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Pictures Added, Opinions On Rad Filler Neck? *Fixed*
Problem Solved! I doubled up the rubber seal on my rad cap, the seal between the rad neck and the rad cap. (mentioned in last post)
The coolant pressure doesnt seem to hold 15 psi pressure on a new rad cap on 2 different coolant pressure tester tools.
Im looking to do a pressure test, thinking the system would hold pressure overnight and rechecking the system to see if there is pressure loss. How long do you test the system for?
tested it last week at 15 psi, checked overnight and pressure fell to 10psi and never took the tester off after a week and there was still some pressure in there when I finally took it off (didnt check psi when taking off tool)
Im checking because I had a low coolant light but the overflow was past full, soo the coolant travelled from rad to ocerflow and never came back. 98 trans am, 80k, driven since 76k with no low coolant or overheating ptoblems before.
Any advice would be appreciated
Last edited by WS6wanted; 09-11-2017 at 09:10 PM.
Reason: progressing original ?
It sounds like you're using the tester correctly, but the fbodies have a notoriously failure prone coolant level sensor. If it holds 15 psi for over an hour and there are no leaks on your garage floor I'd say your system is good. As far as radiator cap testing they never seem to seal to the tester very well
The coolant pressure doesnt seem to hold 15 psi pressure on a new rad cap on 2 different coolant pressure tester tools.
Im looking to do a pressure test, thinking the system would hold pressure overnight and rechecking the system to see if there is pressure loss. How long do you test the system for?
tested it last week at 15 psi, checked overnight and pressure fell to 10psi and never took the tester off after a week and there was still some pressure in there when I finally took it off (didnt check psi when taking off tool)
Im checking because I had a low coolant light but the overflow was past full, soo the coolant travelled from rad to ocerflow and never came back. 98 trans am, 80k, driven since 76k with no low coolant or overheating ptoblems before.
Any advice would be appreciated
Make sure that if you are losing pressure that you are not filling a cylinder with coolant, through a small leak in a head gasket. Because if you are the second you try to start it you will lose your engine and need to pull it out for a rebuild.
If pressure is maintained within limits....no need to remove all 8 spark plugs.
Unfortunately, the only way to know if this is happening is to pull all 8 spark plugs BEFORE or AFTER you do the pressure test and see if there's water in any of the cylinders.
It blows my mind when people say they are losing coolant and they have no idea where its going....so they plan to do a coolant system pressure test.....and they don't remove all 8 spark plugs before starting it again after the test.
Fill a cylinder with a half cup of or less of coolant, start it, and bam, engine is all done.
Make sure that if you are losing pressure that you are not filling a cylinder with coolant, through a small leak in a head gasket. Because if you are the second you try to start it you will lose your engine and need to pull it out for a rebuild.
If pressure is maintained within limits....no need to remove all 8 spark plugs.
Unfortunately, the only way to know if this is happening is to pull all 8 spark plugs BEFORE or AFTER you do the pressure test and see if there's water in any of the cylinders.
It blows my mind when people say they are losing coolant and they have no idea where its going....so they plan to do a coolant system pressure test.....and they don't remove all 8 spark plugs before starting it again after the test.
Fill a cylinder with a half cup of or less of coolant, start it, and bam, engine is all done.
.
Thanks for that heads up, I have no idea where my leak is. Im going to try again and spray everything with soap and water to see if that helps. I don't believe my car is burning coolant, but there is no way to know for sure until I remove the plugs.
The mechanic that changed my t stat did a pressure test multiple times 3 yrs ago and couldnt find the leak that day either. We started it up and got the car tuned soon after same day. Can't wait to be done with this issue.
The coolant pressure doesnt seem to hold 15 psi pressure on a new rad cap on 2 different coolant pressure tester tools.
What exact tools are you using. Do they replace the radiator cap? If they don't seal the overflow tube, they won't hold pressure during the test.
