Hi Guys, I did search for an answer but unfortunately didn't get a simple answer so I thought I'd ask here. I took my radiator cap off and checked the coolant level in my expansion tank. The car has been sitting for over 24 hrs since driven, so nice and cold. I stuck my finger in it and nothing! I then placed a screwdriver down the hole until it hit the bottom and to my surprise only the tiniest amount of coolant was visible at the end of the screwdriver. About 1/4 of an inch. How much coolant should be in this expansion tank when the car is cold? On Page 68 of the owners manual, it says - "The mixture level in the tank should never be 2.3" below the filler plug base". Excuse my ignorance, but what is the filler plug base? Why can't it just have a MAX marking like every other car? Please help as I don't want to over fill it and have coolant spew all over the place, nor do I want to cook it. Cheers, Bob. Image Unavailable, Please Login
In other 3x8 manuals they refer to the filler neck base. I've always assumed they meant from the top of the tank down. Its a translation though so it could mean either end of the inlet stub. Hopefully someone will chime in with the shop practice.
2 to 3 inches below the filler neck base sounds right even half way down the tank is also ok. This is why they called it Expansion tank so it can expand.
About half full is fine - the level is not going to be critical to within the millimetre. If you over fill it it will just eject what it doesn't want anyway so don't worry too much about that. Worry more about why the level was so low. 99 times out of a 100 its because the spring in the cap has gone weak & so the cap needs replacing. When that happens, as pressure builds up when the engine is warm it starts throwing coolant out the overflow which just drops out on the road as you are driving along because the cap can't hold it. Fill it back up to say half way on the tank - bear in mind that you *might* have air down in the block now so recommend you crack open the bleed valv on the T'stat & check there is no air in the engine. Also bleed the rad. If you have one handy, a radiator pressure tester is a great way to bleed the system - especially if you jack up the right side of the car a few inches. Just attach it to the tank & pump up to 4 or 5 PSI & then open the bleed screws. Then run the car (with the cap on) till it gets properly warm (i.e. the electric fans come on) and watch what happens. If it starts dropping coolant down by the left rear wheel then you need to replace the cap. Original caps were 0.9 bar, new ones are 1.1 bar. If that's holding then start looking for leaks elsewhere. A radiator presure tester will help find leaks - pump up to about 15PSI & if there is a leak you'll probably find it. Wait till the car is cold before you take the cap off the tank though! Also look for staining round the radiator and especially down by the water pump shaft - if its there then you have early signs of WP failure. You might have to remove the airbox to get a good look at it - or take the wheel off and the inner arch liner out. These can fail quite spectacularly when the seals go at high revs - I just replaced mine after such an instance - clouds of steam everywhere!
Thanks Guys, I appreciate the detailed feedbacks. I'll keep an eye on it now that it's at the correct level. Bob.
