Help! OVERHEATING IN MY 90 VETTE

[azblonde]

HELP!!! I AM NEW TO THE BOARD I NEED SOME INSIGHT ON MY 1990 VETTE WITH 115,000 ACTUAL MILES, HERE IS MY PROBLEM,, I HAVE OWNED THIS CAR FOR OVER A YEAR AND A HALF NEVER HAD ANY PROBLEMS WITH IT, ABOUT 4 WEEKS AGO IT STARTED TO OVERHEAT, THE FANS ARE WORKING, BUT WHEN I CAME TO A STOP LIGHT THE TEMP WENT DOWN BUT WHEN I TOOK OFF THE TEMP WENT BACK UP, IT GOT TO ABOUT 250, IT HAS A NEW THERMOSTAT AND THE RADIATOR HAS BEEN FLUSHED, ALSO DISCOVERED THAT I HAVE 2 FUEL INJECTORS #5 AND #7 THAT ARE NOT WORKING, I AM NOT LOOSING ANY WATER, IT DOES HAS A HESATATION WHEN TAKING OFF I AM GUESSING THE FUEL INJECTORS, BUT JUST CAN NOT FIGURE OUT THE OVERHEATING, MY CHECK GAUGES LIGHT DOES NOT COME ON, AND MY CHECK ENGINE LIGHT ALSO DOES NOT COME ON, I KNOW THEY ARE WORKING, IT RUNS TO GOOD TO BE A BLOWN HEAD GASKET, I HAVE A 160 THERMOSTAT IN THE CAR, I HAVE ALWAYS WANTED A CORVETTE SINCE I WAS 10 AND FINALLY GOT ONE, THIS IS MY BABY ANY ADVICE WOULD BE APPRICATED. ;help

 

[gmjunkie]

Well first thing I would remove the plugs,and check if any coolant has been entering the cylinders!
Second, I'd run a compression test!!
Then I'd get the injectors replaced!!!
Bad Injectors can Make it very lean and raise the the engine temp!!!!

PS With 5 and 7 injectors not working I would think that it should trip a code,It's definitely got to be Lean on Bank 1!!!!!

 

[TedC]

Welcome to CAC!!! Did you confirm the temp changes using another source? I would validate what the dash is displaying. Could air be trapped in the cooling system? Also, check the space between the radiator and a/c condenser? Bottom feeders are street cleaners and collect all kinds of stuff. I filled a bucket full of of gum wrappers, leaves, newpaper, plastic from bags ...

 

[topless82vette]

My friends 1990 is doing what yours is doing to. Fans running all the time, high coolant temps, car loses power when temp gets up there, etc.

His also has a small leak at the front of his intake manifold where you can see coolant come out. However the car never shows to be low of coolant in its resevoir.

It has had new fan motors, new injectors (sadly 19lb ones) and it still continues to do it even with the a/c off.

I told him to check his pre-cats to see if one is plugged, I will let you know the outcome. But his is doing pretty much what yours is doing.

 

[azblonde]

