BMC 1.5 Burning engine oil

[Theo]

No. 1 son and his wife have taken Theodora over to Burton on Trent in the past few days. It seems that she has started burning lube oil. Apparently it goes from max to min on the dip stick with a couple of days motoring.

 

Is this something that needs to be attended to as an emergency measure or will she happily go for years like this? I am just thinking of the over running thread that I read a few weeks ago.

 

Nick

[bottle]

Hi

 

I do not know how much the oil is costing but surely some repair/reconditioning would pay for itself pretty quickly.

 

 

Watch out for the green brigade all that pollution burning oil, unless you have a leak somewhere

[Theo]

Hi

 

I do not know how much the oil is costing but surely some repair/reconditioning would pay for itself pretty quickly.

Watch out for the green brigade all that pollution burning oil, unless you have a leak somewhere

 

 

I would probably agree but burning lube oil could be pricey to sort. Engine out, big ends undone, pistons out, new rings...

 

Nick

[Supermalc]

Hi Nick - first thing is to find out just where the oil is going. Is it under the engine, or in a container slung under the breather, or is there a trail of blue (not black) smoke.

 

If this has started fairly quickly it is a possibility of a blocked breather, so the sump oil mist has nowhere to go, so is either blown out of the breather, or burnt.

 

As I discovered on my old Renault van, as soon as the breather gets blocked the oil is blown out very quickly, although I doubt your engine will be revving hard enough.

 

In any event, check and clear all the crankcase breathers, also any going to the air intake, or into the rocker cover.

 

It's very difficult to diagnose engine faults without actually inspecting them.....unless it's a particular fault with a certain type of engine....for instance with my YSE12, the governor needle valve gets a flat spot that can cause the engine to stop, and fail to restart, unless you tug on the governor arm. Something I was not only pleased to discover, but was able to pass on to others, who are in fact very grateful, as I would be.

 

I don't mind having a look if Theo is back at Thurmaston next weekend when I come over for the BBQ, and I expect Roger will also go, and he is a very clever engineer.......little he doesn't know, or hasn't experienced.

 

It's 1500 to 2000pounds to recondition one of these engines properly btw.

Edited May 27, 2007 by Supermalc

[Guest]

Has this started suddenly? Has the engine been doing a lot of out of gear battery charging of late? Are all breathers clear?

[Theo]

Hi Nick - first thing is to find out just where the oil is going. Is it under the engine, or in a container slung under the breather, or is there a trail of blue (not black) smoke.

 

If this has started fairly quickly it is a possibility of a blocked breather, so the sump oil mist has nowhere to go, so is either blown out of the breather, or burnt.

 

As I discovered on my old Renault van, as soon as the breather gets blocked the oil is blown out very quickly, although I doubt your engine will be revving hard enough.

 

In any event, check and clear all the crankcase breathers, also any going to the air intake, or into the rocker cover.

 

It's very difficult to diagnose engine faults without actually inspecting them.....unless it's a particular fault with a certain type of engine....for instance with my YSE12, the governor needle valve gets a flat spot that can cause the engine to stop, and fail to restart, unless you tug on the governor arm. Something I was not only pleased to discover, but was able to pass on to others, who are in fact very grateful, as I would be.

 

I don't mind having a look if Theo is back at Thurmaston next weekend when I come over for the BBQ, and I expect Roger will also go, and he is a very clever engineer.......little he doesn't know, or hasn't experienced.

 

It's 1500 to 2000pounds to recondition one of these engines properly btw.

 

Thanks very much for the offer, Malcolm. Unfortuately we will not be able to get her back until late Sunday, I would think. I will have a good check around for breather blockages and get back to you. I will be going down to Fradley on Wednesday to start bringing her home.

 

I have the engine manual but have not looked to see where the breathers are. How will I clean them out if they are blocked?

 

 

 

Nick

 

Has this started suddenly? Has the engine been doing a lot of out of gear battery charging of late? Are all breathers clear?

 

 

The first time I noticed it was when the engine was worked quite hard on the Soar. It came on quite quicky. After she had cooled down over lunch the problem went away, though.

