BMC 1500 ENGINE OIL PRESSURE PROBLEM

[Buddyboy]

Hi everyone .....I'm a fairly new member and would appreciate some help

We are just in the process of buying a narrow boat with a 1500 BMC Diesel .

Both the surveyor and i have noted it seems to have an oil pressure problem, the gauge went sky high, and  there has been oil leaking from the air filter in the bilge and the top end seem to noisy...even for this type of old engine engine.

We have identified the oil pressure switch/valve as the culprit.....Has anyone come across this before and can give advice?

Many thanks in anticipation 

Buddyboy

 

 

[Bee]

V. high oil pressure could be oil pressure relief valve - not the oil pressure 'switch' or sender unit to the gauge. Oil leaking from the filter, its a while since I had one of these but if the engine has a pipe from the crankcase or the rocker box to the filter body then it is a means of making the engine re breathe its own fumes, if there is oil present it probably means that rings / bores / pistons are very worn. Noisy top end, could be rockers clattering away or pistons wobbling around in the bores and tolerances measured in 10's of thou's rather than 10ths, I would be very wary of this engine but others will have more knowledge.

[WotEver]

57 minutes ago, Bee said:

V. high oil pressure could be oil pressure relief valve - not the oil pressure 'switch' or sender unit to the gauge. Oil leaking from the filter, its a while since I had one of these but if the engine has a pipe from the crankcase or the rocker box to the filter body then it is a means of making the engine re breathe its own fumes, if there is oil present it probably means that rings / bores / pistons are very worn. Noisy top end, could be rockers clattering away or pistons wobbling around in the bores and tolerances measured in 10's of thou's rather than 10ths, I would be very wary of this engine but others will have more knowledge.

I don't know this engine particularly but TonyB does. From my 'generic' knowledge of engines I'd agree with your diagnosis - it sounds well worn to me. 

[Tony Brooks]

I don't like the sound of this. The sky high gauge could be a faulty sender because they are not the most reliable of things, especially the old bi-metalic ones.  A noisy top end and oil in the air filter suggest a  worn engine and one way of quieting the bottom end for a short while could be to stretch or pack the spring in the oil pressure relief valve. That would also give sky high oil pressure for a while.

Yes, advice, put in an offer that reflects the cost of an engine rebuild.

[cuthound]

4 years ago we replaced the BMC 1.8 on our last shareboat with a Beta 43. Cost then was £7k. I suspect the Beta 38 might be the ideal replacement for a BMC 1.5.

My current boat has a Beta 43.

The Beta 43 is a much better engine than the BMC 1.8, smoother, quieter and more economical.  Anecdotally they last at least twice as long too.

I would find out the current cost of replacing with a Beta, and offer asking price less that subject to survey.

[Tony Brooks]

Just seen what Bee said about it not being the sender.

When a BMC oil pressure relief valve starts to get sticky the normal thing is that the pressure keeps on rising (as one would expect) until it opened the valve. The valve, being stick, then sticks open. This gives a low hot oil pressure and not much more than zero on hot idle.

Generally I would suspect the sender long before a PRV stuck closed.

In this case the apparent poor sate of the engine makes me wonder if a bodger has been at work.

[alan_fincher]

48 minutes ago, cuthound said:

The Beta 43 is a much better engine than the BMC 1.8, smoother, quieter and more economical.  Anecdotally they last at least twice as long too.

A strange anecdote then!

The BMC 1.8 was I think first produced in the early 1970s, so many are still going strong after at least 40 years.  For a Beta to last twice of long there would need to be surviving examples produced in the 1930s, which clearly there are not.

Smoother and quiter a Kubota engine maybe, but I am not overly convinced about being significantly more economical, and I'm certainly not convinced they will ultimately have as long a service life as a BMC.

[peterboat]

8 minutes ago, alan_fincher said:

A strange anecdote then!

The BMC 1.8 was I think first produced in the early 1970s, so many are still going strong after at least 40 years.  For a Beta to last twice of long there would need to be surviving examples produced in the 1930s, which clearly there are not.

Smoother and quiter a Kubota engine maybe, but I am not overly convinced about being significantly more economical, and I'm certainly not convinced they will ultimately have as long a service life as a BMC.

My kubota always started without heat was quiet and economical, also its built to modern tolerances which in the way of the world is far better than BMC used with 1500s [I have just taken a good 1500 BMC out of my bathtub to replace it with an electric drive]

[alan_fincher]

I guess the key thing here is, (and I am guessing!) that if the OP is buying a boat with what sounds like a potentially part knackered BMC 1800 in, then they may well be on a bit of a budget.

Whilst it is fine to tell them that if they then invest £7,000 or more on a brand new Beta that it may then be a much better boat, I'm kind of thinking that someone negotiating for a boat with a half knackered BMC in is not going to have an extra £7,000 kept in reserve for an engine swap.  I am also thinking the vendor is unlikely to quickly take a full £7,000 of the agreed price to allow them to do this.

Therefore it seems more realistic to explore what might be wrong with this engine, and likely costs to repair or swap out for a better or rebuilt example of the same, (likely cost about 1/3 of that of a new Kubota based engine, possibly???)

(Or walk away from this boat, and look for one where there are not so many concerns about the engine condition.)

[cuthound]

54 minutes ago, alan_fincher said:

A strange anecdote then!

The BMC 1.8 was I think first produced in the early 1970s, so many are still going strong after at least 40 years.  For a Beta to last twice of long there would need to be surviving examples produced in the 1930s, which clearly there are not.

Smoother and quiter a Kubota engine maybe, but I am not overly convinced about being significantly more economical, and I'm certainly not convinced they will ultimately have as long a service life as a BMC.

Many of the Ownerships fleet were originally fitted with BMC 1.8's by Calcutt Marine.

