70 LS1

iTrader: (1)

OK, I went for a drive today and had some issues.

First I noticed the car pulling to the left when I braked. The car has never done this. A few minutes later I noticed the temp gage was pegged high (not accurate, but I use it for trends. Usually it sits in the lower quarter). I pulled over and noticed the radiator had puked out the relief hole near the cap. I don't have a catch can so it puked down the inner fender and coated the rotor. Well that answered the brake pulling question.

I also noticed it threw the serpentine belt so that means no water pump. I had it towed home and let it cool off for about an hour. I opened up the radiator and the coolant was still visible and only about 1" low. I started up the car and the temp gage rose slowly and the level in the radiator started to rise until it overflowed.

I put the radiator cap back on and let it run for a few minutes. The temp never came back down, but the hoses were still cool enough to touch (warmer than off, but not too hot).

So whats the deal? Any suggestions? Bad temp gage? Air/steam trapped in the heads? I'm really stumped by the rising water level and gage.

G-Body

iTrader: (4)

bad head gasket maybe? Sounds like what my cousins 3rd gen camaro was doing with the 305 SBC and his turned out to be a bad head gasket. Pressure test the cooling system and see what happens.

Slow5.0.

iTrader: (5)

If I lost alot of coolant I would pull the upper water pump hose off and fill the motor up with coolant and top off the radiator. You need to make sure your thermostat opens up. My buddies did what yours did until he finaly did what i told him.

Pop N Wood

iTrader: (1)

Water expands as it heats up. That is the whole point of an overflow bottle. The water comes out when the motor heats up then gets sucked back in when it cools down.

the hoses will stay cool until the thermostat gets hot enough to open. they will really stay cool if you have no belt such that your water pump isn't pumping.

Don't make this harder than it is. Replace your belt, add an overflow can that has the drain hose going to the bottom of the can, top off with coolant and take another drive.

builder1

iTrader: (4)

I had the same problem on my initial startup, The gauge started to climb after awhile The fans would come on so it wouldnt overheat and the lower radiator hose was cool. The brand new thermostat wasnt opening. After i put in another new thermostat it was fine and when it opened i could top it off with fluid

70 LS1

iTrader: (1)

Whats weird is I have had the same radiator setup with no overflow for 7 years and never had a problem. Looks like I should put one in, though.

About a month ago, I replaced the water pump and heater core. I purged the coolant system at that time and have driven it 4 or 5 times with no problems.

I replaced the belt a few days ago and the tensioner is right on the center mark so thats right where it should be. I drove about 15 miles on the new belt with no problems including some 6K RPM WOT bursts through 2nd gear.

Yesterday I take it out to calibrate the speedo and baby it maybe 5 miles or so. I noticed the brake pull when I was getting off the freeway and just afew minutes later we noticed the temp gage was high.

So now I am thinking I threw the new belt for whatever reason, the car heated up hotter than normal, the coolant expanded and puked out the overflow coating the rotor and caused the brake pull.

So what threw the belt? Too tight? Too loose? Everything looks like it lines up and the only things different than the past 7 years is the belt itself, the water pump and I took off and put back on the tensioner.

bczee

iTrader: (12)

Hmmm.. how about checking the Thermostat ?.. maybe it is stuck ? try purging again for air pockets and refilling it from the top radiator hose again !

Are the Fans coming on as what they are set to ? I would not think that the belt is a problem as long as it is not slipping !? are you sure the water pump is not defective.

Not being there, I can only suggest and maybe one of them will be it.. or help.. Good Luck.. and keep us posted..

70 LS1

iTrader: (1)

Thanks for all the suggestions. Unfortunately I am sitting here at work with not a lot to do. Makes for a long day fixating on my problem. Hopefully after some time away from the car, I can go back to it and it will be something obvious.

70 LS1

iTrader: (1)

Well I think I can explain the belt. The alternator was loose so that could have thrown the belt.

I filled everything back up and ran it for a bit today. The temp kept going up and up. Slow fans kicked on, then fast so that tells me it was around 235ish. Didn't cool down. I had the radiator cap off and the radiator began to rise, then overflow slowly. There was a little bit of steam coming out of the radiator.

I shut it off and let it cool. Then pulled the thermostat. I put the thermostat into a pot and boiled it. It opened and seemed to flow well.

Tomorrow I'll put everything back together and fill the block from the upper rad hose then the radiator. We'll see how it goes. I'm really leaning toward an air pocket in the block/heads. It would explain the temp senders reading high.

bczee

iTrader: (12)

hmmm. Did you notice if there was oil in the coolant or water in the oil ...?.. head gasket.. (hope its not).

