New radiator in my future?
07-11-2009, 05:34 PM
#1
Rennlist Member
Thread Starter
New radiator in my future?
Just did a coolant flush/refill with a 70/30 water/coolant mix using Zerex G-05, 2 bottles Red Line Water Wetter, and distilled water. Got it good and hot, heater turned on, multiple drain and refill to get all the flush and old coolant out, etc.
She continues to run 1 needle width above the white 190 line whether sitting still or at highway speed.
What sayeth the collective wisdom of the list? Thanks in advance!
P.S. On the bright side, the heater works REAL good.
She continues to run 1 needle width above the white 190 line whether sitting still or at highway speed.
- Front flaps are open when hot
- Both electric fans run when hot or when A/C is on
- New Behr coolant reservoir cap installed
- Don't know the age of the thermostat
- Radiator appears to be original
- Test conditions today were 95 degrees with an Accuweather RealFeel of 104 degrees
What sayeth the collective wisdom of the list? Thanks in advance!
P.S. On the bright side, the heater works REAL good.
Last edited by JWise; 07-11-2009 at 10:04 PM.
07-11-2009, 05:55 PM
#2
Basic Sponsor
Rennlist
Site Sponsor
Rennlist
Site Sponsor
Sounds normal to me - gauge is very inaccurate.
As long as it stays where it is its fine.
Why did you put all the crap in it 8>) 50/50 Dexcool is pefect.
As long as it stays where it is its fine.
Why did you put all the crap in it 8>) 50/50 Dexcool is pefect.
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
07-11-2009, 06:03 PM
#3
Rennlist Member
Thread Starter
Part of my concern is it used to run 1 needle width BELOW the white 190 line. Now it's running on top of, or one width beyond.
Dexcool scares me. I've seen what it can do if it gets exposed to any air in the system. Not pretty, and fortunately it wasn't on one of my vehicles. I'm sure it can be safely used in our cars, but I'd rather not chance it.
I went with 70/30 because it rarely gets below 0 here, and the 928 wouldn't be out then anyway. She'd be in the garage, which stays above freezing (obviously way above 0). The 70/30 mix should offer better cooling capacity than 50/50, while still offering sufficient freeze protection and anti-corrosion properties.
Dexcool scares me. I've seen what it can do if it gets exposed to any air in the system. Not pretty, and fortunately it wasn't on one of my vehicles. I'm sure it can be safely used in our cars, but I'd rather not chance it.
I went with 70/30 because it rarely gets below 0 here, and the 928 wouldn't be out then anyway. She'd be in the garage, which stays above freezing (obviously way above 0). The 70/30 mix should offer better cooling capacity than 50/50, while still offering sufficient freeze protection and anti-corrosion properties.
Last edited by JWise; 07-11-2009 at 11:17 PM.
07-11-2009, 06:25 PM
#4
Jarrod, both of mine run like that. The '88 runs cooler than the '90 since I put in the rebuilt behr. On the 104 days we've been seeing, it's running one needle tick above 190. I think you are fine.
07-11-2009, 07:32 PM
#5
Addict
Rennlist Member
Rennlist Member
I just had a flush done and mine is running 1 tick below to 1 tick above depending on outside temps. That is with front and rear A/C running.
07-11-2009, 08:41 PM
#7
Chronic Tool Dropper
Lifetime Rennlist
Member
Lifetime Rennlist
Member
I think the gauge is valuable for seeing when things change. I'm not so sure that absolutes are that reliable. You can verify the gauge readings against an IR gun, but still you will be watching for changes in the gauge as a telltale of something wrong in the way the engine cools.
My gauge used to run midway between 170 and that next unlabeled line. Maybe a bit below. When I changed to the rebuilt LHA box, gauge moved up two needle widths. Fuel economy improved too. No other changes. Point is that lots of things affect the temp indication. More or less fuel? Timing changes? All affect what you see.
Roger, the coolant mix that Jarrod used is perfect for a non-freezing climate. It has enough for some boilover protection, water pump lubrication, corrosion protection, and the Water Wetter helps with heat transfer. Dexcool is not the best choice.
