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1990s Range Rover 4.6ltr V8 Timing failure
Posted: Wed May 21, 2025 7:19 pm
by bbutc
Hi all, hope you are all out and about in your V8s enjoying the great weather, I was.
At about 70 the engine began to splutter and backfire, so I pulled over and now it won't start again. The AA man said it sounded like engine's timing is totally out, like the timing chain has jumped, but as far I know, the 4.6ltr 1990's Range Rover engine only has 2 pullies and is very simple, is it possible for it to jump teeth under heavy load, or is there another common point of failure on the timing system?
Engine was developed by RPI engineering and has only done 5K miles and was recently dino'ed with a clean bill of health.
https://1drv.ms/i/c/2f45721d87dd50c4/EQ ... A?e=pzrpz4
Thanks for any advice.
Ben
Re: 1990s Range Rover 4.6ltr V8 Timing failure
Posted: Thu May 22, 2025 10:06 pm
by bbutc
OK - Got an update on this, been talking to an 'expert' on the Range Rover V8s and he says he's never heard of a 4.6ltr timing chain jumping as it's more likely to snap rather than jump, but what he has heard of is the distributor shaft striping its teeth where it meets the cam shaft sprocket, and this is most likely what has happened given what I told him.
So what I need to know now is what part of the engine has to come off in order to replace the parts? Just a cam cover or the front plate, or does the distributor shaft go all the way down through the engine like the American V8s? This is a worst case scenario, but I think the ignition system on this engine is purely mechanical so its not going to be the failure of some cheap electrical component because there aren't any.
Thanks.
Re: 1990s Range Rover 4.6ltr V8 Timing failure
Posted: Fri May 23, 2025 12:37 pm
by garrycol
If it is a standard Rover 4.6 it will have Gems or Thor injection/ignition systems - neither has a distributor.
The engine may have been modified to replace the timing case with a earlier system which may have a dizzy. If it is a standard 4.6 it should not have a dizzy.
Re: 1990s Range Rover 4.6ltr V8 Timing failure
Posted: Fri May 23, 2025 3:38 pm
by scudderfish
Post some pictures so we can see what you've got.
Re: 1990s Range Rover 4.6ltr V8 Timing failure
Posted: Sat May 24, 2025 9:32 am
by bbutc
Hi - Picture of the engine in the first post above (seems to be working). Thanks.
https://1drv.ms/i/c/2f45721d87dd50c4/EQ ... A?e=pzrpz4
Standard Rover CAM covers have been replaced with some Edelbrock ones, dizzy at the front.
Re: 1990s Range Rover 4.6ltr V8 Timing failure
Posted: Sun May 25, 2025 5:58 am
by Ian Anderson
I hate to say it but if you have stripped the gear on the distributor I see a complete engine tear down, clean and check.
The metal that was stripped of could have made it anywhere in the oil ways. So any bearing would now be suspect in my opinion.
Sure the oil filter should collect all the debris but there is also a bypass so……
Ian
Re: 1990s Range Rover 4.6ltr V8 Timing failure
Posted: Mon May 26, 2025 8:09 am
by stevieturbo
Simple things first.
If you rotate the engine, does the rotor arm turn ? And does it appear to point at cyl1 tower/lead when cyl1 TDC is on compression ?
If the dizzy drive is busted, yes there will be debris. But also hopefully the engine will have stopped too before that debris could get too far, as the dizzy will also stop working....as will the oil pump.
Re: 1990s Range Rover 4.6ltr V8 Timing failure
Posted: Tue May 27, 2025 1:07 pm
by SuperV8
bbutc wrote: ↑Thu May 22, 2025 10:06 pm
OK - Got an update on this, been talking to an 'expert' on the Range Rover V8s and he says he's never heard of a 4.6ltr timing chain jumping as it's more likely to snap rather than jump, but what he has heard of is the distributor shaft striping its teeth where it meets the cam shaft sprocket, and this is most likely what has happened given what I told him.
So what I need to know now is what part of the engine has to come off in order to replace the parts? Just a cam cover or the front plate, or does the distributor shaft go all the way down through the engine like the American V8s? This is a worst case scenario, but I think the ignition system on this engine is purely mechanical so its not going to be the failure of some cheap electrical component because there aren't any.
Thanks.
First I would pull the dizy out - just undo the clamp and it pulls out - and inspect the drive gear.
Do you have a high oil pressure spring? The oil pumps are driven by the end of the dizy on the older front covers, and the higher oil pressure puts more stress on the drive gear.
The later front covers have crank driven oil pumps.
If it is the gears - you would need to pull the front cover and drop the sump to check for debris in the strainer.
This might be interesting:
viewtopic.php?t=13544
Re: 1990s Range Rover 4.6ltr V8 Timing failure
Posted: Tue Jun 03, 2025 4:19 pm
by bbutc
Needs a CAM shaft.
[
https://1drv.ms/i/c/2f45721d87dd50c4/EX ... Q?e=K2egwn
https://1drv.ms/i/c/2f45721d87dd50c4/Ee ... Q?e=bKtwtg
Can anyone recommend a garage familiar with this engine and can carry out this work at a reasonable rate? - Thanks.
Ben
Re: 1990s Range Rover 4.6ltr V8 Timing failure
Posted: Wed Jun 04, 2025 7:31 am
by SuperV8
bbutc wrote: ↑Tue Jun 03, 2025 4:19 pm
Needs a CAM shaft.
Can anyone recommend a garage familiar with this engine and can carry out this work at a reasonable rate? - Thanks.
How do you know is needs a camshaft?
Could it just be the bolt has undone/failed from over/under torque? Can't see from your photo.
Also - it would be helpful to let people know where you are in the world, as you are asking for workshop recommendations.
Re: 1990s Range Rover 4.6ltr V8 Timing failure
Posted: Thu Jun 05, 2025 1:18 pm
by GDCobra
Looks to me like you need a new distributor/oil pump drive gear, neither picture indicates a camshaft problem.
The gear is a seperate part.
Re: 1990s Range Rover 4.6ltr V8 Timing failure
Posted: Thu Jun 05, 2025 1:28 pm
by SuperV8
Looking at your cam dizy drive gear again - the corner looks quite rounder off - vs the genuine gear which has quite sharp corners - though it is hard to tell from your images.
Re: 1990s Range Rover 4.6ltr V8 Timing failure
Posted: Thu Jun 05, 2025 9:49 pm
by bbutc
Thanks to all, this is very useful information as I thought the helical gear was part of the CAM shaft. Now I know it can be replaced separately it should be a much simpler and cheaper job!
I based in Derby but can transport the car to anywhere in the country if anyone wants to recommend a garage who could do this work.
Re: 1990s Range Rover 4.6ltr V8 Timing failure
Posted: Sat Jun 07, 2025 11:43 am
by bbutc
Update: Both gears are now on order from Turner Engineering. However, Turner Engineering were not very comforting about the outcome as they said that the timing gear would not fail in isolation and something must have caused it but I won't find out what until the front cover is removed.
I'm currently trying to talk the garage across the road from me into doing the work.
Re: 1990s Range Rover 4.6ltr V8 Timing failure
Posted: Sat Jun 07, 2025 8:10 pm
by Ian Anderson
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