Bouncing temperature on 85' K5

1985 Chevrolet K5 162,000 miles 305CUI
My temperature bounces from just below 210 and 235, sometimes going as high afs 265. This is after the engine has warmed up, is running just
fine.
Happens at 35MPH, 70MPH, 0MPH (IE speed doesn't seem to affect it.)
My thoughts, in order:
A: Failing fan clutch B: Failing temp sensor C: Failing t-stat
~TLGM
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Bouncing temperature on 85' K5 Group: alt.autos.4x4.chevy-trucks Date: Sun, Jan 11, 2004, 10:15am (CST-2) From: pde_on snipped-for-privacy@hotmail.com (Lonely G-Monkey) 1985 Chevrolet K5 162,000 miles 305CUI My temperature bounces from just below 210 and 235, sometimes going as high afs 265. This is after the engine has warmed up, is running just fine. Happens at 35MPH, 70MPH, 0MPH (IE speed doesn't seem to affect it.) My thoughts, in order: A: Failing fan clutch B: Failing temp sensor C: Failing t-stat ~TLGM
On an 85 isnt the fan bolted to the waterpump? you could have an airpocket in your system... Temp sensor maybe...T-stat just pull it out and see if you have the same problem....My guess is your stat..... Steve C
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Don't you mean change the t-stat? I hear it's very bad to just remove it...
~KJ~
(Lonely G-Monkey) 1985 Chevrolet K5 162,000 miles 305CUI My temperature bounces from just below 210 and 235, sometimes going as high afs 265. This is after the engine has warmed up, is running just fine. Happens at 35MPH, 70MPH, 0MPH (IE speed doesn't seem to affect it.) My thoughts, in order: A: Failing fan clutch B: Failing temp sensor C: Failing t-stat ~TLGM
On an 85 isnt the fan bolted to the waterpump? you could have an airpocket in your system... Temp sensor maybe...T-stat just pull it out and see if you have the same problem....My guess is your stat..... Steve C
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Re: Bouncing temperature on 85' K5 Group: alt.autos.4x4.chevy-trucks Date: Sun, Jan 11, 2004, 11:49pm (CST+6) From: snipped-for-privacy@psudo.com (KJ) Don't you mean change the t-stat? I hear it's very bad to just remove it... ~KJ~
(Lonely G-Monkey) 1985 Chevrolet K5 162,000 miles 305CUI My temperature bounces from just below 210 and 235, sometimes going as high afs 265. This is after the engine has warmed up, is running just fine. Happens at 35MPH, 70MPH, 0MPH (IE speed doesn't seem to affect it.) My thoughts, in order: A: Failing fan clutch B: Failing temp sensor C: Failing t-stat ~TLGM On an 85 isnt the fan bolted to the waterpump?   you could have an airpocket in your system... Temp sensor maybe...T-stat just pull it out and see if you have the same problem....My guess is your stat..... Steve C
OK let me revise my statement in the last post.....In Autos with out ele controlled fans in them or ones useing DEXCOOL...Can safely run their engine without the T-Stat.....This is a debated topic of which diffrent parts of the country will say different things....Sure if you are in freezing weather you need a T-Stat but if you live where i do where the temp barley drops into the low 40s in the dead of winter then one is not needed....I donot recommed running it without a Stat for too long but rather than set a pan of water on the stove trying to get it t open if you dont have a torch....Then pulling it out and running it tp see if the same problem presists then there is no problem.... If using coolant like Dex-Cool how ever a Coolant which is known for making problems on its own or when have ele controlled fans which have a habbit of failing (then it will heat up twce as fast and cause bigger problem)Then running it without a stat for a long time will cause more damage than its woth... Steve C
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Seeing as how you just had slush/air in the system, I'd bet it's just some air in the system. Burp her for 10-15 minutes and see if that helps. A venting rad cap makes this process MUCH easier and MUCH less messy! Well worth the $5.
Doc
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It was actually happening before.
How do I "burp" her. Do you mean running it with the cap off?
Also, I have the small hole on the radiator that the previous owner fixed with JB Weldbond. It is weeping slightly. Could this be attributing to it? If so I'll have to chip it off and braze it.
~KJ~
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Re: Bouncing temperature on 85' K5 Group: alt.autos.4x4.chevy-trucks Date: Sun, Jan 11, 2004, 11:52pm (CST+6) From: snipped-for-privacy@psudo.com (KJ)
1985 Chevrolet K5 162,000 miles 305CUI My temperature bounces from just below 210 and 235, sometimes going as high afs 265. This is after the engine has warmed up, is running just fine. Happens at 35MPH, 70MPH, 0MPH (IE speed doesn't seem to affect it.) My thoughts, in order: A: Failing fan clutch B: Failing temp sensor C: Failing t-stat ~TLGM Seeing as how you just had slush/air in the system, I'd bet it's just some air in the system. Burp her for 10-15 minutes and see if that helps. A venting rad cap makes this process MUCH easier and MUCH less messy! Well worth the $5. Doc It was actually happening before. How do I "burp" her. Do you mean running it with the cap off? Also, I have the small hole on the radiator that the previous owner fixed with JB Weldbond. It is weeping slightly. Could this be attributing to it? If so I'll have to chip it off and braze it. ~KJ~
No running it without a T-Stat will not harm your system...Why would it? It will just take longer to heat up if you want to like use your heater or something....It is a Very common Down here where i live to getem in with out stats...Also I didnt say keep it out i said pull it out and run it to see if he had the same problem....If not it would have been up to him to put it back or replace it..Personally I wouldnt run it all the time without it....Also no dont run it with the cap off you need it to build up pressure in order to get the air out....And yes a weeping hole will be a problem(If something can come out------something will get in also) thus being air getting to the system.... Doc has stated many times about using the the vented Rad cap This is the best thing in the world for burping older engines without the bleeders.....And also is fool proof....Just need to make sure you keep checking the coolant level during the process..Or youll just be defeting the purpose... Steve C
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I was told that without a restrictor (a t-stat that is always open?) the water will flow through too fast, and while the engine will appear cooler, the cylendar wall temperatures will 'soar' (according to alt.trucks.chevy

