Water Pump

[Blue-S]

I will have to drive my 2000 "S" this evening and look at how the HVAC control panel diagnostic mode display for coolant temp compares with the needle position on the gauge. I should look at oil temp, too. Right now, ambient temp is in the neighborhood of 100 degrees in the inland areas of Southern California.

Here's the procedure for putting the HVAC panel in diagnostic mode:

Originally Posted by Lil bastard

On '97-'00 cars, you can access the diagnostics by holding the recirc and Air ↑ buttons for about 5 sec. Now you're in the diagnostic mode. The + - buttons allow you to scroll through the 36 different codes. The center button switches the display (left) from the code # and the actual value. To exit diagnostic mode, press Auto.

0c - ERL
1c - Oil temp
2c - Cabin temp as measured from the sensor mounted at the side of the dash.
3c - Outside temp - from AC air inlet
4c - Outside temp from ambient temp sensor on front grill (continuous)
5c - Outside temp feed from OBC display (5 sec. sampling and hold when stationary)
6c - Coolant temp
7c - Footwell discharge temp
8c - Sun sensor
9c - Sun sensor
10c - Cabin fan speed
11c - Cabin fan voltage
12c - Temp mix flap - 1=Cold, 100 = Hot
13c - Temp mix flap position
14c - Central flap cmmnd.
15c - Central flap position
16c - Footwell/defrost flap cmmnd.
17c - footwell/defrost position
18c - Recirc valve cmmnd - 1=Off, 100 = On
19c - Recirc valve position
20c - Vehicle speed in KPH, 1 sec. sampling, actual speed - no safety margin
21c - Engine RPM (hundreds) - 1 sec. sampling
22c - ??
23c - ??
24c - Display panel illum. voltage
25c - ??
26c - ??
27c - ??
28c - Fan speed
29c - ??
30c - Engine run time in sec. (255 max.)
31c - timing counter
32c - Display test
33c - Sftwr. ver.
34c - ??
35c - Outside temp from inlet sensor post filter
36c - Temp.

This unit is built by audi and the codes marked ?? have to do with different applications.

[pk2]

Blue_s.

Let me know what you find. I think I have that setup too but quite frankly, I never saw much of interest. Looks like you have though. Be nice to see some alternative numbers.

Only a hundred in Corona eh? It was 97 the day I did my test, about as hot as it's been, I live about 40 mi. south west of you. Figured at least 110 further inland.

Regards, PK

[ddb]

Originally Posted by Blue-S

I will have to drive my 2000 "S" this evening and look at how the HVAC control panel diagnostic mode display for coolant temp compares with the needle position on the gauge. I should look at oil temp, too.:

After recently installing a new water pump, 160F thermostat and new coolant in my 2000 2.7 I've been monitoring my coolant temperatures. With ambient temperatures in the mid-eighties and speeds in the 70 MPH range I'm running between 80-85C (176-185F). When I slow down or stop in traffic the temperature quickly rises to 95-99C (203-210F). I haven't cleaned my radiators in 5 years so I assume they aren't ideal. I haven't yet looked at oil temperatures but will on the next outing.

Curious to see what you are running with your S.

ddb

[cnavarro]

That's typical. The only way to keep the coolant at the cruise temp is to make the fans come on earlier. There's a thread on the 996 forums at Renntech on how to do the mod:

http://www.renntech.org/forums/index.php?showtopic=28093&st=0&p=148785&#entry148785

I plan on doing this mod to our Boxster myself as I see the very high trigger point for the fans as the real limiting factor.

[jhandy]

I will have my car back from Raby soon with, amoung other stuff, a 160 Stat, however lets take this thinking to the extreme.

If lower is better, what would happen if the Tstat was removed and water was allowed to flow unhindered?

Not to hijack, just to understand better.

[ddb]

I think the water (and maybe oil) temperatures could be too low for too long. Maybe not a big issue in your climate, but in colder areas you wouldn't have any (or enough) heat. Engine oil and coolant temps. too low probably isn't good for the engine just like too hot isn't ideal.

