BMC 1.5 oil problem under rocker cover

[Polly Graff]

Firstly, I'm completely new to engine mechanics so not very knowledgable. I have a BMC 1.5 which started to produce lots of blue smoke some while ago. I suspected a head gasket problem but knew that the problem could also be caused by worn piston rings, worn bores etc. I removed the cylinder head and contacted a local engine rebuilding specialist who is highly experienced and was recommended to me by a narrowboat hire company - so I trust him. He came and checked the bores and said they were in good condition, showing very little wear but that he could see the gasket had gone between the second and third cylinders. He said he didn't think the engine was burning oil in the normally accepted sense but that he thinks oil must have been getting into the second and third bores where the gasket had gone and being blown out through the exhaust. I stripped the head down myself and he skimmed it and confirmed that it had been warped slightly. He fitted new valves, stem seals, etc I then refitted it - with a new head gasket and other bits that needed to be replaced which I got from Calcutt boats, using the workshop manual, various You Tube videos and making a nuisance of myself ringing various companies and asking questions. I then adjusted the valve clearances, bled the fuel system, checked the oil (just above the minimum marker because I've been told not to overfill). By some miracle, the engine started with very little difficulty and ran for about fifteen minutes when I noticed that oil was seeping out from the front end of the rocker box cover on the starboard side. I also couldn't help noticing that the engine is still producing blue smoke - which is a massive disappointment. So my questions are - is it likely that the oil leak is just due to me not getting the cork rocker cover gasket seated correctly? Is it possible that an excessive amount of oil is getting up into the rocker area causing it to leak out under or over the gasket? Is it possible that something is blocked and preventing oil from draining back down into the engine block? Could any of these possibilities result in the continuing production of blue smoke. Apart from the work on the head, I have done all the work myself and I know nothing! Is there anything that anyone can think of that a complete numpty may have done wrong that I could check. All suggestions will be most gratefully received.

[Tracy D'arth]

The rocker box gasket is not fitted properly, full stop.

Oil burning is due to:-

1  Broken or worn piston rings.

2 Rings seized in the piston grooves with carbon.

3 Glazed bores due to prolonged idling charging batteries.

4 Worn pistons.

5 Worn valve guides and/or valve stems.

6 Hardened valve stem seals.

7 Diluted lube oil due to fuel entering sump. Lift pump diaphragm or injection pump seals.

8 Wrong lube oil.

9 Excessive crankcase compression due to blocked side chest breathers.

10 Air filter contaminated with oil due to #9.

 

Is the blue smoke constant at all revs if you hold the same engine speed?  Or if you leave it idling for a while and it is OK but smokes badly when you rev it up?

[Tony Brooks]

58 minutes ago, Tracy D'arth said:

The rocker box gasket is not fitted properly, full stop.

Oil burning is due to:-

1  Broken or worn piston rings.

2 Rings seized in the piston grooves with carbon.

3 Glazed bores due to prolonged idling charging batteries.

4 Worn pistons.

5 Worn valve guides and/or valve stems.

6 Hardened valve stem seals.

7 Diluted lube oil due to fuel entering sump. Lift pump diaphragm or injection pump seals.

8 Wrong lube oil.

9 Excessive crankcase compression due to blocked side chest breathers.

10 Air filter contaminated with oil due to #9.

 

Is the blue smoke constant at all revs if you hold the same engine speed?  Or if you leave it idling for a while and it is OK but smokes badly when you rev it up?

 

Just confirming what Tracy said.

