Thread: Range Rover 3.9 Tuning

Originally Posted by JHolds

Hi All,

If you have suggestions for other things to check, i am all ears.

Hello...and welcome to AULRO......the best garage on the net.

Can't help with the timing but as for other things to check.

I would recommend a check and/or refurb of the cooling fan viscous hub. These 3.9s' do not tolerate any overheating at all. This is small dollars when compared to an overheating incident and the following expensive consequences of such. Also - if it wasn't done before when the top end was done perhaps also consider a rodding of the radiator.

What's the 3.9 in.... a classic RR or a Disco?

Originally Posted by Grumbles

Hello...and welcome to AULRO......the best garage on the net.

Can't help with the timing but as for other things to check.

I would recommend a check and/or refurb of the cooling fan viscous hub. These 3.9s' do not tolerate any overheating at all. This is small dollars when compared to an overheating incident and the following expensive consequences of such. Also - if it wasn't done before when the top end was done perhaps also consider a rodding of the radiator.

What's the 3.9 in.... a classic RR or a Disco?

Much appreciated! The 3.9 is in a 91 RRC. I would have to say the viscous hub has probably never been checked or refurbed, I guess i never gave it thought because the temp gauge has always been so steady, though I am not sure how much faith I should put in the temp sender and/or gauge accuracy haha. So i will put that on the list!

Rodding the radiator, is this more cost effective than straight out replacing it? I have replaced the water pump and the heater core recently (because it started leaking - I NEVER WANT TO DO A DASH OUT JOB EVER AGAIN!!!)

A classic Rangie eh......that automatically elevates you to elite status.

I wouldn't put much faith in the factory dash temperature gauge. By the time it moves damage is already done. Been there and done that with the result being a new short engine and a top end rebuild.

What you might consider is a combined low coolant level/overheating sender fitted to the top of your radiator. This will allow you to save an engine if say a stray stick takes out a radiator hose. Instant notification is the name of the game. My sensor sits in the very top of the radiator and if the coolant level drops just a few mm the dash mounted warning light turns on.

Sorry - can't help re radiator costs.
Coolant pump replacement was a good move and 'onya' for removing the dash.

There are a few basic tuning tricks for a 3.9 that's using more fuel than usual.

1. Check that the idle timing is set at around 10 degrees BTDC at idle, then check that the mechanical and vacuum advances are both working. Cost to the owner: one cheap timing light off ebay, around $30.

2. Check that the fuel pressure regulator vacuum hose is plugged into the little vacuum nipple at the back of the stepper motor housing, and also it's not dripping fuel into the inlet manifold.

3. Check the resistance of the ECU temp sender, a 2 wire plug just behind the engine thermostat. It should read around 300 ohms with a hot engine. Note: this sender is totally separate from the dash gauge sender which is a single wire jobbie next to the ECU sender. Cost: a small multi meter, not much.

4. Find out where to measure the voltage at the output wire of the MAF and adjust according to specs. Multi meter used as above. Use the search function to find specs. Alternatively use a CO meter, you may have to borrow one. The adjustment screw on the MAF is facing the engine from memory.