 

I have only run the engine for a total of about 3 hours battery charging at Thurmaston. Apart from that it has been all normal cruising, but not a great deal of that until this week.

 

Nick

[Chris J W]

Wasn't there a thread a month or so back about engines that started to run on their own oil? Seem to remember it came under the heading of "a bad thing"? (Why can I never get the bloody search to work??)

 

Haha! Found the thread I was thinking of, but I admit I may have miss-remembered.

 

The Run-Away Engine Thread

Edited May 27, 2007 by Chris J W

[Supermalc]

Ok......I'm probably being too cynical, but you may???? have found the reason you have the boat. Many boats seem to be sold because of some problem or other.

 

For instance, my Norman had no oil pressure on the little Honda outboard. The Microplus had a bent prop. My boat had a prop of the wrong direction fitted (the biggest fault). If??? the Mk1 22 Freeman I've just spent the day with yesterday has a hydraulic gearbox, it seems this has problems, which is why it was sold very cheaply. The Senior/Project at Bardney was sold with too duff engines and boxes.....1000s spent repairing last year. And I could go on and on and on.

 

BUT......just to look on the bright side, it does sound like a blocked breather, and keeping clean oil and filters, regularly clearing, even replacing the breather pipes, and keeping the revs down, will keep things going for years.

 

With my old van I ran it for a few more years, just keeping the speed to about 55 to 60 on long runs, or stopping every 50 miles or so.

 

Even if you don't have Theo back I'll still come and have a look with you if you want. Hope you can make the BBQ anyway.

[David Schweizer]

I have the engine manual but have not looked to see where the breathers are. How will I clean them out if they are blocked?

 

The first time I noticed it was when the engine was worked quite hard on the Soar. It came on quite quicky. After she had cooled down over lunch the problem went away, though.

Nick

I have three Workshop manuals for the BMC 1.5, and none of them actually show the crankcase breather arrangement, only the Thorneycroft versin illustates it. The crankcase breather is welded to the forward tappet cover plate on the right hand side of the engine, underneath the manfolds. On the earlier models there is a short lenth of rubber tubing that carries the air into a gauze filled Air Filter. If this gets soaked withn oil it can cause excessive smoking. On later models the air is taken diectly into the Inlet manifold where any excess oil is burnt off and will be emitted as smoke. There is also a Gauze filter inside the tappet cover, which should be cleaned out at (unspecified) regular intervals, it is a real pig of a job without taking the manifolds off.

 

It would be advisable to check the crankcase breather facility first, but if the amount of smoke becomes excessive and does not go awauy, it is probably the sign of something worse. All BMC 1.5 engines tend to smoke a bit, especially when cold and when worked hard after they have been on light load for a while. But large volumes of smoke will probably be being caused by broken or sticking rings, or worn bores, both of which require complete stripdown to rectify.

Edited May 29, 2007 by David Schweizer

[Theo]

I have three Workshop manuals for the BMC 1.5, and none of them actually show the crankcase breather arrangement, only the Thorneycroft versin illustates it. The crankcase breather is welded to the forward tappet cover plate on the right hand side of the engine, underneath the manfolds. On the earlier models there is a short lenth of rubber tubing that carries the air into a gauze filled Air Filter. If this gets soaked withn oil it can cause excessive smoking. On later models the air is taken diectly into the Inlet manifold where any excess oil is burnt off and will be emitted as smoke. There is also a Gauze filter inside the tappet cover, which should be cleaned out at (unspecified) regular intervals, it is a real pig of a job without taking the manifolds off.

 

It would be advisable to check the crankcase breather facility first, but if the amount of smoke becomes excessive and does not go awauy, it is probably the sign of something worse. All BMC 1.5 engines tend to smoke a bit, especially when cold and when worked hard after they have been on light load for a while. But large volumes of smoke will probably be being caused by broken or sticking rings, or worn bores, both of which require complete stripdown to rectify.

 

Thanks, David. We are going down to Fradley tomorrow to start getting her back. I will assess the situation while we get her back to Raynesway. I will be off line (internet wise) from tomorrow until Sunday.