[Polly Graff]

Hi - many thanks for your response - much appreciated. I think I can rule out 1 - 4 because there was no evidence of wear/damage to the bores when the engineer checked them and 5 - 6 because the valves, guides and stem seals are all new and 8 because I'm using Morris Marine 10W - 40 which I understand is recommended for these older engine. I don't do a massive number of hours but oil has been changed five times in the two years I've had the boat. Also 10 - air filter had to come off with the heat exchanger in order to the head off and it was dry. So that leaves 7 and 9. Re 7, do you mean that a leaking lift pump diaphragm or injection pump seals could lead to the oil being contaminated with fuel? Is there any way of checking that and would it be evident in the oil - say - on the dipstick? Re 9 - I don't really know what side chest breathers are. Are they something to do with the tappet side covers - are they checkable/clearable? Before the head was done, the smoke was constant regardless of revs, time running, etc. Started the engine today for the first since the head was done but only ran it at idle for fifteen mins and turned off as soon as I saw the oil seeping from the rocker box. Blue smoke throughout. Only other thing of note was that the engine fired up unexpectedly while I was bleeding the injector pipes. It used to require 25 secs glow plugs - but not today.

[Stilllearning]

11 minutes ago, Polly Graff said:

Hi - many thanks for your response - much appreciated. I think I can rule out 1 - 4 because there was no evidence of wear/damage to the bores when the engineer checked them and 5 - 6 because the valves, guides and stem seals are all new and 8 because I'm using Morris Marine 10W - 40 which I understand is recommended for these older engine. I don't do a massive number of hours but oil has been changed five times in the two years I've had the boat. Also 10 - air filter had to come off with the heat exchanger in order to the head off and it was dry. So that leaves 7 and 9. Re 7, do you mean that a leaking lift pump diaphragm or injection pump seals could lead to the oil being contaminated with fuel? Is there any way of checking that and would it be evident in the oil - say - on the dipstick? Re 9 - I don't really know what side chest breathers are. Are they something to do with the tappet side covers - are they checkable/clearable? Before the head was done, the smoke was constant regardless of revs, time running, etc. Started the engine today for the first since the head was done but only ran it at idle for fifteen mins and turned off as soon as I saw the oil seeping from the rocker box. Blue smoke throughout. Only other thing of note was that the engine fired up unexpectedly while I was bleeding the injector pipes. It used to require 25 secs glow plugs - but not today.

Have the injectors been serviced since you bought the boat?

Blue smoke does suggest burning oil rather than unburnt fuel, but it may be worth thinking about.

BMC rocker cover gaskets can be a total pain to get to seal, BTW.

[Tony Brooks]

Personally, I would use 20W50 in an old BMC diesel.

 

 I am pleased you found an engineer with Xray eyes, because I have no idea how he ruled out oil control rings stuck in their grooves.

 

The side covers are fund on the port side of the engine block below the manifolds heat exchanger. They are held on with one screw in each. One has a hose connection that usually runs to the air filter. The one with the hose has an oil baffle on the inside and in some cases it contains a wire mesh. If this or the hose becomes blocked, then the inside of the engine will be pressurised and that can force oil down the valve stems.

 

engines often smoke for a while after major work until the oil/cleaner used during the work burns off, plus these BMCs do have a tendency to smoke for a short time after a cold start. Maybe you did not let it run for long enough.

 

You can get silicon rocker cover gasket that holds their shape better than the cork ones. In the end, I tended to glue the cork gasket to the rocker cover with a little silicon. It is all too easy to allow them to slide into the chamber on the manifold side, so they leak.

 

 

[john.k]

How much smoke ?....oil smoke smells like ..oil smoke ,......unburnt fuel is a kerosine smell and makes your eyes water .............a lot of diesels will fill the exhaust with oil when running light ,idling ,or run for hours charging a battery...............the exhaust simply doesnt get hot enough.......and when it does ,all the oil may make a lot of smoke ,when there is actually very little wear .............Dorman Diesels were notorious for passing enough oil to have fires in the exhaust .

[Polly Graff]

Thanks Stilllearning - no the injectors have not been serviced since I've had it and I'd not thought of that as a possibility. I know I'm inexperienced but I do have a 'have a go' mentality. Is it something I could have a crack at myself or should a professional be involved?

 

Thanks Tony - good point about the oil control rings - sorry I misunderstood the terminology first time round. I'm familiar with the side covers - had to get those off to re-seat the cam followers. Yes - one does have a hose outlet but no hose to the air filter. My air filter is a chrome job - I think they call it pancake style. Is that something I should rectify? Not sure where on the filter it would attach to. Also I didn't notice any baffle or mesh - I clearly need to take another look at that.

