# Coolant leak



## BatmanGTO (Jun 18, 2011)

Hi all, warning, more noob questions 

It appears I have a slight coolant leak but need to know what to replace. In the pic below you will see it looks like it might be coming from the hose. That clamp is tight. Should I replace the hose?

What type of coolant do you use in these engines? Same as modern cars?










The radiator is full of coolant, but this little container is empty. And what is the black one for?










Thanks


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## likethat (Oct 5, 2007)

Black bottle is for washer fluid. The other one is a home grown shade tree engineered catch tank. If the radiator is full leave it alone, it has plenty. Originally there was no catch tank and a couple inches below the radiator cap would have been normal level for coolant. As for the thermostat housing. It could have pits from corrosion and not sealing well against the hose. It could be the hose or the clamp. If you replace any of it I would replace the thermostat and the gasket plus what ever is wrong. No sense in doing things twice.


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## Rukee (Feb 8, 2007)

:agree
Looks like it is coming from both the hose connection and the thermostat housing to intake gasket. I would replace the thermostat and gasket and renew the clamp on the hose cleaning anything bad on the neck of the thermostat housing.


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## BatmanGTO (Jun 18, 2011)

If I undo that hose will coolant pour out? Will I be able to tell what temp that sensor is?

Thanks


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## likethat (Oct 5, 2007)

Not sure what your asking.


I see ARP bolts if there are more on the engine some one sent some money.


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## BatmanGTO (Jun 18, 2011)

I assumed I am supposed to take those 2 bolts off and there is a thermostat in there? I mean if I removed those bolts then will coolant start spilling out? And there are many thermostats listed, so I would need to know what temp this one I have operated at.

What does ARP mean?


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## likethat (Oct 5, 2007)

If you want good heat 185 to 195. I run my cars cool at 165 or no Stat at all. You need to drain out some coolant from the radiator before you remove the 2 bolts on the housing that the hose goes into. Like an oil pain full. The bottom of the radiator inside by the engine should have a petcock to drain from. 185 should be about an all around good temp for almost any older V8. It should be stamped into the old thermostat around where the gasket goes as to what temp it is. You can put it in a pot on the stove heat it up with a temperature gauge/ thermometer in the pot with it and watch when it start to open. 

If you look at the top of the bolts holding the thermostat housing and the intake there is ARP printed on them.


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## pontiac (Mar 6, 2011)

coolant leak is due to water neck being cast iron while intake is aluminum, should use an aluminum water neck so dissimilar metal expansion is not causing the leak. Based on the questions, a service manual would be a help for this learning curve. downflow radiator, lose the home made overflow tank unless you are running at the track. Antiseize the bolts on the water neck as well as put sealant on the gasket as well as the hose. Hose is pushed too far down on the neck which causes it to flare out.


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## Eric Animal (Oct 28, 2007)

ARP is a brand name of top quality hardware (nuts and bolts) Yes,you have a leak, it looks like at least the hose connection, possibly thr T-stat housing also. Housings are $25 new, t-stats cheap, and hoses $20ish....I would purchase the parts and lovingly replace all 3...but I tend to "over repair" stuff....must be the helopilot mentality.:cheers Eric


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## BatmanGTO (Jun 18, 2011)

Thanks guys, looks like I'll just replace everything. Parts are cheap enough, so well worth knowing the problem is fixed.

What type of sealant should I use?


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## GTO JUDGE (May 14, 2005)

Batman ..... Do this: Replace the thermostat with a high flow 165* one from NAPA.. (stant). You will get a gasket with it. Clean the neck of the housing. Lightly sand the neck to remove any burs. Make sure its smooth. You don't need to but if you have some form a gasket lightly place some on the underside of the thermostat housing and carefully place atop the gasket. This is added protection. Tighten the bolts evenly. Place a small amount of 50/50 Prestone type anti freeze into the neck. Then place the hose back on the whole way down and use a new worm screw clamp. The heat from the motor will help the form a gasket set up... You may want to consider using a bottle of water wetter in the 50/50 mix of anti freeze in the radiator.

I use the 165* thermostat I have no issues at all... I get plenty of heat and on a 70-80* day I run about 165-170*. On the hottest days this year I never got above 190*.


