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purge line?


dabomb1

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Hi guys,

I have a 96 seville and its been overheating all of a sudden.

Like 250 degrees.

Coolant is full and has been changed about a year ago.

Just replaced the thermostat.

Was told to check the purge line.Where in the heck is this on my car?

Could my cap if its bad cause overheating too?

And if its not the purge line would you think its the water pump?

108,000 miles

Also checked for leaks and do not see any hose leaks or anything.

Thanks

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The purge line runs from the throttle body to the coolant surge tank. Probably across the top of the engine, under the beauty cover. If you disconnect it from the surge tank momentarily with the engine running, it should pee coolant toward the surge tank.

A bad cap could be part of the problem. Pressure test it and replace with an AC Delco if its bad.

You may also want to have the coolant tested for hydrocarbons at a radiator shop.

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Check your water pump belt and tensioner also, if your belt is slipping from age or the tensioner is bound and not applying tension, it will slip. Water pumps are either good or bad, meaning it does NOT leak or it leaks.

Replace the cap, if it can not hold system pressure at 15 to 16 psi, coolant will boil, causing coolant and pressure loss and overheating.

Here is the location of the purge line, moving in a clockwise direction you see the transmission cap, thermostat and WP housing, WP CAM pulley and then the purge line (bolt with a hole in it and hose). It runs over to the tank, DO NOT blow through it with AIR if it is not flowing coolant at the tank, take the hose off remove the bolt and clean that metering hole . As jack noted it should flow coolant if not, it will not allow air to get out of the system

WaterPumpandRadiator022-1.jpg

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

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So your saying if the water pump was bad it would leak?

I'll check the belt and tentioner

I found the purge line took the hose off from the surge tank.

No coolant would come out of it.

I tried to take the other end of the hose off on the line but no go.

Any ideas what to stick down in there to try an unclog it?

Also the other end of the hose by the housing wouldn't come off either.

Thanks

Mike

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Water pumps DO NOT cause overheating, they simply circulate water. A water pump has a shaft seal and a bearing, if it leaks replace it, otherwise its a dumb part that simply turns.

Since you have no coolant coming out of the purge line that is probably your problem.

DO NOT DO NOT stick ANYTHING in the bolt hole. TAKE THE BOLT OFF and clear it. DO NOT DISTURB the clog, you need to take that bolt out and clean the hole through it out.

What does THIS MEAN >> I tried to take the other end of the hose off on the line but no go.

That is a VAGUE statement, please elaborate

What does this mean >> Also the other end of the hose by the housing wouldn't come off either

What housing? The purge line is connected at that BOLT I circled and the other end at the TANK.. what housing?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I think the purge line leaves the water pump area and then connects to the throttle body circuit. From there, it goes across the top of the engine to the surge tank. You need to remove the hose at the start of the path and check the hollow bolt for an obstruction. If the hollow bolt is not obstructed, then remove the hose from the throttle body, start the engine and watch for coolant flow. If there is coolant flow, the obstruction is between the throttle body and the surge tank.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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What happened with this purge line, WHY did you replace the water pump? Was it leaking? Did you get the purge line flowing?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Took the bolt off and it was clear in the middle of it.Put another new thermostat in and a new surge tank cap.Drove it around a little and temps ranged from 220 to 248.I don't know what else to check?The upper radiator hose did get hot so it did seem like it was flowing.Could the heater core have anything to do with it?Although it is blowing hot when i turn on the heat.Its lookin like its out of my league now!

Mike

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Took the bolt off and it was clear in the middle of it.Put another new thermostat in and a new surge tank cap.Drove it around a little and temps ranged from 220 to 248.I don't know what else to check?The upper radiator hose did get hot so it did seem like it was flowing.Could the heater core have anything to do with it?Although it is blowing hot when i turn on the heat.Its lookin like its out of my league now!

Mike

OK Mike pull the purge line off the tank with the engine idling, coolant SHOULD flow. Does it flow? If NOT, that is your problem. Lets get back to that...

