I will point out that if we go by the 177F temp performance (3 F under stat rating) and you go to a 195, that should be 192 - 199; which is still quite some difference from the 221 that some are running. Install new stat without hole and see how you do, you can always add a hole (you can also close one up with small brass or stainless bolts - just not RTV)

 

R u sure that is correct? It would seem to me that the coolant coming out of the block to the stat would be the hottest, and then cooled by the radiator and then back into the block to get hot again and back to the stat, and on and on.
Now the whole air thing makes since, it would be tuff to bleed the system until it was hot if I am following you correctly.

 

OK - stat opens, and allows hot water to flow by, pulling cooler water from radiator into engine via water pump. This keeps flowing until the temperature at the stat drops below 180F, at which time the wax pellet inside that coiled part of the stat hardens up, and makes stat close. So water at stat is below 180F at that point (no, it is not ice cold). With no hole to allow a weep of water to get by, the remote stat, more than a foot of cooler water behind it will wait. It waits for that column of water inside the pipes and hoses to warm up by convection to above 180F so it can open. Think of convection as your heater in the truck with no fan. It will warm up eventually, but with the fan circulating the air it warms up quicker.

Compare that to the same stat, mounted inside the engine block (where Buick intended it to be - see pix), exposed to the hot water circulating around in the intake structure. The stat inside the block will open sooner. By adding the weep hole(s) you reduce the lag time added by the remote stat.

The other thing that the weep hole does is allow trapped bubbles to pass. While coolant bleeding is a plus, if you have a closed stat, with a big air pocket trapped behind it (even for stats in-da-block), the steamy air is warm, but it is not coolant. Think about a pot of boiling noodles. Hold hand over noodles, pretty warm. Put hand in noodles, lot quicker reaction (don't really try this). Watching this with a digital scanner, you might notice that when cranked up the truck would go to like 221 - 229 before stat opens and cools down.

Now for the 0126 code. The RAVE lists multiple things that must all be "true" for that code to trigger. The last two are:


Engine coolant temperature is greater than 90 °C (194 °F).

 

Found more info on code 0126 in Bosch diagnostics manual:

A second ECT sensor is installed in the outlet from the radiator. If the enablement criteria are met and the ECT is less than the normal thermostat opening temperature the diagnostic will run.

The diagnostic compares the difference between ECT and the radiator outlet temperature. This gives the temperature drop across the radiator.

If the temperature drop is less than a threshold, and there is flow across the radiator, this is caused by leakage through the thermostat.

So, if your engine temp is less than 180F (the opening temp of a D2 stock stat), it will run an extra diagnostic program that is (Engine temp - bottom outlet radiator temp), and if that number is less than a sliding scale, the code is set. The system states "opening temp" of the stock stat, which is stated elsewhere in the RAVE as 180F. However in the text for this code, they state that engine temp must be above 194F (which I think is a typo in the RAVE, the formula shows it as "below" rather than "above" the opening temp, and 194 would be the fully open temp rather than opening temp.) The system is designed to detect a stat that is sticking open.

And it did. The 2nd hole may have made the difference. It would be possible to install a stat with no drilled holes, it will have a longer cycle time, and would need the jiggle device to be sure a steam pocket could not form.

But the D2 may be designed to prevent running a cooler stat with this feature.

Of course, the existing 180F stat in the in-line might not be opening at 180 (stats vary).

And if a 195 stat is used, the problem should go away.

 

The whole point of the thermostat is to keep the coolant from leaving the engine so it can reach optimal operating temp, once that temp is reached it opens and allows the hot coolant to circulate through the radiator to be cooled.
If this system is by-passed then the engine will run to cold.
If you bleed the cooling system properly you do not need any extra holes for air to circulate, thats why the engine needs to idle until the t-stat opens and any trapped air can then be purged.
Thats why you bleed the system with the heat on full hot and the radiator cap off, so that the coolant and air can be pushed through the entire system and the air can escape from the open radiator.

 

Well, in a D2 full hot heater = same as AC heater, because no valve. And on our D1 that stat is inside the block, where the heat is. The heat will eventually make it to the remote stat, which will open, then close back. On flat road, in cool weather. On hills in summer, it may have to stay open a lot more, and holes make no difference. They are only part of the system when the stat is closed.

With just the jiggle device, you will have protection aganst the steam bubble being trapped behind the stat. Usually those things stay pretty closed when water pressure is on the back side, when just hot air up close to the stat the jiggle device loosens up and air seeps by. This is a good thing in any car, and most stats come with those (rattles when you shake it). And air may find a way into the previously purged system (hose leak, etc.).

I will admit that in this case maybe a single and perhaps smaller hole. With no weep hole, stat will still open, just take longer and temp bumps (like you see on your with the Ultra Gauge in the morning) could be larger and last longer.

And, in light of the detection system for a stuck stat at the wrong temperature, I must conceed your point that a 195 would be the first choice. Other posters with 180F in-line have not noticed this problem, but they could be operating in a different climate (Miami vs Detroit).

 

I love this site and all the thought that goes into these responses that help so many of us.
After driving today (High was 46f) it is not getting up to operating temp unless I let it sit and idle to 180f before I take off, once it gets there it maintains the 175f to 184f. It is not warming up for two reasons i think.
1. is because the electric fan is tied into the AC compressor and when it cycles it kicks on the fan (which happens long before it gets to 180f) it cycles because of the defrost I am sure, I just set the temp to 72 and keep it on AUTO.
2. because of the holes in the stat.

I think that a 180f stat with no holes in it would allow it to get to operating temp the quickest, and if the fan kicks on it will have very little affect on cooling it down until it is released into the radiator. or a 190f with one very small hole would be two answers to my problem. However I still have the electric fan issue, I believe I can just disconnect it from the AC compressor and set it up as a manual switch inside the cab that I can turn off and on when ever I want. But when I am in the summer months I might wish I had left it connected to the compressor????

I will be trying the 180f with no holes first, So Spike if you would jump in and tell me how to bleed the air out of the system I would greatly appreciate it. I know how to get it out before the stat by elevating the overflow but I did that when it was cold, not clear on how to do it when it is running.

And Savannha Buzz what is the jiggle device? is this like the fail safe thermostats? And what year make and model vehicle would I search that would have a 190f stat with a jiggle device?

thanks guys

 

See pix, circled in red. It usually rattles when you shake the stat. Nope, not the fail safe one. Is your electric fan stock or after market? Stock condenser fan on a D1 runs whenever AC engaged, but is controlled by ECU on the D2 and runs when ECU thinks it should. If after market to replace main rad fan, what turns it on/off?

 

Yes aftermarket fan to replace clutch fan, I snapped off one of the blades on the clutch fan and on the 03 and 04 the blade and clutch are one piece and u can not just buy the fan. anyway had to order one and because my disco is my daily driver I needed something right away. It is powered by a probe that gets installed in the radiator fins and detects the temp, and the AC clutch fan. I enjoyed the performance of the fan so I have never reinstalled the clutch fan again. It worked really well with the stock set up and now to well with the inline setup.

 

To bleed the cooling system, start witha cold engine, remove the radiator cap and start the engine, put the heater on as hot as it will go.
Let the engine idle until the t-stat opens, once open the air will be pushed out of the open radiator cap. Keep checking the coolant temp and make sure the heater is blowing hot, I put the HVAC on vent and roll down the drivers window so I can just stick my hand in the window and feel the air as wella s stick my head in to see the temp gauge.
Once all the air is out replace the radiator cap and then shut off the engine.
Drive as normal checking the coolant level while the engine is cold for the next couple of days.
Top off as needed.