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Discussion Starter · #1 ·
Hi guys,

This is what happened: I decided to be proactive with my '04 Z06 in replacing my lead-acid battery before it started leaking. I installed the replacement battery and then started the car. The voltage at idle was reading between 13.8 and 14.1 volts at first, and after letting the car idle for another ten minutes, the voltage was showing between 13.3 volts and 13.7 volts.

At this point, the gauges were reading normal, with the water temperature at a steady 194 degrees - exactly where it sits when the a/c is on. Everything looked okay, so I put my tools away, changed my clothes, and took the car out for a spin. I was watching the voltage so I'm not sure how quickly the water temperature rose, but exactly 6.3 miles later (I know since I later clocked it on my truck), my water temperature gauge was pegged, and the water temp on the DIC read "xxx." I immediately pulled over and shut the car off. When I opened the hood, there was no steam nor were there any water leaks. The coolant overflow tank did look to be full, however. I checked the radiator for trash bags or debris, but there was none.

I had the car flatbedded to Showcase Chevrolet in Westminster, CA, but just made it before they closed, so I don't know what's wrong with the car. Looking back, I did not hear any warning chimes, nor did I smell coolant. Aside from the water temperature reading, the car didn't seem to be acting strangely either.

What are your thoughts? Has anyone had this happen to them? Could the replacement battery have caused this? Please help, and thanks in advance.
 

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From what you describe there's probably no damage. Don't know if the guage and DIC have different sensors, but I'd suspect a bad one (2 at once is unlikely). Of course, since you were fooling with the electrical system by changing the battery, maybe a connector came loose.
Good luck with the troubleshoot, but I'd bet your engine is fine.
 

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I bet the connector on the temp sensor fell off. Pegging the gage is a typical indication. The sensor BTW is right behind the alternator on the left head.
 

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There is an Overtemp mode the car will go into at like 278 or something where it converts into a 4 cylinder and fires the cylinders in an order that allows the cylinder to cool before firing it again. Once in that mode you can drive 50 miles. When my waterpump went out I hit 253, never went into over temp mode and drove it home like 25 miles. On the highway with a bad pump it ran like 190 then at lights it would reach 250. Had the pump replaced and haven't seen any issues.

I thought I also read that there is some place around Phx thta does DE's and they run with the temp pegged. Good chance your fine I'd say.
 

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Discussion Starter · #7 ·
Thanks for the replies! I'm on my way to the dealership to supervise whatever they do to the car. Would the water temperature sensor just randomly fall off? I haven't touched anything in that area of the car. Thanks again!
 

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Not usually. They are clipped on pretty tight. It still sounds like a break in the path though. Maybe the sensor. Who knows. After working on cars for 30 years I've seen all kinds of weird stuff.

Let us know what the dealer finds.
 

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pat03z06 said:
There is an Overtemp mode the car will go into at like 278 or something where it converts into a 4 cylinder and fires the cylinders in an order that allows the cylinder to cool before firing it again. Once in that mode you can drive 50 miles. When my waterpump went out I hit 253, never went into over temp mode and drove it home like 25 miles. On the highway with a bad pump it ran like 190 then at lights it would reach 250. Had the pump replaced and haven't seen any issues.

I thought I also read that there is some place around Phx thta does DE's and they run with the temp pegged. Good chance your fine I'd say.
That's nice reminder about a feature that our cars have. :jammin: :jammin:
 

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Once I jump started a 71 Challenger cause i'd left the lights on. About a day later the fuel and temperature gauges quit working. I knew for sure i didn't cross the cables or anything, just maybe the voltage spike screwed with something. of course that car was 25 years old at the time... but maybe something similar happened to you. i too doubt your motor overheated. good luck
 

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pat03z06 said:
When my waterpump went out I hit 253, never went into over temp mode and drove it home like 25 miles. On the highway with a bad pump it ran like 190 then at lights it would reach 250. Had the pump replaced and haven't seen any issues.
Hmmm. I'm having suspicously similar issues.

How did the water pump "go out"? I'd think it'd either turn or not turn. Do you know what about the pump was actually bad?
 

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Originally Posted by pat03z06
When my waterpump went out I hit 253, never went into over temp mode and drove it home like 25 miles. On the highway with a bad pump it ran like 190 then at lights it would reach 250. Had the pump replaced and haven't seen any issues.
RocketSled said:
Hmmm. I'm having suspicously similar issues.

How did the water pump "go out"? I'd think it'd either turn or not turn. Do you know what about the pump was actually bad?
If the radiator fans don't come on it will overheat in the city also. Make sure the fans come on in the proper sequence and at the proper temperatures.
 

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This happened to me this past weekend...

