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Water Pump Tensioner


Scotty

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I replaced my water pump tensioner last week and after a week of driving that car I have noticed that at highway speeds I am running between 4 and 6 degrees cooler (197 to 199 when it was 203). I am not sure what is causing this drop in temp unless the tension was not adequate after 10 years. The bearing in the pulley seems ever so slightly rough. I just wanted to report this for all you that have older NS's.. you may benefit from changing your tensioner...

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Just something I have observed over the years.

In the Winter (cooler weather) on average my engine will run a few degrees hotter.

Then in Summer, the engine will run a few degrees cooler.

Is it possible now that it's warmer, your engine is just running a bit cooler anyway ?

Barry

2008 STS V8
2016 Colorado Z71
1970 Corvette LT-1 Coupe

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Just something I have observed over the years.

In the Winter (cooler weather) on average my engine will run a few degrees hotter.

Then in Summer, the engine will run a few degrees cooler.

Is it possible now that it's warmer, your engine is just running a bit cooler anyway ?

Barry

I have observed the same thing, 206 in summer and 213 in winter.

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Maybe that is possible guys. I did not notice the drop last year but then again I wasn't really looking for it.. To be honest I have NEVER seen 197 on my car at highway speeds and its a welcome site. Why do you think it will run cooler in the summer than the winter? I would have thought that the additional cooling provided with the heater core would have worked against that thought... Mike

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I think Guru had addressed this once. As I recall he said it had to do with the fact that during the summer your most likely using the A/C and that activates the cooling fans thus pulling more air across the radiator. I think the thermostat also played a part in it.

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Ah my situation blows that theory as I run in ECON because I have no freon... the cooling fans don't run in ECON.. whatever the reason I am happy to see 197 at highway speeds, I can't help but think that better tension on the water pump belt helped..

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Maybe the original tensioner was sticking and by replacing it, the new tensioner is applying the proper tension to the belt?

I replaced the serpentine belt and the water pump belt on my '96 SLS last month and the tensioner was free but I gave it a shot of spray lithium grease. The bearing was a little rough so I repacked it with bearing grease and it is smooth again.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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If the tensioner was failing, causing the belt to slip, I would imagine the belt wouldn't last very long.

I think the observed temperature differences with changes in ambient temperature (radiator airflow is in excess, e.g. highway cruising) are a result of the thermostat and the temperature sending unit being in different locations, as well as the flowrate across the thermostat affecting slightly the temperature in various parts. At low ambients, the thermostat will always be 'controlling' (i.e. not fully open); the volume of hot coolant leaving the engine (outlet thermostat) or the volume of cold coolant entering the engine (inlet thermostat) will be lower. This may affect the localised flow rate at the sending unit, or affect slightly the temperature of the coolant the sending unit 'sees', both being location dependent.

___________________________________________________

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Maybe the original tensioner was sticking and by replacing it, the new tensioner is applying the proper tension to the belt?

I replaced the serpentine belt and the water pump belt on my '96 SLS last month and the tensioner was free but I gave it a shot of spray lithium grease.  The bearing was a little rough so I repacked it with bearing grease and it is smooth again.

I think you are right Kevin, the tension has improved and its providing a more consistent tension, that combined with my pulley bearing that seemed worn and slightly rough. I suppose I could have taken it off and sort of 'tuned it up' by cleaning and lubing it good with some type of dry lube on the pivot. But I figure that given that its 10 years old its time.

I was kind of surprised upon hearing that some were getting highway temps of 195 to 197 I was not even getting that in the winter months, in single digits. When I heard it, I chalked it up to my cooling system needing to be flushed. Now when I replace the stat, flush it and blow out the radiator fins when I pull the condenser she will ride nice and cool. I am finally done with family obligations and can finally get to the AC this week and not a moment too soon with the heat arriving :rolleyes:

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If the tensioner was failing, causing the belt to slip, I would imagine the belt wouldn't last very long.

I think the observed temperature differences with changes in ambient temperature (radiator airflow is in excess, e.g. highway cruising) are a result of the thermostat and the temperature sending unit being in different locations, as well as the flowrate across the thermostat affecting slightly the temperature in various parts.  At low ambients, the thermostat will always be 'controlling' (i.e. not fully open); the volume of hot coolant leaving the engine (outlet thermostat) or the volume of cold coolant entering the engine (inlet thermostat) will be lower.  This may affect the localised flow rate at the sending unit, or affect slightly the temperature of the coolant the sending unit 'sees', both being location dependent.