If the system wasn't holding pressure, you should have constant overheating problems... (but you don't mention that this is happening - so I'm guessing there is an issue with your test)
Originally Posted by WS6wanted
Im checking because I had a low coolant light but the overflow was past full, soo the coolant travelled from rad to ocerflow and never came back. 98 trans am, 80k, driven since 76k with no low coolant or overheating ptoblems before.
This sounds like a classic bad coolant sensor. Some will tell you to unplug it - but it serves a purpose. I'm a big fan and it has saved my engine. There are failure modes where the water pump can fail and pump air in to the system - so you want this part working properly and telling you when the radiator is really not full.
[QUOTE=wssix99;19645644]What exact tools are you using. Do they replace the radiator cap? If they don't seal the overflow tube, they won't hold pressure during the test.
Yes, its a proper tool that replaces the rad cap, one is a rental tool and the other i bought used which has a 1989 snap on sticker on it, lol. I do get the system pumped to pressure but I don't see or hear anything.
Previous owner had stop leak in it, and he had a front end collision with the car in the past. The car tho has never ran hot, almost runs too cool with the 98 temp gauge always in the lower than a 1/4 temp mark.
Are you talking about my coolant temp sensor? That one is newer and the rad was low on coolant.
I will post my findings if I ever find anything wrong
Pulling the plugs is pretty drastic, I think it's a great idea, but at this point after the test if he didn't notice smoking after starting the car after the test his head gaskets are probably fine
Thanks for that heads up, I have no idea where my leak is. Im going to try again and spray everything with soap and water to see if that helps. I don't believe my car is burning coolant, but there is no way to know for sure until I remove the plugs.
The mechanic that changed my t stat did a pressure test multiple times 3 yrs ago and couldnt find the leak that day either. We started it up and got the car tuned soon after same day. Can't wait to be done with this issue.
Also, when you look for a coolant leak you need to get the engine up to operating temp...meaning as soon as it reaches 200-220*F.....then keep driving it for another 30 minutes....get heat it totally heat soaked through and through. If you just drive it till the temp gauge reaches 200-220*F, only the coolant itself in the drivers side head is at that temperature. You want the entire block and heads heat soaked......
Then pull it into the driveway and pull it right up on front end ramps. Then turn it off and walk away for 20 minutes. This will allow the temp to rise even further and the pressure will increase also,.......then with a flashlight go looking for the leak.
No. There is a coolant level sensor (that feeds the low coolant light), which is located in the middle of the radiator on the passenger side pointed back towards the firewall. It's square, about 1.5" by 1.5".
You probably have two issues. ^The level sensor is one, but unrelated to your pressure problem.
The newer coolant pressure tool was not holding pressure because it was not sealing to the rad properly. And it was a bitch to put and off.
The rental kit came with a thick rubber washer that I used with my older pressure tester and the system dropped half a psi from 15psi over a 3 hr period.
I also mity vacuum tested the overflow tank, it seems to hold vacuum as well.
I think my problem is either an air pocket that was there from changing the coolant in the fall
Or the neck of the rad where the cap seals to may be worn, scuffed up or distorted or something from past tests and owners or whatever.
Or a worn rad cap?
Im going to order a new rad cap and a few of my older rad hoses that feel hard and brittle and just drive the car.
Should I change the low coolant sensor too? Are they known to cause issues? My car is a 98 TA
If you have fluid at the neck and your low coolant light is on - you have a bad sensor and should change it. It could save your engine some day.
*Corrected - On the siphon, you could have a problem with the radiator cap or siphon tube but... you should have a gap of air at the top of the radiator if you did loose your siphon. Did that happen?
If you have fluid at the neck and your low coolant light is on - you have a bad sensor and should change it. It could save your engine some day.
*Corrected - On the siphon, you could have a problem with the radiator cap or siphon tube but... you should have a gap of air at the top of the radiator if you did loose your siphon. Did that happen?
After my low coolant light, my overflow was an inch or more above full hot line and the rad was low, right about where the low coolant sensor light is. The sensor is working, I was definitel 3-4 inches lower than the filler neck.
