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1.5 oil pressures, pressure relief valve


garym999

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Hi All,

 

Since my last time on here my sister in law has managed 50 hours of river and canal cruising on her own. We met up for days cruise and it gave me a chance to see how the engine was. 

 

At at start of the day the oil pressures were fine. 20 psi on idle and 40-60 on cruising. As the day progressed the pressures started fluctuating more but overall getting lower and lower until it would not get much above 20. After a discussion it would appear that this normal behaviour after days cruise.

 

The boat is new to her this year and was supposedly serviced. I trust the electric oil gauge as it is new and fitted by myself. Water temperature seems to top out at about 80c. After a days cruise the engine bay is hot as there is little air ventilation, no side vents etc.

 

The engine weeps oil but nothing alarming and seems to be keeping its levels.

 

Would I be right to suspect the oil pressure relief valve? If so apart from cleaning it what should be done to check/service it?

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If when revving well (in or out of gear) the pressure is fairly high but drops almost instantly to very low (say about 10psi) on idle then yes, it may be a stuck PRV. Anyway as it is external well worth withdrawing the valve plunger and ensuring it and its seat is clean and free.

 

I would want to check what oil was used on the service. If it was something modern like 5W30 then a change to 20W50 may sort it. As this engine could be over 50 years old one must also consider wear in the bearings. If its not the PRV or too thin an oil then its probably best to use 20W50 oil and keep boating while saving for another engine. It could go for years like that - or not, as the case may be.

 

 

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Frankly, if the oil pressure is 10 psi on tickover when hot after extended cruising I would not worry. 30 to 40 psi when running at a fair cruising speed hot is fine.

I have seen many where the oil warning light flickers on at tickover, they still run for years providing the oil and filter are regularly changed.

 

Yes, check the pressure release valve by all means, its under the large dome headed nut on the port side of the engine under the exhaust/heat exchanger.

If the coned end is worn, fit a new one. Do not stretch the spring in an attempt to get more pressure.

 

Use 15W40 oil, it circulates faster, 20W50 is also fine but may be slow to build pressure on a cold start.

Low oil pressure on an otherwise sound engine could also be oil pump wear.

Don't neglect cleaning the injector pump skew drive gears when servicing.

 

Get some ventilation into the engine bay, the cooling effect on the sump is beneficial.

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As always thanks gents. I'm not sure what oil was used for the service but the guy was familiar with BMCs so I would hope he used the correct sort. I seem to recall 20W50 but that might be simply from trawling these forums. I'll check to see what the container of top-up oil is, I know its Morris.

 

The running pressure seems to drop during the day from the inital 30-40 to 20ish.

 

I see the cost of a new PRV is not that much so is it worth just replaceing it, does it need to be lapped in, if so what's the best approach. What about the spring, do these ware?

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1 hour ago, Boater Sam said:

Frankly, if the oil pressure is 10 psi on tickover when hot after extended cruising I would not worry. 30 to 40 psi when running at a fair cruising speed hot is fine.

I have seen many where the oil warning light flickers on at tickover, they still run for years providing the oil and filter are regularly changed.

 

Yes, check the pressure release valve by all means, its under the large dome headed nut on the port side of the engine under the exhaust/heat exchanger.

If the coned end is worn, fit a new one. Do not stretch the spring in an attempt to get more pressure.

 

Use 15W40 oil, it circulates faster, 20W50 is also fine but may be slow to build pressure on a cold start.

Low oil pressure on an otherwise sound engine could also be oil pump wear.

Don't neglect cleaning the injector pump skew drive gears when servicing.

 

Get some ventilation into the engine bay, the cooling effect on the sump is beneficial.

 

I doubt Sam really means the bit in red. I suspect he means clean the injector pump skew gear oil jet and strainer. Their hexagons are below the back of the exhaust manifold. One vertical and one horizontal. Ignoring this is likely to cost you a new camshaft and skew gear at the very least.

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So the strainer is on the LHS (exhaust side) and PRV on the RHS (oil filter side)? The pictures on the manual I have does not make the location clear

 

Just got a photo back. The oil being used for top up is Morris Marine 10W40. Don’t know what was used for the service

Edited by garym999
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1 minute ago, garym999 said:

So the strainer is on the LHS (exhaust side) and PRV on the RHS (oil filter side)? 

 

Just got a photo back. The oil being used for top up is Morris Marine 10W40. Don’t know what was used for the service

Sam says so and I thought the PRV nut was close to the strainer and oil jet under the manifold on the PORT (LH) side of the engine but a quick look in the manual will confirm.

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Also just checked the Morris oil beeing used for top-up

 

" SAE 10W-40 classification makes the lubricant suitable for use in all canal boat engines where a SAE 15W-40 may be specified. The SAE 10W-40 properties will ensure that the lubricant flows easier at lower temperatures providing improved component protection "

 

When I get to service it I probably use Morris Golden Film 20W-50 Classic Motor Oil

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9 minutes ago, garym999 said:

Thanks, nice and easy to get to in my case. So one of these two (domed one I guess) on the port side.

image.png.5f8258442051127f4992cd8f835d09fc.png

 

Yes, top one is the strainer for oil going to the skew gears, bottom one is the pressure release valve.

