Hi all! Has anyone tried making under trays for their Monte? I'm trying to improve the flow of hot air out of the rear of the engine bay, so I've removed the air dam and installed a (temporary) cardboard under tray to encourage high speed flow under the car. I'm hoping that the high speed flow will create a low pressure under the car and "suck" hot air out of the rear most part of the bay. If anyone has done this I'd appreciate any advice you have!

 

I don't think I've ever seen a monte owner do that for the reason you're asking about.

I do recall seeing one under tray for a 6th gen years ago - they went from just ahead of the front bumper (so there was a couple inch lip protruding from their front body kit) to the back of the engine cradle to try to help aero (but essentially sealing off the bottom of the engine bay).

Just curious, why the concern on lowering engine bay temps - are you having a hard time keeping the engine cool?

 

Forgot I started this thread, whoops. But essentially yes, I've installed a 160 thermostat, but haven't turned the fans yet (I know I know) but I find it strange that the car now gets hotter in the summer than with the stock 195-200 therm. Coolant temp peaked at 226 just the other day. I did a coolant flush on the car a couple years ago, replaced the thermostat and the water pump. Everytime I shut off the car bubbles come through the line to the overflow. I'm going to attempt to bleed the system tomorrow just to check levels. Other than that I'm not sure why temps would be increased so significantly compared to stock.

 

No air out of the bleeder valves, though when I removed the radiator cap before running the car there was a fair bit of air. Having not tuned the fans I understand the car still getting up to 200 pretty easy, but going 50 on an open road should keep me under 200 even on a 100 degree day right? Or is that unreasonable?

 

Air can be an issue for sure. Another way is to drive you passenger side front wheel up onto a ramp type area, so as to make the radiator cap area higher than the rest of the radiator. Remove the cap and let it run for 10 minutes, that will burp out any trapped air. Have your heater operating when doing this too.

Also I read where you removed your air dam. Was the car getting hot before you did that? had a guy work on my Monte years back, he did not put the air dam back on and after a lot of head scratching for high temp problems, that ended up being the solution. Buying another one and then that allowed the air to be scooped up and forced onto radiator face.

How new is your cap? Even simple things like that can be a problem, even though with those one typically hears a gurgling sound from the overflow bottle.

 

Do you have certain data that it was able to hold 200 before under the same operating conditions?

If so, it sounds like something went wrong from the tstat swap. Even if the system isn't physically capable of cooling even a single degree lower than it did stock, it would still be able to at least maintain that same level as it could before with the lower temp stat.

If it got worse just from that change:
-Id try to see if its possible to burp more air out of it - like using the elevating idea Zippy mentioned to make sure its the highest point in the system.
-If that doesn't work, I'd probably pull the stat, stick it in a pot of water on the stove with a thermometer, and see if its actually opening right. Maybe its defective or isn't opening as much as stock until it gets much hotter.

I wouldnt automatically count on it being able to go notably below 200 with no other changes, especially as you're approaching the upper limit of temperature operating conditions.

The requirement of the stock system is to hold it in the low 200s at steady state up to the hottest normal outside temperatures. Certainly its likely it has some headroom beyond that (ie they can't have an engine that melts down if a single leaf gets stuck in the radiator).

The other thing to keep in mind is that the lower the temp delta, the harder it is to cool-

For example, its 100 degrees outside (probably a low estimate as the road can radiate solar energy- especially asphalt). You've got your ac on max which is raising the air temp to 120 (just making up a number) before it hits the radiator. The speed at which the radiator can shed heat to the air is significantly lower when you've got 160 degree coolant inside vs 200 degree coolant inside.

Again, thats all just theory as there is always some headroom built into the stock system. Im just trying to say that it may not be possible for coolant temp to get down to 160 as you're shooting for.

Thats a good question. Ive seen that on c6 vettes too. Its very common for people to remove them since they scrape / get damaged so often with the car so low. But people often run into cooling issues in hotter climates when they do.

 

What gasket did you use when you changed the thermostat?

 

Removing the airdam did raise the temperature, the next day I replaced it with a cardboard scoop/duct and that brought it back down. the radiator cap is as old as the car. I think I mentioned before but I'm not sure, when I shut off the car a lot of bubbles come through to the overflow bottle, but the level in it never seems to drop, is that what you mean by gurgling?

I tried the burp when I tried the bleeders on Monday with the car pointed up the driveway, problem is even though the radiator neck is empty when open cold after maybe 15-30 seconds of idling the radiator starts overflowing. I have also read that antifreeze is not as good a coolant as pure water, and when I refilled my system I aimed for 70% antifreeze. (at the time I believed the opposite, it is referred to by some as "coolant" after all lol)

wht02monte: All I know is a rubber gasket came with the therm.

 

[QUOTE=1st-monte-ls;729381]Removing the airdam did raise the temperature, the next day I replaced it with a cardboard scoop/duct and that brought it back down. the radiator cap is as old as the car. I think I mentioned before but I'm not sure, when I shut off the car a lot of bubbles come through to the overflow bottle, but the level in it never seems to drop, is that what you mean by gurgling?

Yes, I would call that gurgling. Inspect the cap, its gasket shrivels and distorts over time. Get a high quality one and it being as simple as it is could very well solve the over heating issues. They are very important to keep the system sealed and maintaing system pressure thus not letting it over heat.

 

Considering that the cap is as old as the car and I've got employee discount at the GM dealership across the street, I'm gonna replace it regardless, even though it doesn't look all that bad. Thanks for the help guys.