My gauge used to run midway between 170 and that next unlabeled line. Maybe a bit below. When I changed to the rebuilt LHA box, gauge moved up two needle widths. Fuel economy improved too. No other changes. Point is that lots of things affect the temp indication. More or less fuel? Timing changes? All affect what you see.
Roger, the coolant mix that Jarrod used is perfect for a non-freezing climate. It has enough for some boilover protection, water pump lubrication, corrosion protection, and the Water Wetter helps with heat transfer. Dexcool is not the best choice.
Trending Topics
07-11-2009, 09:46 PM
#8
Rennlist Member
Thread Starter
Nooooooo! 
Thanks Dr. Bob.
Unfortunately, I don't have an IR gun. You are certainly correct about change vs. absolute. The recent change in the norm is what had me concerned. Last summer, it was a needle width below the line or partially on it. Now it's on it to a needle with above.
Your second points intrigue me.
Regarding fuel - I know in piston aircraft, fuel mixture is a primary factor in CHT's. I would think it's possible to have an impact in our cars as well.
Regarding timing - my experience last summer was with dead knock sensors and a bad Hall Sender. Not only does this situation result in retarded timing, but I suspect the fuel mixture was richer then as I was getting 20mpg max.
Earlier this year, Sean and I did an intake/cam cover refresh including new knock sensors and Hall sender, so I know the timing's more advanced. I am also now seeing 23mpg, an indication that she's running leaner. I wonder if these are the reasons I'm seeing warmer temps? Something to think about...
BTW- forgot to mention in the OP that I put a new Behr coolant reservoir cap on as well. I'll go back and edit the OP.
I think the gauge is valuable for seeing when things change. I'm not so sure that absolutes are that reliable. You can verify the gauge readings against an IR gun, but still you will be watching for changes in the gauge as a telltale of something wrong in the way the engine cools...
...Point is that lots of things affect the temp indication. More or less fuel? Timing changes? All affect what you see.
...Point is that lots of things affect the temp indication. More or less fuel? Timing changes? All affect what you see.
Unfortunately, I don't have an IR gun. You are certainly correct about change vs. absolute. The recent change in the norm is what had me concerned. Last summer, it was a needle width below the line or partially on it. Now it's on it to a needle with above.
Your second points intrigue me.
Regarding fuel - I know in piston aircraft, fuel mixture is a primary factor in CHT's. I would think it's possible to have an impact in our cars as well.
Regarding timing - my experience last summer was with dead knock sensors and a bad Hall Sender. Not only does this situation result in retarded timing, but I suspect the fuel mixture was richer then as I was getting 20mpg max.
Earlier this year, Sean and I did an intake/cam cover refresh including new knock sensors and Hall sender, so I know the timing's more advanced. I am also now seeing 23mpg, an indication that she's running leaner. I wonder if these are the reasons I'm seeing warmer temps? Something to think about...
BTW- forgot to mention in the OP that I put a new Behr coolant reservoir cap on as well. I'll go back and edit the OP.
Last edited by JWise; 07-11-2009 at 10:08 PM.
07-11-2009, 10:20 PM
#9
Rennlist Member
Jarrod,
Is the temperature stable under heavy load-- i.e. up a steep grade or at sustained high speeds?
(On a closed course with a professional driver of course
)
If the temperature is stable then your radiator is keeping up with the heat load, and the temperature is whatever the thermostat says it should be. So maybe the thermostat has shifted its thinking a bit, or the temp gauge has shifted calibration a bit.
The digi-dashes don't seem as "creative" about the gauge readings as the earlier ones. An IR gun is not overly expensive and very handy to have around to answer questions like this.
Cheers,
Is the temperature stable under heavy load-- i.e. up a steep grade or at sustained high speeds?
(On a closed course with a professional driver of course
) If the temperature is stable then your radiator is keeping up with the heat load, and the temperature is whatever the thermostat says it should be. So maybe the thermostat has shifted its thinking a bit, or the temp gauge has shifted calibration a bit.
