: Changed radiator - no pressure on radiator hoses? Normal?



LAC_STS
01-05-13, 03:00 PM
So I had to change the radiator out because I hit a huge rock on the interstate. Insurance paid $2400 after my deductible so I just ordered all the parts myself and did the work myself. Plus they wouldnt pay for the upgraded 2008+ front fascia anyways.


So I changed the radiator using the instructions on GM techline that I have. Everything went fine but after I filled the rad with coolant (slowly through the expansion tank) I let the car run at 2K RPM until it warmed up then let it idle for a couple mins. Then I topped off the coolant.

Problem is (or maybe it isnt a problem) there is no pressure in any of the rad hoses. The engine is not overheating. I checked with the scan tool and the coolant temp stays around 200 degrees. I have ran the car for 2 days now and it never overheats but even after the T stat should obviously be open there is no pressure in the hoses.


Is this normal? Any help is greatly appreciated.


Thanks

Submariner409
01-05-13, 04:40 PM
Under normal operating conditions, no coolant pressure = faulty coolant reservoir cap.

LAC_STS
01-05-13, 04:54 PM
Thanks


When I take the expansion tank cap off I can hear it un seal and some pressure come out. Kinda hard to word but hope you know what I mean. It seems to me like there is some pressure in the expansion tank but just not in the hoses. I have drove the car for almost 3 days now and it never overheats and my scan tool says the coolant temp is 199-204 degrees.

orange57
01-05-13, 05:35 PM
Are you checking the pressure on the hoses after you open the expansion tank cap? I'm in the process of flushing the coolant, and finishing putting the hoses back on, I can't think of anything that would prevent pressure build up.

KRSTS
01-05-13, 05:38 PM
Sounds like the vent hole in the cap is plugged. Should not be pressure in the expansion tank.

EChas3
01-05-13, 05:59 PM
Sounds like the vent hole in the cap is plugged. Should not be pressure in the expansion tank.

If this is so, why are there warnings to not open the cap when hot?

curtc
01-05-13, 06:04 PM
If this is so, why are there warnings to not open the cap when hot?

Was thinking the same thing...definitely has a pressure warning right on the cap.

Submariner409
01-05-13, 06:13 PM
There SHOULD be pressure in the coolant reservoir with the engine at normal operating temperature: In these systems the reservoir is not solely an "expansion" or "coolant recovery" tank - it's an integral part of the pressurized system and provides the "air spring" against which coolant expansion and contraction works to control system pressure. Under normal conditions the hoses should be firm - not rock hard - firm. Normal reservoir level - cold - is about half full. NEVER check or adjust a modern cooling system coolant level when the engine is anywhere near operating temperature - cool or cold ONLY.

FWIW, in the changeover from top radiator tanks (downflow radiators) with pressure caps to our crossflow radiators with NO end tank caps/fills, there was a "coolant recovery" system used by about every car manufacturer: A radiator end or top tank pressure cap had a double internal seal and a flex hose piped from between the radiator and cap seals which led to a vented recovery tank hung on the firewall or inner fender. The main system was kept completely full and the recovery tank hose went to the bottom of the tank. As the engine heated and coolant expanded, coolant was bled off by the pressure cap seal system and sent to the recovery tank until the pressure cap setting stopped any more coolant from bleeding off. When the engine was shut down, as it cooled, contraction caused the coolant in the tank to be drawn back into the system, thus preventing any air from entering. The entire concept of keeping the cooling system air-free prevents corrosion and water pump cavitation which accelerates overheating.

I believe that KRSTS is referring to the obsolete coolant recovery system.

KRSTS
01-05-13, 08:11 PM
Thanks for the correction submariner. My bad

LAC_STS
01-07-13, 04:12 PM
So there still isn't any pressure on either of the rad hoses. The car will not overheat. I have drove the car through stop and go traffic, interstate, etc. It never overheats.

I assume this system is self bleeding? If not is there a bleeder valve somewhere? Or what would be the best way to bleed any air out of the system?

Im at a loss of what to do next. Any suggestions would be greatly appreciated.

EChas3
01-07-13, 09:04 PM
It certainly sounds like you still have a leak. If you're not losing coolent, it must be at a high-spot of the system. I'm not sure the best way to find the leak, so I'd be seeking a professional pressure test.

If you're using Dexcool, I'd recommend a flush & fill after it's fixed. Air exposure is not good.

orange57
01-07-13, 09:19 PM
You may be able to pick up a simple pressure tester at an autoparts store. When i finished my flush and fill the upper hose had some pressure to it. I dont know that it was as firm as i have seen on other cars. What are your ambient temps? It may be running on the cooler side and not building up much pressure.

LAC_STS
01-08-13, 03:35 AM
The only thing that was leaking was the radiator and I installed a new one. I am not loosing coolant at all. Nothing else was damaged. I checked everything over 2 or 3 times. The damage was confined to a pretty small area.

