SprayedLT1

iTrader: (8)

Before:
I've been having a problem for quite some time where my radiator needs to be topped off because it's a bit low. Car never runs hot, and I know the gauge is reading correctly. It didn't seem like I was burning any coolant. I always just assumed my cheap radiator cap wasn't sealing and the coolant was steaming out.

Now:
I just did a ported head and intake swap (car was previously cam only). I got it all back together, and when we filled the coolant up, my buddy that helped me also filled the reservoir/overflow up to the top with water. Car runs fine, still not hot at all. Doesn't seem to be burning coolant. After driving the car a few times, I checked the radiator while it was cold and it was a bit low again, reservoir was still full to the top. I topped the radiator off then drove to the grocery store, about a mile away, but far enough to get up to operating temp. Thats when I first noticed water was coming out of the overflow. I went to the dealer and bought a new cap, but it's still making enough pressure to push past the cap and into the overflow as soon as it gets hot. I'm guessing I never noticed it was pushing into the overflow before because I've never filled it before, so it never overflowed.

It doesn't boil the coolant, and there's no bubbles in the coolant when I run it with the cap off. I have squeezed the hoses while the engine running, and I don't feel any pressure in them.

Any ideas? I am almost inclined to buy a new radiator.

toomany

Have you bled the cooling system properly? If not you could have an air pocket trapped. I've seen trapped air cause some weird problems. If the overflow jug was filled to the top and the car warmed up, it will be normal for quite a bit to overflow, I wouldn't be too concerned with that part. If you have to keep topping off, then it's going somewhere. Having just changed the heads you already could probably rule out a bad head gasket. It's possible your water pump or radiator is leaking a small amount and burning off/evaporating before it makes itself know.

SprayedLT1

iTrader: (8)

My next step is Im going to try bleeding the system again. My buddy did it when we did the head swap, he knows what he's doing, but he did do it differently than I normally do. I dont see any signs of leakage around the water pump, and there's never been a puddle of coolant under the car anywhere except when it comes out the overflow.

I forgot to mention I hace a CSR ewp, not that it really matters.

I just checked the levels now that it's sat a few hours and cooled off. The overflow level is down and not visible, and according to to markings on the "dipstick it is at the top of the markings above "full hot". The radiator is pretty much full, just under the radiator cap seat, level with where the steam tube goes into the radiator. When I checked it before when it was hot, they were both filled to the top.

I also forgot to mention that the other day when I drove it to the store, before I started it, I used a turkey baster and took water out of the overflow and used that to top off the radiator. I don't know what the level was in the overflow when I did that, but I imagine it was close to where it is now.

SprayedLT1

iTrader: (8)

Just tried bleeding it. Completely cold, I started it up with the caps off. Cracked the bleeders open, and the coolant immediately gushed out of the radiator. I put the radiator cap back on and cracked the bleeders open again. Water came out right away, but because of the engine vibrations I couldn't tell if there was solid streams or if it was sputtering . I just left the bleeders open for a bit then closed them. I let it get up to operating temp and looked at the overflow tank, and the level never went up. Took the car for a spin around the block, and checked the overflow again, level still didn't rise. Loosened the radiator cap, and there was pressure, but apparently not enough to push by the cap.

Keeping my fingers crossed. Car is supposed to be tuned Sunday so I don't want any problems. I'll check it out again tomorrow after it sits all night.

TrybalRage

There are two lines that come into the radiator where the overflow comes in, about the same size. If you have them switched, you will get the boil over in the overflow tank. Try switching them and see if you still have the problem.

Dave357LT1

If you got ur csr pump from summit call them and tell them its going bad and send it back for a diff brand. Ive had to send several back. CSR is junk.

SprayedLT1

iTrader: (8)

My pump is pretty old, but I have sent it in to CSR to be rebuilt about 2 years ago

speed_demon24

iTrader: (6)

That's your problem right there.

gregrob

iTrader: (8)

I doubt its the pump if the temp gauge doesn't show it.

As mentioned above, make sure the two small lines going to the radiator are not reversed!

SprayedLT1

iTrader: (8)

I have the lines right, overflow is above the steam tube, but that's a good idea. I can see how that could be easily overlooked

speed_demon24

iTrader: (6)

Lets keep ignoring the fact that you filled the reservoir up to the top when it is supposed to only have a bit of coolant in it based on the dipstick attached to the cap. Our cars are designed to push coolant into the reservoir when they get hot since water expands when it heats up and needs a place to go.

