Ok to keep this short heres a link to my 1988 383 tpi;
http://www.v8havoc.com/rides/gm/barry.htm ,inregards to my stats.
My car overheats to the point that it redlines on the stock dash gage, so I have to shut it off. If I let it idle from a cold start it takes about 10-15 minutes. What I have tried is the following;
1. 180º thermstat
2. larger aftermarket cooling fan
3. hypertech cooling fan switch
4. radiator is for a 5.7 engine and has about 300miles
5. have aftermarket coolant additive that lowers temp by 40º
6. vented the radiator cap for about 10-15 minutes
7. If I drive it around it overheats too and i'm going about 20-25mph
8. When its in idle I'm running a house fan next to the radiator on high still overheats
9. I have the radiator fan on constent
10. I have an Edelbrock waterpump
11. My timing is about 8º and my idle is about 800rpms the best i can do for the cam I have.
12. I have aftermarket chip from fastchip.com
I thought about getting different plugs would that help if so any recomendations.
Thought about putting in straight coolant.
Any thoughts or ideas would be great.

 

Are all shrouds and airdams in place on the car?

Both above, below and sides of the radiator?

Does the radiator actully exhibit coolant flow?(new or not contaminanats can clog it or plugged/improper tubes)

Does the water pump actually move coolant?(they do break internally)

Have u verified the thermostat actually opening and closing?

Have you checked for collapsed hoses?

Your fans are working, are they in reality moving any air?

Sounds like u need to go back thru the basics one step at a time and retrace your steps.

I have a 383 in my Formula 350. It runs just fine with stock radiator and fans. I do program my won chips and change the fan temp to match the 180 stat. Also run a grand national/t-type secondary fan switch, turns on at 200-205F.

Improper tuning will also cause an engine to otherwise run hot as can bad sensors. Get it on a scaneer and see if you can spot anything amiss

later
Jeremy

 

Forget the factory gauge, stick a mechanical gauge on there (test only, you don't need to install it).

Factory gauges are very, very bad. Some read good, more times then others their off 20-30° but somtimes they just plain suck and could read 100° higher.

You could also change your temp sensor and see if that makes a difference.

 

Thanks for the advice I'll give it a shot

 

Hate to ask a dumb question, but what Edelbrock part # water pump did you install?
I've seen this type symptoms before, when someone installed a standard rotation water pump instead of the reverse rotation one used in a serpentine setup.

 

No it is not a dumb question. As a matter of fact I almost did get the wrong one. But someone else I knew metioned that to me. Thanks for the replie though. I also believe I have solved the problem. I originally replaced the old stock radiator right before I decided to restore the car from the ground up. The radiator was a bone stock single core. It is not sufficent enough to cool a 383 tpi 10:1 compression. I need a 3-4 core radiator, which I ordered and I should have tomorrow.
Thank you again for all your help.

 

I'm back with the same problem. The radiator did not solve the problem.
So I have a question; the original fans died on me awhile ago. So I replaced them with a Hayden 16" single fan that puts out 1600-1900 cfms.(AC is disconnected and removed)
1.)Does this fan put out enough air, what does a stock fan put out cfms? Should I have bought 2 small fans? The fan is on the engine side and is pulling air out of the radiator.
2.) I did vent the new radiator so as no air is in the lines.
3.) I also have a Autometer mechcanical temp gage on order I should get it Sat.-Sun.
4.)I have removed most of the plastic thats between the inside bumper nose and the radiator. Thus I have the air intake which houses the air filters and nothing but open space below. I thought this would get more air flow to the radiator.
5.) I only have the center air dam in place. I have the side air dams but they are not mounted.

 

If the temp gauge is accurate the fan may be the trouble. You sure it is wired correctly and is pulling air through the radiator and not pushing air through the radiator? Those Hayden fans are really cheap. Their ratings are highly overrated. Spal makes the absolute best electric fans there are. I once had their dual fan setup and it would suck my pant leg in the grill if I stood in front of the car when they come on. They are not cheap though, I paid $179 for the dual fan setup mounted to a shroud. It cooled down my hot running 383 real quick when they come on. I did all kinds of cooling mods like you but nothing helped.

Are you very sure it's actually overheating? Radiator overflow bubbling and overflowing? Have you got access to a scan tool to see what temp the computer is seeing? It uses a different temp sensor then the gauge does.

Lastly, how's the condition of the radiator cap? If the system won't hold pressure it will overheat.

Just FYI, straight water cools better then straight antifreeze.

 

Thanks for the tips. I was not sure about the Hayden fan. Because my 94' Z28 still has the stock fans and it seems stronger than the Hayden. So i'll look into "Spal"

 

I searched and searched and never found an answer on what stock fans move, clutched or electric. Kind of frustrating, no idea what GM deemed necessary to work in most all climates, so no idea what to get to work aftermarket.

From the posts I've seen on other boards, it seems 2500CFM is about bare minimum to keep a 350 cool, but there are so many variables that it seems more a crapshoot than anything. You can't "overcool" with the fans, you don't want to put an undue strain on the electrical system, but the most you can afford/fit would be my recommendation.