The temps while I have been driving have been about 65-75 or so. So it has been cooler out then usual.

I'm thinking I have a lot of air in it or something. I am not sure but I think this system is supposed self bleed somehow. Does anyone know if that's correct?

Even if it did maybe I just have way too much air in there. I'm going to try to find some way to let some air out of it.

I just know I have absolutely 0 pressure on either hose. Top or bottom. It doesn't seem right to me at all.

orange57
01-08-13, 09:27 PM
When the car is cool, remove the coolant res cap, and lightly squeeze the upper hose. Do it several times quickly to get some movement in the cooling res. You may be able to get rid of any trapped bubbles.

Also, have you pressure tested the res cap? Make sure it is holding pressure.

EChas3
01-08-13, 11:02 PM
This comes down to a pressure test. Get 'er done.

Does your car have transmission fluid lines running to the radiator you replaced?

Are you sure the replacement radiator is tight?

orange57
01-08-13, 11:25 PM
This comes down to a pressure test. Get 'er done.

Does your car have transmission fluid lines running to the radiator you replaced?

Are you sure the replacement radiator is tight?

I wouldn't think transmission lines to the radiator would impact the coolant pressure. If it is a dual purpose radiator, for both engine coolant and transmission fluid, the fluid circuits would be separate so as the coolant and trans fluid don't mix.

But in generally, a Pressure test is definitely in order.

EChas3
01-09-13, 08:32 PM
You got the point. A defective radiator could ruin the tranmission.

LAC_STS
01-10-13, 04:35 PM
Ok so I went and got a pressure testing kit.

Tested the expansion tank cap @ 15 PSI and it was good.

Put the other adapter on and tested the system via the expansion tank. 0 pressure. It wont hold anything. It just sounds like its not even screwed onto anything. It wont even temporarily go up to 1 PSI. Absolutly nothing.


What does this mean? I would think there would be a leak somewhere but I am not loosing any coolant. I park in a garage and I havent saw a single drop of coolant.


Any ideas?


Thanks again for all the help everyone.

LAC_STS
01-11-13, 04:47 PM
Ok so I drained all the coolant and refilled it slowly as per the instructions. I figured if there was a bunch of air in there somewhere maybe draining it and re filling it would get it out.

So I drained all of the coolant and when I went to refill it it only held about half of the coolant that I took out. So I started the engine got it up to temp then let it idle for a min. The level on the expansion tank barely went down and then the temp needle jumped a little bit above half so I shut it off. I waited a while but I guess not long enough and took the expansion tank cap off. When I did this a good bit of air came up through the expansion tank. like it was gonna come out at me but it didn't.

So since this air came out the level in the expansion tank dropped some and I put the rest of the coolant in it. Then I let it run and it runs fine. Not overheating. I ran it for about 15 mins just idling with the A/C on full blast and it wont overheat.

I called my mechanic who used to be my service tech at my local Cadillac dealer. He said as long as I am not loosing any coolant and its not overheating that it is fine and normal.


This just doesn't make sense to me. I understand the basics of an engine as I have built quite a few SBC's and LS engines from scratch. I know these are two different beasts but I just dont see how there shouldn't be any pressure on any of the hoses.


If I squeeze the bottom hose I can see the top hose flexing like they are both full of fluid. But like I said the coolant system doesnt hold any pressure at all. Of course when I was pressure testing it the engine was off and cool. So I dunno. Im at a loss.

EChas3
01-11-13, 05:42 PM
Although it's good you have no overheating, it is still important for a cooling system to be pressurized properly. In adverse conditions, the pressure prevents the coolent from boiling and then fail to transfer heat properly.

If you can't find & fix your leak, find someone who can. If not now, someday you will need a Cadillac dealer. Find the best in your area and build a good relationship. This might be a good time to start.

orange57
01-11-13, 06:34 PM
Since you are not loosing coolant and you don't hold pressure, makes me think it is at a high point, maybe the res itself. Can you remove the res nd apply pressure to it only?

On an older car i had an overflow tank fail at the seam. But it wasn't pressurized on that car.

As said before, if you don't hold pressure you will start to boil off the water in the system leading to unknown concentrations of water/coolant. Coolant doesn't transfer heat as well as water, so if the concentration gets too high you will start to lose cooling capacity.

LAC_STS
01-12-13, 12:30 AM
Although it's good you have no overheating, it is still important for a cooling system to be pressurized properly. In adverse conditions, the pressure prevents the coolent from boiling and then fail to transfer heat properly.

If you can't find & fix your leak, find someone who can. If not now, someday you will need a Cadillac dealer. Find the best in your area and build a good relationship. This might be a good time to start.



I have a good relationship with my dealer. I havent been there since my warranty went out since I have been able to do everything myself.




orange57

Since you are not loosing coolant and you don't hold pressure, makes me think it is at a high point, maybe the res itself. Can you remove the res nd apply pressure to it only?

On an older car i had an overflow tank fail at the seam. But it wasn't pressurized on that car.

