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Discussion Starter · #1 ·
I have a totally stock 2005 Buick Lacrosse with the 3800 series III. My panel temp gauge runs in the middle between the first and second mark 98% of the time. It doesn't matter if cruising at 80 or sitting in traffic and 90 degrees out but sometimes when going up hills in the mountains like the flip of a switch it will start climbing and will go up past center and up to the next mark. I had a temp gun with me so I pulled over and shot the thermostat housing and it read 220. Both fans were on and after a min or two the temp started coming down. I was near the top of the hill so I continued to the top. When we started down the gauge was erratic for a 10 sec or so and it settled down in its normal spot. When its in its normal spot the gun reads about 185-190 on the thermo housing.
1. Is this normal?
2. It's strange 98% of the time its great. I think something is up. I guess a scan tool the plugs in to the obs port would help.
3. Whats the thermostat temp?
4. How much engine temp will do damage?
Thank You
 

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Thermostat is 195 stock.

You may have some air in the system that isn't too bad, but enough to cause some fluctuations in different scenarios. I'd look into a fill/bleed funnel kit to top it off and let the air out. Just mentioned this to elsewhere, and I just did it when I finished my upgrades on the turbo setup.

Also, you can do a pressure test yo see if there's a leak in the coolant system somewhere that needs to be addressed (another active New post is looking into this, if you want to read our discussion there).

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Also, keep an eye out for small leaks near the alternator bracket elbows (connect to engine and route coolant to heater core in dash), and possibly consider digging in to replace the lower intake gaskets if they're original. I'll have a video out soon that shows the condition of 67k 2004 engine that already needed them replaced/upgraded due to leaks.
 

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Discussion Starter · #3 ·
Thanks for your reply. I was thinking it might be air. Where would I get that fill/bleed funnel kit? My local auto parts doesn't carry it. I've tried bleeding it through the bleed screw a few times and only get coolant to come out. Thanks
 

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I got my funnel kit at NAPA, and see them at random Advance stores.
 

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How does the coolant look? When’s the last time you changed it? I gave up on Dexcool. Through two flushes, I witnessed it turn into sludge. I now use only “Green” coolant. It works.
 

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I have a totally stock 2005 Buick Lacrosse with the 3800 series III. My panel temp gauge runs in the middle between the first and second mark 98% of the time. It doesn't matter if cruising at 80 or sitting in traffic and 90 degrees out but sometimes when going up hills in the mountains like the flip of a switch it will start climbing and will go up past center and up to the next mark. I had a temp gun with me so I pulled over and shot the thermostat housing and it read 220. Both fans were on and after a min or two the temp started coming down. I was near the top of the hill so I continued to the top. When we started down the gauge was erratic for a 10 sec or so and it settled down in its normal spot. When its in its normal spot the gun reads about 185-190 on the thermo housing.
1. Is this normal?
2. It's strange 98% of the time its great. I think something is up. I guess a scan tool the plugs in to the obs port would help.
3. Whats the thermostat temp?
4. How much engine temp will do damage?
Thank You
Have you replaced the thermostat yet? 220 degrees is normal. The cooling fans come on at 224. GM likes for these engines to run that way for better fuel atomization. If you change thermo get a 195 degree STANT.
 

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Your stock thermostat is 195 (pretty sure I mentioned that before). Yes, it'll get a bit above that in some hot & heavy conditions, but these engines are very stable. It takes an hour of hard mountain driving to budge mine off the 160 stat temp with minimal cooling upgrades.

Once you do the fill/bleed/checks, see if it stabilizes. If there's a leak somewhere, that'll be your next point to address.
 

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Discussion Starter · #9 ·
I got my fill/bleed funnel kit. I had two pints in the funnel and when the Thermostat opened it all drained in. That was a surprise.I put more in it and ran it for awhile with a very few bubbles. It seems to run at the same temp around town and I haven't had a chance to drive in the hills. One other note my heater doesn't work so I thought I would back flush the core and replace the thermostat and check it again, Thanks
 

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I got my fill/bleed funnel kit. I had two pints in the funnel and when the Thermostat opened it all drained in. That was a surprise.I put more in it and ran it for awhile with a very few bubbles. It seems to run at the same temp around town and I haven't had a chance to drive in the hills. One other note my heater doesn't work so I thought I would back flush the core and replace the thermostat and check it again, Thanks
If your heater doesn't work either the heater core is clogged or you have a blend door issue. The back flush would be a good place to start.
 

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If your heater doesn't work either the heater core is clogged or you have a blend door issue. The back flush would be a good place to start.
By the way 220 degrees when running is normal. Your cooling fans should easily pull that right down to 200-205. The factory gauges are not that precise.
 

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I saw that last post about coolant being completely full......In days gone by, I have filled the cooling system thru the thermostat opening. I opened up a heater hose and filled the coolant till it began to over flow a bit and then closed the open hoses. This has always worked well(but a little messy), Not a big deal and a quick splash of coolant and away you go. I have done it this way to be sure the cooling system is 100% full. This has always worked 100% of the time.
As always. best of luck! Jake(mr goodwrench) ....
 
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