Jump to content
SAU Community

Recommended Posts

OK, from my understanding, the radiator cap is meant to seal the radiator and when there is to much pressure, it pushes the radiator cap spring and releases some pressure and then it seals again. Correct?

Problem I am having is that the coolant is getting dumped into the overflow before pressure builds up. It dumps the entire contents of the rad into the overflow and then pisses out. When the engine cools down, it sucks it back in but leaving it dry as most of it has pissed out on the road.

The car doesn't over heat when this happens Just the smell of coolant and a kettle sound. The temp stays on half.

Ive done a gas test and it shows no problems there. I bought a genuine Nissan rad cap and it still does it. I took the radiator to a specialist and he reckons that the radiator cap is 2mm to short and isn't even making a seal and insists that the cap is the wrong one.

This doesnt sound right so I thought id ask what you guys think. Im thinking of getting a big washer and gluing it into the radiator neck so the bottom of the cap makes contact.

Advice??

Link to comment
https://www.sau.com.au/forums/topic/446610-issues-with-overflow-and-radiator/
Share on other sites

Radiator expert sounds right.

You should be able to feel the cap seal onto the rad when you first put it on, then when you do it up it compresses the spring inside it to allow the outer edge to seal.

Yeah the cap and the sealing surface are the only thing that controls flow between the radiator and overflow bottle. Nothing else will cause coolant to pass between the two.

Post up some photos of both the radiator sealing surface and the cap so we can help a bit more

You can check if the cap is sealing when cold by sqeezing the top radiator hose. Make sure the radiator is full of coolant first - if the cap isn't sealing, when you squeeze the hose you will see coolant going into the overflow bottle - this shouldn't happen until the pressure builds to the cap's rating, which it won't reach by sqeezing the hose.

Does it feel tight when you do the cap up? As in do you have to press it down to get it to go in.

For some reason something doesn't look right but I'm not around my car to have a look to compare. Was the cap definetly for a skyline?

Does it feel tight when you do the cap up? As in do you have to press it down to get it to go in.

For some reason something doesn't look right but I'm not around my car to have a look to compare. Was the cap definetly for a skyline?

Nah dont have to press down at all. Just put on and twist. The cap is definitely for the car as I asked for it at the Nissan dealership.

Great, thanks for the replies and yeah when I squeeze the hoses there is coolant going back and fourth.

Looks like the cap isn't sealing than. Have you got a way to measure both the cap height & the radiator neck internal height - the cap should be a bit bigger. A vernier caliper would be the go.

I have seen this many times lately, if you can't feel the force of the spring as you push it down, the cap is too short. Get a new one that sits a little further into the radiator.

Radiator specialist said it.

I said it.

89CAL said it.

Scotty said it.

It is pretty obvious. Get a new cap.

Radiator specialist said it.

I said it.

89CAL said it.

Scotty said it.

It is pretty obvious. Get a new cap.

Its a brand new cap from Nissan. Ive even checked in car shops for other caps and they are all the same size. Its so weird...have even compared with a mates Skyline cap and it looks the same. Ill see if I can just buy a longer one or use a washer or something.

though it may be a new cap from nissan. whos to say that it isnt defective from factory? a worn rad neck seat where the cap seal interfaces with rad could be worn out - which would mean a new rad but for what its worth try a new cap before the rad itself.

Well more to the point, whos to say they didn't go and grab the first radiator cap they could find OR for some reason your radiator is different.

I'm not saying I'm right but these things do happen

Go to supercheap and have a look at the ones they stock, compare and buy one that seems better. Caps are different, they should have one that will work. And make sure its a 1.1bar cap because .88 seems low for some reason. I cant remember what my stock cap was but think it was about 1 bar.

Its a brand new cap from Nissan. Ive even checked in car shops for other caps and they are all the same size. Its so weird...have even compared with a mates Skyline cap and it looks the same. Ill see if I can just buy a longer one or use a washer or something.

Swap cap with your mate for a day. 88kPa seems a bit low.

I couldnt find another cap so I found a rubber grommet that fits perfectly and sits just below the overflow hose hole.. I glued it in with Sikaflex will see how it goes once its dry. Good point about the guy at Nissan just grabbing any cap.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • just an update to this, poor man pays twice  Tried sanding down the pulleys but it didnt do the trick. Chucked another second hand alternator in the na car which I got for free off my mate and its fixed the squelling. Must have been unlucky with the bearings.    As for my turbo car, I managed to pick up a cwc rb alternator conversion bracket + LS alternator for 250 off marketplace, looked to be in really good nick. Installed it , started the car and its not charging the battery.... ( Im not good with auto elec stuff so im not sure if this was all I needed to do but I verified such by using a multimeter on the battery when the engine was running and I was only getting 12.2v )   I had to modify the earth strap for the new LS alternator , factory earth strap was a 10mm bolt which did not fit the bolt on the LS alternator which was double the size so I cut it off , went to repco bought some ring terminals that fit, crimped it onto the old earth strap and bolted it up to the alternator , started the car and same issue. Ran like shit and was reading 12.2 at the battery.  For a "plug and play" advertised kit thats not very plug and play but alas.  My question is , am I missing something ? Ive been reading that some people recommend upgrading the stock 80 amp alternator fuse to a 140 amp but I dont see how that would stop the alternator charging especially at idle not under load.  Regardless ive pulled it out and am going to get it bench tested by an auto elec tomorrow but it would be handy to know if ive missed something silly or have done something wrong.   
    • My wild guess is that you have popped off an intake pipe....check all of the hoses between the turbo and the throttle for splits or loose clamps.
    • Awesome, thanks for sharing!
    • To provide more specific help, more information is needed. What Android screen? What is its wiring diagram? Does the car's wiring have power at any required BAT and ACC wires, and is the loom's earth good?
    • So, now all you need to do is connect the 2 or 3x 12v feeds into the unit to permanent 12v, ACC 12V and IGN 12V that you can find in the spot behind the stereo, and the earth, and then it will switch on with the car.
×
×
  • Create New...