First off Thank you everyone for the help. This is for a 1986 coupe.
I replaced the water pump do to the gasket between the engine and pump going bad and leaking. I ordered a new Delco pump from Rock Auto. Installed the pump and now I am not getting any cooling. The temperature goes right up, and the top radiator hose is dry. I installed a new thermostat and that did not change anything. I will say that the heater hoses are now getting hot, but the temp just climbs.
What do you think it is. If it is an air bubble I have never had one this tuff to burp. Bad water pump. The casting was the same in every way, but that does not mean the impeller is correct.
Thanks again for the help.
Matt

 

Take few minutes to read the stickys at the top of C4 Gen forum.

There is recent sticky by PLXR on just this topic








!

 

Hi
One thing to check is that the waterpump is a reverse direction? normal 350 chevs have a water pump that turns clockwise, the corvette runs the water pump anticlockwise.

I would replace the thermostat next, they can fail if it has been overheated and not open again.
Most thermostats have a tiny hole for bleeding, that may explain why you have heat to your heater as it exits below the thermostat.

Get your old water pump and remove your impeller cover, check the angle of the impeller (most have the stupid pressed tin impeller) some have the proper brass curved vane impeller to flow better.

If you are having the same problems after fitting the new thermostat then you have to remove the water pump and the impeller cover to check it is correct.

When i fill the vette with new coolant after draining i add the 50/50 mix of coolant and water slowly, will take time to fill the engine and remember the thermostat only has a small bleed hole.
When i know she has most of the coolant turn the heater on full and run the engine and rev it a little and keep filling till the radiator is full, then fit the cap and let the engine idle and warm it up to 195-200f if you have the standard 195 thermostat. Then feel the top hose and make sure i am getting hot water.

Having the car on an incline really helps bleed the coolant when filling.

Most likely your water pump is good but you have a bad thermostat.
Do not forget to check your lower radiator hose has the spring inside to keep it from colapsing as the water pump pulls coolant from the radiator. Remember the radiator is a bit of a restriction to flow.

Good luck there

 

Did you "burp" and "pack" your cooling system when you refilled your coolant?

If you are unfamiliar:

Burp - elevate the front of the car to get the radiator opening about as high as the top of the engine and run with the radiator cap off until the thermostat is open to remove air bubbles

Pack - have a helper hold the engine at 2,000 RPM after the thermostat opens to pull down the coolant level in the radiator so you can top it off and install the cap before returning the engine to idle. This will prevent the "low coolant" light from coming on.

 

I visited with Alex who is one of Rick Hendrick's top Corvette mechanics. I was having problems with my 88 vert. with temps running up to 237 degrees with the A/C on. If I shut the A/C off it will drop about 10 degrees. In Az our ambient temps hit 117-120 degrees and our pavement will be @150 degrees. I run a 195 degree thermostat, keep my "snorkel" in front of the radiator clean and keep clean anti-freeze in it with a bottle of "Water Wetter" in the tank. The radiator core on my car is aluminum, stock from the factory. I spoke to Alex about the temps being high (C4 in Mesa) has had his up to 245 degrees as we have both spoke to each other about the temps. Alex at Hendrick's said that the early C-4's are prone to high temps and anything under 245 just run it and enjoy it. They were made to run high. He also said that new Chevy trucks are coming out and they are running high but not to worry. Burp your system very carefully, keep clean anti-freeze in it, repair your water pump, keep your air intake clean and keep good hoses and you should be fine. Anything over 245, and your A/C is NOT running then shut the car down and let it cool. This is what Rick Hendrick's lead Corvette technician told me and I trust what he says. As far as anti-freeze/water mixture, I run mine 60/40 with 60% being anti-freeze. A 50/50 mix using distilled water should be fine for your operation.
Good luck!
Tommy

 

im not trying to start a big thing but in over 35 yrs both as a tech and as a certified gm trainer i have never heard such a thing in my life untill i cam on this site. Pleas tell me what raising the front of the car does or even packing. all closed systems get the air out on their own. if you dont belive me read your fsm or i even think it covers the cooling system in the owners manual. You can have a massive air pocket when installing a new pump. the best thing to do with this is 1 make sure you dont let the car get to hot.(the temp gauge may be off at this point because fluid is not hitting it) add fluid till full when you think the cooleant is up to temp pump the upper hose this pulls cooleant across the stat. if at this point the stat does not open shut the car off let it sit for a little while then re start and add cooleant as needed. once the stst has opened (the upper hose will be hot) top off the fluid in the rad and in the recovery tank test drive then refill as needed

 

I would like to ask you what you mean when you say don't let your car get too hot. What temperature would you think is "too hot"? I think it depends on your geographical location. I am old school and at one time if a motor hit 210 degrees we were almost in a panic state. Most all of new cars today are running @ or about 210-220 degrees which sends us old timers into orbit. I was very concerned when mine hit 237. There were so many conflicting comments on what temp is too hot. Some consider 210 as too hot while others it doesn't bother. My fan on my 88 doesn't kick on until 226 degrees or it will kick on as soon as the A/C is turned on. Can you give me your opinion please?
Thank you!
Tommy

 

I thought about this and realized years ago that the system is self-purging.

