Thermostat sticking

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Alan Bajada & Jo-Anne Allchin
Member
Posts: 15
Hello, don't know if there are any old posts, but I need to replace the thermostat, it has caused me grief and headaches recently, it has failed to open and the temp went through the roof, then returns to normal when it opens, so it needs to be replaced. I have original Perkins motor, done 220,000kms, replaced radiator core 5 years ago. When traveling up north in the heat with air con on, at 95kms/hr, temp just below red, reduce speed, temp drops. So, the question is - what is best thermostat replacement? Or is this a unrelated problem?
Thanks regards Alan
September 3, 2011 at 11:26 PM Flag Quote & Reply

oka 098
Member
Posts: 58
gday replace thermo check temp gauge vdo swaped pos and neg so a bit of wiring but easy , reduce speed, temp drops, radiator flow? mabey flush check head temp with hand held temp gauge just a thought on a day of scotch, cheers happy old mans day all,
September 4, 2011 at 3:55 PM Flag Quote & Reply

Dandj
Member
Posts: 367
Alan, standard thermostat should be OK, about 80º.
Easy to change since you don't loose much water but you should get a new gasket which might be tricky to find, it's a figure 8 rubber O ring and Perkins specific. If you get stuck the old one could be reused with a bit of gasket goo. If you have a plastic thermostat cover, don't over-tighten the bolts, you could crack it.
The temperature should stay around 80-90º (low green) most of the time but can rise in hot conditions with the a/c on. Shouldn't get above 100 (red). We often have to turn off the a/c when pulling up long hills to keep it cool. If it overheats, turning the heater on full blast while ticking over can cool it but it's not pleasant for passengers.
Keith Harris has fitted a larger diameter thermostatic fan to his Oka (from a Ford Falcon apparently) to improve cooling.
Obviously check the water level often. It shouldn't use any.
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David and Janet Ribbans, Oka 148

September 4, 2011 at 5:26 PM Flag Quote & Reply

Dave and Pauline Gray
Member
Posts: 84
Hi Alan as Dandj says standard thermostat should be ok but a mate of mine had a similar problem re tempretures being a bit irratic and after much expense re new radiatior cores and water pumps it turned out to be the temp sender unit just a thought
Cheers Dave
September 4, 2011 at 7:38 PM Flag Quote & Reply

Aussie Bight Expeditions
Member
Posts: 109 The o-ring is just an ordinary o-ring.Buy the right section and length one for the temp youw will be fine. They are not preshaped as on thinks as I have replaced these on JCB loadalls, they run the same motors on the 2 we had a few tears ago and they are just circular O-rings to start off with. Make sure they are for the temperature range firstly. When you remove them they are that shape because of the housing and temperature forms them to the housing shape. Regards ABE TONY
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September 5, 2011 at 10:54 AM Flag Quote & Reply

Dandj
Member
Posts: 367
Tony, mine new spare is a figure 8 but there are different thermostat housings, the plastic variety and a steel housing. Maybe the steel housing gasket is different. Section 2 of the XT manual shows both a figure 8 gasket and a flat normal gasket option.
Note the 6 cylinder version of the engine has provision for 2 thermostats, which is why the housing is larger than normal.
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David and Janet Ribbans, Oka 148

September 5, 2011 at 11:04 AM Flag Quote & Reply

Aussie Bight Expeditions
Member
Posts: 109 Doing this on a IPAD an one must. look and check as one goes as you can not reread, makes this hard so sorry for spelling mistakes. Pity they did not make all things the same for motors etc as it can become a quessing game sometimes. Regards ABE TONY
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September 5, 2011 at 11:13 AM