Overheating at 100Mph in 115 degree weather

[RangerBob]

I work out in the desert and routinely drive fast on long deserted highways.
I replaced my water pump at that seemed to help some.
The water temp gauge doesn't go over halfway.
The first symptom is that the AC quits blowing cold (new compressor).
Before I replaced the water pump, the transmission was slipping in high gear before I shut down.

Possible culprits:

Radiator cap
Radiator needs cleaning
Hose collapsing

I don't want to replace the radiator, and I drive the speed limit now!

I don't want to damage my engine.

I could use some advice on troubleshooting.

Thanks

Bob
Kuwait

[Jeff_in_Atl]

Are you sure the car is overheating (you said the gage isn't going over half way) and it's not the A/C freezing up?

If you replaced the compressor did you clean the orifice tube? Usually when the compressor seals come apart they go down the line and clog the orifice tube (why you changed the compressor).

[RangerBob]

Yes the screen thing that fits inside the AC line was changed.
The engine is hot because I can tell by touch that it is above normal temperature.

I also had my thermostat changed out.

BTW: I have some difficulty communicating with the people here, but they all speak $.

Bought my wheels and lights from Afghanis
Bought my tires from a Egyptian
AC guy is a Pakastani
Engine mechanic is an Iranian

Bob
Kuwait

[Jeff_in_Atl]

ha ha ha.

Do you have a scanner? I wonder what the computer thinks the temperture is.

I don't really understand why the A/C would quit working at "highway speeds" (lol) unless the belt is slipping.

[RangerBob]

No scanner. I had the belt replaced when my AC compressor was replaced.
Maybe it is the incorrect belt.

The engine doesn't have EGR or an air pump anymore, and it had a check engine light on since I bought it.

The removal of the air pump requires the use of a different size belt. Does anyone know the correct belt I should be using?

[dochidalgo]

How's the cooling fluid level?
How's your water/DexCool mix? Is some kind of debris or rust in the cooling fluid? how about a radiator complete flush inside and outside?
With those temps should be 60/40 not 50/50 as manual service says
Is the belt tensioner OK? (well there is one in the LT1 engines). Agree with you about to check the right serpentine belt for your engine.

take care!
dochidalgo

[RangerBob]

Well I flushed it tonight. I will post results tomorrow. Air pump and EGR do not have a belt driven pulley. Hey I don't have a repair manual and this is my first LS1. It is kinda cool, flushing my radiator water out on the street as Muslims go to the mosque next door. I need to post some photos...... unless I turn up in an orange jump suit. LOL

[Christopherrr]

Quick question Bob, do anyone take notice of your car...I'm just quite surprised to know you've got an f-body there. Are most of the people there friendly?

[RangerBob]

Quick question Bob, do anyone take notice of your car...I'm just quite surprised to know you've got an f-body there. Are most of the people there friendly?

I stand out a lot more than my car does. Not very many blond haired, blue eyed folks around here.

I don't wear any sniper T-shirts in public anymore LOL.

But anyway, this place sucks, but it sucks less since I have a F-body.

[00 Ragtop Z]

Seems I recall that if the cooling system is not properly bled after doing work like you did, that it can cause an air bubble in teh system that can create such a problem. Might be dreaming, but swear I have seen this discussed before.

[Jeff_in_Atl]

Seems I recall that if the cooling system is not properly bled after doing work like you did, that it can cause an air bubble in teh system that can create such a problem. Might be dreaming, but swear I have seen this discussed before.

On the LT1 that is true. I didn't think the LS1 had to be bled like the LT1.

[Joe 1320]

Bob, I've seen instances where the A/C shuts down and the only way to get it functioning is to shut off the car and restart. Simply turning off the a/c and turning it back on does not work. It must be something with the relays.....


Now if the car overheats, is the front air deflector still in place? Without it, the car will overheat on the highway.

[RangerBob]

Well I flushed the system last night using 2 bottles of Prestone flush. I ran the car 10 minutes, then released pressure (very carefully) looked in the rad, decided it wasn't clean enough. I added hot water, then ran 10 minutes again.

Repeated the above twice.

Flushed w/ clean water twice.

Put in 2 qts of Preston AF (all I had) and filled w/ water.

Drove to work, everything working fine.

I got on it (40 to 120 mph) then backed off.

AC blowing warm air.

I shut the AC off. 5 minutes later turned the AC on. Now its blowing cold!

What actually turns off the compressor under load? Is the computer looking at vacuum?

Maybe there was oil on my crankshaft pulley that contaminated the new AC compressor belt, causing it to slip.

Any ideas?

[Christopherrr]

From what I know, under WOT or RPMs over 4500 the AC compressor clutch releases and doesn't run, when back to "normal" operating, the clutch reengages and AC blows cold. Heck if you listen hard enough, you can hear the hissing inside the dashboard when the compressor turns on and off.You can see this working when you start your car with the AC botton at the "on" position. It takes a few seconds before the AC actually runs...you can hear and watch it engage.

[Jeff_in_Atl]

With a hand held scanner you can see when the A/C clutch engages along with the engine temp and a bunch of other stuff while driving down the road. I said it before but everyone who works on a fuel injected cars should have a scanner.