I have yet to start the car or anything since the light came on, I have just done pressure tests till now and I believe no leaks on the high pressure side.
I think i lost the siphon because of the high overflow jug level. Thats where I am at right now, about to buy a new ac delco rad cap.
After my low coolant light, my overflow was an inch or more above full hot line and the rad was low, right about where the low coolant sensor light is. The sensor is working, I was definitel 3-4 inches lower than the filler neck.
OK. Making sense now. This is an example of that sensor working and doing good!
This exact thing happened to me and it was due to a bad water pump. I actually had a good siphon, but my failing seals on the water pump were sucking air in to the system. (very odd...) Others have had this issue, as well - but not everyone.
I would try putting a Mighty Vac to the overflow line to make sure it holds suction. Then, if your new cap doesn't do the trick - you probably have the same problem I had.
How many miles are on your water pump? Do you have any drips of fluid coming off the back of your A/C compressor? (When the weep hole on the water pump indicates bad seals, water will weep down and drip off of the compressor. Even though my coolant was red, it dripped green for some reason...)
I had a little time this morning to vacuum pump the overflow tank and it doesnt hold vacuum. The cap on it is stripped and doesnt tighten. If i hold my hand tight against fill hole, it holds vacuum.
I had a little time this morning to vacuum pump the overflow tank and it doesnt hold vacuum. The cap on it is stripped and doesnt tighten. If i hold my hand tight against fill hole, it holds vacuum.
I'm a little confused about what you have tested here...do you mean just the overflow line or the entire bottle? I don't think the entire bottle should ever be holding a vacuum, in fact there is a vent in the cap (and it's not a very tight seal in the first place.) However, the line running from the top of the radiator to bottom of the overflow should be leak free and always submerged in coolant so that air does not mix with coolant going in either direction.
I'm a little confused about what you have tested here...do you mean just the overflow line or the entire bottle? I don't think the entire bottle should ever be holding a vacuum, in fact there is a vent in the cap (and it's not a very tight seal in the first place.) However, the line running from the top of the radiator to bottom of the overflow should be leak free and always submerged in coolant so that air does not mix with coolant going in either direction.
Thanks for replying RPM, I was just about to buy a $20 cap from the dealership.
I thought I unconvered the problem, I vacuumed tested the whole bottle like an idiot. lol. I know the small rad line is leak free at least.
Hopefully I don't need a waterpump, I will update if I do.
I pressure tested my cooling system and found no visible leaks. Car loses coolant from the rad while coolant level in the reservoir stays the same. My car does not burn coolant either.
I used my mity vac with spare heater hose connected to the overflow nipple with the rad cap on and the rad empty. It sounded like I had a leak between the filler neck and my brand new gm rad cap.
I took pics of the top of the rad and how i tested. Can you guys let me know if you think I nailed down my issue being a chewed up filler neck causing the reservoir not to refill the system because no vacuum can build. And also, let me know if I tested that right or if there is a better way to test if the rad is sealed ro the cap.
I'm having some trouble seeing the pics, my ancient computer doesn't seem to always cooperate with showing multiple images for some reason
Anyway, keeping in mind that I can't fully see the images....
Originally Posted by WS6wanted
Car loses coolant from the rad while coolant level in the reservoir stays the same. My car does not burn coolant either.
Can you guys let me know if you think I nailed down my issue being a chewed up filler neck causing the reservoir not to refill the system because no vacuum can build.
If the level in the overflow never changes but the level in the radiator keeps dropping, then coolant must be getting pushed out somewhere other than to the overflow (otherwise, overflow level would keep rising as hot coolant is pushed out during operation/expansion, but never drop back down when the engine cools.) So if the neck is the problem, then it would have to be bad enough that coolant is escaping from that area rather than following the proper path of least resistance (which would be the overflow tube.) Do you see any evidence of that happening?
06-09-2017, 07:25 AM
Pictures Added, Opinions On Rad Filler Neck? *Fixed* 
