Heating issue 4.8

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Craig Lord
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Heating issue 4.8

Post by Craig Lord » 31 Oct 2019 12:08

Hi guys

So we havent done a trip in the patrol for a while now and last week we left the tuli block to go to durban. As you know there was quite a heat wave recently and the outside temp got to 40 degrees. Soon after on the up hills the patrol started to heat up to the 3/4 mark but came back down to below half very quickly if I backed off the throttle and slowed to 100.

At this stage the patrol was empty and we were towing a small empty venter trailer which I think weighs about 200kg.

I had a small leaking pipe at the oil/water heat exchange and I thought maybe I have an airlock. I called Graham at g-tech and he told me to open the bonnet to the first latch and secure it so it cant fly open as I didnt have time to stop in pta. That solved the issue all the way to durban.

On the way back the outside temp was 25 degrees all the way back to polokwane. Now we were towing a full trailer at about 700kg and even going up the pass at harrrismith we had no issues at all. Only at alldays it got to 33 degrees and again the heating started.

So today I checked everywhere for leaks, the coolant levels look good and I ran the engine up to temp turned the heater and fan onto full and took the cap off the pipe at the fire wall to bleed the system. At first there was alot of pressure as I took the cap off but it soon went to a trickle then basically stopped only spurting a few drops every now and again. I left it running like that for 10min but no solid stream of coolant appeared.

I ran it for longer and it seems like the thermostat opened and both the top and bottom pipes got hot. Still no solid stream of coolant from the bleed cap unless I rev the engine and as it the revs come down it shoots a short solid stream then stops again...

Please does anyone have any ideas? I have a trip around bots in 10 days which I wont be able to do if I cant get my baby back to good health :helpsign:

Graham was also worried about my viscous coupling.
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Craig Lord
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Re: Heating issue 4.8

Post by Craig Lord » 31 Oct 2019 17:39

Does someone know the proper bleeding procedure on the 4.8s?

What should it look like when you take the cap off the pipe at the fire wall ? How do you know when the system has ben bled properly and there is no air left ? Should there be a constant solid stream of coolant coming out ?

What settings does the heater have to be on? I had it on full heat full fan and on the vents I had it coming out the main ones. Should it be set to something else on the vents like to the footwell or to the windscreen or does it not matter?

Just want to know when I should be satisfied that I dont have an airlock in the system.

Thanks guys :thumbup:
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Tinus lotz
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Re: Heating issue 4.8

Post by Tinus lotz » 31 Oct 2019 18:59

Dude check your pressure cap it can make troubles

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Re: Heating issue 4.8

Post by Tinus lotz » 31 Oct 2019 19:00

I will pm you quick

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Re: Heating issue 4.8

Post by Craig Lord » 31 Oct 2019 19:16

Tinus lotz wrote:
31 Oct 2019 18:59
Dude check your pressure cap it can make troubles
Thanks Tinus I will get it checked. Had the radiator replaced at the end of last year also but maybe the cap is giving trouble. I still have my original nissan one somewhere maybe I should try it for comparison if it fits the new radiator...
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Re: Heating issue 4.8

Post by Tinus lotz » 01 Nov 2019 06:00

Dude you need to hear the fan come in and out as it heats up and clutch lock up if not the viscus is stuffed just turning but slipping ....lets see . :mytwocents:

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Re: Heating issue 4.8

Post by graham1 » 01 Nov 2019 07:09

Craig Lord wrote:
31 Oct 2019 12:08
Graham at g-tech and he told me to open the bonnet to the first latch and secure it so it cant fly open as I didnt have time to stop in pta. That solved the issue all the way to durban.
I dont have any input here unfortunately, but, this is a great tip, thanks for sharing it. :thumbup:

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Craig Lord
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Re: Heating issue 4.8

Post by Craig Lord » 01 Nov 2019 08:10

I dont have any input here unfortunately, but, this is a great tip, thanks for sharing it. :thumbup:
[/quote]

100% crazy how that little bit if extra airflow helps so much. I used a heavy duty ratchet from the bonnet hook down to the bull bar, no way it would open after that...
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Re: Heating issue 4.8

Post by Africa_Trekker » 01 Nov 2019 09:33

I called Tinus from the Namib Desert just 2 or 3 weeks ago with the EXACT same issue. Overheating to 3/4 when going uphill but coming back down when I let off the throttle and slowed down a bit. Ambient temp was 38 and we were also towing, plus the wind was coming from directly behind which did not help the issue.

Came to Solitaire and there was actually quite a lot leaves in between the two radiators. Blew all of this out and topped almost 2,5L of water into the overflow. This helped but very little.

We limped on to Swakopmund the next day where we found a very good mechanic specialising in 4X4s. He almost immediately told me (as did Tinus the first time I called him) that the Viscous was not working properly although it was turning. I just did not know what it was supposed to sound like. The mechanic opened the viscous and it was completely dry. He put in new viscous oil and now that fan sounds like a small plane trying to take off. He also noticed a bit of "sweating" of coolant where the thermostat was, so he replaced that seal. He took out the radiator and properly cleaned it with water and air to get all the seeds out.

Although the sweating and the seeds in the radiator were not helping the issue, the main problem was without a doubt the viscous. Once he added oil (40ml I believe?) it was working like new.

The tip of the open bonnet is helpful though...wish I had that tidbit during the trip.

Hope you get your problem sorted soon...I would really have a look at the Viscous as your problem sounds just like what we experienced.
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Re: Heating issue 4.8

Post by Tinus lotz » 01 Nov 2019 12:08

Jip thats why i always ask guys to start a tread on this forum watsupps phone calls facebook dont help follow patrollers.....at least when someone from south Africa do a search...he will get the info ....one problem in namibia and one in botswana :lol:
Guys please i always help and give info where i can but iam just a patrol fan the mechanics normally has proper advice....but will do my best to research before i give answers :salute: :salute:

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