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Cooling system 6BT

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19 Aug 2018 06:42 #1 by Adventurer
Adventurer created the topic: Cooling system 6BT
I have just had a 6BT conversion done to my OKA 295 and taken it for its first run up the Kimberly
Whilst it performs fantastic, it tends to run hot especially with the aircon on when it starts working a bit on the hwy hills around 90km/h
I have a new radiator, correct fan , clutch and shroud
Not sure if my mechanical fan is obstructing air flow, I’m thinking of going to a couple of thermo fans
I would appreciate some feedback on the cooling system on other 6BT fitted
Thanks
Rainer

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19 Aug 2018 08:32 - 19 Aug 2018 08:33 #2 by Holmz
Holmz replied the topic: Cooling system 6BT
When I saw that fantastic looking thing in Perth Dean said it would go 145 without overheating.
My perky is also hot ~95kph... in the 40+C onditions I can use the speedo or the water temp as a speedo.
But I suspect in Vic or Tassy they run cool.
Obviously I have nothing relavent to add from experience.

However my travel companion on the last trip is good friends with some friends of yours in the hills outside of Perth. Maybe around mondering?

On the theory side, the cooling transfer rate is proportional with:
1) airflow volume through the core
2) water flow volume rate
3) temperature differential between the water and the air
4) exchange rate through the core (material, scale, #cores, ...

#3 is low when in the tropics.s the aircon heats the air, then if that is front of the radiator, it will not be helping a lot.

#1 - The fans mostly help when the vehicle is not moving. Unless the fans are blowing backwards, the airflow will be constant unless you have a bigger inlet or airflow is blocked getting out.
Or the radiator is somehow blocked.

Therefore I would probably start with #2... thermostat, pump... somehow determining if the water is flowing well.
The thermostat should be an easy change.
Last Edit: 19 Aug 2018 08:33 by Holmz.

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19 Aug 2018 08:43 - 19 Aug 2018 09:12 #3 by Outback Jack
Outback Jack replied the topic: Cooling system 6BT
Couple things to check... Sorry for the long post.

I am no expert and others maybe help as well.

Check what thermostat you have, there are a few different types. Some open up at lower temps, others higher.

What radiator do you have? Some people talk about 4 or 5 core. Trouble with Radiators, cores aren't cores... Core size etc is also important. I have a 4 core radiator, however it is a staggered core that is more efficient.

Radiator Cap check your pressure on your cap, this will effect boiling point etc

The fan needs to be about 3/4 into a shroud, other wise it will not be effective.

I have one thermo fan with thermo switch. It is not inside a shroud etc.

I don't have a engine fan. I don't have a heating problem, rather I have a over cooling problem. I live in the NT and my vehicle has worked hard on sand etc, Running around when its humid etc. I have never got over about 90 degrees C.

I also recommend to people to get rid of AC condenser from the front if possible. Last OKA I had it was mounted on the roof rack. Easy enough to do and gives engine radiator the cleanest and coolest air possible.

Water pumps. Again there are several water pumps to suit a 6bt.
A 6BT water pump operates at around a 2-1 ratio so for the average engine cruising along at 1800-2200 rpm the water pump is spinning around 4000 rpm and will peek at around 5200 rpm with stock governors
The 24 Valve 6.7 Litre has a 7 blade water pump, rated for more HP etc. So that would also be a good option to fit.

Cummins have at least three different pumps, below is for Dodge Rams

1. 12 valves from 89 to 98
2. 24 valves from 98. 5 to 07
3. 24 valve 6. 7 liter 08 on

So a bit of trail and error on pumps maybe the go. I have a standard 5.9 Litre water pump.

Cummins 6BT 12 valve water cooling bypass kit - Improve coolant flow to cyl #6 helps if not already fitted as well.

Check your temp gauge and make sure it is accurate. I carry a thermo gun, handy for a lot of things. Including wheel bearings, gear box temp and block temp.

Feel free to private message me and let me know a contact number.
Last Edit: 19 Aug 2018 09:12 by Outback Jack.

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19 Aug 2018 09:48 #4 by Adventurer
Adventurer replied the topic: Cooling system 6BT
Thanks guys for your detailed reply’s
I think I will start with the thermostat for a start as I’m I heading off to Darwin via the Gibb in a couple of weeks
I think the best long term fix is to remove the condenser and relocate it and Re shroud with thermos fans

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19 Aug 2018 10:57 - 19 Aug 2018 10:58 #5 by Holmz
Holmz replied the topic: Cooling system 6BT

Adventurer wrote: Thanks guys for your detailed reply’s
I think I will start with the thermostat for a start as I’m I heading off to Darwin via the Gibb in a couple of weeks
I think the best long term fix is to remove the condenser and relocate it and Re shroud with thermos fans


I would be interested in what bunch of kit you end up with for the relocation.

I would pack away the old thermostat in a baggie incase you need on in-situ.
If the old thermostat is getting to a stable temp snd staying there, then it os probably working... But sometime they do not open fully according to legend (I have not witnessed that meself)

Testing the new thermostat on the stove in a pot of water may give you some certainty that it is working as expected before you install it... Make the cuppa tea before you chuck in the thermostat - and one for any partner(s) you have nearby B)
Last Edit: 19 Aug 2018 10:58 by Holmz.

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19 Aug 2018 12:10 #6 by Outback Jack
Outback Jack replied the topic: Cooling system 6BT
I was originally going to run with twin falcon fans. Peter got to it before I did. He didn't have any success. When you get to Darwin, I will show how I did it with the one big electric fan. It brings the temp down real quick.