[Jake Raby]

Removing the T stat makes the engine run HOTTER.. The coolant goes through the radiators too quickly to cool.

[pk2]

Originally Posted by jhandy

I will have my car back from Raby soon with, amoung other stuff, a 160 Stat, however lets take this thinking to the extreme.

If lower is better, what would happen if the Tstat was removed and water was allowed to flow unhindered?

Not to hijack, just to understand better.

-----------------------------------------------------------------
No problem

I like that attitude. I can see your ratcheting it up bit by bit.

I did take the thermostat out of my old 6cyl bmw cs coupe a long time ago. The problem was it never really warmed up. In fact it was down right cold, in the blue at speed somtimes.

With alot of trial and error, I think 3, 1/8th" holes through the thermostat gave me the temp I wanted (140??...maybe?). To be honest though, I didn't really notice a diff. Only that as db said, it took a little longer to warm up. I guess we're talking 5 hp here? I built the whole engine and tweaked quite a bit. 5 hp just might not have registered.

But, I think I agree with db, It's used to be, and I pretty sure it's still true to a degree, only when the engine was warmed up and running within a certain temp window that all the moving parts have expanded and fit together correctly as designed (we hope). So in a way I think driving around a cold engine is just as hard on it as driving it to hot.

Anyway, pop in any time. I'm the hijacker here. Till I arrived this thread was about changing a water pump. PK

[pk2]

Originally Posted by ddb

After recently installing a new water pump, 160F thermostat ...traffic the temperature quickly rises to 95-99C (203-210F). I haven't cleaned my radiators in 5 years so I assume they aren't ideal. I haven't yet looked at oil temperatures but will on the next outing.

Curious to see what you are running with your S.

ddb

DB, your fans aren't turning on very early. Mine come on within a minuet or 2 of hitting traffic. Once It''s warmed up, for what it's worth, the needle doesn't move much.

Don't know what your using for coolant, pretty sure it's not your prob but, your ready for a change. Might consider something like a quality version of GM.s Dex cool. Most of us traitors use Xerex dex-cool (compatible), about 1/5th the price of Porches exclusive juice and chemically identical where it counts (no silica or phosphates).

You probably knew all that already. If not, don't trust me, do some research. That's how I figured it out. It may still be controversial, so is the current issue at hand though.

Regards, PK

[Blue-S]

I had some time this evening to drive a bit and collect some data from the HVAC control panel's diagnostic mode as explained above. The car was a 2000 Boxster S 6-speed, with a new Porsche water pump and a 1-year-old standard replacement thermostat (presumed to be 80 deg C). The A/C compressor was off throughout the testing.

* During warmup, with the temp gauge needle exactly on the "tic" mark above the "8" in the "180" label, the HVAC panel (in 6c display) read 79 degrees C coolant temp. That converts to 174 degrees F.

* After allowing coolant temp to stabilize by driving approximately 10 miles with cruise set at 71 mph indicated in the digital speedometer display, I saw the following in the HVAC panel diagnostic mode:

Outside Temp Average (5c display) = 30 deg C (converts to 86 deg F)

Coolant Temp (6c display) = 91 deg C (converts to 196 deg F)

Vehicle Speed (20c display) = 111 km/h (converts to 69 mph)

RPM (21c display) = 2700

The coolant temp gauge needle in the instrument cluster was pointing straight up between the "8" and the "0" of the "180" label.

Oil temp was unavailable in the HVAC control panel diagnostic mode, because (I think) the 986 Boxster does not have an oil temp sensor in stock form.

------------------------------------------------------

When I returned home, I idled the engine for a while and gathered some more data:

* at 100 deg C (6c display on the HVAC) the gauge needle was approximately in the middle of the "0" in the "180" label.