 

The cork gasket was sliding all over the place when I fitted it - I'll try the glue idea to the cover side. Thanks for all this.

Hi John - thanks for your reply. Not sure I know the difference between the smells. All I know is that its blue. Pre the head work there was enough of it for passers by on the towpath to comment on it. Just before I took the head off I took the boat out for eight hours and it was smoking just as much at the end as it was in the beginning. Obviously, it was only 15 mins idling today before I switched off due to the leak. I will need to take it out for run but we are enjoying typical

... British summer weather now so mechanicking and boating have come to a standstill.

[Tony Brooks]

1 hour ago, Polly Graff said:

Yes - one does have a hose outlet but no hose to the air filter. My air filter is a chrome job - I think they call it pancake style. Is that something I should rectify? Not sure where on the filter it would attach to. Also I didn't notice any baffle or mesh - I clearly need to take another look at that.

 

Make sure that you can easily blow through the hose boss on the side cover. if you can, then my advice would be to put a length of hose on it, terminating in an old milk carton. These BMCs tend to blow a bit of crankcase fumes plus oil droplets through the hose. Forget about routing it to the air filter, yours so probably a replacement without the required hose boss.

 

If there were no oil stains from that hose boss on the side cover, my suspicion is that it is blocked. Early ones had ones both side covers the same but the one with the boss had a smallish baffle plate welded on the inside. On later ones, the one with the boss was more box like with wire mesh inside the box. They would be fun to clean out, I think.

[Polly Graff]

Many thanks - I'll take look at it. i've often wondered what that outlet was for.

[Polly Graff]

Thanks to all who have contributed on the basis of which my next steps will be to refit the rocker box gasket using glue/silicone and if that doesn't work I'll get a rubber one; check the outlet from the side cover, clean if necessary and attach a hose to a container of some kind; change to 20/50 oil then take it out for a few hours to put the engine under load and heat up that exhaust. If the smoke persists I'll check out/renew the lift pump diaphragm and the injection pump seals (once I've discovered how to do these things); service the injectors (or have them serviced). If the problem still persists I'll have to assume the cause lies deeper in the engine (seized piston rings for example) and I'll have to consider my options.  I don't have the facilities or skill set to take out the engine myself and I can't get to the pistons through the sump - not enough room. That may be the point that I have to throw in the towel. Once again - thanks to all.

[Tony Brooks]

17 minutes ago, Polly Graff said:

Thanks to all who have contributed on the basis of which my next steps will be to refit the rocker box gasket using glue/silicone and if that doesn't work I'll get a rubber one; check the outlet from the side cover, clean if necessary and attach a hose to a container of some kind; change to 20/50 oil then take it out for a few hours to put the engine under load and heat up that exhaust. If the smoke persists I'll check out/renew the lift pump diaphragm and the injection pump seals (once I've discovered how to do these things); service the injectors (or have them serviced). If the problem still persists I'll have to assume the cause lies deeper in the engine (seized piston rings for example) and I'll have to consider my options.  I don't have the facilities or skill set to take out the engine myself and I can't get to the pistons through the sump - not enough room. That may be the point that I have to throw in the towel. Once again - thanks to all.

 

If the oil level is at or below the maximum mark, it is not gradually rising, and when you rub it between finger and thumb it feels as "thick" and as slippy as some new oil from the can, then changing the lift pump and/or injector pump will be a waste of money and time. Those things are only applicable if fuel is leaking into the oil and so far you have given no indication that it is or that the level is rising all on its own.

 

Please don't even think about trying to deal with the injectors yourself. By all means take them out, but it would be very surprising if you have the kit to test them and set them up.

 

 

[Sea Dog]

19 hours ago, Polly Graff said:

Firstly, I'm completely new to engine mechanics so not very knowledgable.

This may be true, but you're listening to good advice, your knowledge is increasing fast and your skills will doubtless do the same given your attitude and application. Good on yer, and the best of luck with sorting this issue.