 

Thanks for searching, I did too from talking to mechanics at a couple of dealerships too running through all my books. I did notice that in Summit racing 2800cfms is barley addiquite for a small v8. I should get my fan tomorrow, and my temp. gage came in but I still have to hook it up.

 

Chevrolet thermostats are notorious for being defective. Before you do anything else, pull out the thermostat and do not put one in. I know that you are not supposed to remove the thermostat, but on my 88 TBI and 96 LT1, I run no thermostat and have not had anymore heating problems. Both cars used to run abnormally hot before I removed the thermostat.

On installing many a brand new thermostat, they still failed. If removing the thermostat solves the problem, you can either leave it out or try replacing it with another new one. You can test the thermostat by boiling it in water to see if it opens up. However, just because it looks like its open, does not necessarily mean it is open all the way.

If that doesn't cure the problem, physically check to see that your fan(s) are coming on. Just because you may have your fans switched to high does not necessarily mean that they are working. An easy check for your fans is to turn your ignition to the run position(without) starting the car, and then turn your air conditioning switch to normal or max. The fans should come on. If they do come on, start the car and idle it with the air conditioning on. If the car still heats up, your problem is not with the fans. If the fans don't come on with the air conditioner, then a wire is loose or not grounded or it may require a new relay(if applicable on your car). If the fans are working properly with the air conditioner on, they still may not be working when the air conditioning switch is in the off position. Have you gotten out of the car when it is heating up to visually inspect that the fans are working?

Usually a hi performance engine will only overheat at higher rpms. The stock coolant system should be more than adequate in keeping your car from overheating at 20-25 miles per hour.

I had exactly the same problem. The thermostat was the culprit in my 96 and the fan would not come on unless the air was on in my 88.

Hope this helps.

 

I have tested out both my thermostats and even ran it with them out of car. I will go back to usung my 160 though as I was told the 383 TPI's run hotter than normal. Also I have my new fan and temp gage came in, which i'll be working on today.

 

If it overheats at idle, you've got a problem a lower temp t-stat isn't going to fix.

It may give you a couple more seconds/minutes coming off of cruise before it overheats (due solely to the coolant temp being 160* IF it can get there during cruise) but that's it.

As was suggested, I'd say pull the t-stat out and do your idle test again, watch how long it takes to get up to temp.

I did a test this past weekend that would be very applicable in a situation without a thermostat to see if cooling was adequate. I started the engine at a base temp (68-70* as seen by the ECM) then waited until engine temp reached t-stat temp. Recorded time. Then repeated after forcing both electric cooling fans on all the time. (I was disproving somes theory that electric fans help an engine warm up faster)

If you removed the thermostat, BUT waited until your engine reached your INTENDED t-stat opening temperature, and turned the fan(s) on, you would see how effective your cooling is. If temp keeps climbing after your fan is activated, then you've got a cooling system inadequacy.

It seems as if you believe the present fan to be inadequate, so without doing all sorts of testing, install your new fan and see what happens. Installing a lower temp t-stat to try and solve overheating problems is a band-aid.

 

it can be many variables. Do a search where i setup dual fans in my ride. My old man told me to check to see if i had coolant in the car. That was it. That is why i always tell everyone, follow the flow chart in your service manual.

 

a 383 10:1 is in no need of a beefed up cooling system. On my 383 10:3:1 I run stock water pump, 180 stat, factory fans and factory rad. It never gets over 200. Ar eyou loosing any coolant? Small headgasket leak can cause over heating.

 

Did you get your new fan installed?

The reason I had made the suggestions earlier on removing the thermostat and visually checking your fans was because it eliminates several things that could be wrong with your cooling system.

By physically checking to see that your fans were operating when your car is overheated, if the fans are on, then you know that your ECM is more than likely turning them on at the right temperature. Also, it means that any relays associated with the fan operation are also okay. So if the fan is operating while it is heated up you can eliminate several things from being faulty. The ECM should be ok, any fan relays should be ok, coolant temperature sensor should be ok and the actual fan and wiring should be okay. By removing the thermostat you can figure out if it was a faulty piece or not. With the thermostat removed, pull the radiator cap off and start the car. Rev the car to about 2000 RPM(or more), you should see coolant flowing fairly fast in your radiator. That will let you know that your water pump is working properly.

By eliminating all of the above, that doesn't leave much to check.
Your block isn't bored over .60, is it? Because if it is, that could be part of the problem. As suggested by someone else, are you checking your coolant level or to see if coolant is being lost from under the car. The things that could still be causing problems are any of the following. Blocked water passages, a faulty gauge, radiator needs to be cored out(are you sure the radiator only has 300 miles on it). If your coolant level is dropping, you have a leak somewhere in the system. As someone else suggested, check the coolant with a temperature gauge that you know is accurate. That will tell you if your guage is faulty. I have to agree with Mkos1980 on that a regular cooling system can handle your engine combination.

Let us know what happened with your new fans.