austinseanchris

So I'm going ahead and trying to prepare myself for what tomorrow may bring...

With that said, I hit 263 degrees on the way home tonight in my 96. Went out for dinner and all was well. Got done and when driving home, I was sittin on about a half a tank of gas. Decided what the heck, Ill stop and fill her up. Filled it up, no problems or anything unusual. The service station is 2 miles from my house. One mile from home, the "check gauges" light came on. Im like, "WTF?!?" 255 degrees, 260, 263...I threw the car in neutral and coasted for about the last half mile and temps fell to 258 before coasting in the driveway and rose back up to 260. These readings were from the analog gauges but the needle was pegged on hot. Immediately, I shut it down but didnt hear any pops beforehand.

Of course, the system was boiling over and you could hear it. I popped the hood and antifreeze was boiling/overflowing out of the puke tank up front and all on ground underneath.

First off and foremost, I hope I didnt damage my $2500 AFR heads? Hopefully driving no more than a half mile they didnt crack them. Normal operating temps while moving are 195-205. Sitting in traffic on a hot day can hit 236 then comes down quick when fans kick in. I know these cars run on the hot side but dont know how much or long it can take 260+ degrees?" So, being dark out, I took a glance with a flashlight for anything noticeable. Upper and lower radiator hoses are both good. Heater hoses are good and radiator is fine. Both fluid tanks are fine. Checked all fuses at battery and inside, all good.

I do have the Meziere electric water pump and its been on for 4-ish years with no issues. New T-stat was installed at that time and was a 180 I believe.

I was so irritated I said **** on it for the evening. I forgot to check the inline fuse for it...thats a possibility I suppose. Could the water pump go out so soon? This is a rarely driven car. And I wouldnt imagine its air in the system b/c it has not been opened in probably 2 years.

Any other ideas anyone? Hopefully someone else has had a similar issue and its a quick fix? Thoughts, opinions, etc?

scrappy76

First off, check your fluids, especially your oil, then your coolant level. Make sure your oil level hasn't gone up and your coolant level gone down. You said it was boiling so we know your gauges work. If all the fuses are good Next thing you can do is start it up and let it warm up to the point the fans should come on, if they do you know they are doing their job and you would think your sensor and computer is following thru. If the temp continues to rise, I would think you have an issue with your water pump or thermostat. I am not positive since I have never had an electric water pump, but if you splice into the wiring tail of the pump with the car off, and go directly to power, wouldn't you hear the pump come on? if that is true and the pump doesn't come on then I would think the pump is bad. If the pump does come on as it should, next maybe your thermostat should be looked at. I might not be correct in my method, but maybe what I have said can give you ideas that help.

WVZR-1

I believe you first confirm the "inline" fuse(I would think you've got one) and relay for the pump, then perhaps the wire direct for operation as was suggested. If it were a pump failure Meziere I believe has a rebuild policy that's quite reasonable.

Did you do the pump install yourself or was it a "for hire"? If installed yourself you should be very familiar with the wiring. If a "for hire" maybe a bit more difficult.

ex-x-fire

Did you lose heat? First thing I do if I suspect a car is overheating is crank it up on hot.

austinseanchris

Thanks guys for the help thus far. Earlier this afternoon, I started checking some things to see if I could find anything that was obvious. Just so we all know the test conditions, today was a quite warm day for weather here in February...it was 80 degrees. I decided to start with the easy steps and work my way up.

FYI: Last night on the boil over, I probably lost 2 quarts of fluid total. I did not and have not added any more prior to or after these tests.

First off, I checked the front of the radiator for obstructions(leaves, trash, etc). Nothing, zilch!

Next, I checked the in line relay running to the Meziere pump(no in line fuses). The way its wired in is coming from a hot source running into the relay. From the relay, it runs to a pigtail plug that plugs into the wire coming off the water pump itself. The relay was good. I took a volt meter and check the voltage at the end of the pigtail plug, it read 12v. I took a battery charger and ran power directly to the electric water pump, and I could hear it spinning once I did that.

On a side note discussing power running to the water pump...When I plugged everything back in and turned the ignition on(without cranking all the way), I did not hear the water pump spinning. So, Im not sure why it was powering/spinning when I applied power straight to it? But then I cant hear it when running it through the wire(remember, even though the wire I checked has 12v running through it).............?(Still scratching my head on that one)???

To verify the fans were running correct and properly, I decided to start her up and let her run. Ran fine with no issues...After about 8 minutes, were were getting close to 200 degrees. Slowly creeped up as normal and made it into the 220's. At 226, the fans came on and the temperature came down as normal. We let the car idle for 30 minutes...never once did it go over 230...fans came on as usual and dropped back down to about 210(which has always been normal for this car).

