Thread: My 86 Rangie Hiline

Originally Posted by bacicat

My theory on putting extra vents in is purely based on Top Gear by the way... Jeremys red RRC he had in that jungle special or whatever it was kept overheating until he took to the bonnet and put 2 huge holes in it - after that, it was the most reliable vehicle they had...

Scientific or what!

He said it only overheated because he broke the fan blades using it as a bulldozer to make a trail through the brush... right at the start of the show.

There was some guys on the Citroen DS lists that put a lot of effort into the heat soak issue. They worked out the best you could do was make sure you didn't clutter the back of the engine bay with insulation etc... you see getting the air under the bonnet wasn't the issue, it was exhausting the air (which has to past down the back of the engine and out underneath).

Isn't the back of the bonnet where most people put the vent a high pressure zone ? So will aggravate any cooling issues when moving. We found a pretty good article on this somewhere back then ....

AutoSpeed - Undertrays, Spoilers & Bonnet Vents, Part 1

You would need to put the vent in a low pressure zone so it allows air out ... and therefore more air into the engine bay through the radiator.

seeya
Shane L.

So, where's the low pressure zones?

Originally Posted by bacicat

So, where's the low pressure zones?

There is this guy with a manometer down in Melbourne, he's on the land rover forum .. and seems to know how to use one ... He might be able to work it out Seriously, scuttle area usually is a high pressure zone (that's why the air intakes for your ventilation is there).

Can you tape your manometer to spots around the top/side of the bonnet and see if you can find a low pressure zone

seeya,
shane L.

Gav.
This applies to the D2 so might not work for the RRC but;

Tombie has fitted RRS vents to his old D2, and chopped holes all the way through to the engine bay on at least one side, right where the side indicator is (can find pics if you want).
He reckons you can feel the heat coming out of them.
IIRC Serg (uninformed) also cut holes in the same spot on his 300tdi Defender and noticed lower under bonnet temps.
How hot should a 3.9 get?
I see 95 on my Td5 idling with the AC going, normally runs 88-90 on the highway 😊

Originally Posted by bacicat

My theory on putting extra vents in is purely based on Top Gear by the way... Jeremys red RRC he had in that jungle special or whatever it was kept overheating until he took to the bonnet and put 2 huge holes in it - after that, it was the most reliable vehicle they had...

Scientific or what!

Originally Posted by DoubleChevron

There is this guy with a manometer down in Melbourne, he's on the land rover forum .. and seems to know how to use one ... He might be able to work it out Seriously, scuttle area usually is a high pressure zone (that's why the air intakes for your ventilation is there).

Can you tape your manometer to spots around the top/side of the bonnet and see if you can find a low pressure zone

seeya,
shane L.

Sounds like an opportunity to do some science.

A manometer can be easily made with a length of clear hose and a ruler. Affix both to a board fo extra cool points.
Tape the ends of the hose to the area you want to measure, and the other to the radiator intake area for reference.
Low pressure will show as a higher waterline within the test area on the 'test' side (relative to the reference side.
If you have high pressure, other way around.

A few controlled runs with the apparatus atached to the vehicle should be sufficient. Mix up the speeds etc and you'll have plenty of data to make an informed modification.

A differential pressure gauge would also work. There are digital units that can be sourced off ebay relatively inexpensively, if you want something more bling than the $2 tube ruler and 2x4" solution.

Well, I never actually thought about getting that scientific with it, or thought about using a manometer even though I have one....

I'll see if I get time in the next few days to run some experiments.

Muppet - not sure what the temp should get to, but I'm paranoid about it as a 3.9 only needs to get a slight fever to kill it...

It was at 98 when I turned it off - as hot as I would ever like to see it. At a guess I'd think 105 upwards would be curtains for it, but not sure.

The td5 high temp warning on the nanocom is 96.5 iirc. Fans kick in at 110 until 105, I think 120 is when the idiot light comes on.

Sent from my HTC One using AULRO mobile app

Originally Posted by Disco Muppet

Gav.
This applies to the D2 so might not work for the RRC but;

Tombie has fitted RRS vents to his old D2, and chopped holes all the way through to the engine bay on at least one side, right where the side indicator is (can find pics if you want).
He reckons you can feel the heat coming out of them.
IIRC Serg (uninformed) also cut holes in the same spot on his 300tdi Defender and noticed lower under bonnet temps.
How hot should a 3.9 get?
I see 95 on my Td5 idling with the AC going, normally runs 88-90 on the highway 😊

all the vents will work when stationary ..... What if they reverse flow at speed and reduce the cooling capacity though vents through the side of the bonnet/guard would have to be a low pressure area wouldn't it