a little hotter, since it's hard to get the thermocouple to connect with the thermostat housing perfecty. I had thermo-grease on it, but it's still tricky with the engine running).

I agree with you, I don't think I would want to take it too much lower.

scalbert

I'll d a screen capture tonight as I need to hook up my laptop. But I assure you the temps are in the 195 - 200 range when fully warmed.

BTW, has anyone seen a P0217 in the manual?? I didn't see it in the index nor a P1299.

scalbert

Here are the captures and what I expected.

Cooling fan turning on:


Cooling fan turning off:


However, there is an intersting point to this. The 6-Speed has only one fan switch versus three for the auto. Additionally with the AC running, the temps were running about 180 - 185 degrees F versus 195 - 205 F without the AC on.

What this says is that we might be able to get away with just the fan switch to keep the temps down at about 180 F. This will be easy to try but since I have my laptop I might still drill a small hole in the stock stat. I guess it is time to order that switch then...

BTW, that P1299 was incorrect, it was P1399 or temporary code for an intermitent misfire. But as expected, I can't get it to repeat when I have the laptop hooked up so I can get the freeze frame data. Oh the joys of DTCs, if you experiment you had better expect them. I'll wait until I run some Techron and swap the plugs before running a compression test.

The P0217 hasn't repeated...

ChucksTL_RENAMED

Scalbert nice work -- if you drill a small hole and or get the switch please let us know how it turns out. Cooler temps are good. Thanks.

EricL

Steve, I really have a very strong feeling about just putting in a fan override switch in the car (non-harness butchering way).

It seems that leaving the A/C on (a 1/4-mile no-no) is a round town must-do (A/C turns off at WOT, but keeps fans blasting at full during switch cycling).

Why not just "alter" the system to keep the fans cycling at high when it’s "power-time?"

(Or, better yet, just keep them on for a dyno or run...)

Do you have a Service Manual that includes 2003 model year with manual (#61S3M02)?

scalbert

Yes, a simple switch and a diode would work easy enough, I just want something without the need for a switch. I guess more for everyday driving.

Yes, I just got my '01 - '03 manual today.

BlueCLS6

Just a note of caution:
Removing the thermostat alltogether (as someone mentioned in here) is not a good idea. One of the functions of the thermostat is to reduce the flow velocity which increases heat tranfser. Removing this restriction will definitely make the coolant cooler but the engine may actually run HOTTER because these is not enough time for heat transfer to take place. A much lower temp. needle will mislead people into thinking the engine is running cooler when in fact it most likely is not. Much more heat will transfer between a metal slab and slow moving cool water than with fast moving cold water. Just trying to remember my heat transfer and thermodynamic classes...

EricL

I wouldn’t do that since the temp would be “unregulated”; that alone makes it a non-starter. (I’m not fond of having a moveable flap of cardboard blocking the radiator via a servo or stepper motor)

Once you have a pressurized system, you want MORE flow as opposed to less flow. MORE water or air moving (at a given pressure) means more heat transfer per unit time.

You need a lot of explaining to make this statement correct. I can think of some “far out” situations that might make this so… however, the situations that could make your statement above true are the exception rather than the rule

As it stands and without further clarification , the statement is nonsense…

Well, if you’re talking about having no coolant or water in a system and having the temperature sensor reading low while the engine explodes from only having water vapor left… that’s one thing. In general, a lower needle means lower temperature.

Faster water moving across a surface == more heat transfer. There are limits that have to do with boundary conditions, but that’s what pressure caps are for. I think you may have some confusion over cavitations issues and how they relate to pump efficiencies. It is possible to over spin an impeller and xfer less water through a system. However, moving more water over a “flat plat” will result in more heat transfer between the boundary of the metal and fluid. I’m assuming a laminar flow. If you increase the speed of a fluid to such a degree that you introduce turbulent flow, this can get confused.