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BMC 1.5 oil leak got worse after replacing filter O ring


Ianph
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Hi all, first time post here and new to boating and these engines. Another oil leak issue to add! 

 

We have a BMC 1.5 on a narrowboat. Had boat for about a year, although not been out much with lockdown etc. Just headed out for the summer. Did service, replacing oil filter before heading out. After first day noticed oil was level was dropping and ended up in bilge, steadily through a day (4/5 hours of motoring, dropped from MAX Mark to just below MIN, but not empty). 

 

After looking at this forum, I checked while running and saw it sheeting down side of oil filter housing, assumed something up with the O ring. 

 

Took filter off - with the single bolt from the top, as had done for the filter change, and this time took 'bracket' off (two horizontal bolts), I'd read somewhere that it was OK to do this, to actually see the O ring. Sure enough, it was wonky and split, I replaced this with a spare and reassembled. Filled with oil to max mark. 

 

Ran engine at mooring for about 20 mins, with container under filter, watched for a few mins and stayed close by for the time. Filter seemed fine, not sheeting down side as before (hard to see down under it, but felt around and certainly no major drips). After a while running engine note changed and oil pressure dropped. Immediately turned off engine, and dipstick showed hardly any oil. 

 

Rechecked filter housing and tightened bolts, everything is oily in there at the moment but looked fairly clean around there (certainly didn't look like a whole engine worth of oil had just dumped out from it). 

 

Put last of spare oil in and ran for a few minutes while looking underneath (as best as possible in there), and persistent drip/stream coming from underneath, sort of looks somewhere under what I think is starter motor (hard to see). This continued for a few seconds after stopping engine, then stopped.

 

Definitely wasn't leaking to this extent yesterday, it was dropping but over hours not minutes/seconds. Only touched the filter housing today, and fairly sure I didn't knock anything. Wish I hadn't touched anything now! 

 

Any ideas what's happened here? 

 

Thanks! 

 

Ps. I've added a couple of pictures of the top, with the oil filter, and one from the bottom (as best I could) - not that I think it shows much (except all the oil in the bilge) 

IMG-20210721-WA0004.jpg

IMG-20210721-WA0005.jpg

IMG-20210721-WA0003.jpg

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First time you got the seal between the top of the filter and the head fitting wrong. Second time around you corrected this, but my guess is that the head fitting/bracket is not properly sealed to the crankcase. So the oil is running down the side of the engine, and not down the outside of the filter.

Did you make sure the gasket went back between the bracket and crankcase? Was it undamaged? Are the bolts holding the bracket on tight?

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Just above the starter is well back there is the oil switch/pressure sender/pressure gauge take off. Is this leaking? I think the thinner black crinkly trunking has the cable in it that goes to that connection.

 

I think close by, there is a very large domed hexagon that has the oil pressure relief valve under it. There is absolutely no reason for it to start leaking, but best check that as well.

 

Did you clean the filter "bracket" mating faces and fit a new very lightly greased gasket?

 

When you were tightening the filter bolt, just as the housing came in contact with the ring seal did you gently twist the canister so you can feel that it was sitting on with rubber and not steel. Although not strictly necessary on that type of filter, I would always lightly oi; the face of the seal before fitting the canister.

 

A sump gasket leak might look  as if it was coming from under the starter or oil from the gasket could be running backwards down the block "flange" the sump sits on.

Edited by Tony Brooks
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1 minute ago, Tracy D'arth said:

There is a paper gasket on the oil filter head mounting to the block, did you replace it?

 

Isn't the rocker box on back to front?

 

Yes, but some AMC marinisations had funny oval rubber stud seals that allowed it to be fitted "backwards". Without taking the lifting eyes off, we can't see them. Also, there have been so many different versions of the B series engine, I could not be sure it's not correct for that particular base engine.

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1 minute ago, Tony Brooks said:

 

Yes, but some AMC marinisations had funny oval rubber stud seals that allowed it to be fitted "backwards". Without taking the lifting eyes off, we can't see them. Also, there have been so many different versions of the B series engine, I could not be sure it's not correct for that particular base engine.

I know of many of the variations but there is only one cylinder head for the 1.5D. I always thought that the rocker box would only fit one way round without leaking on the manifold side.

 

I am always amazed that folk have problems refitting square section o rings so that they don't leak. Perhaps it because I have done it countless thousands of times.  I did used to have the odd problem with the ones with a cooler take off sandwich between the filter bowl and the filter head, the pipes always seem to push it out of line.

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Hi all, thanks for your speedy replies. 

 

Just checked again and there's a jet of oil from the top of the filter housing, and it feels like the o ring is popped out. 

 

Don't ask me why people (me) can't fit o rings... I was (thought I was) careful about fitting it. I'll take off and have another look. 

 

 

 

 

 

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One other thing to bear in mind. If the water/oil in the drip tray gets up to the flywheel housing level it can leak in, get picked up and thrown around into the starter motor itself. It then tends to drip out of the starter.

2 minutes ago, Ianph said:

Hi all, thanks for your speedy replies. 

 

Just checked again and there's a jet of oil from the top of the filter housing, and it feels like the o ring is popped out. 

 

Don't ask me why people (me) can't fit o rings... I was (thought I was) careful about fitting it. I'll take off and have another look. 