[Tracy D'arth]

Carefully monitor the oil level over several days before getting involved with the pumps.  If it is falling the more you run the engine then it is most probable that you are burning it due to a worn engine, if it is rising then you have the fuel dilution problem.

You cannot do anything to service the injectors other than take them to a diesel specialist for overhaul. If you do, mark them all and ensure that you get the same ones back, there are some who may try to palm you of with the wrong ones. BMC injectors are different from others that just look similar.

[LEO]

Hi,

 These BMC 1.5's are lovely engines. I bought a boat in 1989 with, marinised by JG Meakes, I had lots of problems which needed sorting, fix them it ran like a dream........but they are getting very old now, and have been much 'fiddled with'. perhaps we are reaching the stage where they are collectors items and whilst the basic engine is fair they need rebuilding. in workshop by an Engineer.....

[magnetman]

I've got a pair of 1.5s in one of my boats. Lovely engines. When I bought the boat the starboard engine was a bit loud and making some blue smoke. 

 

Had a good look round and it turned out one of the rockers had a completely shot bearing and it had also significantly worn away the rocker shaft. Presumably due to previous oiling problems. 

 

Also some of the tappet screws, which originally had ball ends had mushroomed. 

 

I think someone had done some top end work previously and put bad quality parts made of marshmallow on it. 

 

Rocker shaft replaced (MGB GT) and the nackered rocker and the dodgy tappet screws and it runs better. 

 

They both start on the button in summer so I think the rest of it is alright. 

 

Worth having a really close look at all the rockers and the adjuster screws just to rule them out. 

 

 

I was lucky with mine as despite being rather elderly (Ex Austin J4) they are in a bone dry well ventilated engine room and only have about 2,000 hours on them. Museum pieces is an interesting theory. Probably true really. 

 

Higher hours and being banished to a cruiser narrow boat engine hole would probably cause issues. 

 

 

[David Mack]

23 hours ago, Tracy D'arth said:

Carefully monitor the oil level over several days before getting involved with the pumps.  If it is falling the more you run the engine then it is most probable that you are burning it due to a worn engine, if it is rising then you have the fuel dilution problem.

And if you have both problems in equal measure the level may not change much at all.

[Tony Brooks]

5 minutes ago, David Mack said:

And if you have both problems in equal measure the level may not change much at all.

 

and that is where the feel and smell test comes in.

[Polly Graff]

Thanks again for all these further responses. I've still not run the engine since the rocker gasket leak and I'm not back at the boat until next week. I will most definitely step back from the injectors other than taking them off for someone else to look at, if necessary. Same goes for the pumps. At the moment, I can only comment on what was happening before I did the work on the head. As I said earlier, I've done quite a few oil changes and I've never noticed anything unusual about the smell or feel of the oil - including when I checked the dipstick or spotted the leak. I'll examine it more closely next time. Even though it was smoking before, I never seemed to lose much oil - I hope that does not mean I have both oil burning and dilution problems, as suggested above. Someone said I was probably changing the oil so regularly I wasn't noticing it going down. I don't know about that.

 

As far as the rocker assembly is concerned, I completelly dismantled it when I was refitting the head because I was unable to locate a crow foot socket so as to torque the nuts down in the correct order. So I dismantled the rocker assembly, fitted its brackets and torqued everything down in the right order and then reassembled the rocker assembly by sliding the shaft back through the brackets and repositioning the rockers, springs, etc., as I went. It took a while because everything was a tight fit but gentle persitance and patience meant i did not have to force anything. So I was able to have a really good look at its components (using an excellent You Tube video on the subject by Darren Crouch Marine). There was very little wear at either end of the rockers or their centres or the pushrods, come to that.

 

I'm really hoping that I find its a breather issue combined with engine oil thats too thin. On that subject, I have been checking out 20/50 oil on line and trying to get my head around the API ratings. Some of the oils that claim to be made for classic engines seem to have API ratings that indicate they would not be suitable at all. Tony - you recommended I switch to 20/50 - would you be able to recommend a brand ... or anyone else?

