Bullbar causes overheating?

Engines and Engine Systems
dieselfan
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Bullbar causes overheating?

Post by dieselfan » 09 May 2011 13:26

Hi there

I was reading up on bullbars on some OZ forums and the guys hint and poorly designed bullbars from ARB, TJM etc as a potential cause for the hand grenade issue. Looking at the bullbars for the pathfinder I tend to agree with them - bad airflow design.

How many of the guys who have had issues with the 3.0 had an aftermarket bullbar?

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Re: Bullbar causes overheating?

Post by Peter Connan » 09 May 2011 13:33

Dieselfan you certainly make a valid point, but remember that the handgrenade symdrome is not normally actually connected to engine water temperatures.

The piston crown is not directly cooled by the water cooling system, and the problem occurs without high water temperatures being present. If you have something disrupting airflow at the intercooler, this might contribute, but I doubt many bullbars really make much of a difference to airflow at the intercooler intake on the bonnet?
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Re: Bullbar causes overheating?

Post by dieselfan » 10 May 2011 01:39

Hi Peter

Check this site www.nissan.com.au goto pathfinder - > accessories - > bullbar, see around the number plate, the grill? directly behind that is the intercooler. All the bars I've seen block off a large % of the intercooler, surely this would increase the charge temperatures.

A year or so ago we had a big 800kw engine, sadly it was only producing 380kw we increased the airflow to the intercooler by about 30% and built ducting to direct airflow, we tested the engine to over 1000kw. The initial inlet charge temp would cause the engine to cut out at 90C, now at 1000kw it sits at 70c and water temps around 81C.

So how many of the guys with the diesels have bullbars?

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Re: Bullbar causes overheating?

Post by JG Shields » 10 May 2011 06:16

I agree with Peter. Yes, an aftermarket bullbar can surely contribute to reduced airflow, however I think it will be unfair to generalize. Only a proper test will determine to what extend a particular bullbar reduces airflow. Futhermore, if aftermarket bullbars are responsible for the 3.0Di grenade syndrome, why is it not responsible for the same problems in the 4.2, 4.5 and 4.8.....and for that matter in the Toyota Cruisers?
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Re: Bullbar causes overheating?

Post by Peter Connan » 10 May 2011 07:46

Dieselfan remember that the intercooler on the 3l Patrol sits on top of the engine and is fed air only through the bonnet scoop, it does not sit at the front of the car with the other radiators.

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Re: Bullbar causes overheating?

Post by Herrie » 10 May 2011 09:14

Maybe the top part of the bulbar deflect the air flow over the intercooler-scoop!
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Re: Bullbar causes overheating?

Post by AndriesS » 10 May 2011 09:32

Maybe it is not just the bull bar but the winch and the extra spot lights also hampering air to the radiator.

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Pieter du Toit
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Re: Bullbar causes overheating?

Post by Pieter du Toit » 10 May 2011 10:02

Hi All,

I would like to add my :mytwocents: as well.

For dieselfan's info I used to have a 3.0lt DI that also went boom!!!! I then did a 4.2 turbo diesel conversion - all factory specd. And yes I do have an aftermarket bullbar on my vehicle with two spotlights and a winchbox in between slap bang in front of the grill.

As you all will remember I also experienced an overheating problem after my conversion (dieselfan which I never ever had with the 3.0Lt diesel) - and I conducted several tests to investigate the cause and possible solutions to it. Well in the end I did all of the following alterations to improve the airflow to the extend where I have not yet experienced any overheating problems.

I started by moving the winch control box to the underside of the bumper. This already made a slight improvement but did not stop it completely.
I then removed the radiator and had it properly cleaned at Silverton radiators. Still not the required results I was looking for.
I then added an extra 25 row oilcooler which definately made a hug difference but still I was not satisfied that it completely overcame the problem.
I then moved my aircon condenser to the underside of my Patrol - this solved my issues completely with overheating and put a stop to it.

Dieselfan if you are interested you can read up on my alterations here viewtopic.php?f=51&t=1453&start=40

As a further enhancement for better hot airflow out of the engine bay I will be adding two air vents (Opel Astra type vents) on top of the bonnet soon - the vents have been ordered and will then be fitted more or less on the left and right sides of the intercooler. I will be doing this purely as a pro-active measure to prevent overheating as I am changing to an off road caravan which is standard a much heavier item to tow than the off road trailor.

I will post pic's once the job has been done.


For what its worth my :mytwocents: on dieselfan's statement.

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Re: Bullbar causes overheating?

Post by tour de frans » 10 May 2011 18:34

Pieter,en as ek kan bylas.Die waterpomp pully en ander fan blade wat n baie groot verskil op my 4.2 gemaak het.
Ek wil net noem vir wat dit werd is oor die thread.
The pully and fan made a huge diierance but did not slove the problem.Pieter has the same fan and pully on his engine,and he did all the other that fixed his overheating.Rather it's not overheating it's running hot.
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Re: Bullbar causes overheating?

Post by davejones » 11 May 2011 01:53

On all my longer trips, when fully loaded and on a hot day, if i steam up to a hill, i will manage egt's below 600deg but inevitably engine temp will rise, even with egts of 500deg.

I think this is nature of the 4.2 diesel engine whether with bullbar and front end kit (which i have) or not, turbo or not. I think you go through steps like Pieter and you dont see changes then yes you can start to worry!

Interestingly through, i went to see Alpine Developments shortly before eater holidays. The owner (i always forget his name) did mention that on the land cruiser air restriction from a bullbar is a real problem (he did not say what series and i did not ask), although ive never seen reference to this on the landcruiserclub forum.
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