Strange cooling behavior?

jmonica

Original poster
Member
Apr 2, 2013
384
Hamburg, NJ
Hey Guys. I am all of a sudden having all kinds of problems with my Envoy. Multiple problems I will be attempting to diagnose at the crack of dawn tomorrow but one of them has me stumped and hoping someone with a bigger brain than me (Not hard to find) can help me understand what's going on.

I'll try to keep it short. I was going through a carwash on Sunday and as I am going through I noticed the engine temp rising. It got to about 20-30 degrees over the center line on the temp gauge (I can't remember if that center line is 200 or 220).

So it heated up and then I pulled out and started driving, Within about 15 seconds after I started down the road, the temp immediately went back down to normal and has stayed there ever since. I mean it was instantaneous. I could see the needle move back down very fast. It was as if all of a sudden coolant started circulating into the block.

I REALLY do not feel like I have a sending unit or gauge problem because a week ago I was driving it after being parking for a few months and it got very hot, just under overheating but that was because the coolant was very low. I put coolant in and it was fine. I drove it a 100 miles today in some traffic, some city stop and go and all was normal.

Has anyone ever see this type of thing before and did it turn out to be a warning sign like maybe the water pump is going bad, or the thermostat is close to failing?

Thanks!
 

Blckshdw

Moderator
Nov 20, 2011
10,665
Tampa Bay Area, FL
I'll try to keep it short. I was going through a carwash on Sunday and as I am going through I noticed the engine temp rising. It got to about 20-30 degrees over the center line on the temp gauge (I can't remember if that center line is 200 or 220).

Was the temperature increase over the entire time you rolled through the car wash, or at a particular point? In order for the temps to climb like that, but your cooling system to be in proper working condition, and operate as normal once you left, I assume something temporarily blocked proper air flow through the radiator.

Given that it was a car wash, having stuff sprayed into the grille, like foam soap or something could possibly restrict the flow of air enough if you've got bugs, leaves and other stuff in your radiator. Then once it's rinsed off or sucked through, everything goes back to the way it was.

For me, after love bug season ends, I usually pull my grille and hose down the radiator to rinse out the bugs. Besides, the weight reduction makes more horse power :tongue:
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
I'd suspect the fan clutch. Check it out:
How to test the electro-viscous fan clutch

Once you were moving again, you had more air flowing through the radiator. When the fan clutch fails, it mostly freewheels and doesn't pull much air. Getting that hot it should have kicked in fairly strong.
 
  • Like
Reactions: Beacon and jmonica

budwich

Member
Jun 16, 2013
2,027
kanata
I would guess a stuck thermostat. Further, you mentioned earlier that you had low coolant. Running the system with low coolant (and thus air in the system) like dexcool MAY cause the coolant issues which could result in "clogging" and possibly things like a stuck thermostat.
Low coolant is a sign of other problems (ie. leaks in some form). The system should almost never have to have any adds done.
 
  • Like
Reactions: Beacon and jmonica

jmonica

Original poster
Member
Apr 2, 2013
384
Hamburg, NJ
I would guess a stuck thermostat. Further, you mentioned earlier that you had low coolant. Running the system with low coolant (and thus air in the system) like dexcool MAY cause the coolant issues which could result in "clogging" and possibly things like a stuck thermostat.
Low coolant is a sign of other problems (ie. leaks in some form). The system should almost never have to have any adds done.
Thank You. I’m going to install a new on based on your information. I appreciate your reply, thank You!
 

jmonica

Original poster
Member
Apr 2, 2013
384
Hamburg, NJ
I'd suspect the fan clutch. Check it out:
How to test the electro-viscous fan clutch

Once you were moving again, you had more air flowing through the radiator. When the fan clutch fails, it mostly freewheels and doesn't pull much air. Getting that hot it should have kicked in fairly strong.
Thanks Mooseman. I’m going to do the test tonight. All of these replies make sense so I’m going to start with the one that doesn’t cost anything to check.
ive got much bigger problems at the moment. I’ll report back once the test is done. Thanks again!
 
  • Like
Reactions: Redbeard

jmonica

Original poster
Member
Apr 2, 2013
384
Hamburg, NJ
Was the temperature increase over the entire time you rolled through the car wash, or at a particular point? In order for the temps to climb like that, but your cooling system to be in proper working condition, and operate as normal once you left, I assume something temporarily blocked proper air flow through the radiator.

Given that it was a car wash, having stuff sprayed into the grille, like foam soap or something could possibly restrict the flow of air enough if you've got bugs, leaves and other stuff in your radiator. Then once it's rinsed off or sucked through, everything goes back to the way it was.

For me, after love bug season ends, I usually pull my grille and hose down the radiator to rinse out the bugs. Besides, the weight reduction makes more horse power :tongue:
Hi. Well I’m fairly sure that the climb came on fairly quick inside the car wash. It LS a really dinky carwash snd the trio though can’t take more that 2 minutes tops. I noticed the raise in temp near the end.
When you pull out two people dry it for about a minute. The whole time I was watching the temp while the my were drying. I couldn’t take the pressure so I just said thank you after 30 seconds. It was about 50 feet up the road that I watch the temp gauge needed fall right back to normal.
In retrospect, the needle fell so fast that it struck me as odd.
Even if the air had started flowing because I was moving, I don’t think the engine could cool down that instantaneously. I’m not even confident a stuck thermostat suddenly opening up could cool it down that quickly.
Well the coolest level is staying put. The thermostat is opening and so I guess it’s just one more of those mysteries I will have to wait snd see if it happens again.
Once again a sincere thank you for your help!
 

Forum Statistics

Threads
23,272
Posts
637,482
Members
18,472
Latest member
MissCrutcher

Members Online