I REALLY APPRICATE THE INSIGHT, AS FAR AS THE PLUGS MY HUBBY PULLED THEM AND THEY LOOK BRAND NEW, MY HUBBY IS THE WRENCH TURNER AROUND HERE BUT GROWING UP AROUND MY DAD'S SHOP AND RACE CAR'S I KNOW A LITTLE, IT IS JUST A PAIN IN THE YOU KNOW WHAT NOT TO BE ABLE TO DRIVE MY CAR, WE ARE PLANNING ON REPLACING THE INJECTORS BY THE LOOKS, IT LOOKS LIKE MOST OF THEM HAVE ALREADY BEEN REPLACED, THE INJECTORS IS WHAT MY HUSBAND THOUGHT WAS THE REASON IT WAS RUNNING HOT, AT FIRST HE THOUGHT I WAS WACKED WHEN I TOLD HIM IT THE TEMP WENT DOWN AT A RED LIGHT OR IN STOP N GO TRAFFIC, BUT WHEN HE DISCOVERED THE INJECTORS HE SAID THAT MAYBE AT A RED LIGHT IT WAS SPRAYING JUST ENOUGH FUEL IN THE CYLINDERS TO COOL IT DOWN BUT WHEN I TOOK OFF DID NOT HAVE THE SPRAY, HE ALSO TESTED THE PLUG GOING INTO THE INJECTOR AND IT IS HOT SO THERE IS POWER GOING TO THE INJECTOR, ALSO UNPLUGGED #5 NAD #7 INJECTOR AND IT DID NOT MAKE A DIFFERNCE IN THE WAY CAR RAN, UNPLUGED #3 AND THE CAR STUMBLED UNTIL HE PLUGED IT BACK IN, SO AGAIN ANY ALL SUGGESTIONS IS REALLY GREATLY APPRICATED. THANKS

 

[G Winter]

Have hubby check the ohms on the injectors. should be in the neighborhood of 16 ohms , plus minus about 1.5 . My manual says anything over 10 ohms is ok but I really wonder about that. I have a couple on my 90 down in the 8 and 9 ohms area. Replacement of all injectors is on the calender for me.


Glenn

 

[azblonde]

JUST WANTED TO SAY THANKS FOR EVERYONE'S INSIGHT ON THIS PROBLEM, HUBBY IS GOING TO FIRST CHANGE OUT INJECTORS, IT WILL PROBALLY BE AFTER THE 19TH SINCE WE WILL BE OUT OF TOWN, WAS HOPEING TO TAKE THE VETTE BUT I AM OKAY WITH IT SITTING AND BEING FIXED RIGHT, SO I WILL LET YA ALL KNOW IF THAT CURES IT,

 

[topless82vette]

azblonde on my friends 90 when his injectors took a dive he said his car was like pulling a boat just totally unresponsive. But his injectors were ohming out as low as 3.0 ohms. I think only 4 injectors on his car read normally and he says thats around about the time his started running hotter then normal. then when he had 19lb injectors put in it ran a bit cooler but still climbs way up there.

 

[blu88]

You may want to check for debris build up in the space between the front of the radiator and the back of the A/C condensor. There's just enough room in there to catch all kinds of things and mat up the face of the radiator cooling fins. My '88 had a similar symptom and after cleaning out the crud and spraying water outward through the fins, it hasn't ran hot since.

 

[topless82vette]

I think one poster is wrong about it tripping the check engine light. My friends 90 never did when its injectors took a dump at all.

But here is another TBI car I once had that baffled the hell out of me was a 89 camaro RS 305TBI. ran pretty nice but hesitated under a load. But here is a really odd thing the car did it would light up it's intermediate pipe from the cat converter all the way to the muffler (no restrictions mind you) The culprit was later found to be low fuel pressure caused by a hairline crack in that rubber hose between the fuel pump and the sending unit.

Not sure if a vette will light up its catback like this but that had to be one hell of a lean condition to make that pipe bright orange. This car also did not throw any ecm codes at all.

So someone answer this when rich or plugged would the headpipe glow but when lean the rear most pipes glowed? I can understand a plugage causing it. but how does a lean condition cause it. Another thing this car had during this was the intermediate pipe turned a whiteish color.

