I just swaped the 305 to a 350 in my 91 TBI. Everything worked perfect up until now (3 months after the motor swap. One day everything was fine the next day the car started running 15-20 degrees hotter! It will even run just under 220 on the freeway at night. It has a 3 row radiator and I changed the thermostat to solve the problem(195 degree thermostat), but no change. The guage and sending unit work fine because the fan turns on at the same temp as it did before the problem and after the problem. I am lost as what it could be. Can someone give me any ideas as what it could be! I live in So. California and as the car is now I wont be able to drive it during the summer without the motor frying and the car will have to go bye bye! PLEASE HELP!

 

Hmm... See if anything's blocking the radiator... Other than that...

Coolant level? Clogged radiator? Clogged water pump? I have no idea.

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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

 

The lower air dam, 6" tall strip of black plastic below the front of the car, immediately under the radiator? You know, the thing that always scrapes on concrete parking lot bumpers...

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"So many Mustangs, so little time..."
ICON Motorsports

 

Coolant level is fine and I'm pretty sure the radiator and waterpump are not clogged. As for the air dam it is there but worn a little bit and is bending backwards a little bit but not enough for this sudden change in temprature

 

you could try adding red line water wetter. that could help it to run cooler - that is, if you cant figure out the other problem.

 

I used Redline Water Wetter a couple of years back and it seemed like the car rad hotter. Since then I have never considered using it again.

 

Make sure there is no road trash between your radiator and condensor. Pull the top radiator support and look.

After I replaced every other part on the cooling system, one at a time, I decided to get a new Radiator. When I removed the original 120,000 mile radiator, there was a medium sized plastic shopping bag spread out between the radiator and A/C condensor.


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91 RS/3.1 - Stock except stereo system, daily driver.

86 IROC - Pep Boys 350 longblock, Performer 750 carb, Performer RPM intake, Comp Cams 280 magnum, Hooker 1 5/8" shorties, Flowmaster Y pipe, 3" pipe to Flowmaster 2 chamber Dual outlet, TH 350 performance rebuild w/shift kit, Daco 2600 Stall, 3.42 Gear Moser 12 bolt w/Eaton posi.

 

nothing inbetween radiator and A/C condensor just checked last weekend
I sware I have checked everything imanginable and came up with nothing! Im begining to think that it is somthing internally in the engine causing it to run hotter and not a problem in the cooling system. Anyone agree?

 

Ok, try this if you haven't already. Take the radiator cap off when the car is cold. Then start up the car and let it begin to warm up to the point that the stat would open. If the rad fluid is not percolating or is barely moving, your water pump may be at fault.
What helped my car a little was when I bypassed the tranny cooling core that's in the radiator and installed a separate tranny cooler. Car runs about 5-10 deg cooler now. (Ignore this if you have a man.trans.)

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DR Stevens
Car #1: my ride
1984 TransAm
305HO(L69) 96K & counting
750 cfm Q-Jet/Holley rem.
K&N filter
700R4/Superior shift-kit
and trans cooler
3.42 rear/3.73 blew up!!
underdrive pulleys
Accel HEI Super-Coil
180 stat/hi flow water
pump/Jet fan switch
dual snorkel/'84 ram air
3" exhaust of some sort
partial emissions delete
Car #2: My wife's ride
1991 Firebird/Formula
305TBI(LO3) 99K & smoking
K&N air filter
Hypertech Chip
more engine mods later
"Hey, Uncle Sam!! Where's my f**king tax return??!!"

 

i've heard of water pump impellers spinning on their shafts

 

I just did some checking. I started up the car and let it idle. When the car warmed up I squeezed the top radiator hose and it was almost solid as a rock. Is this normal? Or is it too much pressure and could this be part of the problem?

 

or maybe your temp. sensor just hit the sh*ts?

 

I assume you've already changed the radiator cap? Since your system is holding pressure that's a good thing.

A vacuum leak? Look for any sign of leaking between the carb/TBI base and the manifold. Also inspect all the vacuum hoses.

 

Um... what coolant/water ratio are you running??

 

Try changing your stat to a 180 or 160 easy fix????


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89 formula 305 H.O. accel plugs and wires, 3" exhaust w/ flowmaster, MSD coil, Stage 3 A.D.S super chip, open air k@n filter, Energy Suspension Hyper-Flex Master Bushing Set, TCI Custom built 700R4 and more mods SOON to come!!

 

That hose shouldn't be "solid as a rock". Sounds like a possible clog somewhere. Did you look with the rad cap off to see if the coolant's percolating? That would tell you a lot right there. Saw a problem really similar to this on a Caddy engine once; turned out the stat was put in upside down.

DR

[This message has been edited by eightTfourTA (edited March 27, 2001).]

 

is it posible a lower rad hose is colapsing.

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when the green flag drops the bull$hit stops

Curent: 350,performer RPM intake ,650dp, 700r4, headers, 3inch exhast
Spring 01: 406, Comp 282 solid cam, 2400 stall converter, every thing else the same.

R.I.P #3