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Leaking under pressure cold is different than leaking under pressure HOT. When a radiator shop pressurizes your cooling system up to say 16 to 18 PSI, cold, you will see seals, hoses, hose clamps leak, radiator end tanks, coolant tanks, actually weep or leak.... it will DROP pressure on the pressure gage over time and you will see coolant leak. You could get fancy and put dye in the cooling system and look for leaks with a disclosing light to see leaks

However, when the coolant is HOT and under pressure, it typically will vaporize when it hits atmosphere from a leak and you wont see it but will probably smell it

Thanks BBF, that's what I was looking for. You understood what I was saying. The reason I asked is because, I read, you will not see leaks under HOT pressure leaks. So I was thinking, how would you know, if you dont see it? YOU SMELL IT. Also, that's why I asked what is the symptoms, because if you didnt see the coolant leaks, it should give other tell signs. Thanks again BBF. When the radiator shop do the pressure test, they will only be able to identify external leaks correct? If they do not identify any leaks, then is that a definite internal leak?

Edited by Mr Slimm

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If you smell coolant its external. If you had an internal leak, like a head gasket, you would have other symptoms.

Places to look for a leak are

radiator end tanks, dried white deposits may be obvious

water pump body seal, on the pulley side

crossover seals (4 total, 2 on each head)

heater pipes, they tend to rust, two pipes behind the engine

coolant tank

hose clamps


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 read, you will not see leaks under HOT pressure leaks.

That is not a given. Sometimes it is true, but not always. It depends on where the leak is an how bad it is. I have seen many hot pressurized leaks.

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I know I'm late for the party, but "overheating" issues have been beaten to death in this and other Cadillac forums.

....Here are the symptoms:

After driving for about 30min, the temp needle goes up 1 notch past midway. This is mainly highway driving. After a while the needle goes back to midway....

One question:

Are the plastic close-off panels at the top of the condenser/radiator and the bottom from the rear of the bumper cover to the front of the engine cradle in place?

The reason I ask is because you said "mainly highway driving". Ram air flow control at highway speeds is important and the close-off panels handle that function.


Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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I can help with an over heating 1999 caddillac seville sts. There is always one problem no one ever brings up

Hi Jake367. Welcome to CaddyInfo. What is the problem no one ever brings up?


Bruce

2016 Cadillac ATS-V gray/black; 2013 Cadillac ATS 2L Turbo Premium (Wife's)

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Our problem started when my wife's 97 deville water pump drive belt idler froze and it overheated, after changing it, it started leaking around the radiator, after changing it, it started leaking around the front of the water pump, after swapping the front water pump gasket, I did a pressure test and had two leaks around the back of the engine, which I had a mechanic repair, shortly after getting it back, it started really heating up, so I pulled the thermostat, which seemed to help, but then it started overheating again, so we ran the block gases test and it passed with flying colors.  That's when I discovered a leak around the passenger side rear engine area, so now I've got to pull those lines and either braze them are alumiweld them, not sure, I know not to run the car with the A/C on, which by the way I was able to get my front vents working with a suggestion I read on this forum, thank you very much, I also read a suggestion of removing the two front mounts and the lower mount to jack up the rear of the engine to get to the lines, what would you suggest about repairing the lines?

Regards,

Rick 

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PS, I also had the replace the radiator cap, and unplug the cross over pipe, both seemed to fix the problem temporarily. And as far as balancing out the coolant, I will do this as soon as I can get it to hold coolant long enough.

Rick

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:welcomesmiley: Hi Rick -- welcome to CaddyInfo.  Sounds like you are well on the path of diagnosis & repair.  I am repeating your question to highlight:

Quote

I also read a suggestion of removing the two front mounts and the lower mount to jack up the rear of the engine to get to the lines, what would you suggest about repairing the lines?

 


Bruce

2016 Cadillac ATS-V gray/black; 2013 Cadillac ATS 2L Turbo Premium (Wife's)

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There are a few things at the passenger rear of the engine that can leak.  There are two heater hoses and two steel heater pipes that wrap around the rear of the engine.  Those pipes over time can corrode and begin to leak.  It sounds like that is what you are referring to, the heater pipes.  

The 97 deville should have 2 engine mount "dog bone" struts on the top of the engine between the engine and the radiator support.  Remove those and put turnbuckles you buy at a hardware store in place and tighten them to pull the engine forward.  

To gain more room you can loosen the front carriage bolts an inch or so to tilt the front of the engine down.  

You need about 3 inches of room.  Remove the ignition module and set aside and mark and remove the plug wires from the rear bank.

On the right side are two green hoses, leave them alone, they are high temp silicone hoses.  

There are three retainers that must be removed, the hardest of which will be the pass rear corner. 

Here is the rear retainer, there is also one like this on the driver side.  Be careful, the small bolt can snap soak them with rust penetrant.

