JDennington

Let me start by saying that I have read all I can and tried everthing before posting here. I have a 91 305 TBI with 170,000. I bought the car from a wrecker service that I used to tow from part time the tags and inspection went out in 05. Anyway while driving the car gets to 220 and keeps climbing. The water pump has been replaced recently and my single fan is on a toggle switch in the car. My air dam is brand new and installed. The cooling system has been flushed and I have great coolant flow (as seen by the return line). I installed a 180 t-stat and new upper and lower rad hoses, and serp belt. The car will idle all day about 180 with the fan on but if you go for a drive...up it goes any ideas/help would be greatly appreciated. Thanks!

VenomX-87

Where is youre timing set? If to far advanced it will get HOT under load.
Other than that well.... I think you got almost everything coverd.

JDennington

Base timing according to the label is 0* TDC right?

thedude

Maybe the radiator is clogged with debris, or maybe something is blocking the air from getting trough it...

When I replaced my radiator, it was pretty dirty in there.

VenomX-87

I have been thinking about this and there is 2 things i can think of.

1: Timing to advanced but I duno where it is ment to be, i just advance it till I get max vacume then take it back a little.

2: youre Temp guage is dodgy, try fitting a aftermarket one to the intake if you got a free spot see how hot that reads (my OEM guage reads 260'F when a aftermarket one reads 235'F).

JDennington

OK, I re-set the timing to what I believe is TDC per the label under the hood. Radiator has been flushed well as has the rest of the cooling system. Again, new hoses, belt, water pump, air dam, thermostat, and fresh coolant. Single fan on a toggle. Still running warmer than I'd like. Bringing the timing back helped but its not solved. Any more help?

j dezzy

iTrader: (12)

does it continue to climb or does it just get drastically hot then stop somewhere?

77monte

What kind of fan shroud is on the car.. my problems were similar because the area covered by the fan wasn't enough with its built in shroud. So i just made one that covered the entire radiator and haven't been over 185 since

j dezzy

iTrader: (12)

That's a good possibility. I don't even run a fan...actually don't even have one on the car...165* thermostat and a 4 core radiator and I'm good. I've got open grilles though, that helps a lot. but I rarely even break 200* without the fan.

I think Venom's got it though...I think you just have an issue with your guage. pick up a cheap aftermarket from autozone and see what happens.

VenomX-87

u seroius u don't have a fan!

Thats nuts, I need mine bad but i got the stock 23 year old OEM radiator :P

j dezzy

iTrader: (12)

even when I had the stock radiator I was running without a fan. on the HOT days I may get to around 220*. but that's not hot enough to worry. but yup...no fan. always had trouble with the way it was mounted. so one day I just yanked it out to see what I could do. and never had a problem. lol. I'm getting a be cool radiator and fan setup though. but for now I don't have any problem without one.

JDennington

OK, I have a new aftermarket gauge in only to reveal that the factory gauge is as correct as my new aftermarket one. Now I'm really at a loss. I have the factory single fan that is mounted to the factory fan shroud. I guess my next option to get a new radiator. Its odd that the car will idle all day long at 180 WITH THE FAN ON but even with the new air dam in place, 180t-stat, and the fan on it still climbs while driving. Any ideas as where to get a better radiator that isnt as expensive as a be cool? ( I know I can get one at AutoZone or O'Reillys for 120.00) I'd like something better than a stock one if I'm going to do it since I'm planning a 383 LT-1 Turbo'd for the car. All of your help is greatly appreciated.

j dezzy

iTrader: (12)

If you want something better than stock then unfortunatly you're going to have to pay extra for it. The cheapest that Summit has is $130(P# PLI-433918). after that they're about $300 up.

VenomX-87

Have you flushed the cooling system? maby it is all gunked up inside the engine.

Is youre lower radiator hose colapsing when RPM is being raised?
stand over the engine and raise the RPM while looking at the lower hose.

j dezzy

iTrader: (12)

yeah, definatly make sure that everything is flowing good. unkook the lower radiator hose and pour water in and make sure it's flowing good.

VenomX-87

okl i just spoted in youre first post that it was flushed, Did you do it youreself or did you get a shop to do it?

If it was done by a shop just to make shure id pull the hoses off and do it myself.
take the T/Stat out and preshure feed warer down the top hose and let it drain then do the bottom hose both directions (top to bottom, bottom to top), do the same to the radiator.

As for the bottom hose since the warter is pulled in threw that one sometimes if there is a bit of a weak point in the hose or it is bent to mutch it will colaps at high rpm causing the warter to be greatly restricted.

JDennington

I replaced the lower rad hose and it doesnt collapse under load I also flushed the cooling system myself with a pressure washer and the garden hose as well as using that prestone super flush crap. Then I took the radiator out and pressure washed it to get the rad fins good and clean. I drove it again today and it took it a while but it got to 240 before I got it home and let it cool down.