Were you getting a lot of condensation/water out of the exhaust pipes on start up ?

LS6427

iTrader: (2)

There's no need for an over flow reservior if you don't mind it pouring out onto things. Coolant that gets pushed out the coolant system into the over-flow reservoir NEVER GOES BACK INTO THE RADIATOR. I don't understand why people think this is possible. Very few cars ever built in history had a set-up that can do that. They were called "expansion tanks".

Anyway.....

Sounds like you have air in the system. Losing your belt stopped the coolant flow, that caused your pressure to build up while you were overheating, that over-pressure caused your coolant to get sprayed out through the over-flow port. But now you have empty space in your cooling system. Your t-stat will not open until you get that air out.

Start the engine when cold with the radiator cap "OFF".
Top off the coolant.
You need to massage your upper and lower radiator hoses while you wait for the engine to warm up.
You should see little bubbles appear at the radiator fill hole while your waiting.
When the t-stat opens and coolant level drops, top it off again. Then I would wait for the t-stat to close and stop flowing. Wait again for it to open, top it off again if needed.
That should do it.

Maybe just a bad belt, a dud. Or if you have a stock belt tensioner, you finally got bit by the old "bouncing tensioner" and it tosed it off. Thats why the Katech fixed tensioner is a great piece to have.


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70 LS1

iTrader: (1)

Nope. Both the oil and coolant look good. No more condensation in the exhaust then usual.

LS6427

iTrader: (2)

You need to take the t-stat out of the housing, bolt the housing back up, start the engine and top off the coolant, and go for a drive and see if everything is fine.

That will rule out blockages, a 1 in a milliion broken water pump shaft and the air bubble issue.

If you still have a boiling over problem....you have a blown head gasket(s).

Also, make sure nothing is jammed up in front of the condensor/radiator.


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Pop N Wood

iTrader: (1)

Well, yes. It is suppose to.

http://www.tpub.com/content/construc.../14264_223.htm

cooks 7

Have to agree w/ Pop N Wood,
as long as your overflow has a hose that nears the bottom or is attached near the bottom, the radiator will suck coolant back in once it cools. If it didn't you'd be adding coolant everytime you drive the car. Once your coolant heats up and expands it "overflows" into the can, when it cools the vaccum left behind pulls coolant back through the tiny metal flap on the bottom of your rad. cap. I think every car I've owned has a similar setup.

bczee

iTrader: (12)

Also.. you will be better off putting the Thermostat back in or us a restrictor plate. One of the functions of a Thermostat is to throttle back the coolant from passing through the system too fast.
The coolant needs some time to absorb and transfer the heat via the Coolant out of the engine (source) and to the radiator (the heat exchanger). So.. only remove the Thermostat to check the flow, but put one back in after you have checked the flow.

Some have used a plate shaped like a washer with a hole the correct size, trial and error there.. but 1/2" to 3/4" hole might do it.

70 LS1

iTrader: (1)

Now that I think about it, in my case any overflow wouldn't get sucked back into the radiator. My radiator has a pressure cap on it that lifts to relieve pressure above 15#. Once the cap lifts then the excess pressure / fluid escapes through the overflow line. Once pressure comes back down the cap re-seals and would prevent any fluid from flowing back into the radiator.

bczee

iTrader: (12)

Well.. that might be one problem.. replace it with the correct cap and give it a try again.. but lets see if it help and is the problem, keep us posted.

Those type of caps are used for overflow only, not with a coolant recovery system.

LS6427

iTrader: (2)

You just posted how an expansion tanks works. We DO NOT have expansion tanks.

Look, its simple. The radiator cap, if its a good cap with good tension, holds the coolant and pressure created in the cooling system when its hot. When the engine is turned off it starts to cool. The vacuum that "PULLS" on the radiator cap....JUST MAKES THAT RADIATOR CAP SEAL...TIGHTER. Nothing gets in and nothing gets out.

Any time that spring loaded cap gets pushed open, NOTHING can get in because cooant and air is trying to get out under pressure. Its not gonna suck anything in if that cap is ever pushed open.

We have unpressurized "over flow" tanks. NOT sealed "expansion tanks".

My over-flow tank has never had a drop of water/coolant go into it. Its bone dry and looks factory new. If your coolant system works, you can take the over=flow tank out of the car and not use it. Just like the guy in the "General Maintenance" section has done for years and he's never run low on coolant. Now he's got another issue he's trying to track down.

When you have an overheat situation the "over-flow" reservoir gets filled, but its never going back in to the radiator. Its an impossibility. The more vacuum, the better the seal you'll get.


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LS6427

iTrader: (2)

Thats right. Once it leaves, its never coming back.


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