Coolant Temperature Rising on First Trip Out
01-05-2008, 04:17 AM
#31
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this might be unrelated, but for those of you remember, my "sticking" thermostat situation, i think i found the cure. as long as the reservior is 3/4 full, i dont have the problem. at the min fill line, on cold start up, the t-stat doesnt seem to get heat soaked to open, even if the lines are bled. I have to turn the engine off for a few seconds, and then on re-start it opens and everthing is fine.
MK
MK
01-05-2008, 03:05 PM
#32
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You might also check the inside of your radiator hoses. Since the car has been sitting for yrs dry rot may be the culpurt and the small black flakes hard rubber not metal. As hoses get to this state flaps can be created in the hoses causing very poor flow, thus the engine overheats. toofer
01-05-2008, 11:55 PM
#33
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OK....went out of town today and got the IR thermometer (Sears). Installed the battery and was taking the temperature of EVERYTHING - truck interior, my pant leg, my hand, heat coming out the heater vent.....even my wife liked using it. Went to HF later on and got her one there too. Very nice tool! Here's a pic of the one I got at Sears...
When I got home, I took the 928 out for a drive to get the temp up so I could use the thermometer to see if the hose temp was actually as hot as the guage was indicating. So I'm driving my regular course (it's about 25 miles long with a couple of moderate grades). All conditions the same as my earlier tests. However, I could not get the temp guage needle to go past the mid-point - it stayed between the 2 white lines. This was strange because the day before, I ran the same course and the guage was near the 2nd white line. I got back home, still no difference - right at mid-point. Here's a pic:
So I try the IR termometer. This is my first time using the IR and trying to take a picture so the readings may be a little blury. Here's the top radiator hose temp at idle with the guage reading mid-point:
Temp is between 185F and 190F at the hose. I measured the bottom/return hose and got this:
Temp between 145F and 150F. I also measured a few other things. The heads measured between 205F and 210F. The radiator core at the cool/return end (driver's side of the car) had some interesting readings. Near the top, next to the side tank, the temp was between 110F and 115F. As I moved down the radiator core with the IR, the core/cooling vane temperature steadily drops - midway down the radiator core temp is about 95F and at the bottom it's about 80F. I couldn't get a good position to take readings on the other end of the radiator (at the inlet/hot end).
The test I ran today and the temperature readings I took seem to be pretty normal to me (i.e., assuming the temp guage normal position is mid-point, the termostat is 180F and the temp coming out of the engine is between 185F and 190F). My test scenario also includes a long straight and level stretch where I turn on the heater (unfortunately, my heater fan is not working so hot air is only produced when I have outside air speed - car moving). When I turn on the heater, I can actually see the temp guage drop slightly below the mid-point position when I'm at hiway speeds. This has been consistent in all my tests.
At this point, I'm thinking I need to drive it more and monitor the temp guage and carry my IR. Take IR readings when/if I see the guage rise above the mid-point. I may even just drive it a few more days (or a week) and then completely drain it all again in the white bucket and see if any more debris shows up.
The one question that still eludes me is "where did all the black gritty material come from?". All cooling and heater hoses were replaced when I re-installed the engine this summer, New metal Y pipe and metal pipe that preceeds the heater control valve at the back of the engine, new thermostat. The parts that weren't replaced were:
1) the radiator
2) the heater core inside the dash
3) the coolant resevior
4) thermostat housing/bridge
I understand the heater core doesn't rust and I cleaned the resevior tank when I had the engine out as well as the bridge. I also took the engine completely apart down to chunk aluminum and took the part to the machine shop for cleaning. The engine block and heads came back spotless and shiny. That would seem to leave only one source of the black grit - the radiator. Right? THANKS for reading....opinions welcome!