You can't lap a new valve slug into the seat without stripping the engine, else the grinding paste gets in the oilways. There should be no need to unless the seating is damaged in which case I don't know what the repair method would be without a fully stripped block and wash out afterwards.

 

Manual is here, free!

http://the-norfolk-broads.co.uk/downloads/bmc1500L-diesel-workshop-manual.pdf

Edited by Boater Sam
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Sad to say this has all become short lived. I'm away on hols only to find that the boat broke down with a clonk. After which it could not be started. Luckily the boat was near a marina but upon diagnosis the news is terminal. Lots lost in translation but basically a bottom end failure. Not sure of the cause but it could have been blocked oil ways.

 

So the advice being given is a recon BMC 1.5 (£4K) or a new Canaline 38. Given the boat is being used as a live-on-board with cruising and little onboard mechanical knowledge, reliability is an issue. With only £1k difference in cost and a 3yr warrenty the 38 is looking like a better bet

 

Whats people's thoughts? The boat is 35'

 

 

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It wasnt that long ago I was on a 35ft nb with a 3 cylinder Mitsibushi in it (about 24 hp ish I think). Coped with all the floodwaters on the Nene easily so loads of power-  a smaller engine would save a good few quid and still be plenty powerful enough I would think-though where you use it may be a factor.

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1 hour ago, garym999 said:

So the advice being given is a recon BMC 1.5 (£4K) or a new Canaline 38. Given the boat is being used as a live-on-board with cruising and little onboard mechanical knowledge, reliability is an issue. With only £1k difference in cost and a 3yr warrenty the 38 is looking like a better bet

 

I'm surprised the price difference is that small.

How easy though is it to drop a Canaline in lieu of the BMC, and what else may you need to change?

Engine beds at correct height and separation?

Prop suitable for new engine, (and gearbox?)?

Etc.

(Presumably a skin tank adequate for BMC will also be OK, with Canaline, but check).

Fine if you haven't got to change much, but starts to get costly if you do, (unless you are doing much of it yourself).

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I’m leaning towards the Canaline too but it’s not my dosh and I’m not sure how much additional integration is needed. 

 

From what I have read it comes with gearbox, engine mounts, twin alternators, control panel, gearbox and a 3 year warranty and is a pretty good fit in place of a BMC. It gives a very good and known reference point. Won’t get that with a recon.

 

What value is there in a broke BMC?

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9 minutes ago, garym999 said:

I’m leaning towards the Canaline too but it’s not my dosh and I’m not sure how much additional integration is needed. 

 

From what I have read it comes with gearbox, engine mounts, twin alternators, control panel, gearbox and a 3 year warranty and is a pretty good fit in place of a BMC. It gives a very good and known reference point. Won’t get that with a recon.

 

What value is there in a broke BMC?

Possibly as spares, head, starter, alternator, heat exchanger, injector pump, injectors etc £300 to £400 surprisingly. Then the gearbox and possibly drive plate, engine mountings and flywheel housing.

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  • 2 weeks later...

So I got chance to meet up with my sister-n-law to be confrounted with this (see attached pics). Unfortunatly the engineer was not at work being the weekend to discuss. But the therory is that something relating to the valve push rods or the like broke and the resulting part dropped to the sump and jammed against the crank causing it to break. Although I dabble I'm no mechanic but I expected the general condition of the engine to appear a lot worse all gummed up etc. You may well tell me otherwise.

 

So if anyone is interested there is an engine for spares or repair, she would rather that than just selling it for melting down as scrap. A bit of recycliing and hopefully some cash to soften the blow. I'll post it in the forsale section. It used to start instantly since its started motor and upgraded alternator were referbished. It has new glow plugs. It did not smoke and comes with the gearbox. It weaped oil as they all do but did not drink it.

 

I guess this is me signing off the BMC section, but I'm a bit of a lurker. So thanks everyone for help on this little voyage.

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Crankshafts break from fatigue....especially if worn bearings are causing misalignment......misaligned gearboxes causing sideloads.......a shipload of pushrods woulnt break a crank........I would say think yourself lucky it didnt break crossing a bar with a heavy sea running.........you'd all be feeding the fish.

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  • 4 weeks later...
On 16/08/2019 at 21:45, Boater Sam said:

Possibly as spares, head, starter, alternator, heat exchanger, injector pump, injectors etc £300 to £400 surprisingly. Then the gearbox and possibly drive plate, engine mountings and flywheel housing.

As a clue.

Earlier today for a replacement flywheel housing/rear mounting, register plate and gearbox adaptor (PRM 150) and a few bolts I paid about £600. All for  BMC 1.8

 

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