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## 66tempestGT (Nov 28, 2009)

pontiac said:


> coolant leak is due to water neck being cast iron while intake is aluminum, should use an aluminum water neck so dissimilar metal expansion is not causing the leak. Based on the questions, a service manual would be a help for this learning curve. downflow radiator, lose the home made overflow tank unless you are running at the track. Antiseize the bolts on the water neck as well as put sealant on the gasket as well as the hose. Hose is pushed too far down on the neck which causes it to flare out.


 i dont see any rust on the housing. looks like the one i have thats made from aluminum. its bolted to a cast iron intake. what was john delorean thinking?


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## BatmanGTO (Jun 18, 2011)

Will this work? I can't find an aftermarket one that isn't at an angle.

CSR 9114C CSR 360 Degree Swivel Thermostat Housings

And is the one above worth the extra cost over one like this?

Mr. Gasket 2667 - Mr. Gasket Chrome Thermostat Housings

Thanks!


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## jetstang (Nov 5, 2008)

Just replace the gasket, and put a little blue RTV on the gasket, it's just a little leak. Also, clean the area that the hose mounts so it seals better, looks easy. You said it runs cool, leave the thermostat alone. It's going to dump the water in the hose and to that level in the radiator. Leave the overflow can in place, the old school cars didn't have one, but the rads were always an inch or so low, nice upgrade from none..


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## BatmanGTO (Jun 18, 2011)

If I put a nice coating of RTV on there it will stop the 2 different types of metals from touching and rusting? I think that is the main reason why they were saying to replace the housing too.

It runs cool, here is a pic after driving it an hour (temps will rise to 200 if sitting for like 10-15 minutes):


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## jetstang (Nov 5, 2008)

Your pics dont' show a leak, nothing wet, they just show where something leaked in the past. Are you losing water?
Just put a new gasket in it and a very small amout of RTV, it will seal. Don't use too much RTV, trust me, people see it.. They are dissimilar metals, but all is good, your gasket is leaking. You don't need to get all the parts.. If it still leaks you might have to flatsand the gasket surfaces, but I'm sure it won't come to that, been there done that, never looked at it again..:cheers


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## pontiac (Mar 6, 2011)

Permatex #2 gasket sealer, no RTV. "Leave the overflow can in place, the old school cars didn't have one, but the rads were always an inch or so low, nice upgrade from none" Actually downflow radiators are not meant to be full, which is why the factory had the level marked for where full is. Now the crossflow ones are filled because the cao is on the return outlet tank side of the tubes, which is why crossflow have overflow on them to keep air pockets out.


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## BatmanGTO (Jun 18, 2011)

Anyone know what type of temp sensor I have? I've never sen one without a plug. Seems mine has stopped working  Worked fine Thursday, when I started it up today it never moved. I even took the temp gun out to verify it was up to temp (I drove it 6 miles, so it should have been). I was getting about 160* at the sensor.


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## Eric Animal (Oct 28, 2007)

66tempestGT said:


> i dont see any rust on the housing. looks like the one i have thats made from aluminum. its bolted to a cast iron intake. what was john delorean thinking?


 He was thinking about cocaine sales.......:rofl:


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## pontiac (Mar 6, 2011)

mechanical temp sensor, must replace the whole gauge if bad.


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## 69Goatee (Aug 14, 2009)

Yes, install an electrical guage and sender. Quicker to react and more accurate. About the overflow tank, keep it. Yes it is not original, but think about it. These cars were built over 40 years ago when gas has lead in it and had a higher octane rating, so you could ramp the timing up. These aided in cooling the engine which modern fuels don't have today. Modern fuel injected engines are lower compression and have improved cooling systems and have more aluminium used in the overall construction, which transfers heat alot better than cast iron. The added quart or so that an overflow tank adds can only aid in cooling, not hurt. Plus it won't puke any coolant on the ground if you fill it beyond the "full" mark on the rad. My 69 has a crossflow radiator and didn't come with an overflow tank, just a full mark about an inch down from the cap, and a tube running to the ground for an overflow. Don't put any rtv on the top of housing where the hose clamps to, it could act as a lubricant and the hose could pop off when at pressure. Enjoy!


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## BatmanGTO (Jun 18, 2011)

69Goatee said:


> Yes, install an electrical guage and sender. Quicker to react and more accurate.


