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Tool Hut
Tool Hut, ASE Certified Technician
Category: Chevy
Satisfied Customers: 550
Experience:  Owner of a mobile diagnostics company assisting auto technicians with difficult vehicles
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It overheats every time driven, Have replaced water pump

Customer Question

It overheats every time driven, Have replaced water pump with 55 gpm electric water pump, new radiator, new 160 degree thermostsat, both fans working, installed additional 2800 cfm auxillary fan and still overheats. No air in line either
JA: Has the vehicle ever overheated? And when was it last serviced?
Customer: Just bought it, but has new plugs, wire, filters, etc
JA: What is the model of your '800 Chevy?
Customer: 94 camaro z28
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: are you real, I told u everything at beginning]
JA: No. I'm the Chevy Mechanic's Assistant.
Customer: well I have told you everything I replaced so far
JA: Anything else you think the mechanic should know?
Customer: hotter it gets the richer it seems to burn, gets the vapor smell of raw gas. Also backfires on ocassion
Submitted: 11 months ago.
Category: Chevy
Customer: replied 11 months ago.
At idle it typically wont go above 220, once under load it will go 230 and then I have to turn heater on and it will usually stop at 240
Customer: replied 11 months ago.
Also AC wont come on without jumping relay, new compresser and condensor and relays.
Customer: replied 11 months ago.
outside temps have a major effect on this, temps have been between 80 and 90 degrees outside when this has been driven. But the other night I took it out and was doing 80-90 mph for almost 30 minutes and it never got above 180 degrees (outside temp about 60). Usually it will go to 220 in about 10 minutes and continue rising unless I turn on heater
Expert:  Tool Hut replied 11 months ago.

Hi, My Name is ***** ***** for posting your question to just answer. I am a independent contractor for just answer, and ASE Certified Master Auto Technician with 20 years experience. I am confident we can resolve your problem together.Please remember I don't know your skill level. I can't see, smell, hear, or touch the vehicle. It may take a few back and forth replies to get to a satisfactory resolution.There will probably be some equipment needed for a proper diagnosis. If you are not comfortable with this or do not have any test equipment please let me know ASAP. I also try to give all of the information you may need expecting a positive rating. I am not compensated for my time until you leave a positive rating. Your rating should be based on the service you received.

What are the details on the engine? Is it stock?

Can you hold a piece of paper opposite of the fan on the radiator and tell me if it is pushes or pulls the paper?

Are you confident you do not have a head gasket issue?

Customer: replied 11 months ago.
I just bought it, so don't know much about it's history. There was paperwork in glovebox flywheel, rear main and clutch seal replaced last year. Also had notes transmission removal and replace, radiator small coolant leak, intake manifold gasket leaking oil, coolant leval sensor on, alternator noise. To my knowledge the coolant sensor and radiator have been replaced and thats it. No I'm not confident theres not a head gasket issue, have almost concluded there may be issue because what else is left to cause this?
Expert:  Tool Hut replied 11 months ago.

Does your state require emissions testing?

If yes I would seek out a shop and explain you need the HC read out of the radiator. They should understand what you need. Explain you need to rule out a head gasket problem. Once they give you the readings here is what to look for.

>40ppm indicates combustion is entering cooling system. Minor problem at this point some radiator sealer should correct this problem.

> 200 ppm indicates immediate service required.

Customer: replied 11 months ago.
no, emission test is not required
Customer: replied 11 months ago.
Have added alumaseal already "just in case"
Expert:  Tool Hut replied 11 months ago.

There still is a chance that you could find a shop with a gas analyzer. I would definitely start with finding a shop with a gas analyzer as this could determine your problem easily. otherwise it can be a teardown situation.

Did you try the paper on the radiator opposite of the fan?

Customer: replied 11 months ago.
Its 3:30 am here right now so I dont think my neighbors would like me firing it up right now, I will try the paper on the radiator in the morning and look for shop with gas analyzer
Expert:  Tool Hut replied 11 months ago.

That is my advice. I will be happy to assist further. This is just a start here kind of suggestion. You need to rule out a few things before we go further.

Customer: replied 11 months ago.
Will a chemical HC readout work? They don't have a sniffer
Expert:  Tool Hut replied 11 months ago.

The chemical is a good start. Unfortunately it takes 1200 ppm to make it change color and 200 ppm signifies need for immediate repair. SO if it changes color it is definitely needs repair. If it doesn't change color it doesn't mean it isn't in need repair.

My recommendation if you cant find a shop with a gas analyzer have a chemical test done or buy a chemical test at the parts store. Just understand this doesn't mean its not broken.

Customer: replied 11 months ago.
Ok the chemical test showed no HC's in the system. When I place a piece of paper between the stock fan and the engine the paper blows towards the engine.
Expert:  Tool Hut replied 11 months ago.

Why did you replace the water pump? was it overheating before you replaced it? Is it possible the pump is running backwards?

Customer: replied 11 months ago.
it has overheated since day 1 of getting it. Replaced water pump because had already replaced radiator, thermostat and was still overheating so we bumped it up to a 55 gpm electric water pump
Expert:  Tool Hut replied 11 months ago.

OK. I am going to ask you to destroy a thermostat, destroy an old one if you have it. can you remove the thermostat completely and cut the inside out. What you will end up with looks like a washer. Place that where the thermostat goes and see if it still overheats.

Also try running the water pump with the thermostat out and see if it flows.

My concern is you have an internal restriction in the block or a blown head gasket or plugged intake. Unfortunately this means tearing the engine down and inspecting.

Customer: replied 11 months ago.
Ok, my mechanic is coming today at 5 and I'll have him do these tests
Expert:  Tool Hut replied 11 months ago.

Ok. let me know if you need further assistance

Customer: replied 11 months ago.
Removed stock dual fan assembly and replaced with a 1350 cfm pusher fan and initial tests on a 20 minute run were good. Temp never got above 230 and was run without heater being on. Normally would have to turn heater on in 5 minutes and would go past 230 by 10 minutes. Will do longer drive times tonight and push the speeds to see if can get to overheat
Customer: replied 11 months ago.
Ok took it out and ran it up to 100 mph and then temps ran to 230 then 240 and at 243 I turned the heater on and it started backing down and held at 230 as long as heater was on. Tomorrow am going to cut out thermostat as you described and see what happens. It is flowing because can see movement in radiator
Expert:  Tool Hut replied 11 months ago.

What size radiator do you have? Is this a high horsepower car? Where do you have timing set? What is timing at 3000 rpm?

Expert:  Tool Hut replied 11 months ago.

Hello, I have not heard from you in a few days. Do you still need assistance? I also noticed you haven't left a rating. I have assisted in good faith and am only compensated when you leave a positive rating. Please let me know if there is anything else you need to leave a positive rating. Conversations can always continue after a rating is received.