Oil consumption

[405dh]

Hi Peter. If the engine has had very little use in the 4 years since being rebuilt and only just had a decent run, I would suspect sticking piston rings or possibly a broken ring(s) as a result of long period of inactivity.
I would advise the rebuilder of your problem and seek their advice as to how best to determine the cause. Only when you have found the cause can you decide if the rebuild has been at fault or something caused by long term inactivity.

A 4 year period since the rebuild puts you in a bit of a difficult position so tread carefully as I think you need some goodwill from the rebuilder to help in the diagnosis of the problem and its rectification. Good luck!

Chris.

[Geoff Dowdle]

peterg,
that is massive oil consumption regardless of the 4 years since the rebuild .
Did any of the spark plugs foul during the long run ??
I suggest you inspect all the plugs to see their condition and oil content .
Check if they are all the same . A compression test is also worthwhile but not an indication of oil consumption

I'm my experience even one pint in 200 miles is more than excessive during a run in period.

It will not be the valves !!
I agree you should talk with the rebuilder as the engine will most likely need a total strip down .

Geoff D

[peterg]

My specialist reccommends a rebore with Cosworth pistons at an estimated cost of £6,400 assuming no other work is required.

In between the car has been doing about 400 miles per year and has had 4 oil changes, hence I didn't notice the oil consumption although I thought it a bit low last time.

While I'm thinking of it on the trip to Germany the car was run at 3,200 - 3,500 rpm (65 - 75 mph aprox) at mid 20's c. and the water and oil temperature rose to 90 o F. (oil about 5 degrees lower) with no oil cooler. Fuel consumption was between 24 and 31 mpg.

The engine ran smoothly but was rather lumpy at tick over speeds (5 -900 rpm)

[peterg]

Further to this, is it feasible to replace the rings and hone the bore without taking the engine out?

I am faced with getting the work done at a low cost or disposing of the car, having poured tens of thousands of pounds into the car and still not having a reliable vehicle.

[Geoff Kingston]

It is possible to get the Pistons out to hone the bores and replace the rings with the engine still in the car but the head obviously has to come off.
£6400 for a set of Cosworth pistons and a rebore sounds absolutely crazy money to me, how much are the pistons and the rings?
If the pistons were left in place one would hope excessive wear was not an issues but if the bores were glazed that would not help especially if you have stuck worn or broken rings.

[peterg]

Works out about £1,000 for the pistons, £4,000 labour plus any other costs - boring, honing and materials.

Hence if if they can be replaced and honed without the head coming off and engine in situ there should be a big saving in labour and piston costs.

The engine was completely rebuilt with new liners and pistons (from Bristol's) 40 years or 20,000 miles ago, so there should be minimal bore wear. I do remember the specialist saying that he could still see the honing marks in the bore of the cylinder.

If there are any people in the west country who can do the job for less I would be very interested!

[Kevin H]

Peterg, that's a huge amount of oil for the engine to burn in 40 miles and continue running properly. Are you sure you haven't got an oil leak? It's possible for an engine to leak little or no oil when ticking over, but leak quite a bit under load when the oil pressure is higher, although even then, a pint every 40 miles is still a lot!

Have you driven it several times and each time experienced the same loss of oil?

As for replacing the pistons, £6400 seems very expensive. How many hours labour are included for £4000?

I think you need to do some proper diagnosis before getting too gloomy. As Stefan says, a compression test is essential and while you're at it you can check the state of the plugs. If it's really burning that much oil I would expect the plugs will be heavily oil fouled, to the point where the engine is missing and probably becoming hard to start.

Never had an engine "rebuild" where they leave the pistons in place, I hope you didn't pay much for it!