Oil Leak BMC 1800

[The Boat Studio]

We have a BMC 1800 engine. Engine oil is leaking into the exhaust pipe. The engine cooling water is not contaminated with oil and there is no water getting into engine oil.

 

The engine has been running smoothly with clean exhaust no smoke.

 

Any suggestions as to where we should start looking for the fault?

 

 

 

[RLWP]

Exhaust valve guides, possibly broken rings.

 

Richard

[Chalky]

Check the oil separator first. This is on the front tappet chest cover. Inside there is a wire 'pan scraper' which collects the oil vapour and returns it to the dump. If this is clogged then it won't separate the vapour and it will get fed into the inlet.

 

If this is OK then as Richard says.

Edited September 29, 2016 by Chalky

[RLWP]

Check the oil separator first. This is on the front tappet chest cover. Inside there is a wire 'pan scraper' which collects the oil vapour and returns it to the dump. If this is clogged then it won't separate the vapour and it will get fed into the inlet.

 

I'm constantly amazed at the amount of oil you can pass unburnt through a diesel engine

 

Richard

[David Schweizer]

We have a BMC 1800 engine. Engine oil is leaking into the exhaust pipe. The engine cooling water is not contaminated with oil and there is no water getting into engine oil.

 

The engine has been running smoothly with clean exhaust no smoke.

 

Any suggestions as to where we should start looking for the fault?

 

 

 

 

This is not a very optomistic comment, but that started to happen on our old BMC 1.5. It turned out that everything was badly worn, and we ended up having the engine completely re-built.

[The Boat Studio]

 

This is not a very optomistic comment, but that started to happen on our old BMC 1.5. It turned out that everything was badly worn, and we ended up having the engine completely re-built.

Oh dear! This is what we are fearing!

[Mike Jordan]

I had a similar problem with a 1.8 a few years back, it took some time to find the cause of the problem but it turned out that I had caused it myself.

I had previously taken the head off and lapped in the valves, on reassembly I had put valve stem seals on both inlet and exhaust valve stems (they were included in a set of pattern parts which included the head gasket and all other parts for the job) the engine didn't originally have seals on the exhaust valve stems.

It turned out that the heat of the exhaust valves had welded the rubber seals to the stems after a few hours of use, this turned them into superb little pumps which went up and down with the valves, forcing a small amount of oil down the stem with each stroke.

I managed to shine a torch through the valve spring to spot the problem and then found that it's possible to put the Pistons on TDC and remove the valve collets using an ad hoc compressor without removing the head again! It was not difficult to do but I needed a third hand when replacing the collets. I considered myself fortunate that the oil oozing through a joint in the exhaust system and contaminating the obligatory lagging hadn't started a fire.

It may be that this is not the cause of your problems but it must be worth a look!

Mike.

[The Boat Studio]

Thanks for your replies,

 

We've had a new head gasket put on and going to see whether this helps things (not feeling hopeful) Looks like we might have to re build engine over winter.

[RLWP]

We can supply a reconditioned 1.8

 

Richard