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Discussion Starter · #1 ·
Hello.

I don't know how else to describe it. The issue seems to be mostly when I first start the car in the morning for my commute to work. The temperature gauge will sometimes rise to somewhere between 150 and 155 within 15 seconds or so of starting the car. During the drive, the temperature will read higher than normal, say 210 or 215 for the rest of the journey. It's slightly cranky when first started, but it drives otherwise perfectly well.

At the end of my workday, the temperature will be normal when I start the car, under the 140 mark. The normal temperature I'm used to seeing while driving around it between 185 and 195.

I just replaced the engine because my old one had a cracked cylinder, and I had a new temperature sensor put in.

I thought I'd ask for some input on this. Thanks very much.

~ John
 

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Hello.

I don't know how else to describe it. The issue seems to be mostly when I first start the car in the morning for my commute to work. The temperature gauge will sometimes rise to somewhere between 150 and 155 within 15 seconds or so of starting the car. During the drive, the temperature will read higher than normal, say 210 or 215 for the rest of the journey. It's slightly cranky when first started, but it drives otherwise perfectly well.

At the end of my workday, the temperature will be normal when I start the car, under the 140 mark. The normal temperature I'm used to seeing while driving around it between 185 and 195.

I just replaced the engine because my old one had a cracked cylinder, and I had a new temperature sensor put in.

I thought I'd ask for some input on this. Thanks very much.

~ John
thermostat is bad. or the needle is not calibrated
 

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Discussion Starter · #3 ·
Oh, sorry, forgot to mention the thermostat was replaced, too. How do I get the thing calibrated?

Thanks for the quick response!
 

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Mr. Handy
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It still sounds like a coolant temp sensor or possibly a large amount of air in the coolant system.
 

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Mr. Handy
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Sorry to just jump in and interupt but I'm so agravated .
If it has been bought from a dealer, bring it back :eek:k3: Even so, post in the correct section which would be the 9th gen section. Click "new thread", title it, and ask away :eek:k3:
 

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Discussion Starter · #8 ·
It still sounds like a coolant temp sensor or possibly a large amount of air in the coolant system.
Is there a second temperature sensor? I know he replaced the one that came with the engine, as the fans weren't kicking on when the AC was started. He checked all the relays first.

Sorry I keep forgetting details, but it was recommended that I bleed the coolant. I opened both bleeder valves and a bit of air came out of the second one (driver side), but nothing came out of the higher one (passenger side). Nothing. No air, no fluid. The mechanic was unfazed by this. Any thoughts on that? I know there was a bit of crud on the radiator cap when I took that off.
 

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Mr. Handy
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Crud on the radiator cap likely means too much water or dexcool/stop leak tablets have broken down. I would get a coolant flush and see if that helps.

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Discussion Starter · #12 ·
Well, that seems to have worked for about a week. The past couple days, the temp gauge starts off at 155. During my commute, it's between 215 and 220. Any other ideas?
 

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Mr. Handy
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I would replace the thermostat and bleed the coolant system.

215-220 is too hot. I wouldn't drive it like that for too long.
 

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Discussion Starter · #14 ·
The thermostat was replaced along with the engine. As was the heat sensor. I had the coolant flushed less than two weeks ago.

The problem is intermittent; today the temperature was completely normal.

When I had the old engine, the gauge actually started about halfway a few times and went way, way over 260. But it ran fine and the dummy light never went on in the dash.

Could this be something electrical, maybe?
 

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8th Gen Antagonist
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What is the car? Just noticed we hadn't established that. Could be the gauge itself thats bad.
 

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Discussion Starter · #16 ·
Oh, sorry. It's a 2005 Impala. 3.4 liter. About 168K miles on it. Is there a way I can test the gauge itself?
 

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Mr. Handy
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When I had the old engine, the gauge actually started about halfway a few times and went way, way over 260. But it ran fine and the dummy light never went on in the dash.
Just b/c the t-stat was replaced with the engine doesn't mean anything.

But, now that you say the gauge was acting funny before, I would think its a wiring issue in between the pcm and gauge cluster.

Pull the pcm out of the stock airbox and inspect wires and connector. Unhook battery, remove connector from pcm, clean the pins on the pcm if they are dirty, apply dielectric grease to connector, re-install. If problem still persists it's likely a gauge or cluster harness problem.
 
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Discussion Starter · #18 ·
It's embarrassing how far out of my comfort zone that was, but I did it, and it only took me about an hour. The connectors and such looked fantastic. But I applied the grease as you advised. It seems to have improved things, but I will have to give it a week or two to really see (as it's intermittent). In the meantime, it seems to be shifting a bit better (I'll have to get the tranny addressed at some point), and it now starts almost every time on the the first turn of the key, rather than the standard three times.

So I will report back, but thank you very much!
 

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Mr. Handy
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It's embarrassing how far out of my comfort zone that was, but I did it, and it only took me about an hour. The connectors and such looked fantastic. But I applied the grease as you advised. It seems to have improved things, but I will have to give it a week or two to really see (as it's intermittent). In the meantime, it seems to be shifting a bit better (I'll have to get the tranny addressed at some point), and it now starts almost every time on the the first turn of the key, rather than the standard three times.

So I will report back, but thank you very much!
No problem glad to help out.

Yes unhooking the battery will reset all codes and the PCM so, give it a few weeks to see if the problem comes back. If it does, get the codes scanned and see if anything comes up. If nothing, I would replace the Coolant Temp Sensor and inspect the harness going to it. Also apply dielectric grease to that as well.
 
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