 

 

I can well understand why people have problems trying to it in situ. on some installations, but  if the whole assembly is off the engine I have similar thoughts so either the OP twisted it or it's the wrong seal - perhaps he should try his old one.

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If my memory serves me correct there are usually  two different sized rubber rings in the box with the new oil filter , one thicker than the other . Are you sure you have fitted the correct one ?  I've got a huge collection of these spares on my boat from the number of times I have changed my oil filter although I've now fitted a spin on conversion so even got a complete spare filter with housing now. 

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Well, you've done the hard bit - that,s diagnosing the problem - its one or both of the gaskets. The sometimes fiddly bit is the rubber ring that should just press into the filter housing, that can twist or just not seat properly, don't overtighten anything. If its leaking from the bracket/block joint then the good old cornflake packet gasket will fix it, don't forget to cut out all the holes needed for bolts and oil. People suggest a smear of oil on the rubber ring to help it slide when you re fit the filter. Whenever I do a filter change there is plenty of oil all over everything anyway but it is probably a good tip.

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Just to alay anyone's fears you're dealing with a total idiot, the first time the o ring was damaged (as per some of your suggestions) it was blind without taking the whole thing off the crankcase. On the other hand, the second time the assy was off - I either didn't take enough care, or there's something up/wrong o ring (so jury's still out on the charge of partial idiocy). 

 

A bit of the o ring had actually bulged out, I assume under pressure, from where the oil was jetting out. Don't know if I'd twisted it again, or under/over tightened (I think I'm doing it to about the what it was, but no torque wrench and don't know what the setting would be anyway). 

 

@Troyboy yes, there were two in the box, I think it's the correct one, but typically I don't have the one I took off to double check (not typically I actually tidied up well that day). I'm fairly sure it was the thicker ring and I compared the two at the time, but can't check that now. The other ring is thinner, and I can't see how that would fit bitter - it sits rather loose in the space when I tried (unless that's the design of it? The thicker one, which I'm using, sits fairly snuggly in the gap). 

The filter/ring set was from calcutt boats and for this engine, so I'm assuming it's correct - but I wouldn't know how to check any better (it sort of  'looks' right). 

 

I've refitted, taking (more) care, and it's definitely sat correctly now. On close inspection the whole fitting between the cup and the bracket doesn't look that precise - but I don't think that's anything I've done. I've run the engine for a minute and appears OK for now (wrapped some clean rag around it and it was still clean after). Don't know if it'll pop out again after a while... Daren't run for any longer as there's not much oil in the engine now (all in the bilge...). Going to get some new oil to fill up and try. 

 

Clearly it's not such a unique and issue as I first thought, and similar to some other people's experiences on here. 

 

 

 

 

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3 hours ago, Ianph said:

Just to alay anyone's fears you're dealing with a total idiot, the first time the o ring was damaged (as per some of your suggestions) it was blind without taking the whole thing off the crankcase. On the other hand, the second time the assy was off - I either didn't take enough care, or there's something up/wrong o ring (so jury's still out on the charge of partial idiocy). 

 

A bit of the o ring had actually bulged out, I assume under pressure, from where the oil was jetting out. Don't know if I'd twisted it again, or under/over tightened (I think I'm doing it to about the what it was, but no torque wrench and don't know what the setting would be anyway). 

 

@Troyboy yes, there were two in the box, I think it's the correct one, but typically I don't have the one I took off to double check (not typically I actually tidied up well that day). I'm fairly sure it was the thicker ring and I compared the two at the time, but can't check that now. The other ring is thinner, and I can't see how that would fit bitter - it sits rather loose in the space when I tried (unless that's the design of it? The thicker one, which I'm using, sits fairly snuggly in the gap). 

The filter/ring set was from calcutt boats and for this engine, so I'm assuming it's correct - but I wouldn't know how to check any better (it sort of  'looks' right). 

 

I've refitted, taking (more) care, and it's definitely sat correctly now. On close inspection the whole fitting between the cup and the bracket doesn't look that precise - but I don't think that's anything I've done. I've run the engine for a minute and appears OK for now (wrapped some clean rag around it and it was still clean after). Don't know if it'll pop out again after a while... Daren't run for any longer as there's not much oil in the engine now (all in the bilge...). Going to get some new oil to fill up and try. 

 

Clearly it's not such a unique and issue as I first thought, and similar to some other people's experiences on here. 

 

 

 

 

It Is very unlikely that the ring bulged out of the groove under pressure, more likely it was not properly fitted into the groove.

 

The ring has to be the correct diameter and the correct section to fit snugly into the groove untwisted without falling out. There are 2 O rings in the filter pack, only the thicker one is correct for your engine.

If you have trouble getting it to locate square and untwisted, grease the groove first. Use a mirror to inspect the fit before replacing the canister and after fitting before fully tightening the holding bolt.

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6 hours ago, Tracy D'arth said:

There is a paper gasket on the oil filter head mounting to the block, did you replace it?

 

Isn't the rocker box on back to front?

 

Yes

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Can you actually see it leaking oil anywhere? The reason I ask is the 1.5 bmc doesnt like the oil filled to the max.  In a boat the engine is tilted backwards slightly and gives an incorrect reading.  IIRC the rear engine oil seal is a scroll seal and will leak oil if the level is too high....

 

I fill our 1.5 bmc to the minimum only and she runs just fine... and doesnt leak oil...

Edited by Quattrodave
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