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19 Aug 2018 12:20 - 19 Aug 2018 12:23 #7 by Outback Jack
Outback Jack replied the topic: Cooling system 6BT
Picture below of how did last condenser.

It was done in remote NT, so didnt have two bends...







Just need to source condenser and fans. Hoses just get made on the day... I also had bulkhead fittings. So the hose doesnt pass through the roof. It bolts onto the bulkhead fitting.
Attachments:
Last Edit: 19 Aug 2018 12:23 by Outback Jack.

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19 Aug 2018 12:31 #8 by Outback Jack
Outback Jack replied the topic: Cooling system 6BT
Original Set up



Wiring


I then added a domestic AC cover for hoses. Painted it black to blend in.

Attachments:

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19 Aug 2018 16:24 #9 by Peter and Sandra OKA 374
Peter and Sandra OKA 374 replied the topic: Cooling system 6BT
Rainer are you still running the standard radiator or has it been recored to four or five cores, the standard LT radiator is only two cores and the resulting cooling system is too small for a 6BT.
Mine is 4 core heavy duty and it rarely gets to 90 C even on a 40 degree day with both aircons on. I am still running the aircon condenser in front of the radiator, in cold weather it really needs to have a blind as it probably cools too well.
I too sit at 5.8T most of the time on a trip and it would rarely be below 5.5T and can run all day at 100-110 kph without the temp gauge ever moving and I have the temp sender in the hottest spot at the LH rear of the 6bt head.

OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 1100w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.

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19 Aug 2018 16:59 #10 by Ralley
Ralley replied the topic: Cooling system 6BT
I think that you should stick with the fixed fan with a hub that works as it should. When the fan on ours is driving it really roars. I often think the old perky wouldn’t have had enough puff to drive it.

Can you hear the fan when it’s engaged?

I to am like Peter I’ve done long runs in 40 plus at 100km/h at around 8t gcm and have no issue with temperatures and mine is an XT with 50mm more height in the radiator and a re core. The only thing in my tunnel is the radiator.
I also think it nearly needs a blind in cold weather the heater really struggles.
Rob

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19 Aug 2018 17:08 #11 by Adventurer
Adventurer replied the topic: Cooling system 6BT
No problem i will look you up

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19 Aug 2018 17:14 #12 by Adventurer
Adventurer replied the topic: Cooling system 6BT
Thanks Peter, Yes the radiator is new but original spec. That was my first choice was to up the cores on the radiator to 4 core. Im back to Perth tomorrow for a week or so so i hope i can get one made before i come back to Broome. If not i will take off the two large spotties and relocate the rego plate before i head off as they all comprise air flow.

Rainer

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19 Aug 2018 18:11 #13 by Peter and Sandra OKA 374
Peter and Sandra OKA 374 replied the topic: Cooling system 6BT
Rainer you really need to increase the radiator to at least four core, normal in line tubes will be fine but if you intend to spend a lot of time in the tropics then go for the staggered core like Lobo was talking about. As well as increasing the radiators ability to cool you will be increasing the actual volume of coolant which is also important, Both my LT and Ralley's XT have around 25 litres of coolant despite the difference in radiators between the LT and XT. Ralley also has an intercooler which also helps.

OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 1100w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.

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19 Aug 2018 20:43 #14 by Adventurer
Adventurer replied the topic: Cooling system 6BT
Peter,
Thanks for that info. I will research where i can get a staggered 4 core radiator done in Perth. I will contact Dean from OKA parts when i get back in town. Will the increased cores increase the radiator width? There is not much room to spare with the condenser

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20 Aug 2018 04:33 #15 by Peter and Sandra OKA 374
Peter and Sandra OKA 374 replied the topic: Cooling system 6BT
296 being an LT has the radiator at the front of the tunnel so has a much bigger surface area to start with. The core will stay within the tanks and side frames but depending on the core it may be slightly thicker, mine is about 5mm outside the side frames, the only change I had to make was to fit spacers behind the aircon condenser so it didn't sit against the radiator core. There is plenty of room on the tunnel side.
If you have problems with the end tanks they are from a 6 cylinder Cortina with different hose positions according to a radiator bloke that recognised them.
Mine has a standard 4 core and as I said it borders on being too good in our climate and cold westher.

OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 1100w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.
The following user(s) said Thank You: Adventurer

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29 Aug 2018 13:20 #16 by Adventurer
Adventurer replied the topic: Cooling system 6BT
Well the new 4 core radiator is boxed on on its way to Broome where i will install it next week. What a difference in size, whilst it is no bigger physically it must be nery twice the weight.
Any advice or pointers on removal and replacement ?

Thanks

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29 Aug 2018 16:08 #17 by Peter and Sandra OKA 374
Peter and Sandra OKA 374 replied the topic: Cooling system 6BT
As I said in the last post you might need slightly longer bolts and spacers to stop the aircon condenser touching the radiator core. R & R is pretty straightforward in an LT, the aircon condenser can be hooked back up to the sun visor out of the way just make sure it is well tied up as mine fell down and busted one of the pipes.
The aircon dryer will also have enough slack in the piping to allow it to be pulled forward out of the way as well.
Take care of the rubber blocks and also note the way they sit under the radiator as they are easily misplaced, i also had to trim them slightly for the new radiator so it sat properly.

OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 1100w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.

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