Heres my recap:

Haven't had the time to fix or even look at it yet...

--------------------For the past few days I 've noticed my coolant temps higher than usual but figured it was the much hotter temperatures we've been seeing...but today.....

Today .....I'm cruising at 75 mph in sixth gear and the coolant temps are 207 degrees..(usually 192 degrees)

I turn off the a/c and put the defroster on heat.....and it brings the temps down to 198 degrees..

I'm thinking since I put the stock air box on saturday and found out my aftermarket coupling to the maf was letting some air in...I'd run the stock air box for a few days and sure enough the cars running much much better...but hotter...

So this afternoon I put the aftermarket air filter back in and thought....that would resolve the issue...

Low and behold in 15 minutes of around the town driving...

The car is running 243 or 249 degrees coolant...so I quickly turn off the road onto a side street...turn the car off...and park....turn the key just for a D. I .C reading of coolant about 5 minutes later and the D. I. C says....253 degrees...

I'm like holly shit..so

Wait ten to 20 minutes...start the car and then the coolant goes down about 2 degrees every few minutes..

Now the car seems to be running about 217 to 230 degreess for the most part..sometimes down to 208 degrees but the car really used to run 190 degrees pretty much all the time except maybe bumper to bumper traffic..

I could let the car idle now and it settles in at 208 degrees...and then if I drive it rather gently it climbs to 221 degrees..drive it a little harder and the temps climb to 230...

I didn't sit in traffic today so I'm dumbfounded...

No codes in D. I . C either....

Could it be a fuse for the fan blown..(the passenger side one seems to work...I can't see the driverside one so I can't tell.)

Could it be a slipping water pump belt?

Could it be a bad thermostat?

Could it be the water pump?

Could it be worse like a head gasket?

Could it be the tuning? (found the maf connector to air filter was leaking air in...and fixed it...)

-------------------
\

From my research...so far on the net...most feel my situation is probably the thermostat.....maybe the water pump...Could be fan fuse or fan related issue...

My coolant is about 1/2 inch to one inch lower than the full mark on return tank..

Let us know what you find out...and I'll do the same mid week next week when I get the car checked out.

Good luck

JB
 

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Discussion Starter · #14 ·
Well,

Yesterday morning, I told the dealer to clear the codes on the car and try running it to see if it would act normally. The car ran fine, and the dealership could not duplicate the pegged water temperature situation. The dealership did drive my car 25 miles, but oh well. Long story short, I picked the car up, and it seems to be driving well. Thanks for all of your help. I guess I'll be getting one of the GM shop manuals.
 

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pat03z06 said:
There is an Overtemp mode the car will go into at like 278 or something where it converts into a 4 cylinder and fires the cylinders in an order that allows the cylinder to cool before firing it again. Once in that mode you can drive 50 miles. When my waterpump went out I hit 253, never went into over temp mode and drove it home like 25 miles. On the highway with a bad pump it ran like 190 then at lights it would reach 250. Had the pump replaced and haven't seen any issues.

I thought I also read that there is some place around Phx thta does DE's and they run with the temp pegged. Good chance your fine I'd say.
That's the good ol' Camel Mode. :D
 

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So, I crawled under the car yesterday and took a look to see if I'd sucked anything up into the radiator shroud. Nothing. But then I notice there's about a 1" gap between the A/C condenser and the radiator. I can just barely see "stuff" up between the two. 5 minutes of "delicate" probing/sweeping with a 2' long 1/4" dowel pulled out enough sh!t to make a fairly respectable birds nest.

The car still wants to run hot with the A/C on. The temperatures will come down to about 200 under light load, or if you turn off the A/C, but in traffic or up a long hill, it'll shoot right up to 225-ish.

I'm sure I need to remove the radiator and blow it out with some high pressure air and the problem will dissapear, but it really pisses me off that the Z's radiator is so "marginal". My wife's Sierra PU has an LS1, and it'll pull 10KLbs of horse trailer, with the A/C running, in 95º heat, all day long. I'm figuring, if I'm going to have to remove the radiator anyway, I might as well replace it with something better...
 

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I find that a high pressure stream of water works even better :z:
 

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Aren't these cars supposed to run hot? Mine has always ran 190 on the highway and 215 in traffic since 0 miles!

Hell, my LT1 would run 200 on the highway and 230 in traffic all day long...so does everyone elses.
 

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They do run a little "warm". But with my car, if I can't get it on to the highway or get my foot way out of the gas, with the AC running the temperature just keeps creeping up and up. 240º isn't hard to hit, and that is too warm.
 

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Plug in For the Alternater

Right a The alternator .Before I cleaned the plug in It was 13.7 When I clean the plug In it Went back up To 14.2 ;)
 
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