Let me try once more. How do I bleed the system?
Yes, I am a novice.
~KJ~
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Yep, If that hole weeps a bit when the engine starts to cool down instead of drawing coolant back into the radiator from the overflow tank it draws air through that hole. Presto air pocket...
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What reservoir? Never had a cap for it....
~KJ~

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But that air bubble would rise to the top of the radiator, not the head. It wouldn't cause the problems noted. So the best guess for this problem is the thermostat or a collapsing lower hose. He should still fix the hole properly, though.
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says...

I agree, cheap thermostats often don't work right from the start. The hole MUST be fixed and the overflow tank must be operational. B
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On 11 Jan 2004 10:15:33 -0800, pde_on snipped-for-privacy@hotmail.com (Lonely G-Monkey) wrote:

I wouldn't suspect the fan at those speeds. The fan can hardly pull air as fast as 35 MPH. It is actually in the way at speeds much beyond idle. -- Gordie
'A Lawyer from Genoa, a cousin of Doctor Festa of Rome persuaded that his cousin was in a state of exaltation, decided to go incognito to Padre Pio.
As soon as the Father laid eyes on him he exclaimed: "What are you doing here? You are a Mason!" This was followed by verbal blows and counter-blows which all ended in the lawyer kneeling down in front of the humble friar who had converted him.'
Booklet - Who is Padre Pio?, page 18 - Published 1974 Tan Books and Publishers, Inc.P.O. Box 424 Rockford, Illinois 61105
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I know that it's supposed to 'go away' but if at idle it bounces, I thought it might not be working....
~KJ~
(Lonely

cousin
here?
which
had
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============================What exactly do you mean by "bounces"? Bounces as fast as a ball would bounce or a more slowley up and then down kind of thing? If it actually jumps up and down -jerky kinda fast I'll vote on the gauge or sensor.
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Slowly climbs up, and drops rather suddenly, over and over. If I had to say it stops after a LONG ride (1+ hours).
~KJ~

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say
======================If after it is cool, you pull the rad cap and it is full of coolant: I would guess the t-stat is sticking. It gets hot then pops open, then cools off, closes and does it again..........Besides, the things only cost like 5 bucks. The cheapest first try :)
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I'll vote for a bad intake gasket. Run a pressure test to check for leaks.
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