When I got home, I took the 928 out for a drive to get the temp up so I could use the thermometer to see if the hose temp was actually as hot as the guage was indicating. So I'm driving my regular course (it's about 25 miles long with a couple of moderate grades). All conditions the same as my earlier tests. However, I could not get the temp guage needle to go past the mid-point - it stayed between the 2 white lines. This was strange because the day before, I ran the same course and the guage was near the 2nd white line. I got back home, still no difference - right at mid-point. Here's a pic:
So I try the IR termometer. This is my first time using the IR and trying to take a picture so the readings may be a little blury. Here's the top radiator hose temp at idle with the guage reading mid-point:
Temp is between 185F and 190F at the hose. I measured the bottom/return hose and got this:
Temp between 145F and 150F. I also measured a few other things. The heads measured between 205F and 210F. The radiator core at the cool/return end (driver's side of the car) had some interesting readings. Near the top, next to the side tank, the temp was between 110F and 115F. As I moved down the radiator core with the IR, the core/cooling vane temperature steadily drops - midway down the radiator core temp is about 95F and at the bottom it's about 80F. I couldn't get a good position to take readings on the other end of the radiator (at the inlet/hot end).
The test I ran today and the temperature readings I took seem to be pretty normal to me (i.e., assuming the temp guage normal position is mid-point, the termostat is 180F and the temp coming out of the engine is between 185F and 190F). My test scenario also includes a long straight and level stretch where I turn on the heater (unfortunately, my heater fan is not working so hot air is only produced when I have outside air speed - car moving). When I turn on the heater, I can actually see the temp guage drop slightly below the mid-point position when I'm at hiway speeds. This has been consistent in all my tests.
At this point, I'm thinking I need to drive it more and monitor the temp guage and carry my IR. Take IR readings when/if I see the guage rise above the mid-point. I may even just drive it a few more days (or a week) and then completely drain it all again in the white bucket and see if any more debris shows up.
The one question that still eludes me is "where did all the black gritty material come from?". All cooling and heater hoses were replaced when I re-installed the engine this summer, New metal Y pipe and metal pipe that preceeds the heater control valve at the back of the engine, new thermostat. The parts that weren't replaced were:
1) the radiator
2) the heater core inside the dash
3) the coolant resevior
4) thermostat housing/bridge
I understand the heater core doesn't rust and I cleaned the resevior tank when I had the engine out as well as the bridge. I also took the engine completely apart down to chunk aluminum and took the part to the machine shop for cleaning. The engine block and heads came back spotless and shiny. That would seem to leave only one source of the black grit - the radiator. Right? THANKS for reading....opinions welcome!
01-06-2008, 12:39 AM
#34
Maybe there was a stubborn air pocket that finally pruged. My temp gauge runs right in the middle like yours was showing in the pic. Hopefully the issue is resolved and will not return. Those little IR temp checkers are fun little toys aren't they.
01-06-2008, 12:52 AM
#35
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I don't know how I got along without the IR before now!! Seems like everything needs to have it's temp taken now!
01-06-2008, 12:57 AM
#36
Dwayne. I think I have the 180 deg stat. Not 100% sure. It has been a while since I replaced it.
01-06-2008, 01:05 AM
#37
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well thats good news, what i have seen is the temp gauge reading a bit higher upon the first time of refilling the cooling system, after it is filled and driven with the heater control full on and left to cool down is when the coolant seems to find its correct level . Although the 928 is a self purging system, it only seems to fully purge when the heater is opened and the car is driven for about 5 miles, and then left to cool, thats my experience anyway,
The IR gauge is a good tool to have , it tells that the themostate is opening at about the temps it needs to, There is still a chance that the cooling fan clutch is also going bad, to test it with the engine cold try to turn the fan if it has moderate resistance for most if not all of a full revolution then it indicates good, If however it turns with some resistance say a quarter turn then starts to turn freely for a bit then resistance again the silicone dampening fluid is probably leaking out .Get a mirror and check the front of the clutch hub see if it looks like there is a oil leak indicated by dirt sticking to the fan clutch.
In this case your cleaning efforts may have erased this possible clue to the fan clutch condition
The IR gauge is a good tool to have , it tells that the themostate is opening at about the temps it needs to, There is still a chance that the cooling fan clutch is also going bad, to test it with the engine cold try to turn the fan if it has moderate resistance for most if not all of a full revolution then it indicates good, If however it turns with some resistance say a quarter turn then starts to turn freely for a bit then resistance again the silicone dampening fluid is probably leaking out .Get a mirror and check the front of the clutch hub see if it looks like there is a oil leak indicated by dirt sticking to the fan clutch.