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Also

Make sure your cooling fans are coming on

and

Make sure your coolant concentration is 50/50. You can buy a coolant tester at an auto parts store, it will tell you your concentration.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Coolant is coming out of the line.Cooling fans are running.And i'll have to get a tester to see if its 50/50 but i would think is.Just had it changed about a year ago.One thing it does do is my check coolant light comes on all the time.But it is full.

Mike

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Coolant is coming out of the line.Cooling fans are running.And i'll have to get a tester to see if its 50/50 but i would think is.Just had it changed about a year ago.One thing it does do is my check coolant light comes on all the time.But it is full.

Mike

Given that you have done all of these tests and done as much verification as you can, its time to have your cooling system tested for combustion by products that enter the coolant from a breached head gasket I am sorry to say. you can buy your own tester from NAPA or you can have a radiator shop do the test, Mike

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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  • 4 weeks later...

Hi guys,

I had the car working good again for a couple of weeks but now it started overheating again.

I checked the purge line and no coolant was coming out of it.

Right now i got all the hoses off and the surge tank off.I don't see it clogged anywhere! I had the bolt off before but it was

clear.The only thing

that i don't know about is the hose leading to the heater core.

Could this be clogging my system?

If so how do i get to it to flush it out?OR is there anything else i could try first?

Or since i live in south florida could i just bypass the heater core since i wouldn't need heat?

Thanks

Mike

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You are focused on the heater core, this has NOTHING to do with the heater core. The key is WHY are you NOT getting COOLANT out of the BLEED line, pay attention now, let me repeat, maybe you didnt see me say it above:

The key is WHY are you NOT getting COOLANT out of the BLEED line

ARE WE ON THE SAME PAGE? FORGET THE HEATER...

You have all the hoses off the surge tank? Why? The surge tank is not what clogs (with the possible exception of the bleed lines nipple on the tank)

When you pulled the purge line off, nothing would come out unless you had adequate coolant in the system was the purge tank at FULL hot when you pulled the hose off? BUT, if the bolt with a hole in it is clogged you would get no coolant. HAVE YOU TAKEN THAT BOLT OFF?

Did you pull out the BOLT with a HOLE in it and see if it was blocked?, that is typically where the clog takes place. BOLT WITH A HOLE IN IT, COOLANT MUST COME OUT OF THE BLEED LINE that is attached to that BOLT. SEE DIAGRAM ABOVE

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Yes i just had the bolt with the hole in it off and it is clear.

The car was cold when i started it and looked for the stream to come out of the whole.

The purge tank was full.

Thanks

Mike

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Are you telling me that you took this hose off and saw STEAM coming out of the bolt with a hole?

Boltwithaholeinit.jpg

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Yes that is the bolt i took off with a wrench and it was clear!

Thanks

Mike

And you started the car with the hose off that bolt and got STEAM from out of the bolt?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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yes i took the hose off the bolt and started the car and nothing was coming out of the bolt.

Mike

Vetty Interesting.......

That means to me that you are not getting coolant into your engine somehow. Now I understand why you have the hoses off the tank (sorry). Look at #6 pipe and hose off of the bottom of the tank, coolant should flow into the engine through that pipe I believe. That is connected to green hoses via a long pipe around the rear of the engine. I doubt that pipe could be rusted so badly that its clogging the coolant. I would check the by-pass hose for a kink or a blockage look at the nipple at the water pump housing for a clog. It does not seem that you are getting coolant into your engine, you should get coolant out of that bolt. Pull that bolt and look to see if you have any gunk, sludge, etc. Could your thermostat be locked CLOSED, have you replaced it?

NSHeaterHoses.jpg

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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The by pass hose is attached to the water pump cover see this photo.

WaterPumpandRadiator011.jpg

Here is the cooling system circuit, notice how the coolant comes out of the tank, into the bottom heater pipe around the back of the engine, through a green hose, through a pipe, through a by pass hose and into the WP cover

NSCoolingSystemCircuit.jpg

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Is your water pump turning?, belt slipping?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Here is another angle on those lines

NSHeaterHoses.jpg

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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