Do you have any recommendations on which to buy?
Thanks


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## 66tempestGT (Nov 28, 2009)

pontiac said:


> Permatex #2 gasket sealer, no RTV. "Leave the overflow can in place, the old school cars didn't have one, but the rads were always an inch or so low, nice upgrade from none" Actually downflow radiators are not meant to be full, which is why the factory had the level marked for where full is. Now the crossflow ones are filled because the cao is on the return outlet tank side of the tubes, which is why crossflow have overflow on them to keep air pockets out.


position of the tanks has nothing to do with air pockets or overflow bottles. most jap cars and trucks still run the tanks on the top and bottom. and they put overflow tanks on them.


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## Eric Animal (Oct 28, 2007)

BatmanGTO said:


> Do you have any recommendations on which to buy?
> Thanks


 Check out AUTOMETER brand gauges....good stuff. Eric


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## Rukee (Feb 8, 2007)

If you ever plan on going to a drag strip, leave the tank on as they are required by most places to keep any blow over of the radiator off the track.
Last time I went I had to swap the hoses around with the washer bottle, then they let me run.


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## BatmanGTO (Jun 18, 2011)

I doubt I'll ever go to the track. I guess it's not hurting anything to leave it there. So I will.

What do you guys think about this gauge? Can it run off the power that was used to light the manual gauge?

Auto Meter 6937 Auto Meter Digital Gauges


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## 66tempestGT (Nov 28, 2009)

Rukee said:


> If you ever plan on going to a drag strip, leave the tank on as they are required by most places to keep any blow over of the radiator off the track.
> Last time I went I had to swap the hoses around with the washer bottle, then they let me run.


what did it run?


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## Rukee (Feb 8, 2007)

66tempestGT said:


> what did it run?


13.8-14.2 spinning the tires like mad. 
I wanna go back with some better tires and full race fuel. :cheers


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## 68greengoat (Sep 15, 2005)

BatmanGTO said:


> I doubt I'll ever go to the track. I guess it's not hurting anything to leave it there. So I will.
> 
> What do you guys think about this gauge? Can it run off the power that was used to light the manual gauge?
> 
> Auto Meter 6937 Auto Meter Digital Gauges


Depends on where you're drawing the power. If it's from your dimmer switch then no. The only time you would have a readout would be when the lights are on. If you have power at the wire when the ign. switch is turned on, then you should be fine.. My manual gauges are wired thru the dimmer switch.


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## BatmanGTO (Jun 18, 2011)

OK, ordered the gauge, do you know what wire/cable I need to run?


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## 68greengoat (Sep 15, 2005)

Looking at the description, it doesn't appear they provide the wire between the sending unit and gauge. You think they would. At any rate, they should provide all wiring requirements in the instructions......... Maybe someone has the same gauge installed and can provide the info you requested so you can gather everything you need while you wait for the gauge.


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## BatmanGTO (Jun 18, 2011)

I looked at several and none had that wire included. Maybe the more expensive ones do. Shouldn't be a problem, just need to know what to buy. I'll see if they have a 800 number to call. I assume I can grab the wire from the local Auto Zone.


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## BatmanGTO (Jun 18, 2011)

I got my new temp gauge installed today and also fixed the coolant leak. Th gauge actually comes with all the wires needed. This gauge reads a good 25* hotter than the manual one, so I'll go buy a thermometer to place in the coolant to see which was closer. It runs 200-215 with the new gauge.

The old casket was wasted and took me a long time to scrape it off. But it is all nice and clean now. I bolted it back up and it isn't leaking


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## 66tempestGT (Nov 28, 2009)

:cheersarty:


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## likethat (Oct 5, 2007)

Don't open that radiator cap when the car is hot or you will find out how a lobster feels.


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## BatmanGTO (Jun 18, 2011)

So I guess the only way to verify the temp is correct is to place the sender in some hot water with a thermometer? I'd just like to know if this thing is right. My uncle said I should by a fan shroud and that would help it stay cooler.


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## Rukee (Feb 8, 2007)

Your right on both counts. If you want to test the sending unit you'll need to put it in a controlled situation, like in a pan with a thermometer so you can compare the readings. In order to do that, you'll need to have the sending unit hooked up to the gauge, including grounding the sending unit.
and yes, a fan shroud can make a huge difference in temps. You want the shroud to fit nice and tight around the fan so the fan is forced to pull air through the radiator instead of just moving the air around under the hood.


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