 

Nick

[Guest]

Another thought:what make and grade of oil are you using, and had you changed oil recently before it started burning it? My previous Yanmar was generally better on the low tech supermarket oils (havoline). If you put high spec oil in it used to burn it off.

[David Schweizer]

Another thought:what make and grade of oil are you using, and had you changed oil recently before it started burning it? My previous Yanmar was generally better on the low tech supermarket oils (havoline). If you put high spec oil in it used to burn it off.

Good point. Morris Oils recomend Supreme30 for the BMC 1.5, and advise very strongly against any modern style oils with additives. apperntly they can damage some older style engines.

 

Oh a little bit of advice about the tappet cover, getting it off is simple enough, but re-fitting can be a pig because the gasket always seems to fallout of place when manouvreing the cover under the manifold. To keep it in place run some silicone into the groove on the cover and press the gasket into the groove before fitting.- courtesy of the fitter at Reading Marine, who helped me out free of charge, when I was having problems re-fitting the cover on my engine some years ago.

[Barry]

Oh a little bit of advice about the tappet cover, getting it off is simple enough, but re-fitting can be a pig because the gasket always seems to fallout of place when manouvreing the cover under the manifold. To keep it in place run some silicone into the groove on the cover and press the gasket into the groove before fitting.- courtesy of the fitter at Reading Marine, who helped me out free of charge, when I was having problems re-fitting the cover on my engine some years ago.

 

Or you could go what I used to do when I was at sea - stick the gasket in with a little bit of grease - cheaper

[David Schweizer]

Or you could go what I used to do when I was at sea - stick the gasket in with a little bit of grease - cheaper

I tried that first (it was the way I used to attatch Motorbike crankcase gaskets) but is such a fiddle to manouvre the cover plate into position that it always caught on something and moved it. The silicone worked first time (on a new gasket!!)

[StephenA]

The oil filler cap on our BMC 1.5 has gauze in it and is obviously designed to help vent the crank/rocker.

 

We do get problems with the air filter - if that gets clogged up at all then the engine tends to suck in from the crank case breather pipe. It might be worth checking to see if there is any sign of oil in the inlet manifold.

 

The amount you are getting through would however suggest that its not oil fumes getting burned but you either have a leak or there is something worn in the engine.

 

Oil could be getting in via worn valve stem seals or round worn piston rings. Leaking valve stems do tend to show up at startup when oil has been able to pool in the cylinders.

 

We've had two sets of work done on our BMC in the past 21 years - it had a bottom end rebuilt at Calcutt who did a minor rebore and new rings - that was about 8 years ago and then 2 years ago we had the top end overhauled by Starline at Upton Marina. I can't tell you how much the bottom end work cost but Starline came in at a couple of grand (including some other work)

 

Since the top end rebuild we get a tiny little bit of smoke when its cold and apart from that its pretty smoke free. Which isn't bad for an engine with lots of leading zeros on its serial number.

 

Starline did however tell us that parts for the BMC 1.5 are now becoming harder to get.. which implies that costs can only go up.

[John Orentas]

Hi Nick.

 

Yes there are lots of scenarios for the excessive use of engine oil from blocked breathers to holes in the engine, great if you are a natural optimist but I think you should brace yourself for the realisation that it is in technical jargon 'Knackered'. The overwhelming probability is that it will want re-boring, crank re-grind and so on.

 

Start looking around for a exchange unit. It will certainly not require a complete marine replacement, all the expensive marinising bits you already have and they should be OK.

[Theo]

Right. This is the situation as far as I can establish it from a few days' cruising.

 

I don't know what no. 1 son was doing but when we started the engine there was the usual puff of white smoke and it settle down to a sensible tickover. I did not see any excessive smoke in the nearly five days that we were cruising. I never wound her up to full bore but did some lengthy bits at 5mph (ground speed) against the Soar so that gave the engine a bit of a work out!

 

The actual oil usage was a little more than I would have liked but I found that we were going through about half the min-max range on the dipstick for a day's cruising. I have not yet investigated the nastiness that lies below the engine. It is really difficult to get to it because the propshaft runs under the engine. I do suspect that there might be a leak somewhere but that will only be establised when I have cleaned everything up. How I do that remains to be seen!

