Fluctuating Temperatures - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

Reply
 
 
 
Thread Tools Search this Thread
Old 04-22-2005, 06:37 PM   #1
Senior Member
Certified GM nut
Thread Starter
 
Join Date: Feb 2004
Location: MI
Posts: 2,246
Thanks: 0
Thanked 0 Times in 0 Posts
Logan is on a distinguished road
Default Fluctuating Temperatures

Hey,

I know there are a lot of threads on this, but I could not find one that had a problem quite like mine.

I start my car, wait a couple minutes, then start driving. Temperatures slowly climb to 140*, then quickly go up to 210*ish. That is up until Wednesday. Since Wednesday, three times (out of four) the temperature slowly climbs to 140, shoots up to just short of 250 (I assume that is what the other graduation on the gauge is), holds there for maybe 15 seconds, and then plummets to about 195.

I assume this is the t-stat getting stuck closed, then when it gets way to hot, it finally pops, then the water that hasn't been getting circulated in the radiator finally flows, it cools it way off.

Is this my problem?

Everyone on here talkes so highly of the 180* t-stat. I was told that the engine runs "cleaner" at warmer temps. So whats with the cooler t-stat.

Its an easy replacement right? It is right where the upper radiator hose connects into the block correct? Remove the clamp, slide old one out, slide new on in rihgt?

Thanks in advance.



EDIT: Forgot to mention. In the past, my temperatures have regularly been fluctuating from around 200-220 or 230 (stright up on the gauge). Is this because my t-stat was sticking, but not stuck. So would the 180 t-stat make it so it was always open after the car was warmed up, for more consistant temps.
Logan is offline   Reply With Quote
Old 04-22-2005, 06:53 PM   #2
Senior Member
True Car Nut
 
Join Date: Jan 2005
Location: Montevideo, MN MWBF '05, '06, '07 WCBF '06 '07 survivor
Posts: 3,882
Thanks: 0
Thanked 0 Times in 0 Posts
sonoma_zr2 is on a distinguished road
Default

My SSEi did this recently, only it would go from 200 to 220 and back and forth.
Did a flush and new tstat(195), now pretty much back to "normal"
sonoma_zr2 is offline   Reply With Quote
Old 04-22-2005, 07:41 PM   #3
Senior Member
True Car Nut
 
Join Date: Mar 2004
Location: Ames, Iowa
Posts: 3,066
Thanks: 0
Thanked 1 Time in 1 Post
bill buttermore is on a distinguished road
Default Re: Fluctuating Temperatures

Quote:
Originally Posted by Logan

Everyone on here talkes so highly of the 180* t-stat. I was told that the engine runs "cleaner" at warmer temps. So whats with the cooler t-stat.

Its an easy replacement right? It is right where the upper radiator hose connects into the block correct? Remove the clamp, slide old one out, slide new on in rihgt?

So would the 180 t-stat make it so it was always open after the car was warmed up, for more consistant temps.
The 180 'stat may not be quite as efficient theoretically, but it affords more protection from overheating on engines that are run hard and on older, less efficient cooling systems.

If I have my models correct, you have to remove the housing that the hose connects to, and replace two gaskets; one around the thermostat flange and one for the gooseneck.

A working 180 thermostat will open at 180 and regulate its opening to maintain the temperature at 180 allowing the engine to run cooler. The fans still will not come on until something like 215 however :( unless you do a fan mod.
bill buttermore is offline   Reply With Quote
Old 04-22-2005, 07:51 PM   #4
Senior Member
Certified Car Nut
 
Join Date: Oct 2003
Posts: 19,756
Thanks: 0
Thanked 0 Times in 0 Posts
1993 SLE is on a distinguished road
Default

it might just be corision on the temp sensor on the Rad, the actual sender might be on its last leg, or the gague on the dash is fauliy
1993 SLE is offline   Reply With Quote
Old 04-22-2005, 08:14 PM   #5
Senior Member
Certified GM nut
Thread Starter
 
Join Date: Feb 2004
Location: MI
Posts: 2,246
Thanks: 0
Thanked 0 Times in 0 Posts
Logan is on a distinguished road
Default Re: Fluctuating Temperatures

Quote:
Originally Posted by bill buttermore
Quote:
Originally Posted by Logan

Everyone on here talkes so highly of the 180* t-stat. I was told that the engine runs "cleaner" at warmer temps. So whats with the cooler t-stat.

Its an easy replacement right? It is right where the upper radiator hose connects into the block correct? Remove the clamp, slide old one out, slide new on in rihgt?

