Fox13

Hi all, first time posting, but I've read these forums for years. I finally ran into a problem I can't seem to find the answer to. My corvette has unfortunately been sitting outside for the last couple months as I'm military and preparing to transfer back across the country. I didn't want to renew my lease on the garage in an attempt to save some money for the move. That said I did check, at least everywhere I can think of, for leaves or other debris that may be causing a blockage since it has been outside. Moving on.

My 1996 CE stopped blowing cold air, and I assume it was because of the well known issues with the dash fans, as well as the fact that it was left garaged for the past year while deployed. I went to recharge the A/C (r134a) and after doing so, still no cool air. The compressor is clicking on and off. Well here's where the radiator comes in. I let it sit idling for about 10-15 minutes and when I went back outside there was a large trail of coolant across the ground and steam was coming from the hood! I quickly shut the vehicle off and popped the hood to find the water in the tank "boiling" and it was definitely hot, steam and all. I let the car sit, and cool off. I took the tank completely off, rinsed it out, checked for blockages from the hose and at the tank pipe and found nothing. Also thankfully no cracks in the tank! After rinsing I replaced the coolant mixed with distilled water and started the car.

At first things seemed to be going good, then it started to overheat so again I quickly shut it off. It was back to boiling again and my fluid was draining all over again. I'm at a loss of what to do or where to check and ANY help would be greatly appreciated! (also if anyone has any ideas about the A/C that would be great but it's not a priority right now, all the threads I found have expired pictures so I don't really know what I"m looking for exactly when it comes to fixing the dash vents, I have the famous "no air for about 5 minutes then they kick on" problem)

Also I can't seem to attach any pictures but I'd like to check with someone about where I put the freon. I traced it directly from the compressor, to the only valve I could even attach the can to, but it seems wrong to me... something isn't sitting right in my gut...

Thank you all, I really appreciate the help and time to look at the post!

tbirdsps

One problem at a time. First, the engine should not be boiling over after that short time idling unless the coolant was low to begin with or had trapped air in the engine. Even though the temp gages are very bad and not accurate was it pegged all the way hot? I'm wondering if there's a bad head gasket or was it just overheating. There is a process to get all the air out of the coolant. Air trapped in the engine will cause overheating.

Second, if you don't know where to service the a/c then DO NOT. If you hook up to the high pressure port by mistake it could get deadly. The can can explode. It can only be serviced at the low pressure port. On the 96 the HP and LP ports SHOULD be different sizes.

Sorry I'm not a lot of help but I think you need help from someone with experience and a service manual.

Good luck.

Fox13

I've always agreed that the temp gauges weren't really that accurate. It wasn't pegged all the way, was just really high, and almost pegged on the analog.

I've serviced the A/C before with no problems, which is why this is bothering me. I've had the car for 6 years and performed the majority of minor maintenance myself. You're correct as well, the ports are different sizes.

Just wanted to see if I could get anyone that could point me in the right direction, I've already tried "burping" the coolant system, I may try it again later and go in depth checking all my hoses.

If I can't get anywhere I'm just gonna have to get it taken to Chevy and let them figure out the details. I've never had this problem before or really any problems with the car at all. Thanks for the response.

tbirdsps

I do believe that can be checked with a CO tester. Combusiton gases in the coolant tank means bad head gasket.

tbirdsps

OK, lots of experience. Didn't mean to imply otherwise but it sounded like it was all new to you. Good luck on this but wondering if you start from cold if you are getting bubbling in the overflow tank from cold. If so it's a sure sign of a bad head gasket. It would probably appear to boil before overheating.

on the a/c (I'm more familiar with Ford) a fully, properly serviced a/c can blow warm for various reasons including the blend door didn't move to block the warm air from the heater and only allow cold from the evaporator. I mentioned the port sizes because I'm more experienced with R12 systems where both were the same size. My 90 is an R12 system. I only have one car with 134a and I never touch it. Too new. Ha Ha.

Fox13

I'll be checking if it bubbles shortly. I don't understand how it could be be head gasket. It was running fine just three days ago. I ran out of dex cool so I'm letting the engine completely cool and heading to the store to get more coolant. The weird thing is after it started bubbling or boiling... I turned off the vehicle and let it sit for about half an hour. Came back and this reservoir was bone empty. Both times.

Fox13

And no big deal... Lol I'm sure I sounded like a newbie retard. Was freaking out when my baby started acting up. Had to step away and breathe!

tbirdsps

During the cool down it will suck all the water back in to the radiator if it has become low.

Head gaskets tend to go bad suddenly. Hopefully that's not the problem but the symptoms seem to point that way.

Fox13

Well that's not good news. When I get home ill do one more test from a bone cold start and see what happens just to update everyone. Thank you very much for your time, comments and suggestions, I greatly appreciate it.

