Radiator Troubleshooting

[vamos]

Hi,

 

I have a 1996 Legacy wagon which has done 100,000 miles. I have noticed that even after driving 60 or so miles I can (without waiting for the engine to cool) take my radiator cap off without so much of a hiss and splutter. The radiator cap is only slightly warm to touch. Engine is the EJ22.

 

The top radiator hose is very hot but the coolant in the neck of the radiator (where I take the cap off) is just lukewarm. I am not losing coolant and the temperature gauge is reading normal. Hot air comes out of the heater and the cooling fans do come on.

 

I only became aware of this because I heard a trickling water sound under my dash whilst driving and tried a couple of times to bleed air out of the system without much success I may add. In the course of this I noticed the cool radiator cap. I'm wondering if the coolant is circulating properly.

 

Do I have any cause for concern? Seems odd that after driving so many miles my top radiator hose is boiling hot but my radiator cap can be taken off without a care in the world.

 

Hope someone out there can help. I'm not sure if continuing to drive my Subaru with this condition is going to cause a big problem or maybe I already have one.

[GeneralDisorder]

First of all - your system isn't holding pressure. You need to do a pressure test and find out where its leaking. If you can't find anything - don't forget to test the cap and check the seals and sealing surfaces in the radiator neck.

 

Then once you have it sealed up you can get a temp gun and check your temps across the surface of the radiator... assuming you didn't replace the radiator in the first step which is entirelly possible.

 

GD

[vamos]

Thanks GD for the advice. I'll take the car to a shop to have a pressure test done.

 

I haven't noticed any leaks and the coolant level is OK. As for the radiator it looks new. I recently bought the car and don't know the service history on it.

 

Perhaps because it isn't holding pressure is why I have the air pockets making the rushing water sound under the dash.

 

If you don't mind, would you know the correct procedure to bleed the air out of the cooling system. Is it better to leave the radiator cap on and remove the air vent plug only then start the car and let run? I have tried putting the car front end up on an incline and removing the radiator cap and running the engine until the fans come on but I still hear the noise under the dash whilst driving.

 

Thanks again.

[vamos]

Have been having another look around the radiator and have noticed that while the top hose is hot the bottom hose is only just warm and feels only partly filled when I squeeze it.

 

Would the problem then either be the thermostat (although not overheating) or the water pump?

[tcspeer]

I dont think you have a problem, this sounds normal to me. You might buy a new radiator cap and see if that will improve the pressure.

Edited May 13, 2012 by tcspeer

[bluedotsnow]

GET AN OEM CAP!!!!! and if your checking the overflow as a reference to the total amount of coolant in your system your WAY OFF BASE, I learned this the hard way! if the radiator cap isn't functioning properly its not going to let the reservoir drain and fill properly. so like me at one point you could have a nearly full overflow tank and nearly no coolant in your block and or radiator.

 

if you can check the thermostat when we bought my girlfriends car it had a weird under cooling problem on warm days it would get to half and generally stay in the ball park on cold days it would stay at the c..... on inspection the previous owner or possibly a shop had cut the main part of the thermostat from the round metal housing so water would always flow through unregulated.

 

test your thermostat by boiling some water and dropping it in. WATER MUST BE BOILING and you have to wait a few minutes for it to open if it doesn't budge get a new one. you can alternatively submerge the thermo in a plastic cup of water and microwave it BUT I'm not one for metal and microwaves even if it is fully insulated.

 

 

also check your over flow tank's hose if it isn't sealing it wont draw coolant into the system. as well as the heater bypass hose! these will leak where they are clamped (if old) only on the road and such a slight bit that by the time you pull off to check it the coolant has dried and shows no signs of leaking.

Edited May 14, 2012 by bluedotsnow

[vamos]

Thanks everyone for your advice. Had a pressure test done on the radiator and all was ok there. Turns out the radiator cap was faulty so just needed to replace it and the system is now holding pressure.

 

Mechanic told me the best way to check a radiator cap is to throw it in the bin.