As said before, if you don't hold pressure you will start to boil off the water in the system leading to unknown concentrations of water/coolant. Coolant doesn't transfer heat as well as water, so if the concentration gets too high you will start to lose cooling capacity.



That is a good idea to pressure test the overflow tank. I was wondering earlier if the threads that the tanks cap screws onto could be messed up. I will disconnect the tank and pressure test it. I think that the setup I use to pressure test my boats out drive will work perfect.

I will test it and report back.



Thanks for all the help. I agree even though the mechanic (who was a tech at Cadillac for 15 years until about 1 1/2 years ago) I called said it was no problem I know it isnt right.

LAC_STS
01-12-13, 02:57 AM
So I was looking the expansion tank over really good and I saw another hose going to it. Turns out it is just an overflow drain.


So how is the system supposed to have pressure in it if there is an open hose there?


I have attached pics.

Im really stumped now.

1BadCadSTS
01-12-13, 08:36 AM
That would be the pessure release hose. Without it cooling system go boom if it became over pressured. It's above the cap line and only bleeds off pressure if it exceeds the caps psi rating. Coolant does not freely flow through the hose.

orange57
01-12-13, 08:43 AM
That does not look like cooling line. It looks like the plastic cover put over electrical cables to protect them. How long have you owned the car? It could be someone replaced the tank or sensor or something in that area and didn't connect everything correctly. I can check my car later to see if it also has a rouge plastic hose that vents to atmosphere. I couldn't find much data on Alldatadiy, but it did mention a surge overflow hose. I would imagine that it should have some kind of check valve in line or something similar that would maintain pressure, but allow fluid to pass upon overfill and coolant expansion/over pressure. Are there any other hoses in that area taht look like they may have been connected to the tank? I also find it odd that there was no hose clamp on the hose as well.

stoveguyy
01-12-13, 09:35 AM
U ran over a boulder or a rock bounced up and went thru your grille? Hitting a big road level rock should damage your bumper, radiator core support and so on. But 2400 won't pay a body shop for much work. Maybe a good buff job.

LAC_STS
01-12-13, 02:23 PM
Im going to take the expansion tank out sometime today or tomorrow and I will see exactly what it is. I was assuming that the cap was what vented when it was overpressured. The GM SI instructions for pressure testing the cap say that the cap should hold 15 PSI and then it should vent over that. Or vent at a higher PSI.

I know it looks like a cable for elec wires but its def not because it goes over a nipple on the expansion tank. The question is if the nipple is open or if it is blocked by a pressure valve or something. I guess ill find out when I take the tank out. There is also a little thing to hold the hose thing there on the side of the tank. Its built into the tank.



stoveguyy

U ran over a boulder or a rock bounced up and went thru your grille? Hitting a big road level rock should damage your bumper, radiator core support and so on. But 2400 won't pay a body shop for much work. Maybe a good buff job.




Actually the rock ripped the bumper cover and broke the bottom part of the rad where it connects to the car where the nipple is where you stick a hose on it to drain it. Right below the drain cock. The supports were fine.
And the top grill was fine also. Yea it looked scary and all but when you actually take it apart its not that much work. Im sure the ins knows that.

And I fixed it for about $1200.

300 bumper cover
400 to Cadillac to paint it
200 radiator
200 new lower E&G grill
30 coolant


Its not hard at all. Im the one who put the 08+ front fascia on there to begin with. I guess the other 1200 they paid for would have covered the labor.

carter's_sts
01-13-13, 02:09 AM
Like 1Bad said, that's definitely just the over pressure drain. As long as the cap is working properly that should be fine.

scott9001
01-13-13, 03:51 PM
you should of got a adapter with your cooling system pressure tester to do the cap, you sure its holding pressure?

----------

and btw you are suspoto do the cooling system witht he heat on not the a/c and if everything is fine you will get adiquite heat from your vents

LAC_STS
01-18-13, 11:58 PM
Yea the hose I found in the expansion tank is just an overflow. I took the cap off and can see where it would drain if it were overpressure.



scott9001

Re: Changed radiator - no pressure on radiator hoses? Normal?
you should of got a adapter with your cooling system pressure tester to do the cap, you sure its holding pressure?

----------

and btw you are suspoto do the cooling system witht he heat on not the a/c and if everything is fine you will get adiquite heat from your vents



Yea I got a pressure testing kit. It has all different adapters. I used the correct adapter to test the cap. It held pressure just fine.

I am still thinking that something is wrong with the expansion tank. Threading the cap on doesn't feel the same that it used to before I started all of this. I have a feeling that either the plastic threads are messed up and its letting air in or there is some other leak somewhere in the expansion tank.

I just haven't had any time to take it off and pressure test it yet. I will get to it as soon as I can though and post my results.


Much thanks!

orange57
01-19-13, 12:55 AM
I was just about to reply to this one and see if you had found out what the problem is yet. Keep us posted. I"m curious to know what you find.