The digi-dashes don't seem as "creative" about the gauge readings as the earlier ones. An IR gun is not overly expensive and very handy to have around to answer questions like this.
Cheers,
07-11-2009, 10:27 PM
#10
Addict
Rennlist Member
Rennlist Member
Join Date: Oct 2003
Location: Gone. On the Open Road
Posts: 16,548
Received 1,679 Likes
on
1,089 Posts
How do you know the flaps were open when you were driving? I suggest pulling the fuse and manually opening them for purposes of testing (if not forever.)
Do you know the history and impeller-type of the water pump? Is it a rebuild? From what supplier? (This latter question is only to ascertain the impeller-type if you don't know.)
Does the car otherwise seem to have all its power throughout the load range?
Any history on the fuel pumps? Fuel filter?
Have you thoroughly cleaned the outside of the radiator?
Do you have access to a diagnostic tool/software to interrogate the car through the diagnostic port? (In addition to the obvious, you can use the tool to monitor the NTC-II temp the computer's see.)
What's the age of the MAS? 02 Sensor?
What was done with the injectors during the intake R&R?
Does the car idle at 675 +/- 25 RPM?
Suggestions in addition to any above low-hanging fruit:
Might as well replace the thermostat. Bench testing the thermostat is as easy as replacing it.
Buy an IR temp gauge. They aren't expensive (<$100). Use it to get additional measurements. In my experience the gauges on 89+ 928s are usually pretty close to what the ECUs see from the NTC-II sender. They will typically under-read by no more than 10 degrees or so - but they do under-read.
To double-check the intake refresh work: at idle check that each of the fuel dampeners and the regulator have manifold vacuum and that the vacuum disappears when the throttle is blipped.
Check your fuel pressures against spec with an external gauge, verify 45-ish PSI with a transient pump to 55-ish PSI at idle when the throttle is blipped.
07-11-2009, 11:12 PM
#11
Rennlist Member
Thread Starter
..
Jarrod,
Is the temperature stable under heavy load-- i.e. up a steep grade or at sustained high speeds?
(On a closed course with a professional driver of course)
If the temperature is stable then your radiator is keeping up with the heat load, and the temperature is whatever the thermostat says it should be. So maybe the thermostat has shifted its thinking a bit, or the temp gauge has shifted calibration a bit.
The digi-dashes don't seem as "creative" about the gauge readings as the earlier ones. An IR gun is not overly expensive and very handy to have around to answer questions like this.
Temps seems stable, just higher than I experienced last summer.
Cheers,
Is the temperature stable under heavy load-- i.e. up a steep grade or at sustained high speeds?
(On a closed course with a professional driver of course
) If the temperature is stable then your radiator is keeping up with the heat load, and the temperature is whatever the thermostat says it should be. So maybe the thermostat has shifted its thinking a bit, or the temp gauge has shifted calibration a bit.
The digi-dashes don't seem as "creative" about the gauge readings as the earlier ones. An IR gun is not overly expensive and very handy to have around to answer questions like this.
Temps seems stable, just higher than I experienced last summer.
Cheers,
23mpg in a GT is just wrong. This under the assumption that you aren't listing pure highway in locked-to-55 mode. Even then, 23 mpg might be a bit high. I don't think I've ever seen either of my GTs get above 20.
Both GT's I've owned have given low 20's on the highway, and that's at 75-80mph. Love watching the distance to empty start out at around 325 miles after a fill-up, and then CLIMB after I'm back out on the road. Often times, once I get into the tank a ways, the sum of the distance traveled plus distance to empty will exceed 400 miles. Usually get around 18 in town.
Have you normalized your recollections of the gauge readings with ambient temperatures? Or, IOW, was it cooler last year? One needle about the 190 line is ever-so-slightly warmer that normal. On the other hand 95+-degree temps are a perhaps a factor. In our typical Yankee weather one line over is not normal for a GT.
