XE oil consumption - worrying

[cmsapms]

 

During the recent trip to Le Mans, I noticed that my engine's oil consumption has increased substantially. It's always used a bit since it was rebuilt 2 years ago, especially on track days; but this trip, it used well over 2 litres on the way down (Yorkshire to Le Mans via Newhaven/Dieppe ferry), and I had to tip 3 more litres in before I got home again. The puzzler is that there is no oil collecting in the catch tank, there are no obvious leaks, and the only exhaust smoke is under initial hard acceleration, and is black rather than blue - indicating slightly too much acceleration enrichment.

 

The engine has been fitted with high compression pistons, Q450 cams and solid tappet inserts in the standard followers. The block was rebored for the new pistons, and was run in properly (500 miles on running-in oil with plenty of moderate exercise followed by an oil change, and plenty of stick).

 

As I don't seem to be getting any noticeable smoke, I can only assume that a small amount of oil is being burned all the time....ie not enough to see, but enough to make the consumption fairly horrific. The only thing I can think is that the oil is going down the valve guides. the valve guides were in good nick when the new cams went in 2 years ago. When I installed the solid tappet inserts in the followers, I didn't fill the hole in the follower that originally supplied oil to the hydraulic tappet. Could this oil be overwhelming the guides and/or their seals?

 

Any opinion on where the oil is going would be welcome before the oil consumption outstrips the fuel consumption.

 

Cheers

 

Paul

Westfield SEiW XE

 

[Roger King]

What sort of bore finish did the block get when you fitted the new pistons? Bore finish is critical to oil consumption and the adoption of 'plateau honed' finishes by OE manufacturers is the main reason that oil consumption of modern cars is so much lower than it was 20 years ago.

 

Before we adopted this technology many years ago, we could find that one in three engines used oil, but the problem is practically non-existent now.

 

In our experience, many reconditioners have never even heard of it - although many have.

[cmsapms]

 

To be honest, I don't know what bore finish was used. It looked (to the naked eye) like a 'cross hatch' finish. However, the bloke that rebored the block has a good reputation, and he spoke to QED (the suppliers of the pistons) before he did the work, so I assume the bores were correctly finished.

 

How can I tell at this stage whether the bores/rings are the cause of the problem? And, if they are the cause of the problem, what is the cure? Can I just have the bores rehoned (assuming no appreciable wear) and fit new piston rings? Would another session on 'running in' oil help the rings give a better seal?

 

Cheers

 

Paul

 

 

[Roger King]

All bores will have a crosshatch finish. The plateau honing is only apparent on a microscopic level. The best way is to ask the person who bored the block for you and you may well find that it has been done.

 

So long as dimensions are OK, there is no reason not to rehone and fit new rings. It is highly unlikely that running in oil will do any good at this stage.

 

Guide wear tends to show up as smoke from the exhaust on the overrun, whereas rings tend to let oil past all the time, but to be certain, you need to strip and inspect.

 

A cylinder leakage test might show up something if the compression rings are not sealing, but it won't directly tell you much about the oil rings - however, if the compression rings aren't functioning well, the chances are that the oil rings aren't either. In fact leaky compression rings can stop the oil rings working.

[cmsapms]

 

Thanks for the advice Roger.

 

I think I will struggle through this summer pouring oil into it, and then strip it and have it re-honed/re-ringed over the winter.

 

Cheers

 

Paul