Thanks for the trust but I'm not as clever as you think. Not by a long shot.
I did however just come back from town - leisurely 15km drive and quickly checked the forum and upon seeing this post quickly nipped outside to check my expansion bottle.
Mine is usually at the full mark when cold and now after about 5 minutes standing it is 2.5cm over full mark.
I think expansion is fine as long as it's consistent. The measure of expansion will vary with
- radiator cap pressure variances
- coolant mix variances
- radiator efficiency variances
- viscous fan variances
- A/C fan being used
- auto fluid temp variances as it gets cooled by the radiator
I would just keep an eye on it and as long as you aren't losing coolant and the cold level stays constant then all is well.
To make sure all the air is out, park the car after a hard drive on a slope with the nose up. Rev a bit and switch off. Make sure the expansion bottle is full - once it has cooled it would have sucked some water back into the radiator. Open the radiator cap and top up as necessary.
The Pajero uses a 'low pressure' system, where the expansion tank is at low (atmospheric) pressure.
Some vehicles (most German makes) use a system where the expansion tank is under high (engine) pressure.
What follows holds only for a low pressure system.
The engine block, radiator and expansion tank are supposed to form a 'closed' system.
When the engine heats up, the coolant expands. This causes the pressure in the engine block and radiator to rise.
Once the pressure reaches a specific pressure (dictated by the radiator cap), the radiator cap will open, and excess coolant will be pushed into the (low pressure) expansion tank.
(The expansion tank is called that because it retains the excessive coolant due to the expansion of coolant in the radiator and engine block).
Once the engine cools down (after shut-down), the coolant in the engine and radiator contracts. This causes a low pressure (vacuum) in the engine block and radiator.
The coolant is 'sucked' from the expansion tank into the radiator.
If coolant is pushed into the expansion tank, but is not sucked back into the radiator, there has to be a leak in the system. (Air is sucked back into the radiator, in stead of coolant ).
The culprits are usually one or more of the following:
Some vehicles (most German makes) use a system where the expansion tank is under high (engine) pressure.
What follows holds only for a low pressure system.
The engine block, radiator and expansion tank are supposed to form a 'closed' system.
When the engine heats up, the coolant expands. This causes the pressure in the engine block and radiator to rise.
Once the pressure reaches a specific pressure (dictated by the radiator cap), the radiator cap will open, and excess coolant will be pushed into the (low pressure) expansion tank.
(The expansion tank is called that because it retains the excessive coolant due to the expansion of coolant in the radiator and engine block).
Once the engine cools down (after shut-down), the coolant in the engine and radiator contracts. This causes a low pressure (vacuum) in the engine block and radiator.
The coolant is 'sucked' from the expansion tank into the radiator.
If coolant is pushed into the expansion tank, but is not sucked back into the radiator, there has to be a leak in the system. (Air is sucked back into the radiator, in stead of coolant ).
The culprits are usually one or more of the following:
- The radiator cap is defective.
- The pipe connecting the radiator and the expansion tank has a small leak, so that it won't suck the coolant back into the radiator, but lets air into the system.
- The end of the pipe connecting the radiator and expansion tank is not below the coolant level in the tank. Open the expansion tank, and confirm that the pipe is below the coolant level. Often the pipe goes only to the cap of the expansion tank, and there is a separate little pipe from the cap down into the coolant. If this second pipe is loose or cracked, it will not suck back coolant into the radiator.
- When everything is cold
- When engine is at operating temp.
- When engine has cooled down completely again.
Gerhard Fourie
If you want to shoot somebody, make sure you aim at his head, not your own foot.
Me
If you want to shoot somebody, make sure you aim at his head, not your own foot.
Me
Gerhard,
Your description is more eloquent and technically correct than mine, but in essence we both painted the same picture.
What has me a little worried about TC's Pajero, is the fact that so much coolant pushes into the expansion tank.
If my Datsun 1600 SSS or my dad's Valiant had pushed so much water past the radiator cap, it would have told us that something is not right with the cooling system, because every morning we would have needed to top-up with almost a litre of water. TC's Pajero is forgiving him, because it (hopefully) sucks all the coolent back into the radiator overnight. I can't help but think that his expansion tank is just about ready to over-top. The last thing I want to do is to spook TC into worrying about nothing, but we also don't want him to think all is well and then find out the hard way that it wasn't.
I checked my expansion tank this morning after an hour's to-ing and fro-ing (at more than 16L/100km) and the coolant level was spot-on the full mark. No coolent had pushed past the radiator cap into the expansion tank. We are planning to pull the heavy old Jurgens to Kruger for the weekend, I'll make a point of checking the expansion tank level after some heavy work through the mountains with the caravan in tow.
Thanks
Roelf
Your description is more eloquent and technically correct than mine, but in essence we both painted the same picture.