A cool summer here is 95. A hot one is 105. It was hot today, but not excessive relatively speaking
How do you know the flaps were open when you were driving? I suggest pulling the fuse and manually opening them for purposes of testing (if not forever.)
I can't say for sure the flaps were open when I took it out for a spin, but they were open when it was hot and sitting in the driveway. Same observation with the electric fans.
Do you know the history and impeller-type of the water pump? Is it a rebuild? From what supplier? (This latter question is only to ascertain the impeller-type if you don't know.)
IIRC the pump is a rebuilt from 928 Intl. It was changed shortly after I bought the car in late 2006, so it's not yet three years old.
Does the car otherwise seem to have all its power throughout the load range?
Seems to. I'm going to dyno it at the OCIC, and look forward to the results as a general indication of health
Any history on the fuel pumps? Fuel filter?
No knowledge on the pumps, fuel filter was changed late 2006, IIRC. I drive no more than 2,500 miles a year and dump an occasional bottle of Techron or B12 Chemtool in the tank
Have you thoroughly cleaned the outside of the radiator?
Yes
Do you have access to a diagnostic tool/software to interrogate the car through the diagnostic port? (In addition to the obvious, you can use the tool to monitor the NTC-II temp the computer's see.)
Are you talking Hammer? Had one here last week, but have already returned it to Roger. No fault codes, though.
What's the age of the MAS? 02 Sensor?
Don't know.
What was done with the injectors during the intake R&R?
Uh, I wiped them off. Seriously, I did put new o-ring seals on them but I didn't send them to Marren or anyone. I suppose I could do that, but will have to wait until after the OCIC. That plus it's so darn hot right now any fuel spillage would probably spontaneously combust, LOL
Does the car idle at 675 +/- 25 RPM?
Yep
Suggestions in addition to any above low-hanging fruit:
Might as well replace the thermostat. Bench testing the thermostat is as easy as replacing it.
That thought had crossed my mind.
Buy an IR temp gauge. They aren't expensive (<$100). Use it to get additional measurements. In my experience the gauges on 89+ 928s are usually pretty close to what the ECUs see from the NTC-II sender. They will typically under-read by no more than 10 degrees or so - but they do under-read.
To double-check the intake refresh work: at idle check that each of the fuel dampeners and the regulator have manifold vacuum and that the vacuum disappears when the throttle is blipped.
Are you questioning the work of myself and the Great Sean-dini? OK, how do I go about doing that?
Check your fuel pressures against spec with an external gauge, verify 45-ish PSI with a transient pump to 55-ish PSI at idle when the throttle is blipped.
Don't have one of those, either. Sounds like I need to make a list of things to look at and schedule a trip down to Sean's after the OCIC.
Thanks for all these ideas/suggestions, Dave!
Both GT's I've owned have given low 20's on the highway, and that's at 75-80mph. Love watching the distance to empty start out at around 325 miles after a fill-up, and then CLIMB after I'm back out on the road. Often times, once I get into the tank a ways, the sum of the distance traveled plus distance to empty will exceed 400 miles. Usually get around 18 in town.
Have you normalized your recollections of the gauge readings with ambient temperatures? Or, IOW, was it cooler last year? One needle about the 190 line is ever-so-slightly warmer that normal. On the other hand 95+-degree temps are a perhaps a factor. In our typical Yankee weather one line over is not normal for a GT.
A cool summer here is 95. A hot one is 105. It was hot today, but not excessive relatively speaking
How do you know the flaps were open when you were driving? I suggest pulling the fuse and manually opening them for purposes of testing (if not forever.)
I can't say for sure the flaps were open when I took it out for a spin, but they were open when it was hot and sitting in the driveway. Same observation with the electric fans.
Do you know the history and impeller-type of the water pump? Is it a rebuild? From what supplier? (This latter question is only to ascertain the impeller-type if you don't know.)
IIRC the pump is a rebuilt from 928 Intl. It was changed shortly after I bought the car in late 2006, so it's not yet three years old.
