I know its not my 67 but help on my 91 with cooling issues PLEASE! - Team Camaro Tech
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post #1 of 17 (permalink) Old Sep 2nd, 02, 02:48 PM Thread Starter
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My 91 Formula 305 TBI (vinE) has a new engine, new waterpump , new radiator, new intake/thermostat (160 deg.) new plugs/wires/cap/rotor yadda yadda yadda,

It overheats ALL the time. If I turn the AC on , it forces the fan to come on and help, however it still overheats. the fan was totally shot today and it boiled over, I replaced the fan with a 16" hayden electric (about the same size as the stock 17" ) mounted it in the same location, and plugged it into the factory harness, and it still overheats.. there is no sensor on the Radiator that tells it to turn on , its done by the temperature sending units to the ECM , (all sending units are new, there are no pipe thread tape on any of them)

I dont have a clue, I thought that the ECM would turn the fans on when the vehical temp started to rise , however thats a no go . Does anyone have any insight to what the heck is wrong.. I checked everything and the flow is really good, I'm just stumped... Someone told me it could be timing, but timing seems to be fine..
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post #2 of 17 (permalink) Old Sep 2nd, 02, 05:17 PM
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define "overheats". those cars are designed to run in the 210-220 range- or higher- for emmissions purposes.if it aint hotter than that, don't sweat it. if it gets that hot, and keeps getting hotter, then you might have a problem. have you tried hot wiring the fan relay to see if it runs cooler with the fan running all the time?
make sure the cap is good. if it is shot, it will allow the water to boil over a lot sooner than if it holds pressure.
is it the proper water pump? those are reverse rotation, i think. if you put a regular rotation pump in there, it will overheat real quick. also, make sure the lowere hose isn't collapsing under pressure.
is the catalytic converter plugged?

------------------
1971 Nova(looks like 69 camaro from underneath!)
355sb, vortec heads, HOT cam,T-10 tranny, 3.70 gears 16X8" IROC wheels. 12" Corvette brakes on the way.
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post #3 of 17 (permalink) Old Sep 3rd, 02, 03:50 AM
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Biggest overheating problem with newer cars after a rebuild or transplant is some of the plastic shrowding gets left off. Usually on the under side of the car. With smaller grill openings it's imparative all the factory trim is in place.

As derrik asks, describe when the car over heats and what temps it reaches...

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...Dennis
"The '69, the '96 & the club"
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post #4 of 17 (permalink) Old Sep 3rd, 02, 02:10 PM
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Chris,
First of all, like derrik said...define overheat ?? The GM ecm does not turn the fans on until about 240 degrees if I remember correct. You need to take the 160 stat out and replace it with a 195 or whatever is called for or the engine will never get hot enough to run in closed loop mode. This will cause it to run like crap. A missing front spoiler will cause your car to run hot while driving down the road, but should not affect it standing still. You need to replace the fan with the correct factory one...most modern cooling systems are right on the edge anyway, way make it worse with a smaller fan ??? Only thing else I can think of is the proper water pump, and one more thing....how do you know it is running hot ? Is the gauge correct ?? Have a good shop check it out with an IR Temp gun to see what temp it is really at.

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post #5 of 17 (permalink) Old Sep 3rd, 02, 03:42 PM Thread Starter
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Overheat = 240+ - all the way to the red , Radiator cap burping or OOOOOOOOO noise.. hot water into overflow bottle, overflow bottle spills over,

Temp gauge is fine. the fan is a Higher RPM and actually flows more air than the stock one, the Fan shrouds and plastic air dam are fine and intact. the radiator is NEW, flows Awesome, Water pump is the correct Serpantine Reverse Rotation, with the 180* thermostat the thing boiled over in about 15-20 minutes from cold start with the 160* I get an extra 5 minutes ,

it used to stat right around 195 all the time, now its fine untill the thermostat opens and the cold radiator water gets heat up. then its a slow battle to overheat. I tend to turn the A/C on so it forces the fan to come on, this delays the process slightly, but still the temp climbs, I have set the timing with the Knock sensor plug removed so the ECM is not interfering with the adjustments. for the heck of it today I replaced the already new lower radiator hose just in case. and the spring thing inside the hose was fine and intact, the new one was also fine. still no go , I am at a loss.. for the **** of it I removed the intake to check for clogs in the ports and stuff, everything was fine and clean. new gaskets installed correctly, base timing set with the timing light (I know the marks are fine because the double roller timing chain is like new as the engine, less than 1200 miles on it. ) engine runs fine. no clicking or detonation, perfect idle and response. no leaks , No vacuume leaks. I am at a loss...