I have done the packing thing but the most recent time I drained the coolant I did not do that. My method is to fill the radiator, run the car, let it cool down, fill the radiator, etc. It only takes a few cycles to get all the air out using this method. The main thing to watch for is to make sure the overflow tank has enough coolant in it when the system cools down and sucks the coolant back in. I have had my overflow tank go dry because too much coolant got sucked out of it.

 

I also agree with Hooked073 and Cliff Harris..... If the car is cycled 3 or 4 times it will eventually purge any air from the system on it's own.. The method of burping the system is to get the air out on the first try, so the car cools properly from the beginning and you don't have to wait....There have been times when it was more difficult for the air to purge from the system, but it would everntually purge on it's own.....Drilling the small hole in the thermostat also helps speed up the process by starting the purging before the thermostat opens, although alot of the newer stats come with a small hole already in them to accomplish this ..To answer Hooked073s question , the front of the car is usually raised when someone is burping the system, allowing the air to escape to the radiator easier..Raising the radiator makes it the highest point thereby making it easier for the trapped air to reach that point... ..WW

 

TIPS:
- The T-Stat has to have fluid touching its hot side. If not the wax inside its cup won't expand and the stat won't open.
- If the sys was bone dry, you can remove a heater hose, & fill with a hose (or coolant) until you get water coming out the disconnected pipe.
- Burping technique: When filling you should get at the very least 1/2 of the system capacity in. (pay attention to how much came out) If I don't get 2/3rds in there before starting the engine.. I'm thinking something is wrong.
Now start the engine and let it warm up. Put your hand on the returrn hose (from the rad to the eng) and when you clearly feel it getting much warmer (less than 5 second event) suddenly rev the engine 2-3 times. (fr idle to 3500)


btw, every car made for the north american market is able to be burped with the car sitting level.

 

I want to thank everyone for the help. I just wanted to give an update. I have never had this much of a problem getting the air out. I have been running the car about 6 times now until it gets to 200* then turn it off and let it cool down. I am at least getting the heater hoses hot, the bottom hose is hot, the top hose is cool and no water in it. I did something last night I have never done before, I loosened the hose clamp on the top hose and air and a little antifreeze, very little came out. As soon as it stopped I tightened it up. I have also made sure that the over flow tank has a good amount of antifreeze in it. Thanks again for the help as I said earlier I have changed antifreeze many times over the years and have never run up against this before.
I will work on it again tonight, and see what I get. Thanks everyone.

Matt

 

200 is not going to cut it the stat does not come open till app 195 I would let it get to 225 to 230 before shutting it off. remember onece you feel the top hose get hot cooleant is flowing past the stat, now when I say top hose hot in reality it will only be the botton half of the hose

 

Thanks everyone it finally burped. Ran it up to 203. Then the thermostat opened and the temp dropped to 187 and holds there. Your help was great.

Matt

 

Glad you got it. make sure you check it the next few times you drive it. after you shut it down let it cool down a couple hrs and check the overflow tank and make sure it is where it is supposed to be

 

Glad to see you got your problem solved!!! It's always a joy to see things work out and now you can enjoy your toy. Now you have to fix the hole in the back end of the car. (fuel tank). Mine always seems to run low and I have to stop and fill it up. I don't know about the pricing you have but out here in Az gas stations are proud of their gas-usually about $3.90 a gallon. Fix that problem and you are ready to cruise. Again, good job and go have fun!!!
Tommy

 

No big thing. I've been here for few years and some have had better luck with the nose elevated.
Personally, I can't attest that it worked better for me.
I will say that the first time I replaced the coolant, the system was not purged completely.
The next trip I damn near fried the motor.
From there, a lot of reading and searching here, helped me to understand what I did wrong and how many had the same problem.
Now I spend the time to help others from having a similar experience. And why there is a sticky to avoid a lot of unnecessary posts.
And if they find raising the nose helps them, so be it.

I always recommend drilling a 1/8" hole in the t-stat base. Some don't like the idea. OK
Use water wetter? A small advantage. Why not?
Green, yellow or orange? What ever floats your boat...

However, may I suggest using a browser that spell checks automatically?

 

If you want to put coolant in your motor without ever having to worry about air in the system again, get one of these systems.. I bought one a few years ago and use it anytime Im changing coolant...They work every time and never fail to install the coolant without air being present........WW

 

As most of you know because of an accident Iv been out of this bussiness for about 6 yrs now. Altough I have not had a chance to use one of these I do know that certain manfactures will not honor work done at dealerships unless their verision of these are being used. I have seen them in action on a lot od deisel engines. Deisels are big into this becuase of egr coolers ect so so many places for air to get traped and without it would take a tech forever to get all the air out. Im sure if you get one you will not be disappointed.

 

I have one of the Airlift devices and found that my little diaphragm air compressor can't put out enough air to get a good vacuum. I also put a portable air tank in the output from the air compressor and it just wasn't enough. You need a good volume of air to get the necessary vacuum.

 

The very small compressors won't pull the vacuum down far enough..I have a Dewalt portable that works great, and using an average size compressor of about 20-30 gal only takes about 10 seconds to evacuate the air down to the 26 pounds vacuum needed to refill the cooling system..The whole process of evacuating the cooling system of air, and refilling, takes less then 5 minites.........WW