I got to thinking about the thermostat being stuck closed. Thinking the system was like most cars, I checked both radiator hoses and they were about 160 degrees(with a lazer IR meter). So I thought, "well, they're both warm so there's fluid running through each side as opposed to the upper hose being hot and the lower hose being cold or cool"(or vice-versa). But, it was pointed out that this is a reverse flow system and that's not necessarily an indicator of a stuck closed thermostat.

I called my local Corvette Guru and talked with him about a half hour and he recommended some things to look at. His number one hang up was how do we know this water pump is working as efficient as its suppose to(ie. Working half-*** or having a pre-mature failure)? We may hear it running, but that doesnt necessarily mean its running right at the correct capacity. I definitely see that side, but hate to buy a new pump just to take a stab at it so to speak. He also pointed out and was the one who debunked my t-stat theory test and said since it was a reverse flow system, one hot hose and one cold one would be a good indicator on the older vettes, but not these C4's due to the design.

Talking about pre-mature failures...I remember when my first opti went out...kinda the same scenario. Ran fine last 2-3 times I drove it and then it went bananas. Then, next couple drives, perfect. Then wham, acts up again. The problem began getting more consistent obviously till we were able to pin point it. So, I guess what I'm getting at is its definitely a great argument in the fact that, Is the pump working like its suppose to?"

So, long story short, after running 30 mins at idle, everything ran and operated as normal. I was really hoping to find the relay was bad. Plug in a new one and all is well. But instead, I'm left scratching my head even more because I've checked most common sense things and everything looks fine. Ya know, its always when you least expect it lol. Im a little hesitant to take it down the road b/c it climber 40 degrees last night in 65 degree weather in a heartbeat! I dont wanna keep pushing 260 temps. And lastly on that note...I touched on hoping I did not damage a head. The oil looked fine both before the tests today and afterwards...no signs of coolant in the oil.

Touching again on the pump...this is a rarely driven car. Rare = maybe 200 miles/year. The pump has been on roughly 3 years and has maybe seen 500 miles. Just wanted to throw that out there the fact is it hasnt been on 100,000k or a daily driver. It was installed by the race shop that put the heads, cam, new opti, heavy duty chain, etc all at one time.

Dub(my Corvette mechanic) told me to try and see if the water pump is actually pumping correctly by disconnecting one of the hoses to verify its functioning. I plan to try that sometime this week...

And lastly, heres another curveball. About 25 mins into the idle testing, I started hearing a light knocking sound(not loud or like a rod knocking). Then it kinda went away, then faded back in over and over...? Turned it off, cranked it 30 mins later, no strange noises.


WTF?!?!?!?!?

austinseanchris

Well, as for an update...Drove the car about 15 miles today and the car did fine. The highest it got was 201...so at this point, Im still scratching my head

xrav22

Your thermostat could be sticking I would take it out and look at it. I had one that had symptoms then went away for 3 months then on a trip to Vegas decided to stick close limiting me to 50mph or the temp would go up. It will look corroded and tarnished caused by regular water being used.
Good luck

billschroeder5842

Yeah, works one day and not the other; you have T-Stat issues.

Gibbles

Probably a stupid question, but were the new heads installed recently?

And if so, have you re torqued the head bolts a second time after install?

I had some good times there... 300f!

Brand new edlebrock heads survived with out a hiccup, head bolts were very loose...

austinseanchris

Thanks for the help thus far guys and sorry for the silence. Been a busy week at work. Nonetheless, I did get a chance to work on the car today. Just for the hell of it, I decided to go ahead and change the thermostat to cross that off the list. Yes, I used plenty of towels to soak up the coolant to not damage the opti. Got the old one out(which isnt really old...maybe has 1000k on it)and purchased a new one and put it in(180 thermostat). Put everything back together. Opened the coolant reservoir(near firewall) and filled it most of the way up. I put a whole bottle of "Water Wetter" in and filled the rest with water. Also filled up puke tank(in the nose of car) with about 2 cups of 50/50 antifreeze/water. Cranked the car up and let it run about 30 mins. Ran fine as before...once it hit 226, fans came on and temp went down as normal. I turned the car off and will let it set. My next step will be to "burp" the system through the bleed valve on the t-stat housing. Once flowing there, I figured I will re-fill the system with coolant and see how that does.