I did find though , that during the engine swap a wire that goes to temp sensor #3 in the passenger side head had been melted. this sensor controlls the fans. my book says the fan comes on at 215 for a TBI (mine) and 220-230 for a TPI. but regardless of anything, unless I have a hose blasting the radiator, it boils over, driving at 55 on the highway the wind cools it a little, but the temp creaps right back up and over to the red.

i'm lost.. hope you guys can help

------------------
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post #6 of 17 (permalink) Old Sep 4th, 02, 01:08 AM
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I feel your pain, Chris.

Here's a couple more suggestions,
Go to a Marine Supply store and get a high-flow thermostat. It will look like a cup with a cage over the top and be made of brass & stainless steel. The outside cylinder will lower and reveal the open top when it opens. You might even get a 22 lb cap to prevent boilover. Radiators are tested to 60 lbs.

Secondly, remove the O2 sensor and replace with an adapter to place a fuel pressure/vacuum gauge. The gauge is one of those showing a 0-30 in/water and continuing on with 0-15 psi fuel pressure. Run engine up to 2500 rpm for 3-5 minutes, if pressure gets to 3 psi, plugged exhaust system, maybe the cat.

Good luck.......Keep us posted

Reread your last post, "It use to stat @195..." What did you do to change this? Food for thought....

------------------
Everett 68/350/PG/11.90/115mph
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post #7 of 17 (permalink) Old Sep 4th, 02, 01:47 AM
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Chris,
Were there water restrictors on the original intake gaskets. Some engines use none, some one, some two. Just a thought.

On our 94/95 B bodies with LT1 motors and dual cooling fans I installed a temperature switch in the left cylinder head and then it is wired to the fan relays. You can get the switch from Jet Performance Products. The ECM turned the primary fan on at 224 degrees and the secondary fan would come on at 232 degrees if the primary couldn't cool the motor down. With this switch installed it turns BOTH fans on at 200 degrees with or without the A/C on. This modification causes two history codes to set in the ECM for faulty fan relay circuits however it WILL NOT set a "check engine" light. This has helped these cars run much cooler when they are out there beating the life out of them in 100 degree temperatures.

Running a lower temperature thermostat in a car with an electric fan/s will not help because the ECM is programed to turn the fan/s on at a predetermined temperature. The only effect the lower stat will give is a longer warm-up time.

Good Luck
Drew
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post #8 of 17 (permalink) Old Sep 4th, 02, 03:00 AM Thread Starter
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yes there were restrictors on the gaskets, only because the intake does not have those ports. so naturally they block the flow so it has to go through the head instead of the intake (its the back ports closest to the firewall on both sides)

Everett#230, you ask what did I do to change it, well the original engine threw a rod, so we replaced it with a new longblock. ever since then its been happening. and I replaced all the parts except the heater core, I was confused thinking somthings screwed up , I just dont know what it is...

I DID recently replace my exhaust with a Stock replacement kit from Dynomax, same hangers, bolts right up to the catalytic converter,

Maybe the cat's bad... I guess I can drop the pipe and Take all the screens out and / or replace the sucker. cant hurt, it is 12 yrs old...


DREW69 - what size fans are they, Dual 12" fans? I currently have 1 16" fan, it really flows good, I was thinking of a "pusher" with 2 12"'s to assist the 16" in the rear.

also: do you think it would be wise to move my trans cooler lines from the stock radiator location to a external cooler, I would hate to kill my brand new 700R4 that cost me 1800.00

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post #9 of 17 (permalink) Old Sep 4th, 02, 04:00 AM
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What engine did you replace it with? Was it a reverse flow block to match your reverse flow waterpump? I don't know what the difference is in the internal castings to amke a block normal flow or reverse flow, but there is a difference.

