When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
My temp gauge stays at 210 but tonite it went up to 240 and I shut the car off. I waited a while why the fans ran, then I started again and it ran fine. Then a few minutes later it went to 230 then back to 210 back and forth. This is driving about 30-40 mph. I do have an under drive pulley, but driving at that speed shouldn't affect it. Even while in traffic during the day it stays at 210.
I have a freshly rebuilt motor with a new 160 degree thermostat. My radiator and water pump have 103k Miles on them. Even with the 160 thermostat the motor runs at 210.
Right now....water only is in the cooling system, because I've been having belt throwing issues and the car has got hot and blowing the water out the overflow. The belt.issues are fixed now and I need to figure out why it's getting hot then going back to normal.
New thermostat...Can't be bad
Running only water..Maybe, but doubtful
Water pump going in and out?
Bad radiator core?
Air in the system? I topped it off then let it suck the water down and kept repeating till it poured out the overflow.
Does this problem sound familiar? I have read a few posts regarding this but I can't seem to pinpoint it.
I have got a mind to install.an electric water pump.
Hate to say it, but it sounds like a bad water pump to me. I had the same issue with my old T/A. I replaced EVERYTHING (except heater core) in the cooling system except the water pump, and to no avail. Once I replaced the water pump, car ran at 195 all the time.
Oh yea, I hope that's distilled water you're running in the cooling system... if not, you should probably drain it and re-fill to factory fluid specs. Just saying.
Thermostats these days seem to commonly have a
little bleed port with a check-rod in them to let air pass.
An air pocket at the thermostat will act as you describe.
With all your coolant relayed problems I suspect you
may have air in the system. I'd start with the purge
procedure. But also inspect the 'stat, see if you find
a funny little brass bit through the casting next to,
or in the valve plate itself and if so be sure it's free to
do its thing. If you don't find one, I'd say to drill a little
(1/32") hole in the valve plate so there is a way for any
bubbles to pass when closed. This fixed a similar sounding
yo-yo problem on one of my hobby swaps.
I drilled a couple holes in thermostat and it quit having problems....til today it started going to 260 then back to 210 again over and over. It also keeps getting low on water, but I can't find any leaks.
Is it possible there's a pin hole or the water is blowing out the overflow?
When I bought the car, it had a blown head gasket and a bunch of oil and gunk and **** got into the radiator. It's a new engine now, but is it possible the radiator is clogging up and spewing water out the overflow?
I'm just going to install a new radiator and see if it solves the problem.
I think if it were the water pump, it would just go out completely.
These LS motors are sometimes tricky to bleed the air out of the cooling system. Here's what works for me. With engine completely cold lift the front as high as you can. Make the radiator cap the highest point of the system. Remove the radiator cap. Start the motor. You should see it sort of burp, the level will drop, then it will come back up, burp and drop, etc. I look for a good steady stream coming from the vent tube back into the radiator. As long as you see intermittent stream, there is still air.
You might end up overflowing it a few times before it quits burping.
Then I fill the overflow all the way to the rim, cap it off, and drive it. I don't know why that seems to help, but it does. Eventually it will drop to normal levels.
It honestly just sounds like a lot of air in the system which will cause the temp to spike.
So where is my water level going? Basically it seems I may not be able to fill it up because there are air pockets? And I'm going to do this burp method too.
Basically, if it is just air, the water level would be going to displacing air. However thunderstruck has a point about the WP. When they fail, they leak out the bottom. Without any antifreeze (water only) you may not smell it like you otherwise would.
I would definitely burp it first and then if you're still losing water, the pump is a likely culprit.
This might be a little off, but I've seen it get to 240 plus and spew water out the overflow. I'm wondering if it's getting an air pocket and not passing the thermostat and that's causing it to overheat and blow the water out. I've literally drove around for a few minutes and lost half a gallon.
This might be a little off, but I've seen it get to 240 plus and spew water out the overflow. I'm wondering if it's getting an air pocket and not passing the thermostat and that's causing it to overheat and blow the water out. I've literally drove around for a few minutes and lost half a gallon.
Yeah, then that's not something like an air pocket. A half gallon is way too much for that. The only time I ever lost that much coolant was about two years ago when my drive belt broke on the interstate. Then, of course the water pump quit spinning and coolant boiled over.
I tried filling the overflow and water just poured out of hose. So I got down and looked at it and the hose going from overflow to the top of radiator is broken in half. That's where my water has to be blowing out.
Bare with me now, I've only driven this car for a few days, so I'm still learning. I thought it was supposed to be open like that as a relief.....obviously it's supposed to be connected. It's probably sucking air in through that hose.......****! Something so simple
The car had the fast intake on when I bought it and had the cap on the steam port vent on the radiator for some reason or other.
Lol i know... remember i went to see it too. This could of been my night mare dodged a bullet. But anyways . Idk why they had it capped off they f&*K up. But other than that who ever installed the engine and put everything back together should of caught it ....
I'm not putting much stock in the guys who installed my motor. They didn't even bolt my under drive pulley up.
Yeah it's been a pain in the ***, but I paid $4500 for it. Add another $6500 or so and it's I'm at $11,000 with a shitload of new parts. It's in real good shape. I just gotta work a few more bugs out and I think it will be alright. I can already tell that I'm not going to wanna daily drive it though.
Ok, I'll try to find the steam port tomorrow. The car had the fast intake on when I bought it and had the cap on the steam port vent on the radiator for some reason or other.
The steam port is right near the bottom drivers side corner of the throttle. It pokes out between the intake and drivers side head
I know this is not the steam port, but on the throttle body on passenger side there is a red cap and an open tube. Also on the valve cover there's an open vent. Are these supposed to be connected to anything?
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.
Engine overheats, then returns to normal. 