That is an interesting thought, I never would have thought that the stat would control that much, but that makes sense.

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I was kind of surprised upon hearing that some were getting highway temps of 195 to 197 I was not even getting that in the winter months, in single digits. When I heard it, I chalked it up to my cooling system needing to be flushed. Now when I replace the stat, flush it and blow out the radiator fins when I pull the condenser she will ride nice and cool. I am finally done with family obligations and can finally get to the AC this week and not a moment too soon with the heat arriving :rolleyes:

My Seville has the analog gage package that includes a temp gage on the dash. I added the coolant temp. and vehicle speed to the DIC but honestly, I rarely bring up the coolant temp on the display.....I just glance at the temp gage every now and then. If it gets too hot, there will be PLENTY of advanced warning - messages on the DIC, temp. warning light, etc..

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Sorry, slightly off topic, but Kevin's mention of the DIC jogged my brain. Kevin, can you get the ACM Data to show? I was trying the other day and I couldn't. No Data promt came up for ACM, only Codes. Other areas had the Data promt, which I could get (fan up). I wanted to check the commanded/actual position of the blend door. I watched it (removed glove box) as I commanded full cold. It swung to full travel then backed up a bit, all in one move. It wasn't backing up because it was satisfied, as it was plenty warm in there. (I have the analog package as well)

rek

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Sorry, slightly off topic, but Kevin's mention of the DIC jogged my brain. Kevin, can you get the ACM Data to show? I was trying the other day and I couldn't. No Data promt came up for ACM, only Codes. Other areas had the Data promt, which I could get (fan up). I wanted to check the commanded/actual position of the blend door. I watched it (removed glove box) as I commanded full cold. It swung to full travel then backed up a bit, all in one move. It wasn't backing up because it was satisfied, as it was plenty warm in there. (I have the analog package as well)

I'm sure you can get the DIC to show ACM data (although I don't know how... :lol: )..

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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I do 180 in cool weather and 197 in hot weather (highway). I only see 225 on local roads in 95+ degree weather. Coolant temperature is the default display on my DIC.

Regards,

Warren

P.S. Yeah Mike, I'm coolanttempophobic also. :D

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There is no means of avoiding the final collapse of a boom brought about by credit expansion. The alternative is only whether the crisis should come sooner as the result of a voluntary abandonment of further credit expansion, or later as a final and total catastrophe of the currency system involved. - Ludwig von Mises

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I do 180 in cool weather and 197 in hot weather (highway). I only see 225 on local roads in 95+ degree weather. Coolant temperature is the default display on my DIC.

Regards,

Warren

P.S. Yeah Mike, I'm coolanttempophobic also. :D

180? That is really really low thats amazing (great for us overheatingphobics :P ).. I wonder if its possible you have a 180 stat in there?

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180? That is really really low thats amazing (great for us overheatingphobics :P ).. I wonder if its possible you have a 180 stat in there?

I'd guess you could make book on that. I didn't put it there, so I can't really say for sure.

Regards,

Warren

Posted Image

There is no means of avoiding the final collapse of a boom brought about by credit expansion. The alternative is only whether the crisis should come sooner as the result of a voluntary abandonment of further credit expansion, or later as a final and total catastrophe of the currency system involved. - Ludwig von Mises

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I replaced my water pump tensioner last week and after a week of driving that car I have noticed that at highway speeds I am running between 4 and 6 degrees cooler (197 to 199 when it was 203). I am not sure what is causing this drop in temp unless the tension was not adequate after 10 years. The bearing in the pulley seems ever so slightly rough. I just wanted to report this for all you that have older NS's.. you may benefit from changing your tensioner...

I'm really happy now. I remember how concerned you was about whole temperature stabillity. :lol::lol::lol:

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I replaced my water pump tensioner last week and after a week of driving that car I have noticed that at highway speeds I am running between 4 and 6 degrees cooler (197 to 199 when it was 203).  I am not sure what is causing this drop in temp unless the tension was not adequate after 10 years.  The bearing in the pulley seems ever so slightly rough.  I just wanted to report this for all you that have older NS's.. you may benefit from changing your tensioner...

I'm really happy now. I remember how concerned you was about whole temperature stabillity. :lol::lol::lol:

:lol:

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