SprayedLT1

iTrader: (8)

I did not fill it up, but regardless of who did, that was obviously not the problem. You are correct, the system is designed to displace water into the overflow tank, however it shouldn't have been doing it to the extent mine was, or as fast. It should only do it when it gets too hot. "Too much" coolant in the overflow is only going to cause it to...overflow. I think I had an air pocket, because like I said, after bleeding it again, the coolant was no longer pushing past the rad cap.

Oh, and if you would have read, you would have seen I knew there was too much in the overflow, hence taking out as much as I could with a turkey baster.

speed_demon24

iTrader: (6)

It's still going to push water into the reservoir when it heats up. It's not just when it runs too hot or overheats.

SS RRR

iTrader: (2)

One generic thing to check is to make sure the reservoir line is is on the upper port of the radiator where the coolant steam/return line is directly below it.
Rent a coolant pressure tester from most any parts store and pressurize your system. DO NOT pressurize your system more than 18lbs. It also should have an attachment to test the rad. cap. Do that as well. My suspicion is the coolant reservoir hose running from radiator to reservoir may be leaking. So when it gets hot, it will push the coolant away, yet when the system cools, it will draw air in to radiator instead of the coolant that was pushed out. With the pressure tester it's also far easier to check for radiator leaks that may not show when coolant is at operating temperature.

SprayedLT1

iTrader: (8)

My buddy did test the old cap, which did test good, but it was a cheap auto parts replacement and didn't seem to me to fit just right. When you put it on or take it off you can't feel any spring tension like with the new cap. So just for peace of mind I replaced it. I was really hoping that was the problem, but then it still happened after. I'm going to drive it a bit today, so I'll keep an eye on everything. It looks like bleeding the system fixed it, but I didn't drive it far.

Like I said, I know my orientation of the two lines is correct, but that makes sense if the overflow line has a crack in it, that would cause a vacuum leak and not allow coolant to be pulled back. If my problem continues, I'll borrow my buddy's pressure test kit and give it a whirl.

Thanks for the help guys

gearupmd11

I have a 3.8 Camaro and am new to the car. The radiator fill neck has two places you might connect the reservoir. There is a hose connection just above where the cap gasket seals against the fill neck and there is another hose connection below or lower down on the radiator below the cap fill neck. I can see where if the coolant gets hot and expands it would vent out the cap and be directed out the upper hose connection but I don't understand how the coolant would be drawn back into the radiator past the cap seal that's being held closed with a strong spring. Should the coolant tank be connected to the lower hose barb on the radiator?
I am loosing fluid somewhere with no visible leaks, no coolant in the oil, no white smoke or smell in the exhaust. It's either the intake gasket(s) or the cap. I've purged the system. If I drive the car for an hour it will be around 16oz low. It will get lower and lower if I don't top it back off. Any insight would be appreciated.

shbox

While the cooling systems are similar, there might be something in particular to the V6 that people in that forum might know about. You probably would be better off posting your question in that forum, rather than tagging onto an old post in the LT1 forum.

The cooling systems pulls back fluid from the reservoir by vacuum that is created as it cools down. That overcomes the spring in the cap, letting the coolant pass by. They have operated that way for decades.

You might want to consider pressure testing the system and the cap.

donnapr78

I am having the same issue with my car as you mention above. I don't know how to bleed the coolant system but this seems like what I need to do.

In short - I hit a deer two weeks ago and had to get my car repaired. During the repair they noticed my radiator hose had a small hole and needed to be replaced. I also noticed that my reservoir had no coolant in it. This is something I never checked before or added water too and I have had this car a year. I filled the reservoir to the top with coolant/water and that's when my problem started. Since then I have replaced the leaky hose, the thermostat, and thermostat gasket. I still have the problem.

The car never gets hot...even when sitting idle for a long time. However, even after a short drive coolant boils out of the reservoir. LOTS of coolant. Once the car cools it goes back down into the radiator.

HELP... will bleeding the coolant system fix this?

Also, my fan doesn't kick on until the car is running for a few minutes...is that normal?

I have a 2006 ford mustang. I can't see if the radiator has coolant as the reservoir sits right on top of it...but when i got to fill the reservoir I can tell the radiator is full.

pillarpod

You have a FORD and your posting in a mid 90s GM tech forum?

jaycenk

iTrader: (1)