1990s Range Rover 4.6ltr V8 Timing failure

[SuperV8]

This was a known fail point…so much so that in high performance and higher revving engines they fitted an external oil feed to lubricate the gear.

Ian

Especially if high pressure oil relief springs are used putting more force through the gears.

[FBW]

Hello everyone,

I'm pretty sure it's not the oil pump. The problem and the cause is the gear on the distributor shaft.
The gearing is poorly made and relatively rough. That wouldn't be a big deal. It would wear in after a short time.
But! The gear is also much too hard and practically doesn't wear out.

>> Rough surface + high hardness = a file.

A little experiment: Simply scrape the edge of the gear across a beer bottle with a lot of pressure. You can scratch glass with it.

That means the part is as hard as ball bearing rings.

The worm gear on the camshaft needs to be replaced. The one on the distributor needs to be replaced with one from an old original Lucas distributor, and the problem is solved.


Greeting
Frank

PS: Does anyone want to know how I know all this?

[SuperV8]

Hello everyone,

I'm pretty sure it's not the oil pump. The problem and the cause is the gear on the distributor shaft.
The gearing is poorly made and relatively rough. That wouldn't be a big deal. It would wear in after a short time.
But! The gear is also much too hard and practically doesn't wear out.

The problem with the oil pump is that it is driven from this gear. It was 'common' to fit high pressure relief springs in the oil pump - which obviously put more stress through this drive gear and dizzy shaft - exaggerating the gear problem you mention.

[FBW]

Sure, if more load is added, it goes even faster. The engine in the pictures above only had the standard spring in the oil pump.

The basic problem is the poor quality and excessive hardness of the aftermarket distributor gears.


Best regards,
Frank

[bbutc]

The timing issue is now fixed.

Turned out that the CAM shaft retaining plate was never fitted, so another black mark against RPi.

Not out of the woods yet though as the engine has now developed a bad vacuum leak.

Thanks to all commenters.

[FBW]

There's no reason why a wandering camshaft should wear out the worm gear like that.
I'm sure it was the distributor gear.

The worm gear will wear out again after a similar mileage.

Best regards,
Frank

[bbutc]

Vacuum leak has been traced to a faulty idle control valve (the old Land / Range Rover one with the stepper motor) - should be an easy fix.

I've already got a replacement off Amazon. I couldn't get the old one apart so I put it in the bench vice and hit it with a lump hammer - turns out that you can adjust them by turning the plunger - didn't know that.

[bbutc]

Unfortunately, it's NOT the idle control valve, or a vacuum leak because I noticed that the problem is still present with the idle control valve disconnected and the hole blocked up. - Please see the video. The vehicle drives and behaves normally for about 15min, and then all of a sudden the tick over goes up from 1000 RPM (Normal) to 1400 RPM and stays there. Anyone seen this one before? The problem seems to be heat related, so I'm assuming it's a sensor problem - but which one?

Video > https://youtu.be/3F9gOt-qkvE

Thanks for any input.

Ben
DAX Rush 4.6ltr V8

[SuperV8]

What ECU is controlling your idle stepper motor?
1000rpm is still too fast for normal warm idle.

[bbutc]

The car has a standard 1990 Lucas hot-wire fuel injection ECU but with a 'Tornado' chip.

The tick-over was 1000rpm when I bought the car and it seemed fine, even though the chip states it should be 800rpm.

I've just bought a 'Rover Gauge' and will be plugging it in at the weekend. Never used one before, but I'm sure others on this forum have, and can help me diagnose the problem.

Cheers.

[bbutc]

OK, I've plugged everything in and powered everything up but the software doesn't seem to be able to communicate with the ECU even though the laptop can see the device, but there are no LEDs lit up - should there be? I believe there should be communication with just the ignition on. My laptop only has USB3 ports - could that be it? See photos below. Thanks.

https://1drv.ms/i/c/2f45721d87dd50c4/EW ... Q?e=CEVSzB

https://1drv.ms/i/c/2f45721d87dd50c4/EY ... Q?e=hbJC0H

https://1drv.ms/i/c/2f45721d87dd50c4/EV ... w?e=cWgrAl

https://1drv.ms/i/c/2f45721d87dd50c4/Ed ... g?e=EswT4h