 

Nick

Edited June 6, 2007 by Theo
Punctuation!

[Tony Brooks]

snip

 

I do suspect that there might be a leak somewhere but that will only be establised when I have cleaned everything up. How I do that remains to be seen!

 

Nick

 

 

Oil only type bilge blankets or pillow in the area for a couple of days top absorb most of the oil (often white material).

 

Sponge most of the remaining liquid into a bucket for disposal.

 

Spray engine cleaner over the whole area and agitate with something like a toilet brush (stiff bristles and long handle for reaching under engine). Extend handle with insulating tape and stick as required.

 

Spray water onto the muck and agitate again to emulsify the muck. Sponge/pump into buckets for disposal.

 

Repeat as required.

 

Use a bilge blanket from now on.

 

Carry out well known 1.5 breather mod by fitting longer breather hose to side cover and terminate in plastic milk bottle.

 

 

If no major leak is found get supply of cheap oil (Comma 20W50 API CC from motor factors about £5.00 after discount) and stop worrying.

 

Tony Brooks

[Moley]

If no major leak is found get supply of cheap oil and stop worrying.

 

Thanks for all of the comments on this thread, which I've lurked over for a while, but as we've still got no internet connection at our new w**k premises I've only been logging on briefly at home.

 

Our old BMC 1.5 uses oil too, although I would say I only top up a quarter of a pint every other day. The exhaust smokes a little, and there's a drip somewhere underneath, but it's nothing I'm too worried about at the moment. Will clean the filter and check breathers as discussed.

 

Slightly off topic, I dipped the fuel tank last night as we've been away for the week and the tip of the rudder now seems an inch further out of the water, and my sums are as follows:

 

We took on 200 litres at Easter and have used exactly half of the rise on my measuring stick.

 

Since then we have done 176 miles and 202 locks, but don't have any fancy gizmos like an hours meter.

 

176 miles at average 3mph = 59 hours.

202 locks at average 10 mins or 6 locks per hour = 34 hours.

 

100 litres in 93 hours seems quite acceptable to me. How'bout you lot?

[Serendipity]

100 litres in 93 hours seems quite acceptable to me. How'bout you lot?

 

I did a calculation last year from top up to top up and reckoned 0.78 l/h on my BMC. I record engine running hours so worked it that way. 45 foot boat, and a proportion of that would have been stationary for battery charging.

[Theo]

After all the good advice I am now feeling perfectly happy with the engine! Tony Brooks' step by step engine cleaning guide (see above) appeals. When I retire (43days, 4hours and 52minutes ) I will do that and spend all day on it and end up with a sparkling engine and lots of cans of oily and mucky water to get rid of.

 

 

 

Nick

[Liam]

Tony Brooks' step by step engine cleaning guide (see above) appeals.

Nick

 

Tony, Nick... do you have a link please?

[Theo]

Tony, Nick... do you have a link please?

 

I waas referring to his post earlier in this thread but heare is the link to it:

 

http://www.canalworld.net/forums/index.php...st&p=134145

 

 

Nick

[Serendipity]

Since this thread started, my BMC has started smoking big time - and I can pinpoint when it commenced to last weekend when I started it as usual momentarily on full throttle, and it sent out enough smoke in the second it takes to knock the throttle back, to hide my position in the marina. Here are the symptoms i've observed in the four hours running time since:

 

• Tickover - usual gentle blue smoke i've allways seen.
  
• up to 1800, more smoke than i'm used to seeing sometimes - if knocked back to idle and gently increased again, then it reverts to what i've seen in the past (moderate blue smoke).
  
• 2200 revs alarming clouds of blue smoke.
  

Oil pressure 20psi idle, just under 40psi fast idle onward (no discernable change).

 

This seems too much smoke to me to be a breather issue (is it?), and since it has come on suddenly is it more likely to be a broken ring? The variability of the symptoms in the mid rev range puzzles.

 

 

Julian

[DieselDuck]

when I started it as usual momentarily on full throttle

 

Full throttle starting on a cold engine is a sure way to bust a ring or two!!!