In this case your cleaning efforts may have erased this possible clue to the fan clutch condition
01-06-2008, 01:41 AM
#39
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well thats good news, what i have seen is the temp gauge reading a bit higher upon the first time of refilling the cooling system, after it is filled and driven with the heater control full on and left to cool down is when the coolant seems to find its correct level . Although the 928 is a self purging system, it only seems to fully purge when the heater is opened and the car is driven for about 5 miles, and then left to cool, thats my experience anyway,
The IR gauge is a good tool to have , it tells that the themostate is opening at about the temps it needs to, There is still a chance that the cooling fan clutch is also going bad, to test it with the engine cold try to turn the fan if it has moderate resistance for most if not all of a full revolution then it indicates good, If however it turns with some resistance say a quarter turn then starts to turn freely for a bit then resistance again the silicone dampening fluid is probably leaking out .Get a mirror and check the front of the clutch hub see if it looks like there is a oil leak indicated by dirt sticking to the fan clutch.
In this case your cleaning efforts may have erased this possible clue to the fan clutch condition
The IR gauge is a good tool to have , it tells that the themostate is opening at about the temps it needs to, There is still a chance that the cooling fan clutch is also going bad, to test it with the engine cold try to turn the fan if it has moderate resistance for most if not all of a full revolution then it indicates good, If however it turns with some resistance say a quarter turn then starts to turn freely for a bit then resistance again the silicone dampening fluid is probably leaking out .Get a mirror and check the front of the clutch hub see if it looks like there is a oil leak indicated by dirt sticking to the fan clutch.
In this case your cleaning efforts may have erased this possible clue to the fan clutch condition
I'll be taking it on another drive tomorrow and try a steeper grade nearby and see how it does. Perhaps using the heater the first time introduced a large amount of air into the system and that caused the higher temps on the return trip home around Christmas (we didn't use the heater at all on the way out of town and the temps were just fine).
You're right, I did clean the fan and removed all clues to any clutch leakage when I put the engine back in. However, I do remember the fan moving with consistent/moderate resistance full circle when I had it out several months ago. This will be an easy check as you suggest and I will try it out tomorrow morning before heading out for a spin. THANKS again!
01-06-2008, 01:54 AM
#40
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I normally take a week or two vacation to Oregon in late May early June so I need to see if the road trip lines up with those plans.
BTW, I notice you're in Carson City, NV?? I pass through there at least three times a year on my way to Oregon. In fact, going through there this Friday on my way up to OR with my wife. We're stopping in Reno to look at an '89 928 for sale there - we're interested in buying it. Anyway, maybe we'll get a chance to meet on one of my regular trips through your neck of the woods (unfortunately, I'll be driving the Sierra -- the 928 just doesn't carry enough hay and firewood!).
01-06-2008, 02:13 AM
#41
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Dwayne can you say Sharks at the Lake? Clear your calander for Fathers day.
Go to U tube and search for sharks at the lake, play the video, about 8 mins long, ENJOY, Stan
Go to U tube and search for sharks at the lake, play the video, about 8 mins long, ENJOY, Stan
01-06-2008, 02:51 AM
#42
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I checked out the video -- neeto! I remember seeing a post about Sharks at the Lake but didn't read it - just assumed it was some other lake far far away. I'll definitely read up on it and make plans to attend. It would be GREAT to finally meet some of the people that have been so helpful on this list!! THANKS!!!
01-06-2008, 11:26 PM
#44
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Jim,
THANKS for the tip....I didn't know about this one either but did some research....looked at the NORCAL928 site and found a link to Sharks in the Park -- Cool! Now I know what SITP stands for! (...learn something everyday!) I'll keep my eye on this event too. THANKS!
THANKS for the tip....I didn't know about this one either but did some research....looked at the NORCAL928 site and found a link to Sharks in the Park -- Cool! Now I know what SITP stands for! (...learn something everyday!) I'll keep my eye on this event too. THANKS!