Does the car otherwise seem to have all its power throughout the load range?
Seems to. I'm going to dyno it at the OCIC, and look forward to the results as a general indication of health
Any history on the fuel pumps? Fuel filter?
No knowledge on the pumps, fuel filter was changed late 2006, IIRC. I drive no more than 2,500 miles a year and dump an occasional bottle of Techron or B12 Chemtool in the tank
Have you thoroughly cleaned the outside of the radiator?
Yes
Do you have access to a diagnostic tool/software to interrogate the car through the diagnostic port? (In addition to the obvious, you can use the tool to monitor the NTC-II temp the computer's see.)
Are you talking Hammer? Had one here last week, but have already returned it to Roger. No fault codes, though.
What's the age of the MAS? 02 Sensor?
Don't know.
What was done with the injectors during the intake R&R?
Uh, I wiped them off.
Seriously, I did put new o-ring seals on them but I didn't send them to Marren or anyone. I suppose I could do that, but will have to wait until after the OCIC. That plus it's so darn hot right now any fuel spillage would probably spontaneously combust, LOLDoes the car idle at 675 +/- 25 RPM?
Yep
Suggestions in addition to any above low-hanging fruit:
Might as well replace the thermostat. Bench testing the thermostat is as easy as replacing it.
That thought had crossed my mind.
Buy an IR temp gauge. They aren't expensive (<$100). Use it to get additional measurements. In my experience the gauges on 89+ 928s are usually pretty close to what the ECUs see from the NTC-II sender. They will typically under-read by no more than 10 degrees or so - but they do under-read.
To double-check the intake refresh work: at idle check that each of the fuel dampeners and the regulator have manifold vacuum and that the vacuum disappears when the throttle is blipped.
Are you questioning the work of myself and the Great Sean-dini?
OK, how do I go about doing that?Check your fuel pressures against spec with an external gauge, verify 45-ish PSI with a transient pump to 55-ish PSI at idle when the throttle is blipped.
Don't have one of those, either. Sounds like I need to make a list of things to look at and schedule a trip down to Sean's after the OCIC.
Thanks for all these ideas/suggestions, Dave!
07-11-2009, 11:23 PM
#12
Rennlist Member
Rennlist Site Sponsor
"Have you thoroughly cleaned the outside of the radiator?"
Jarrod,
Remember that the outside of the radiator specifically includes between the condenser and the radiator.
You situation sounds normal and acceptable.
Jarrod,
Remember that the outside of the radiator specifically includes between the condenser and the radiator.
You situation sounds normal and acceptable.
07-11-2009, 11:33 PM
#13
Rennlist Member
Thread Starter
As an aside, oil pressures seem fine. I'm running Mobil 1 15W-50 and seeing 1.5-2 bar at hot idle, and of course it jumps to 5 bar at cruise.
07-12-2009, 01:45 AM
#14
Chronic Tool Dropper
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Jarrod--
Did you change injectors when you did the intake refresh? Were they changed to higher-flow injectors? If so, are your mileage readings done by dash display observation or by calculated miles vs gallons at fill-up to get MPG's? If you replaced the original injectors with slightly higher-rated injectors, the display would show the result of the lower pulse time as better mileage. Drive through a few tanks and figure out what the tru mileage is, and see if it' really as good as the dash display shows,
Did you change injectors when you did the intake refresh? Were they changed to higher-flow injectors? If so, are your mileage readings done by dash display observation or by calculated miles vs gallons at fill-up to get MPG's? If you replaced the original injectors with slightly higher-rated injectors, the display would show the result of the lower pulse time as better mileage. Drive through a few tanks and figure out what the tru mileage is, and see if it' really as good as the dash display shows,
07-12-2009, 03:33 AM
#15
Not the sharpest tool in the shed
Rennlist Member
Rennlist Member
Jarrod - I would think everything is okay. If your assumption about the engine running rich before the intake refresh is correct and then lean after.... typically rich equals cooler running temps, lean hotter. I'd say everything is working as it should.