What has me a little worried about TC's Pajero, is the fact that so much coolant pushes into the expansion tank.
If my Datsun 1600 SSS or my dad's Valiant had pushed so much water past the radiator cap, it would have told us that something is not right with the cooling system, because every morning we would have needed to top-up with almost a litre of water. TC's Pajero is forgiving him, because it (hopefully) sucks all the coolent back into the radiator overnight. I can't help but think that his expansion tank is just about ready to over-top. The last thing I want to do is to spook TC into worrying about nothing, but we also don't want him to think all is well and then find out the hard way that it wasn't.
I checked my expansion tank this morning after an hour's to-ing and fro-ing (at more than 16L/100km) and the coolant level was spot-on the full mark. No coolent had pushed past the radiator cap into the expansion tank. We are planning to pull the heavy old Jurgens to Kruger for the weekend, I'll make a point of checking the expansion tank level after some heavy work through the mountains with the caravan in tow.
Thanks
Roelf
When water is heated, it expands.
When it expands, the volume it occupies increases, and this has to be accommodated in some way or the other.
If no water is pushed into the expansion tank, it means one of a few things:
The volume of coolant being pushed into the expansion tank is not a problem per se, provided it is all sucked back into the radiator during the cooling phase.
TC should check that and see whether the radiator is still 100% full after a few heat-cool cycles (which it should).
The coolant can be tested for the presence of exhaust gasses, which, if present, will point to a blown head gasket.
When it expands, the volume it occupies increases, and this has to be accommodated in some way or the other.
If no water is pushed into the expansion tank, it means one of a few things:
- The engine is not heating up
- The expansion is 'absorbed' by the expansion of the rubber hoses.
- There is air in the engine and/or radiator, which can be compressed
The volume of coolant being pushed into the expansion tank is not a problem per se, provided it is all sucked back into the radiator during the cooling phase.
TC should check that and see whether the radiator is still 100% full after a few heat-cool cycles (which it should).
The coolant can be tested for the presence of exhaust gasses, which, if present, will point to a blown head gasket.
Gerhard Fourie
If you want to shoot somebody, make sure you aim at his head, not your own foot.
Me
If you want to shoot somebody, make sure you aim at his head, not your own foot.
Me
Once again thank you veyr much for all the sharing guys. I am going to check the pipes as suggested by 4E as this morning the collant level had stayed up almost as high as it was yesterday when I stopped driving (only went down a little bit).
I will let you know if I find anything.
I did find that the rubber washed under the cap of the expansion/overflow bottle had fallen into that bottle. I had to fish it out and put it back in place. Could that perhaps be the culprit causing the problem?
When I removed the radiator cap this morning there was a distinct sound indicating a release of vacuum pressure but there was capacity for me to blow back some of the coolant into the radiator. I therefore thing that 4E's comments have merit that perhaps air is being sucked back in instead of coolant.
Hence I will check all the pipes.
Roelf I would greatly appreciate it if you could monitor the levels on your Pajero while towing this weekend. Thanks Mate.
I will let you know if I find anything.
I did find that the rubber washed under the cap of the expansion/overflow bottle had fallen into that bottle. I had to fish it out and put it back in place. Could that perhaps be the culprit causing the problem?
When I removed the radiator cap this morning there was a distinct sound indicating a release of vacuum pressure but there was capacity for me to blow back some of the coolant into the radiator. I therefore thing that 4E's comments have merit that perhaps air is being sucked back in instead of coolant.
Hence I will check all the pipes.
Roelf I would greatly appreciate it if you could monitor the levels on your Pajero while towing this weekend. Thanks Mate.
No, I doubt it.Transkeicowboy wrote: I did find that the rubber washed under the cap of the expansion/overflow bottle had fallen into that bottle. I had to fish it out and put it back in place. Could that perhaps be the culprit causing the problem?
Gerhard Fourie
If you want to shoot somebody, make sure you aim at his head, not your own foot.
Me
If you want to shoot somebody, make sure you aim at his head, not your own foot.
Me
TC,
The level on the expansion tank didn't move a mm. I checked about 3 mins after stopping.
Really sorry mate.
Roelf
The level on the expansion tank didn't move a mm. I checked about 3 mins after stopping.
Really sorry mate.
Roelf
and so the serch did continue.....Turns out it was a good thing I didn't join the 4Es for the Eco trail trip last weekend....on the way home from Colchester yesterday I stopped to do my routine check on the cooling system and found a constant drip of coolant from the radiator!!!! 
Took it to the Silvertons agents and they pressure tested it today and found it to be leaking.
They are busy fitting a new one for me.....they better not also be preparing an invoice for the work!
And so the testing period begins again........
Took it to the Silvertons agents and they pressure tested it today and found it to be leaking.
They are busy fitting a new one for me.....they better not also be preparing an invoice for the work!
And so the testing period begins again........