20151120_171216_zpsfkdcs4k6.jpg

Here is the pass corner

0a25b5ef-9fa1-4af2-b6b3-f7641d3457cc_zps

 

 

 


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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On ‎6‎/‎26‎/‎2016 at 10:50 PM, Esygon said:

Our problem started when my wife's 97 deville water pump drive belt idler froze and it overheated, after changing it, it started leaking around the radiator, after changing it, it started leaking around the front of the water pump, after swapping the front water pump gasket, I did a pressure test and had two leaks around the back of the engine, which I had a mechanic repair, shortly after getting it back, it started really heating up, so I pulled the thermostat, which seemed to help, but then it started overheating again, so we ran the block gases test and it passed with flying colors.  That's when I discovered a leak around the passenger side rear engine area, so now I've got to pull those lines and either braze them are alumiweld them, not sure, I know not to run the car with the A/C on, which by the way I was able to get my front vents working with a suggestion I read on this forum, thank you very much, I also read a suggestion of removing the two front mounts and the lower mount to jack up the rear of the engine to get to the lines, what would you suggest about repairing the lines?

Regards,

Rick 

Cooling system problems are very weird.   Cooling system leaks follow a path of least resistance.  A leak has a pressure trigger point. The PSI numbers that follow are only for illustration purposes.  Why do cooling system leaks seem to 'spread', jumping from on item to the next?   The worst leak in your system say a hose clamp may trigger at 6 PSI, when you fix that leak, you have improved the integrity of your system up to, 6 PSI.  What happens next is that your system builds up pressure to 11 psi and the water pump body o-ring begins to leak, you fix that and now your system is good up to, 11 psi.  Then your system gets up to 13 PSI and the pipes behind the engine which are corroded begin to leak.

The point I am attempting to make is that at 6 PSI, the pipes wont leak, but at 13 PSI they will.   The component that is leaking at 6 psi is taking the leak load off of the component that leaks at a higher psi.   Its sort of a cascade of leak failure points as the pressure builds up.  

An engine with cooling system leaks is not 100% efficient, when it cools it allows air to be sucking into the system, coolant is constantly low as you seem to consume coolant but you don't see leaks.  However a telltale sign that you are leaking is a coolant smell.  

To avoid the cooling system domino affect, I have learned to just renovate the entire cooling system, BAM, all leak points fixed all at once.  I did that in my 96 Deville, replaced everything radiator, coolant pipes (mine were corroded but not leaking), thermostat, crossover seals, hoses, clamps, water pump and its o-ring, water pump belt, checked cooling fans, 60/40 coolant concentration, radiator cap and I even replaced the coolant tank.   I was in summer 100 degree heat on 95 south then bumper to bumper toward Virginia beach my temps got into the 250s and while my heart rate was elevated, all was good. When your cooling system is 100% renovated, you NEVER smell a coolant leak, its amazing.  Just like the roof, bathroom and kitchen in your house, they need occasional renovation, the cooling system needs renovation.   Rockauto is your friend.


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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Just bought an 04 DeVille with 150,000 miles on it about a month ago and I gotta say I'm in love other than the small overheating issue it sounds like the other two people have. I noticed after about a week of driving it it would do perfectly fine in town with the AC on and everything. but once in a while(usually on really hot days 100+ degrees) after about 5-10min on the highway the temp would either slowly climb to 2 notches above half way then go back down and other times it would continue to overheat. The times it lloked like it would actually overheat I would pull over shut the engine off and let the fan stop running, give it about 5 minutes more to cool then take off. Most times it wont overheat again for the remainder of the drive and other times it happens again and I sit for longer to let it cool. just this past weekend I drained the coolant and changed the thermostat, filled with new DexCool and it seems to actually run better and the 15min highway test I gave it it just stayed at the half way mark except for one time when I first took off, I had the AC on and it went 1 above the halfway mark so I shut the AC off. Then on my way home(about a 10min drive roughly) I kicked the AC back on and it never went above halfway the rest of the way home. I am going to utilize the check list given where it should be a little hotter out today. Im not much of a mechanic on the newer cars but I love this car and I want to make sure its taken care of.

Edited by JCDeVille04

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Because the car is new to you to eliminate the possiblilty that you have a head gasket leak you should buy a Balkamp block test kit from NAPA and do the test to confirm or eliminate to possibility of a head gasket problem before you do anything else.  Its the first stop.  

Then there is a logical path to diagnose overheating problems.

However, it is not fair in 100 degree heat to judge overheating problems, 100 degrees is just too high.  See this thread it is very similar to the problem you are having and there is a lot of info in it that should be VERY helpful to you

 


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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My Northstar engine  overheats in a matter of 2 minutes on the road or idling in park. Overheating warning comes on, coolant temp says 260 degrees F, and Engine protection flashes. While idling and as it gets hot the engine will rev itself and up and keep pop getting hotter.

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