I am having an issue keeping my car cool on my 15 mile, 25 minute commute home here in the Texas heat.

First, the car is a 2000 Z28, Heads, Cam, 383 LS6. The new setup has a whopping 500 miles on it. I noticed the problem yesterday coming home from the office. I have an Autometer water temp gauge with a sending unit in the passenger side head.

Driving to work in the morning when the temp is in the 80's or low 90's, the car seems to do fine, and never gets to 210, and is usually around the 190 - 195 mark, and I am running the AC, though not at the maximum setting. On the way home, running the AC at max most of the way, the gauge drifts to 210 pretty easily and has even hit the 225 mark or so on the way home today in the 101* heat. I have not tried driving it home with the AC off in the heat - I plan to wear shorts and go for it tomorrow to see if it happens with the AC on or not.

Based on the fact it works ok most of the time, I have, at least in my head eliminated 1. fans (they are running, though I can't really tell if they are at high or low speed) and 2. the thermostat - it would overheat no matter the temp if it were stuck closed. After the car cooled down tonight, I opened the radiator cap and it was filled to the brim. I inspected the condensor and the space between the radiator and condensor closely tonight and both appear clean and free of debris.

When re-assembling the car, and starting it up for the first time, I did "burp" the system by leaving the hose off the crossover to the heads until coolant came out. That and the fact that when I opened the radiator, the coolant was to the top makes me think I don't have air, though I guess it is still a possibility. Just moments ago, I opened the radiator again, and it was down a tad, but less than a cup of water filled it back to the point of spilling it out again. I assumed that was from me opening it earlier. I DID notice the Alternator wasn't putting out the normal voltage when the car was getting hot - does anyone think there is a chance when the car gets hotter the belt is slipping a tad due to it expanding from the heat and disallowing the waterpump to operate as efficiently as possible?

Any ideas would be helpful. The mix is currently 60/40 Water to dexcool.

Thanks in advance.

 

You might need to clean out your A/C condenser. I bet it's full of bugs, rocks and other assorted unpleasantness.

 

Everything sounds good man. 215-220*F on a 101* day with the A/C "on"....you're doing great. If thats happening while cruising steady on the highway, I'd say its a little hot. City driving though, thats not bad.

You will always run hotter with the a/c on, especially on a real hot day.

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I looked pretty closely at the condenser last night, and it seems pretty clean. I've seen pictures of some really nasty condensers, and mine looks darn near brand new. I'm inclined to think that's not the problem. I'll take a close look at it tonight again, but I don't think that is my problem. Thanks for the reply!

 

Yeah, but I've had this car for 9 years, and had the autometer water temp gauge for 5, and keep a close eye on it. I've never had it get this hot, even in the Texas heat. Once it starts flirting with 225/230, it makes me nervous.

I think I'm going to go ahead and put a new belt on it and see if that doesn't help the voltage and the temp a bit as it gets hot...

 

This is pretty much how my car has been, since new.
Heat saps the alternator (I think the field regulator
goes into some kind of thermal/current limit, earlier).
With A/C on my temps are never under control.
Blowing out the rad & condenser did yield me a whole
lot of fine crap and some improvement. But the rad
is too small and the fans are too weak, for this motor
(let alone one that sheds any more heat than stock,
such as (say) your higher displacement, higher
compression, low-end-inefficient converter hop-ups).

Bigger radiator is what I'd be thinking about. Got a
LT1 rad sitting in the garage myself, for someday,
about 50% thicker core and pretty cheap, eBay
new aftermarket. But a "Be Cool" or similar, is probably
even better.

 

Well, I have a smaller converter now and the same compression I used to. I DO have more cubes. This system has never had an issue keeping up with my car before. ...I'm going to do all of the obvious stuff - I'm gonna change the belt, flush the system and go back with more water than before per LS6427's formula, and I'll clean out the radiator and the condenser, though they are both pretty clean. I'll change my cap too, just to be on the safe side - it is stock and thus 9 years old.

Everyone agree that the TSTAT isn't the issue based on the fact it cools unless it is nuclear outside?

Thanks!

 

My experience with my F-Body since I bought it in 1998.......the condensor will keep getting worse and worse...but it will still allow enough to get through until a point, then its almost like it says, "look buddy, if you're not gonna clean me, I'm gonna heat your *** up."