For the hell of it, I checked the old thermostat by boiling water on the stove with it submerged to see if it opened and closed properly. Needless to say, it did open once hot enough and closed once cooled down. So...with that said, not sure that thermo was bad but, at least that potential culprit is crossed off the list.

I guess once burped, I'll drive it and see. Dub told me to check to make sure the water pump was working as it should. He stated that it could be in the early stages of it prematurely failing. I hooked up power to it and you could hear it working. But he did bring up a good point in saying that just b/c I can hear it doesn't mean that its working as it should or in the process of slowly failing. He said I can loosen the lower return line while the car is running to see if its pumping coolant as it should. Figured I'd save that for last if this happens again.

Not sure how common these Meziere pumps are for failing? I've read mostly good things about these pumps online and again, this pump was just installed probably 4 years ago and maybe driven 1000k. So definitely not a daily driver by any means. Oh and yes, the heads are on correctly and have been re-torqued

Anyone with any ideas or thoughts on this, your welcome to chime in...

billschroeder5842

Burp and take for a ride. I bet you are good. There is NO WAY you can run the car for 30 minutes, hit 226 and then back to normal unless your system is moving sufficient amounts of water.

BTW, a sticking thermostat will often react great in a boiling pot.

austinseanchris

Sounds good...just hope the water pump is aok. Will burp it Monday and take her down the road...::fingers crossed::

fredk

I have had a 93 for years and all my reading has told me that they are designed to run hot for emissions.

383vett

This thread is a year and a half old and 260 with the coolant boiling over is too hot.

fredk

Yes I agree 260 is way too hot, 230's is not.

austinseanchris

So...finally about 2 months ago, I bought a brand new Meziere pump identical to the one I had on there. I thought to myself, I've changed thermostats and its gotten no better so what the heck. I put the new pump on and fired it up. Outside temp was about 40 degrees. Ran as normal and when it got to 226, the first fan came on. Slowly crept up to 236 then 238 and the 2nd fan kicked on & then back down to 215 she went. I decided to let it run through another cycle. It continued to idle...slowly creeping up again. It got to 226 and I heard the fans kick back on. Then I started noticing steam coming out of the puke tank. I turned the car off and fluid started overflowing out of the puke tank. You could obviously hear it boiling throughout the entire system. I shut the hood and said **** on it!

So today...I decided to give it another whirl since it was unseasonably warm...bout 70 degrees. Before firing it up, I decided to remove about a quart of fluid(thats on top of what boiled over before) to try and prevent a huge mess. Prior to cranking, the puke tank was completely dry and empty. Fired it up...Same as all the tests before. Ran about 10 minutes and slowly started creeping into the 220's. 226 hit and the first fan came on. Got to 236, second fan came on and back down to about 215 she went. Throughout the first cycle, gave a few squeezes to both radiator hoses. I left the cap off the puke tank to see if I saw it overflowing the hotter it got. Slowly started seeing fluid build up in the puke tank. Second cycle was getting warm and so was the fluid. Started seeing a rather quick fluid build up in the puke tank. 226 hits, first fan comes on, then 236 second fan comes on. At this point smoke is bellowing out of the puke tank. I wanted to let it run but it was about to overflow again so I shut it down.

So at this point I've put 2 new thermostats in and a new water pump and nothing(in which both the original aftermarket thermostat housing and electric water pump were not old at all). Also, the radiator was replaced when putting the AFR heads on few years back(maybe 1000 miles ago).Its a Be Cool aluminum radiator. Also want to point out that I visually inspected the outside of front radiator and what little I could see under the radiator shroud and it appears to be clear. Please note that this car stays inside the garage 24/7 and I havent gone driving through any leaf piles, landfills, etc lol. I also failed to state that I did a block test (the blue fluid that turns yellow if there are hydrocarbons present in the water)... and it came up negative (stayed blue). It also does not appear to be running any different as far as missing or idling poorly. Could something be stopped up in the fluid lines? I thought about taking out the knock sensors and draining the entire block of fluid and starting over but I'm not sure if that'll even help(and theyre a bitch to take out!). I just dont see two new water pumps and two new thermostats being faulty. Could it happen? Absolutely! But I think I'd have a better chance of hitting the lottery...

Any ideas guys...?

Cruisinfanatic

Are you sure the pump works?

austinseanchris

Hot Rod Roy

One of my rules: Everything happens for a reason!

If you don't understand what's going on, dig a little deeper. There has to be a reason. You need to have confidence that when you turn on the ignition switch, the water pump WILL be running! NO COMPROMISES! NO DOUBTS!

ex-x-fire

Does the heater put out hot air? Pull off a heater hose and briefly start it up, it should flow like a garden hose.