BIG_J_420

I can get youa stock replacment with plastic tanks for arround $95 p/shipping I belive we still have some of the copper/brass one's arround but those would be more like the $120p/shipping these are all brand new with a 3 year warranty. Let me know. J

wanta427

Are you setting the timing with the connector disconnected? When I first got my car it ran hot . After finding out the right way to set the timing it was 35 deg retarded when I checked it. If you're setting it correctly you'll have a trouble code to clear . Also are you sure you've got the right water pump ? If you've got a serpentine belt the pump turns backwards from a V groove pump . It might cool at idle but be pumping nothing when you're driving

Formulabruce

Are the stock replacements 3 core?? I think that the stock one in his 305 TBi is a 2 core?? If so that alone could help

86irocu

iTrader: (3)

Do you have pressure in the system? try hooking a pressure tester up. I had the same problem you did. I replaced my radiator and the radiato cap. but my radiator would not hold the pressure it was supposed to. jus a sugestion...

JDennington

The water pump has good flow and is the right pump with counter-clockwise roatation as it is a serp. belt system. I just flushed the cooling system again today for about 3 hours, and replaced the coolant again with a 50/50 mix. Still no improvment. I guess the next thing to do is replace the radiator. Summit makes an all aluminum one for about 250+ shipping. I think its only a 2 core tho. If that doesnt fix it I just light the damn thing on fire. Oh, and yes I re-set the timing with the computer disconnected from the dist. for all your help.

JDennington

Also I do have good pressure in the cooling system. I haven't had any problems with boiling over just running too hot. Also something I thought was strange, it seems like its hard for the car to cool down after it gets hot. The other day when it hit 240, seemed like it took forever to get it cooled down with the hood up, fan on, and engine running.

86irocu

iTrader: (3)

How are you flushing your radiator? Are you using Distilled Water? You can get contaminates in the radiator if you were to use a garden hose and city water. You should try a new radiator. I bought a brass/copper radiator from completeradiators.com for around $125. another suggestion...

wanta427

Before you get carried away changing the rad think about what's happening. If it cools at rest but heats at speed the air is stalling in the rad .If the fan is trying to push air thru the rad while you're moving forward = no air thru the rad . Is the fan going the right way? Is the A/C condenser plugged with something ? If it cools sitting it's not the rad .Try pulling the hood and see if it cools at speed . Are you getting a "check engine" light after you set the timing ? Maybe your light is on but someone removed it and you're running really lean and it's a computer / fuel problem not the rad . Just some ideas for you .

VenomX-87

Yeah running real lean will make it run very hot, I have seen a car burn a hole 1" in size through the top of a piston because it was running to lean at high RPM.

JDennington

My check engine light works and is not on, I replaced the O2 sensor just in case it was a lean problem but I can say with a great deal of certainty that its not a lean problem, also replaced fuel filter. I'll double check the condenser but I dont think that is the problem.

VenomX-87

ok man this is a good one, if you are getting good flow, fans working, good at idle, good timing....
The other thing and that is maby you are not getting the airflow when moving, Have you got a condencer infront of youre radiator?

Are there large gaps at the sides of youre radiator that the air can move through freely, Coz if there is the air will take the easest way with less restriction like a large open gap VS a finned radiator.
If you have a condencer is that cloged or are the fins on the radiator/Condencer flatend from something hitting them?

(Add more in an houre or so, got to do something).

Elthesh

I had a very similar problem with my car. Cool at idle and heated up while driving. It turned out to be a HUGE plastic garbage bag had gotten up in the like half inch space between the radiator and the condensor and was blocking most all of the air flow. Removing it solved the problem. Maybe check for something similar or other garbage lodged in that tiny gap.

cocacolakidd

iTrader: (6)

Hello All,

I once had an old 83 305ci that had almost 200K on the clock. I jumped through every hoop trying to get it to run cooler from overheating without much luck. At the time an old mechanic friend of mine said it was time to rebuild it. Every thing remaining the same after an over bore of .030, and new pistons, it ran cool as normal. I could tell from the beginning that was what was needed because it loved to burn to much oil. So after the old mechanics suggestion I had to agree.

If all else fails I have a radiator that I would sell (Don't really want to though).
It's an all polished aluminum cross flow built by C&R from Gasoline Alley. It's basically like putting two triple core radiators front to back. The water enters the top inlet and flows across the radiator on the back side to enter the tank on the left. Then it turns the corner and flows across the front side to the exit on the bottom right corner. It was originally built for number 10 NASCAR, and they run at 180mph all day with very little air flow. Oh and by the way it is as light as a feather. Even though it's almost twice the size (27" x 20" X 4") it's almost half of the weight of an OEM Radiator. Custom mounts for the radiator would be in order as well as a swivel neck upper radiator hose connection (To aim to the right side).

Good luck in finding the heating problem,

Ed.

JDennington

My cooling problem is solved..... I hate to admit what fixed it but here it goes. I noticed the other day that at highway speeds with the fan off it ran at 180 no matter what I did. Soon as I would exit the highway and turn the fan on up it went. Then it hit me...... wonder if whoever re-wired the fan (before I got the car) wired it correctly. Well after changing the polarity of the fan wires (making the fan spin the opposite way) my problem was solved. The fan was trying to push air from the engine bay through the radiator instead of cool air in. Problem solved, 180 no matter how hard I drive. I feel like I dumbass. Oh well live and learn. Thanks to everyone for your help....goes to show you.....K.I.S.S (Keep It Simple Stupid)
again.
-JD

cocacolakidd

iTrader: (6)

Hello J,

It's great when the problem is finally solved and it didn't cost an arm and a leg. Glad you can get back to enjoying your ride...Have pfunn.

Ed.