* at 102 deg C (6c display on the HVAC) the right side radiator fan came on. This correlates with the specification in the Bentley manual for HIGH speed (stage 2) fan. The coolant temp crept up to 104 deg C (219 deg F) and stayed there for at least 5 more minutes with the right side radiator fan running. The gauge needle was at the right edge of the "0" of the "180" label when the HVAC was displaying 104 deg C coolant temp.

It is apparent that I have a radiator fan problem on my car. According to the wiring diagrams, both left and right side fans should be controlled at the same speed (stage 1 or stage 2) at the same time. It should be pretty simple to begin testing at the relay locations under the dash, since the relays seem to follow the standard ISO terminal definitions. I'll start with my Fluke 88 meter and a fused jumper wire...

So, what's going on here? These coolant temperatures do not match what JFP in PA, cnavarro and Jake Raby have posted on multiple occasions. Is the DME lying to the cluster and/or the HVAC control panel? Is the cluster lying to the HVAC control panel? Is the HVAC control panel lying to me? Or is the HVAC panel diagnostic mode accurately reporting the coolant temp as the DME reads it from the ECT sensor? None of the scan tools I have access to will read DME data, so this might be the push I need to buy the Durametric package...

[pk2]

Blue s,

Great work. So what has been said appears to be true. Have to ponder a bit...Think I'll see if I can get the same in my car... maybe I can even get the oil temp.

Let ya know whhat I come up with.

Regards, PK

[JFP in PA]

Originally Posted by Blue-S

I had some time this evening to drive a bit and collect some data from the HVAC control panel's diagnostic mode as explained above. The car was a 2000 Boxster S 6-speed, with a new Porsche water pump and a 1-year-old standard replacement thermostat (presumed to be 80 deg C). The A/C compressor was off throughout the testing.

* During warmup, with the temp gauge needle exactly on the "tic" mark above the "8" in the "180" label, the HVAC panel (in 6c display) read 79 degrees C coolant temp. That converts to 174 degrees F.

* After allowing coolant temp to stabilize by driving approximately 10 miles with cruise set at 71 mph indicated in the digital speedometer display, I saw the following in the HVAC panel diagnostic mode:

Outside Temp Average (5c display) = 30 deg C (converts to 86 deg F)

Coolant Temp (6c display) = 91 deg C (converts to 196 deg F)

Vehicle Speed (20c display) = 111 km/h (converts to 69 mph)

RPM (21c display) = 2700

The coolant temp gauge needle in the instrument cluster was pointing straight up between the "8" and the "0" of the "180" label.

Oil temp was unavailable in the HVAC control panel diagnostic mode, because (I think) the 986 Boxster does not have an oil temp sensor in stock form.

------------------------------------------------------

When I returned home, I idled the engine for a while and gathered some more data:

* at 100 deg C (6c display on the HVAC) the gauge needle was approximately in the middle of the "0" in the "180" label.

* at 102 deg C (6c display on the HVAC) the right side radiator fan came on. This correlates with the specification in the Bentley manual for HIGH speed (stage 2) fan. The coolant temp crept up to 104 deg C (219 deg F) and stayed there for at least 5 more minutes with the right side radiator fan running. The gauge needle was at the right edge of the "0" of the "180" label when the HVAC was displaying 104 deg C coolant temp.

It is apparent that I have a radiator fan problem on my car. According to the wiring diagrams, both left and right side fans should be controlled at the same speed (stage 1 or stage 2) at the same time. It should be pretty simple to begin testing at the relay locations under the dash, since the relays seem to follow the standard ISO terminal definitions. I'll start with my Fluke 88 meter and a fused jumper wire...

So, what's going on here? These coolant temperatures do not match what JFP in PA, cnavarro and Jake Raby have posted on multiple occasions. Is the DME lying to the cluster and/or the HVAC control panel? Is the cluster lying to the HVAC control panel? Is the HVAC control panel lying to me? Or is the HVAC panel diagnostic mode accurately reporting the coolant temp as the DME reads it from the ECT sensor? None of the scan tools I have access to will read DME data, so this might be the push I need to buy the Durametric package...

