Engine Temperature Spiking in '94 Sunbird - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


Pontiac When starting new posts, please specify YEAR, MAKE, MODEL, ENGINE type, and whatever modifications you have made.

Reply
 
 
 
Thread Tools Search this Thread
Old 12-11-2014, 04:09 PM   #1
Junior Member
Thread Starter
 
Join Date: Dec 2014
Location: Central California
Posts: 7
Thanked 0 Times in 0 Posts
sunbirdgirl is on a distinguished road
Question Engine Temperature Spiking in '94 Sunbird

I am hoping to gain some understanding of a curious quirk exhibited by my 1994 Pontiac Sunbird. When the car is driven out from a cold start, after being underway for several minutes, the temperature gauge begins to rise, steadily and fairly rapidly, sometimes reaching or exceeding the point where the fan comes on (approximately 215-220 degrees F.). The gauge remains at this high point for a short time, and then drops abruptly to around 160 degrees, after which it gradually warms up to a normal cruising temperature (approximately 188 degrees for highway driving). On rare occasions, I have known it to spike twice-the second spike is generally not as high as the first one.
I have had this car for over nine years now, and it seems to me that I have noted this phenomenon, in varying degrees, for a good part of that time. It seems, however, to have become more pronounced in recent weeks, with the high point being, at times, very close to the red zone. This is causing me a certain amount of concern, as this car has, in the past suffered from fairly serious problems related to overheating, and I do not want that particular trouble to recur.
I had some repair work done on the radiator this past summer, I have had some issues with the cap over the thermostat not being tight enough, giving rise to a minor coolant leak (I watch the coolant levels pretty closely!).
My questions are as follows: Would this temperature spiking be caused by a malfunctioning thermostat, or a bubble in the coolant system? And if so, why does it only occur following a cold start? Do I, perhaps, have a faulty sensor? Any insights into this puzzling matter are welcome.
sunbirdgirl is offline   Reply With Quote
Old 12-11-2014, 04:28 PM   #2
Senior Member
True Car Nut
 
jwfirebird's Avatar
 
Join Date: Dec 2009
Location: western,ny state
Posts: 9,616
Thanked 563 Times in 481 Posts
jwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond repute
Default

this is normal operation is just more noticeable in the cold. say its 30deg outside for example your whole car, the rad, all the coolant in the heater core are all 30. you start the engine and the gauge reads what temp the coolant in the engine is, but this is separated from the rad and the heater core and that until the thermostat opens. as it opens it the 210deg coolant in the engine is introduced to a whole bunch of 30deg coolant and it will cycle back and forth till all the coolant is up to 180-190. its just much faster in the summer so its hard to see
jwfirebird is offline   Reply With Quote
The Following User Says Thank You to jwfirebird For This Useful Post:
sunbirdgirl (12-11-2014)
Old 12-11-2014, 11:21 PM   #3
Senior Member
True Car Nut
 
rjolly87's Avatar
 
Join Date: Jun 2003
Location: Las Cruces, NM
Posts: 6,857
Thanked 298 Times in 246 Posts
rjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant future
Default

The temperature swing characteristic is normal, but not to the degree you are indicating. On my previous vehicle, the temp would push to about 200-205 if I was ambitious on a cold engine, then I would see the gauge push up 1-2 more degrees, then lock at 185 (on a 190 thermostat).

My guess is that the thermostat is taking too long to open. It may need to be replaced, or there may be an air pocket that gets trapped behind the thermostat. One is a matter of replacing the thermostat, the other is a matter of bleeding the cooling system to get the air bubble out.

Thermostats are cheap, and typically straight forward to replace. I would replace it, bleed the system, and you should hopefully be good to go.
rjolly87 is online now   Reply With Quote
The Following User Says Thank You to rjolly87 For This Useful Post:
sunbirdgirl (12-12-2014)
Old 12-12-2014, 08:10 AM   #4
Senior Administrator








Certified Car Nut
 
Mike's Avatar
 
Join Date: Jul 2003
Location: Horseheads, NY
Posts: 15,648
Thanked 1,000 Times in 776 Posts
Mike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond repute
Default

I agree, it sounds like you have both, a bad thermostat and an air pocket somewhere.
Mike is offline   Reply With Quote
The Following User Says Thank You to Mike For This Useful Post:
sunbirdgirl (12-12-2014)
Old 12-12-2014, 08:17 AM   #5
Senior Member
True Car Nut
 
jwfirebird's Avatar
 
Join Date: Dec 2009
Location: western,ny state
Posts: 9,616
Thanked 563 Times in 481 Posts
jwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond repute
Default

every car i have had has done this. the only thing i would worry about is the leak. that can cause low pressure which does cause problems. if the cap you are talking about leaking is the pressure cap especially
jwfirebird is offline   Reply With Quote
The Following User Says Thank You to jwfirebird For This Useful Post:
sunbirdgirl (12-12-2014)
Old 12-12-2014, 02:09 PM   #6
Junior Member
Thread Starter
 
Join Date: Dec 2014
Location: Central California
Posts: 7
Thanked 0 Times in 0 Posts
sunbirdgirl is on a distinguished road
Default

Thanks to everyone who responded. It'* good to know that this is, basically, a normal process-but perhaps it is time for a new thermostat.
sunbirdgirl is offline   Reply With Quote
Old 12-13-2014, 08:44 AM   #7
Senior Member
True Car Nut
 
jwfirebird's Avatar
 
Join Date: Dec 2009
Location: western,ny state
Posts: 9,616
Thanked 563 Times in 481 Posts
jwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond repute
Default

the pressure cap operation is important too, if you think it may not be working or leaks, should be replaced. system pressure is what causes the water boiling point to be over normal operating temp of the car, without it the water will boil off and the coolant left isnt what does the cooling. so the car will overheat.
jwfirebird is offline   Reply With Quote
The Following User Says Thank You to jwfirebird For This Useful Post:
sunbirdgirl (12-13-2014)
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Sunbird Computer Chair 94 olds vert Lounge 68 02-11-2013 10:01 AM
1991 sunbird check engine code retrieval islandguy1971 General GM Chat 2 04-04-2011 03:51 PM
Losing a little coolant and temps are spiking. 98 PA GonneVille Buick 13 03-30-2008 01:32 AM
Sold the sunbird JimmyFloyd General GM Chat 8 02-18-2007 02:02 PM
FS: 1989 Pontiac Sunbird GT Convertible Turbo JimmyFloyd Lounge 0 09-07-2006 01:36 AM


Tags
cooling system, engine temperature, overheating, pontiac sunbird

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 01:24 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.