Oil consumption.

[Tom W]

Not a P6 question, but a Rover V8 question I thought I’d ask here as you’re a knowledgable bunch and I’m not a member of a Range Rover forum. Too much opinion over knowledge on the Range Rover/Land Rover forums.

Anyway, hope this is allowed admins. My daily driver 4.6 Range Rover is using a lot of oil. I need to top it up every 1000 miles or it will go below minimum on the dipstick! It’s definitely burning it rather than dripping out. I’ve done the simple stuff and cleaned all the breathers out and throttle body. That didn’t fix it, so I think it must be rings or valve stem seals.

Is there a test I can do to determine which before I have to commit to stripping the engine? Would a compression test differentiate between the two?

It’s had valve stem seals done once before, but that was about 60k miles ago. The engine’s done over 200k now, so maybe it’s just very tired. I pulled out a few plugs to check and they all have a fine white deposit on them, I believe that indicates burning oil. It’s running LPG if that makes any difference.

Thanks, Tom

 

[harveyp6]

Anyway, hope this is allowed admins. My daily driver 4.6 Range Rover is using a lot of oil. I need to top it up every 1000 miles or it will go below minimum on the dipstick! It’s definitely burning it rather than dripping out. I’ve done the simple stuff and cleaned all the breathers out and throttle body. That didn’t fix it, so I think it must be rings or valve stem seals.

Is there a test I can do to determine which before I have to commit to stripping the engine? Would a compression test differentiate between the two?

Worn rings will show blue smoke out of the exhaust under load/acceleration, and the engine will breathe heavily with the filler cap removed, worn valve guide seals will often show a puff of blue smoke out of the exhaust on start up, and also on the overrun with a closed throttle.

If the compressions are low, adding some oil and retesting will show increased readings if the rings are worn, and no difference if it's the guides/seals at fault.

 

[Tom W]

Thanks Harvey, that’s what I thought re the compression test, but it’s good to get confirmation.

I’ll do a compression test and take it from there. I’m not aware of any blue smoke on acceleration, but it’s difficult to judge in a Range Rover. You sit high up and the exhausts point down, so smoke’s usually dissipated before it’s visible in the rear view mirror.

If I’m driving with a closed throttle for a while (downhill on a motorway), then try to accelerate, the engine stumbles, but not every time. I wondered if this was valve stem seals during oil in on the overrun then temporarily fouling the plugs when I try to accelerate. It’s difficult to assess with the LPG as I’m not sure that’s not causing other running issues. I’m too poor to run on petrol for too long. As soon as the weather picks up, I can use the P6 ever day and take my time sorting this out.

Thanks, Tom