 

Lastly - Seadog - many thanks for your kind comments. I'm now over seventy and the boat was supposed to be a retirement project. Trouble is, I forgot to retire 😆. I've done no motor mechanics since I was in my early twenties but I'm now going through life with a set of spanners in one hand and a work diary and laptop in the other. So all your contributions are appreciated at lot more than you may realise!!! Uppards and onnards as they say.

 

 

[cuthound]

26 minutes ago, Polly Graff said:

Thanks again for all these further responses. I've still not run the engine since the rocker gasket leak and I'm not back at the boat until next week. I will most definitely step back from the injectors other than taking them off for someone else to look at, if necessary. Same goes for the pumps. At the moment, I can only comment on what was happening before I did the work on the head. As I said earlier, I've done quite a few oil changes and I've never noticed anything unusual about the smell or feel of the oil - including when I checked the dipstick or spotted the leak. I'll examine it more closely next time. Even though it was smoking before, I never seemed to lose much oil - I hope that does not mean I have both oil burning and dilution problems, as suggested above. Someone said I was probably changing the oil so regularly I wasn't noticing it going down. I don't know about that.

 

As far as the rocker assembly is concerned, I completelly dismantled it when I was refitting the head because I was unable to locate a crow foot socket so as to torque the nuts down in the correct order. So I dismantled the rocker assembly, fitted its brackets and torqued everything down in the right order and then reassembled the rocker assembly by sliding the shaft back through the brackets and repositioning the rockers, springs, etc., as I went. It took a while because everything was a tight fit but gentle persitance and patience meant i did not have to force anything. So I was able to have a really good look at its components (using an excellent You Tube video on the subject by Darren Crouch Marine). There was very little wear at either end of the rockers or their centres or the pushrods, come to that.

 

I'm really hoping that I find its a breather issue combined with engine oil thats too thin. On that subject, I have been checking out 20/50 oil on line and trying to get my head around the API ratings. Some of the oils that claim to be made for classic engines seem to have API ratings that indicate they would not be suitable at all. Tony - you recommended I switch to 20/50 - would you be able to recommend a brand ... or anyone else?

 

Lastly - Seadog - many thanks for your kind comments. I'm now over seventy and the boat was supposed to be a retirement project. Trouble is, I forgot to retire 😆. I've done no motor mechanics since I was in my early twenties but I'm now going through life with a set of spanners in one hand and a work diary and laptop in the other. So all your contributions are appreciated at lot more than you may realise!!! Uppards and onnards as they say.

 

 

 

My last shareboat initially had a BMC 1.8 engine, very similar to the 1.5. It was lubricated with Morris Golden Film 20w/50 oil and lasted almost 14,000 hours in 10 years before being replaced with a Beta 43.

 

Excellent oil in my opinion.

 

https://www.ebay.co.uk/itm/294850685124?var=0&mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338990947&toolid=10001&customid=eb%3Ag%3Avms%3Aeb%3Ap%3A294850685124%3BCj0KCQjw84anBhCtARIsAISI-xdD4abNqiaHR_ipM5lgtv_1dIB9g6pP6MfqztJ4ZIpQ80GQd0_TwiwaAiDmEALw_wcB&gclid=Cj0KCQjw84anBhCtARIsAISI-xdD4abNqiaHR_ipM5lgtv_1dIB9g6pP6MfqztJ4ZIpQ80GQd0_TwiwaAiDmEALw_wcB

[Tracy D'arth]

20w50 is one of the recommended oils. I use 15w40 because it is easier to find at a good price. Don't buy the best expensive oil, these old motors are perfectly happy to run on even reclaimed oil. A change to 20w50 may improve the oil consumption but from your comments it seems not to be a problem.

I am taking the attitude these days that no matter what I do with my engine, 1.8D BMC,  it will see me out.

[Tony Brooks]

5 hours ago, Polly Graff said:

Tony - you recommended I switch to 20/50 - would you be able to recommend a brand ... or anyone else?

 

Certainly not, buying by brand almost certainly means overpaying. I would be looking for API CC, CD or CF which are performance specifications so unless it is a fraudulent claim any brand of oil will do. Look at places that supply framers or motor factors.