It happens quick. I've pulled my radiator out and cleaned my condensor 3 times in 11 1/2 years, each time everything was pretty good until one day, in the summer, BAM....constant overheating.

Here's a thread I started with pictures. 80% of my condensor was completely blocked. 20% of its surface could flow air through. I couldn't see any of this just by kneeling down and looking up in there.

Clean that sucker and you're problems will be over. If you want to really do it right. Go have your refridgerant recovered and held, take the condensor out and give it to a radiator shop to clean it 100% like new. Put it back in and have them put the refridgerant back in. You can do all that in half a day, if they'll clean it as soon as you bring it in. I'm doing that next summer.

https://ls1tech.com/forums/general-m...irty+condensor


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I'm fairly confident the thing is clean, but I'm going to do your bang it on the frame routine and see if that solves the problem. I'm changing the belt simply for good measure and I'm going to get a new radiator cap as well as preventitive maintainance and will flush the system this weekend as well. Hopefully this maintainance will solve the problem. Thanks for all the feedback, guys.

 

I too have been running a little hot lately. the condenser and radiator are clear, the thermostat is fairly new, i flushed out the system and added new coolant. The only thing i can think of is the belt also. Let me know if that helps you out.

 

I'm in Arizona, so I know the kind of summer heat your talking about.
When I first installed my headers- they are uncoated, water temp. was fine, then when I would use the a/c, water temp would shoot way up after several minutes. This never happened before the headers, so I knew it had to be from them. I wrapped them, and temps. went back to normal even on the hottest days with a/c on.
The past month we have had days that are 115 and no problem with temp.

you could have some similar type of situation.

also, my radiator is clean, using 50/50 solution with water wetter added, and a new radiator cap.

 

never thought of the headers adding to the heat, totally forgot about them.

 

I don't think the headers are my issue. I've had headers (uncoated MAC's) for years. I now have ceramic coated long tubes. If anything they should be cooler than the uncoated MAC's were.

I got the belt last night but hit a lazy wall, and didn't get it in. I'll do that tonight and give everyone an update tomorrow. It ran cool on the way home last night, but it was cloudy and rainy, so I didn't have the heat to battle.

Thanks for all the replies.

 

OK! I wanted to post up my results.

After doing all of the searching on this site and reading everyone's input, I decided to take the radiator and condenser back out of the car to clean them both and to flush the entire system and go from 50/50 + water wetter to 1/2 jug of Dexcool + water wetter + water for the remainder of the mix.

Cleaning out the radiator and condesner proved to be a more difficult task than I imagined. Fortunately, I happened to have two 2x4's and a piece of plywood screwed together at just the perfect width of the condenser and radiator (left over's from a motor crate I recently disassembled. I banged both of the units against this assembly being careful not to bend any fins, and got a lot of solid debris out. ...but there was still alot of crud in there.

I tried the airgun at 120 PSI, but it didn't really do anything. ...so, against some of the advise on here, I whiped out the hose. ...instead of using a nozzle, I used the old thumb over the end of the hose routine to get a strong stream. This actually worked quite well, and I got a LOT more debris out using this trick. (cover the AC ports and Transmission cooler ports so they don't get water in them) As I was about to put it back together, a friend called me and I told him what I was up to. He proceeded to tell me that he always used coil cleaner (available at Home Depot) to clean his radiators. 5 minutes from Home Depot, I figured I'd run over and get a couple of cans and give it one more rinse out. This stuff got a good deal more stuff out, as it dissolves the grime and fluff that gets stuck in the radiator. Once all was rinsed out and try, and flushed out (motor, radiator and hoses) I put it all back together and burped the system using the coolant to water mix outlined above. Driving into the office this morning with no AC (system was discharged for this project) the car ran great and very cool, never got past 185-190*. I ran by my favorite shop and got the AC charged up this afternoon, and then drove the car home and it never got past 205*, Max AC, in stop and go traffic in today's Dallas heat of 98*.

Looks like the problem is gone. The effort was worth the payoff.

Good luck to anyone else who tries to tackle this. It seems to have worked out!

Thanks for all the replies and help!

 

Sweet. You should be good to go for another 2 years of daily driving. I do mine every 2 years.




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