So would the 180 t-stat make it so it was always open after the car was warmed up, for more consistant temps.
If I have my models correct, you have to remove the housing that the hose connects to, and replace two gaskets; one around the thermostat flange and one for the gooseneck.
These gaskets that you speak of...do they come with the t-stat, or are they purchased separately? Advanced auto parts should have them? They pretty cheap?
Logan is offline   Reply With Quote
Old 04-22-2005, 08:36 PM   #6
Senior Member
True Car Nut
 
Join Date: Mar 2004
Location: Ames, Iowa
Posts: 3,066
Thanks: 0
Thanked 1 Time in 1 Post
bill buttermore is on a distinguished road
Default Re: Fluctuating Temperatures

Quote:
Originally Posted by Logan

These gaskets that you speak of...do they come with the t-stat, or are they purchased separately? Advanced auto parts should have them? They pretty cheap?
No they don't come with all thermostats. Advance should have them. I think they are about $2-3 apiece.
bill buttermore is offline   Reply With Quote
Old 04-22-2005, 08:54 PM   #7
Senior Member
True Car Nut
 
Join Date: Feb 2004
Location: Western MA
Posts: 2,708
Thanks: 0
Thanked 1 Time in 1 Post
randman1 is on a distinguished road
Default

The electric fan comes on at about 215ish. If yout temp gauge is displaying something higher, check to see if the fan is running. This is a simple test I used to check the accuracy of my gauge. The other way, and better too, is to connect to a scantool and read what the temp is right from the PCM.
randman1 is offline   Reply With Quote
Old 04-22-2005, 09:31 PM   #8
Senior Member
Posts like a Northstar
 
Join Date: Jan 2005
Location: Richfield, MN
Posts: 781
Thanks: 0
Thanked 0 Times in 0 Posts
alec_b is on a distinguished road
Default

I'm only asking to avoid starting a whole new thread, but is it normal for the older cars (LG3 in particular) to kick the fans in at about 1/4 of the gauge. That'* when mine does, and the gauge never goes higher than that. I haven't even had it close to halfway.
alec_b is offline   Reply With Quote
Old 04-22-2005, 10:06 PM   #9
Senior Member
Certified GM nut
Thread Starter
 
Join Date: Feb 2004
Location: MI
Posts: 2,246
Thanks: 0
Thanked 0 Times in 0 Posts
Logan is on a distinguished road
Default

Quote:
Originally Posted by randman1
The electric fan comes on at about 215ish. If yout temp gauge is displaying something higher, check to see if the fan is running. This is a simple test I used to check the accuracy of my gauge. The other way, and better too, is to connect to a scantool and read what the temp is right from the PCM.
I forgot to mention this very important detail. Everytime that it has happened, I was going down the road at 55-60 MPH. I don't think I should need the fan at that speed
Logan is offline   Reply With Quote
Old 04-22-2005, 10:26 PM   #10
DINOSAURUS BOOSTUS

Expert Gearhead
 
BillBoost37's Avatar
 
Join Date: Mar 2005
Location: Enfield, CT
Posts: 41,391
Thanks: 0
Thanked 0 Times in 0 Posts
BillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of light
Default

Alec if you have access to a scan tool, you should check the accuracy of your gauge. I am thinking your sending unit for the gauge is probably bad. I've got the 95 and know that the 92-99 styles had two senders. One to pcm and one to gauge. I haven't heard that your era of gauges have the issues the 92-99 have so I would aim toward the gauge sending unit.

Logan you also should scan if possible to check the accuarcy of your gauge. However in your case the dash clusters are known to have accuarcy and fluttering issues. I recently changed the small circuit board in my 95 that is directly connected to the temp, pressure and boost to correct fluttering. Now with that done, my rock solid 185 degrees for temp shows at about 195 on my gauge. Better...but not perfect. Meanwhile this little board worked perfectly in a 93 cluster.

Which leads me to believe that the fluttering part of the problem was the small board, but the remainder might be the main cluster board.
BillBoost37 is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
High Idle at Cold Temperatures 3000 RPM ucrm4c 1992-1999 8 12-07-2009 07:52 PM
High Idle When Starting, Cold Temperatures ucrm4c 1992-1999 30 01-08-2008 12:20 AM
Normal Operating Temperatures slick94prix 2000-2005 1 04-22-2007 03:06 AM
weird temperatures NERV 1992-1999 3 02-01-2005 11:45 PM
Guages fluctuating 1992 3.8l se BarryBoy 1992-1999 26 04-22-2003 11:46 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 11:37 PM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.