Topping up coolant

[OzRick25]

Originally Posted by Classic Boy

Sometimes many cars find their 'happy' level in the overflow bottle, and no amount of topping up will prevent them from always going to their 'happy' level.

It is only a overflow for heated coolant that necessarily must expand and as long as the rad is full then the engine is cold it doesn't really matter what is in the overflow bottle, because its only job is to catch overflow and return it to the radiator as it cools down.
In short you only need to add to the overflow bottle if the radiator is less than full when cold and simultaneously the overflow bottle's contents are exhausted.

Agreed, mine sits about 1/4 of the way between minimum and maximum all topping up for me does is result in overflow and therefore dilute the coolant. If your confident your not going to get your car that hot again it may be beneficial though. Get it to the hottest you will run it at and see where the coolant level is to gauge how much water to top up.

[Turismo07]

Originally Posted by Geo Jeep

Thank you all for for your replies.

I have been driving around the WA coast for several weeks with quite a few days in the mid 40 deg range and the temp gauge has been getting pretty high so I suspect the expansion tank has boiled over a little from time to time. There is evidence of this in the engine bay so that would account for the missing coolant.

I'll top it up this morning and continue on!

Try to top up the overflow bottle with distilled water if you can, otherwise normal water is better than nothing. Just make sure you get the coolant flushed when you can/get home.

Some JK CRD specific advice:

Are you monitoring your temps via a OBD port reader? The gauge in the dash doesn't move past halfway until coolant temps are 107+ degrees, which is too high (unless for a few seconds only).

If your JK is auto, then if you are seeing high coolant temps then your auto trans fluid is likely going to be very hot as well.

Assuming yours is auto, keep an eye on the temps and try to keep them as low as possible, on long trips at hwy speeds JK CRD's love to get hot and can cook the trans, and/or do damage to the engine.

Manual's very rarely suffer from overheating. This is because the already cramped grill/radiator area is not shared with a auto trans cooler, which is inadequate from the factory, which then transmits heat to the other coolers around it (i.e. radiator and intercooler).

Also the factory Mopar red coolant is junk, it actually eats away at the plastics in the cooling system (overflow bottle and radiator end tanks) over time. If you still have this coolant, then flush your cooling system and run some decent coolant and you will find your average temps will drop 2-3 degrees as well.

[humdingerslammer]

Originally Posted by Geo Jeep

Evening all.

I am in a situation where I need to top up my radiator expansion tank and I only have access to water. Obviously using water is better than cooking the engine but when I return to civilisation will I need to have the radiator flushed or anything drastic like that?

The coolant level is currently at the bottom of the expansion tank and I will fill it to the 'cold fill' level.

I have a 2011 JKU CRD.

Thanks in advance folks.

I suggest that u check that your radiator cap is OK. Is there coolant cooler stain around the radiator cap? If so, put on a new cap.... worth it anyway (only a few dollars) and this may help with the problem. Also is there any coolant colouring around the water pump.If so, need to change that as well.

[Geo Jeep]

Originally Posted by Turismo07

Some JK CRD specific advice:

Are you monitoring your temps via a OBD port reader? The gauge in the dash doesn't move past halfway until coolant temps are 107+ degrees, which is too high (unless for a few seconds only).

If your JK is auto, then if you are seeing high coolant temps then your auto trans fluid is likely going to be very hot as well.

Assuming yours is auto, keep an eye on the temps and try to keep them as low as possible, on long trips at hwy speeds JK CRD's love to get hot and can cook the trans, and/or do damage to the engine.

Wow the needle doesn't move past half until 107 deg! Can I confirm that is correct? Living in Darwin my temp gauge needle spends quite a bit of time above halfway.

Yes I have an auto........

[Geo Jeep]

Originally Posted by humdingerslammer

I suggest that u check that your radiator cap is OK. Is there coolant cooler stain around the radiator cap? If so, put on a new cap.... worth it anyway (only a few dollars) and this may help with the problem. Also is there any coolant colouring around the water pump.If so, need to change that as well.

No sign of coolant anywhere except just below the overflow pipe on the expansion tank. I think when it gets hot it's just coming out of the overflow.

[Turismo07]

Originally Posted by humdingerslammer

Also is there any coolant colouring around the water pump.If so, need to change that as well.

The water pump on the CRD's is tucked away behind the timing belt, and therefore inside the timing belt cover. If it leaks you'll be able to tell from coolant at the bottom of the cover, but highly unlikely.

The water pump on CRD's is a serious unit and made as a 'non-serviceable' item meaning they designed it to last the same amount of time as the engine, if not outlast it. In saying that it is common practice to change it when replacing the timing belt as well (so every 80,000-100,000 kms).

[Turismo07]

Originally Posted by Geo Jeep

Wow the needle doesn't move past half until 107 deg! Can I confirm that is correct? Living in Darwin my temp gauge needle spends quite a bit of time above halfway.

Yes I have an auto........

Invest in a OBD2 reader. It's the only way to properly monitor the engines vitals in realtime (and read and clear any engine codes etc). You could also install a proper coolant gauge, but this is more work and potentially more cost, and you won't have the benefits of being able to do everything else a OBD2 reader can.

All vehicles since about 1990 have very vague coolant gauges. Coolant temps fluctuate a lot so manufacturers wanted to dumb their gauges down to only basically say cold, normal, and hot.

There are many OBD2 readers out there, scangauge is very popular. My personal preference is a OBD2 bluetooth transmitter (eBay $5-15) which is permantly plugged into my OBD2 port under the dash, which then reads the ECU and transmits the data to my Android phone via bluetooth. To make sense of this data I use a app on my phone called Torque (Google Play store $0-15) and I can monitor every single sensor on the motor, which includes the coolant temp sensor.

I am always driving around with one eye on the engine's vitals. You soon learn what is normal what is not, and how your vehicle reacts to different conditions etc.

General consensus is that coolant temps of 107+ degrees for a prolonged period of time is no good. And like I said, if yours is auto, it is very likely that your auto trans fluid is getting too hot as well.

If you have a 2010+ JK, you will be able to monitor trans fluid temps as well via the OBD2 port, early models didn't have this provision.