Thermostats

[undecided]

Excellent
I do not have an overheating problem as such. I have once experienced the XJ get hot running along the beach at high tide. To put it in perspective of the 3 vehicles in our little group one stopped and we had to go back and tow it off at low tide and the other non Jeep has since suffered a blown head gasket.
As I do a bit of this sort of thing I am interested in anything which leads to greater temperature stability not nessecarily trying to get the old girl to run cooler.
And yes bonnet vents are coming prior to my next trip to Fraser in October to try and reduce general under bonnet temps, again not engine running temp.
Great thread folks

[carvesdodo]

Some good general info ..... from the TD2.5 XJ thread --> http://www.ausjeepoffroad.com/forum/...ad.php?t=96380

Originally Posted by drgn1708erin

what r the worn scratch marks in the thermo wax chamber? what do they mean?

Originally Posted by Deezelweazel

They don't mean a lot...
They simply mean it's worn out and the valve can be sticky open or do not open as demanded.
The slight angle, caused by the worn marks, can stop to open it- which leads to engine overheat.

Just keep an eye on those things- hey, after ten years of use things do wear out.
Grabbed the thermostat out of the trash to show you:
The wax expansion chamber is located in the middle.
It is a brass tubing. Can you see the shiny brass part? Thats the worn mark- the rest of the chamber is dark due to oxidation which also means coolant was depleated in the past.
This little mark can prevent proper opening of the thermostat.

[Deezelweazel]

hahaha, cool post here!
Just wanted to ask a question

What shall a high flow thermostat do?

It is a cure for a already faulty radiator.
You increase volume to transfer more heat...

That is the common thought.
Radiator heat transfer rate is fixed you can't increase it with a higher flow. A higher flow does shorten the remain time of the coolant in the radiator. So less heat is transfered.
An early opening thermostat will allow the coolant to get heat soaked earlier. If thermal coolant heat transfer capacity is reached you won't get rid of it. Because of the faulty restricting radiator.

Conclusions:
-Without a proper working radiator everything else is useless.
-Highflow thermostats are good for the dealer wallet
-high flow pumps have the same effect as thermostats if you don't get rid off the heat.
- the faster the coolant flow the less heat transfer:
1: less heat transfer in the engine block!
2: less heat transfer in the radiator!
3: Caviation due to air bubbles causing hot spots in the heads, causing head warp as an extreme result...

So what do you know about the XJ?
- It is american build, but america has some freakin' hot deserts, too(been there and sweat my butt off)
- every XJ is at least 10 years old
- Can a cooling system be called operational after 10 years of neglecting owner use?

You have to replace the radiator and coolant circuit parts to get back to the original condition!
If you want more you have to do more!
Compare the 4.0 radiator volume-there are radiators available with 19mm or 33mm thickness.
Which one would you choose?
Right, at least 39mm like the Diesel...
If not more when you know you will play in a constant high heat area!

[carvesdodo]

Earlier opening thermostat, Deez ... earlier opening thermostat ...

As you said ... A radiator has a fixed cooling ability ... Its a heat exchanger ... not a refridgerator.

Therefore a 185' thermostat allows 185' coolant into the radiator to be cooled by the - percentage cooling ability of the radiator .... which allows cooler liquid to be available for the thermostat to play with - to balance the engine temp.

Of course if the size of the radiator ... or its efficiency ... is insufficient ... or the weather is stinking hot .... or the eth-gly concentration is too high to shed heat efficiently ....... then it wont make a lot of difference.

Yes they have freaking hot deserts .... and during a U.S. summer ... in the distance .... at the back of some of those deserts ... they have mountain ranges which can have up to 15m of snow on them.

Its all about the averages the vehicle has been designed for

Down here, during winter .... a 1.5m winter snow depth would have our nanny state govt scurrying about, worrying about avalanches .... and an invasion of abominable snowmen ..... on our little, 2000m highest hill.

Personally ... I wouldn't class a cooling system as fully operational after 5yrs

[Auberon]

Just thinking out loudly:
I would much prefer my thermostat to be electronically controlled & mechanically acting:
eg:upper and lower point thermistors linked back to a programmable board (like the Arduino system or any other PIC system) so the action is pre-emptive to the operators needs. This would be coupled to a PWM driver and a servo to allow the thermostat to react at any desired time before the temperature event...thus preventing it and flattening the temperature curve of the engine. A PWM driver then linked to the valve I would install in line can open in direct relation to the desired curve.
I do not question Jeeps design engineers for motor op temps but we need a batter system for control to maintain OPTIMAL OP CONDITIONS for combustion, oil longevity etc.

As Carves said it's about the averages they have to elect. These are OK but this system would allow the cooling system to react more effectively and the motor does have internals which we can monitor with such a system. It actually keeps the heat exchanger working at a lower temp thus heat exchange with the hiigh volume air stream is greater as the volume of air needed is actually lower for efficient heat exchange. So a high air volume, as designed, will cool well and design parameters can be maintained.

"For A Few Dollars More". Great movie title and very pronounced message.

As the sensors can be positioned where they need to be, the flow control valve can be simply put in line. Valve action could also be made linear or exponential if desired. EASILY.

THIS IS HOW I WILL FX MINE IF OR WHEN THE KJ ONE FAILS.

Discounts any concerns re positioning of sensing as has been mentioned as the thermistors are tiny and if uninsulated units are used, highly reactive given the right sensor choice.

My problem is the thermosats are post-conditional in that react to the conditions AFTER the event and cannot act pre-emptively.

Same control for a thermo fan would be easy to do.
Pretty basic really in these days of technology.
I never did understand why this had not been one of the systems controlled electronically. It is one of the easiest and if the default is set at full flow no damage will result from system error. INBUILT FAILSAFE device.
Cheers
Auberon

[carvesdodo]

Has been a coupla posts recently ... on US forums ... about finding a little surprise in mopar, XJ thermostat, packages.

Seems MotoRad is now the supplier for the "genuine" thermostat ..

Might be cheaper to buy the Tridon badged, MotoRad t'stat ... from Bursons or wherever ..