 

[azblonde]

UPDATE :HELP MORE PROBLEMS

I JUST WANTED TO GIVE AN UPDATE REGARDING MY OVERHEATING PROBLEMS, SORRY IT HAS TAKEN SO LONG TO POST,
INSTALLED NEW INJECTORS ON #5 AND #7 OVERHEATING PROBLEM FIXED !!!
BUT NOW ANOTHER PROBLEM HAS OCCURED,
FIRST DAY TEST DRIVE WITH THE NEW INJECTORS UNDER NORMAL DRIVING CONDITIONS NO PROBLEMS
NEXT DAY HUSBAND TOOK THE CAR OUT AND ON A BACKROAD GOT THE CAR UP TO 92MPH STILL NO PROBLEMS CAME HOME PICKED ME UP TOOK THE CAR INTO TOWN NOTICED AT AN IDLE THE CAR STARTED TO MISS NOT BAD AT FIRST BUT DID GET WORSE AFTER DRIVING, CAME HOME AND PUT NEW WIRES, NEW PLUGS STILL HAVE A LITTLE BIT OF BLOW BY ON THE DRIVERS SIDE HEAD, WHEN THE CAR IS COLD IT RUNS GREAT, WHEN IT COMES UP TO TEMPERTURE IT STARTS TO STUMBLE AROUND, BUT OUT ON THE ROAD IT RUNS GREAT, ONLY AT AN IDLE DOES IT STUMBLE YOU CAN HEAR IT POPPING ON LEFT EXHAUST, STUMPED

 

[G Winter]

He didn't replace all the injectors ? Have him check the ohms on the injectors. I wouldn't be surprised if there is another bad one. When I had injector go bad it would run better cold than warm. Seems when cold the mixture is rich enough to help out the cyl with bad injector so runs a little better cold. Once it warms up that cyl leans out.

Glenn

 

[John Robinson]

Go out in the dark and start the engine and look for spark jumping from the plugs or wires. I just spent the month of October chasing a miss in my 93 and finally found that two of the new plugs were cracked in the porcelain and when I got that fixed I found that the non OEM Parts store brand wires were shorting across to the engine and each other. I had to get some vacuum hose and make sleeves to go over the plug wires where they crossed each other or came near any kind of metal. I finally have been able to drive the car and it now runs miss free. For the first two weeks I thought the plugs and wires were not the problem after all they were brand new

 

[azblonde]

THINK WE FIGURED IT OUT,, HUBBY WENT AND BOUGHT A CAN OF CARB CLEANER AND SHOT IT EVERYWHERE, HE THEN CRACKED THE THROTTLE AND OUT OF THE DRIVERS SIDE EXHAUST CAME A HUGE CARBON CLOUD REPEATED WITH THE CARB CLEANER, WENT THRU A WHOLE CAN, BLOW BY IS ALMOST GONE AND IT HAS JUST A LITTLE TINY MISS WE WERE THINKING THAT MAYBE A PIECE OF CARBON IS CAUGHT ON A VALVE AND THE VALVE IS NOT CLOSING ALL THE WAY, TOOK THE CAR OUT AND IT RUNS BETTER THEN EVER, JUST FOR THE HECK OF IT WE ARE RUNNING A COMPRESSION TEST ON IT TOMMORROW JUST TO BE ON THE SAFE SIDE, I JUST WANT TO THANK EVERYONE ON THIS BOARD FOR THEIR INPUT, WITH ALL THE HELP WE GOT FROM THIS BOARD I AM ABLE TO DRIVE MY CAR AGAIN INSTEAD OF HAVING IT SIT, EVERYONE WE TALKED TO SWORE UP AND DOWN THAT IT COULD NOT BE THE INJECTORS THAT WAS MAKING IT RUN SO HOT, THEY SWORE UP AND DOWN THAT I HAD A CRACKED HEAD, OR A BLOWN HEADGASKET OR SOME THING ALONG THOSE LINES, I TURNED TO THIS BOARD I FIGURED WHO BETTER TO ASK THEN PEOPLE THAT OWN CORVETTES, AGAIN A BIG THANK YOU

 

[John Robinson]

Thanks for the update

If the problem comes back do a search on this site for EGR problems. You may be right about a piece of carbon but not on the valves. A piece of carbon on the pintle seat of the EGR valve can do strange things like making it run lean which also would have the same results with the temperture as the injectors did and it would stumble at low RPM's.

Now for the important stuff