JoeUser

I'm surprised no one has suggested a stuck thermostat, as that would've been the first thing I would've guessed. If it's been sitting in a closed state for as long as the OP stated the car has been sitting, the thermostat might be stuck shut.

Easy enough to check and replace.

Red Dwarf

This shud help with posting pics....

http://forums.corvetteforum.com/help...es-thread.html

JoeUser

One way to find out would be to remove the thermostat and then see if coolant is still being forcibly purged. But, he also didn't state how long it took for the coolant to start purging into the overflow tank.

Just stating a few of the obvious causes, like others have already mentioned; radiator cap not sealing (or correct pressure rating), thermostat, etc..

ScottMA64

When my '86 was boiling over into the tank I let it cool, took off the rad cap, started the car and looked for bubbles. Luckily no bubbles. Changed the rad cap and all was good. A leaking rad cap will allow the water to boil a lot sooner causing the overflow into the tank.

Scott

Silver96ce

Before I would start pulling the heads I would start by looking at the potential simple causes.
1. How old is the coolant? If you changed it recently did you bleed it using the bleeder on the thermostat housing.
2. How old is the thermostat - if never changed I would pull and test it.
3. How about the radiator cap - if it has failed you would be amazed how fast boiling coolant will shoot out.
4. Have you ever removed the radiator to clean the cooling fins on it and the a/c condenser or the area in which it sits?
5. Check the neck of the surge tank for hairline cracks around the brass neck for the radiator cap - often a problem area.
6. Drain and flush the block as per the Factory Service manual and flush the radiator.
7. After you do all that check for leaking head gasket.

Silver96ce

Oh by way of a quick check - check your oil for signs of coolant.

Silver96ce

One last potential - how old is the waterpump? Pull the front cover and check the impeller. There are pumps with stamped steel impellers held attached to the shaft. Make sure the impeller is still attached and turning with the shaft. Good luck.

Fox13

Alright all, so there's been a lot of responses to this while I was out. I've read through the comments and I'll post the immediate response to what I have found so far. There's only so many hours in the day and I'm juggling a lot with it being the middle of the week.

I returned from the store and before doing anything, (like letting coolant get on the ground again) I added 1 full gallon of distilled water to the reservoir. And removed the metal radiator cap, and started the engine.

I checked inside the black tank, (not sure what to call it) and good news, no bubbles and a steady stream of fluid coming from the lower pipe. I shut the engine off, and replaced the cap.

I removed the cap from the reservoir and started the car again. I let it sit at an idle, I didn't increase RPMs at all, and just let it heat up normally. At approximately the 11 minute mark the temperature started increasing (according to the digital thermostat) to over 190 degrees. It usually runs between 175-185 on my vehicle. At the 12 minute mark the reservoir started to "increase" the amount of fluid inside. The temperature gauge (digital) read right at 200 and the analog read smack middle of 185 and 260, which I ascertain is about 220-225. At the 13 minute mark the reservoir began overflowing, and I shut the engine off. I heard audible boiling coming from the "black tank" next to the radiator cap, with the engine off.

I'm about out of time for this afternoon, but I do plan to check the water pump and around the brass fitting for the radiator cap.

Everything isn't very old, though I can't attest to the water pumps age, I haven't replaced it in the six years I've had it. The vehicle is right at 93013 miles.

At this point I've completely flushed the system indicating at least there's no hose blockages.

I haven't pulled the radiator coils out for cleaning, but there is no definitive signs of debris.

And while the vehicle sat for the year I was deployed it was properly stored, fluids drained and climate controlled garaged. It has only been exposed to the elements for about 3 months now. All new fluids, and has been running like a champion up until today. The A/C is fixed btw, so now I'm only dealing with what could possibly have happened to make my radiator system suddenly start acting up.

Also there is minor damage to the o ring on the bottom of the radiator cap, but it's not close enough to the impact ring created from being shut, regardless I will be picking one up tomorrow on my way home to at least try that method.

Thank you again for everyone's time and helpful advice. I will continue to explore all the options you've all presented as time allows daily. At the end of the day the military still owns my a$$ and I just have to find time around it...

desertmike1

I'd like to say thanks for serving your Country

Now.. I would check the temperature of the upper, and lower Radiator hose's when the digital gauge reach's 190° this will give an indication of flow by feeling for heat, if the engine is boiling over, and the hose's feel cool.. Then I would suspect a; Thermostat stuck, blockage, or water pump. I dout you blew a head gasket while the car was setting in storage, but stanger things have been known to happen..

mxw128

This is where I would start too... If you don't build pressure the coolant will boil...

desertmike1

Very true; north of 212°f at sea level, his problem is slightly different, in that he is rapidly climbing in temperature.. but yes I agree the cap should be in the basics when it comes to troubleshooting..