I have never used the climate control panel, so I cannot vouch for its level of accuracy, or how it compares to those seen on a scanner. You also need to recognize that these cars do vary somewhat in the temperatures they run at, even with the LN stat, due to differences in the cooling system (debris in the radiators, condition of the pump, non linearity of the dash unit, etc). I do know that the water temperature senders, at least those I have had the chance to evaluate, are pretty accurate. When using an OBD II scanner to monitor coolant temps, you are seeing the actual sensor data being relayed to the DME, so the numbers are also pretty reliable, and have correlated well with aftermarket gauge setups in the same cars.

On the Boxster, you cannot see the M96’s oil temperatures with out adding an oil temperature sensor to the engine, and while it can be done a couple of ways for testing, it is not a practical setup for day to day driving; so we only have used it for test purposes.

[pk2]

Originally Posted by JFP in PA

I have never used the climate control panel, so I cannot vouch for its level of accuracy, or how it compares to those seen on a scanner.... I do know that the water temperature senders, at least those I have had the chance to evaluate, are pretty accurate. When using an OBD II scanner to monitor coolant temps, you are seeing the actual sensor data being relayed to the DME, so the numbers are also pretty reliable, and have correlated well with aftermarket gauge setups in the same cars.

JFP IN PA

Very interesting information. You inadvertanly answered 2 sticky questions I was trying diplomatically compose. so moot now. At this quick moment I have, I can recall two comparatively softball questions.

1) As I understand from you and maybe others on this thread, Porsche concocted this whole charade so they could burn up more oil with the extra heat. I thought it was for emission issues but, if it blows out the pipe it's going to hurt not help in this arena(No?) is it blow-by?

Or, Could it be just to mitigate that early morning start-up cloud syndrome that some people have and freak out about? In which case, no matter for me, it would be long gone by the time you get to the smog station.

Tell me they did not do this to try to keep the outside the motor cleaner> avoid build up to...keep the motor running cool? (To ironic)

Thanks as always, gotta run...

PK

Is blow by that going to become aprent or

[JFP in PA]

Originally Posted by pk2

JFP IN PA

Very interesting information. You inadvertanly answered 2 sticky questions I was trying diplomatically compose. so moot now. At this quick moment I have, I can recall two comparatively softball questions.

1) As I understand from you and maybe others on this thread, Porsche concocted this whole charade so they could burn up more oil with the extra heat. I thought it was for emission issues but, if it blows out the pipe it's going to hurt not help in this arena(No?) is it blow-by?

Or, Could it be just to mitigate that early morning start-up cloud syndrome that some people have and freak out about? In which case, no matter for me, it would be long gone by the time you get to the smog station.

Tell me they did not do this to try to keep the outside the motor cleaner> avoid build up to...keep the motor running cool? (To ironic)

Thanks as always, gotta run...

PK

Is blow by that going to become aprent or

The use of higher coolant temperatures is done purely for emissions purposes. Running the cooling system at very high temps has been a crutch used by the OEM’s since the late 1960’s when everyone ran carburetors. Running hot helps nearly any engine reduce emissions with the poorly controlled fuel delivery systems that existed at the time. Unfortunately, even though modern injected and ECU controlled systems do not need to run that hot, the band aid has persisted because it also helps extend the cat converter life, and as the cat is covered by the federally mandated 80,000 mile operational life warranty, they will do anything to prevent having to replace the cats.

Interestingly, jacking up the coolant temperatures also lowers the volumetric efficiency and increases the chances for fuel flame front propagation issues (knock, detonation, etc.), so decreases in ignition timing are needed when the engine runs hotter. Net result is poorer performance, worse fuel economy and shortened oil life.

As for coolant temps allowing the oil to “bun off” contaminants; that rationale has always been somewhat suspect as the oil always runs hotter than the coolant anyway, plus the two main contaminants (water and fuel) would still flash off at lower temperatures as well, so lowering the coolant temp 20-30 F should not be a factor.