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Mark Canning
1969 Indy Pace Car
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post #10 of 17 (permalink) Old Sep 4th, 02, 07:02 AM
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those TBI engines don't have reverse flow cooling systems- just the water pump gets turned backwards by the serpentine belt. the only small blocks that were actually reverse cooled were the LT1 family, and it would be pretty hard to get all the stock stuff to bolt to one of those- they are just so different.
just a thought- maybe something is wrong with the new long block. head gaskets not sealing properly, or cracked head/block. never know with those things.


------------------
1971 Nova(looks like 69 camaro from underneath!)
355sb, vortec heads, HOT cam,T-10 tranny, 3.70 gears 16X8" IROC wheels. 12" Corvette brakes on the way.
see pics here http://community.webshots.com/user/novaderrik
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post #11 of 17 (permalink) Old Sep 4th, 02, 12:45 PM
 
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I did find though , that during the engine swap a wire that goes to temp sensor #3 in the passenger side head had been melted. this sensor controlls the fans. my book says the fan comes on at 215 for a TBI (mine) and 220-230 for a TPI. but regardless of anything, unless I have a hose blasting the radiator, it boils over, driving at 55 on the highway the wind cools it a little, but the temp creaps right back up and over to the red.

Did you replace this sensor & wire?,,My brother's 92 blowed the radiator apart,finally,,,he had put up with alot of grief with it overheating,,finally opted for a police edition,,I think, metal rad and changed that sensor,,I believe he had changed all the others already,,,seems to have fixed the problem..
g'luck!
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post #12 of 17 (permalink) Old Sep 5th, 02, 01:08 AM
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Chris,
The fans on a 94/95 B body 9C1 are 14" in diameter however the primary fan motor is a higher wattage motor and they are mounted behind the radiator so they pull air through not push.
The thermal switch and wiring harness I was telling you about in the earlier post is from Jet Performance Products, part # 60604, cost $60.00 bucks. It can install in either head, whichever one doesn't have your temperature sending unit. Although it has two wires you can use just one. All the wires do is ground the fan relays at 200 degrees. I also added 1/4" plastic wire loom (the wires come uncovered) and a 6" piece of heat shealth because it is close to the exhaust manifold and it makes for a clean installation.

Drew
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post #13 of 17 (permalink) Old Sep 5th, 02, 03:00 AM Thread Starter
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thanks for the info drew, I ordered them a few moments ago,

answering the other question about the block,

I dont know what "kind" it is, its just a replacement 305, but its a recon engine, so they're all punched .040 over , wonder if this is the cause and my stock radiator just cant handle it, I wonder if they make a larger capacity radiator for this car...

yes I replaced the wire, my fans come on , but still lose the battle.

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post #14 of 17 (permalink) Old Sep 5th, 02, 02:25 PM
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Chris,
This has to be something simple, probably staring you in the face. If the old engine was not overheating, the new one should not be either. Someone mentioned the intake gaskets, I didn't even think of them, but usually when they are on backwards the engine will overheat almost immediately, like in 10 minutes.
One thing I have seen more than once is the wrong impeller intalled in the water pump. It was very common when Ford first went to serpentine belts. If you still have your old pump, you might want to pull the cover off it and the new one and make sure the new one is correct. I am pretty sure the impeller is the only thing different in the serpentine pumps.
The main thing is, I think you need to back up and just concentrate on anything that changed when you installed the new engine. If the old one was running cool, then I doubt that the radiator etc has anything to do with your problem. I would try to double check the intake gaskets. I think you can snake a coathanger wire through the thermostat opening and try to see if it is getting into the cylinder head.
Hope this helps,

------------------
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post #15 of 17 (permalink) Old Sep 9th, 02, 03:23 PM
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i have an 88 fromula and i noticed that i had the same problems, there are cowl and ram air hoods that you can get for those cars from a few web sites like http://www.americansportscar.com/
amother thing that i did was i added two electric fans that i baught for $70 a piece at autozone. theat seemed to help drop the temp to about 180 - 190 degrees. your welcome to try that, i found that my sensors had gone out that turned on the fan that i had and resulted in shorting the fan out. so instead of tracing all those wires and sensors i just went to and electric fan with amanual switch
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