They were regularly serviced and accrued about 1,100 hours per year on average.

Most lasted between 10,000 and 13,000 hours before being rebuilt or replaced.  The rebuilds generally lasted about half as long as a new engine before being replaced. 

I have seen several Kubota engines used in hired plant equipment with 20,000 to 30,000 hours on them, so I am definately convinced they last longer.

Your experience is probably of engines in private boats which in the main have easy lives. Engines in hire craft,  shared boats or plant equipment get much harder lives.

Edited September 2, 2017 by cuthound
To add the last sentance.

[Tony Brooks]

I agree with this ^^^^^^

I would suggest that more BMCs drip oil from the filter than do not and its easily solved by cleaning the oil trap on the breather (if it has one) and then directing the breather hose into a milk carton sat beside the engine.

The upper end noise might just be badly worn/adjusted valve clearances. The high oil pressure might be be a faulty sender or a sender and gauge that are not matched - that is unless its a mechanical gauge.

However that is two "mights" and another might is that the engine is at or close to overhaul time. No one here can say much more than that.

If I were the potential purchaser I may well see how it starts from stone cold and if it did with 30 seconds of heat and then a few turns on the starter I would be temped to put in a suitably low offer and hope the problem is valve clearances and sender. If it was a beast to start I would probably walk away. The difference between myself and the OP is that I can do major work on the engine if I had to or even fit a reconditioned one.

The OP needs to asses their finances and competence to undertake repairs and thn walk away or make an offer.

[Buddyboy]

Thank you all, for the sound advice , which seems to follow the same theme....I'm going to talk to the marina on Monday and discuss this as we are going into retirement as 'constant cruisers'  . Its reassuring to know there is such a wealth of knowledge out there to help us.

[Cheshire cat]

To continue with Cuthounds line of thought. we had a share in a boat with a Calcutt BMC and what killed the engine was various ancilliary failures mostly hoses causing the engine to be overheated several times. It seized at least twice to my knowledge but started again once it had cooled down. In the end it was a smokey lump with a badly worn camshaft and low oil pressure once the engine was warmed up. We replaced it on its ninth birthday with around ten thousand hours on the clock. It hadn't had an easy life. 

We replaced it with a Kabota based Nanni which currently is 12 years old and still behaves like it is new. This may be down to the owners having to swallow an £8K bill and therefore wanting to be a little more careful with their new purchase. I still have an interest in the boat and we checked the valve clearances for the first time last winter and they didn't require any adjustment. It has had a new water pump and a new domestic alternator but that is it. Due to a ropey installation hoses have chafed and failed on this installation too but an alarm sounds which has alerted the crew and saved the day.

In our case the Nanni is more thirsty than the BMC but it is of a larger displacement. That was a mistake we should have gone for the 1.9

 

[TNLI]

On 10/09/2017 at 09:31, Cheshire cat said:

To continue with Cuthounds line of thought. we had a share in a boat with a Calcutt BMC and what killed the engine was various ancilliary failures mostly hoses causing the engine to be overheated several times. It seized at least twice to my knowledge but started again once it had cooled down. In the end it was a smokey lump with a badly worn camshaft and low oil pressure once the engine was warmed up. We replaced it on its ninth birthday with around ten thousand hours on the clock. It hadn't had an easy life. 

We replaced it with a Kabota based Nanni which currently is 12 years old and still behaves like it is new. This may be down to the owners having to swallow an £8K bill and therefore wanting to be a little more careful with their new purchase. I still have an interest in the boat and we checked the valve clearances for the first time last winter and they didn't require any adjustment. It has had a new water pump and a new domestic alternator but that is it. Due to a ropey installation hoses have chafed and failed on this installation too but an alarm sounds which has alerted the crew and saved the day.

In our case the Nanni is more thirsty than the BMC but it is of a larger displacement. That was a mistake we should have gone for the 1.9

 

Yes I know it's an old post, BUT I'm very interested in restoring a very old leaky BMC 1500 that I was almost given. It does turn over but fails to start, hence the give away price. It was originally installed in an abandoned yacht, so it is a marine version, with a hydraulic box, rather than a more reliable Hurth/ZF, or other manual 2:1 ratio boxes.

 

The BMC has a cult following and was used for some smaller Thornycroft diesel for very good reasons. One of them is it's almost bomb proof in abuse and overheating terms. It will also fit the engine mounts in my sunken lifeboat project.

 

Any comments on what to think about when rebuilding, other than a recon gearbox ??

[Tony Brooks]

I can't agree that a Hurth box is more reliable than a hydraulic box if the hydraulic box is a Borg Warner or PRM. TMPs were a bit suspect though. Hurths have a poor reputation in the inland world. ZF is a too general term in respect of reliability, if its a ZF owned Hurth designs then they are no better than pre-take over Hurths but other ZF designs have a better reputation.

 

As BMC 1.5s are simple engines and in most respects easy to work on, I would suggest a rebuild would be less trouble than trying to fit a different engine. That way you know the state of the internal parts. You might even find after careful inspection and measurements glaze busting the bores, new rings shells and gaskets are all that is needed.

 

Have you sorted your torsion bar problem yet and done a compression check yet?

 

 

[Alan de Enfield]

21 minutes ago, TNLI said:

It will also fit the engine mounts in my sunken lifeboat project.

 

It must be very upsetting, when your crusie liner has hit an iceberg and is sinking and you decamp to the Lifeboats, to then find that what is supposedly your life-saver, itself sinks. Presumably at that point you need to rely on the 3rd line of defence - your lifejacket - and hope that it has been maintained, serviced and functions correctly.

 

To sink one boat is bad luck, to have two sink is exceedingly careless.

[Tracy D'arth]

Before you get too involved, measure the bores. As far as I can remember +60 thou is the biggest oversize piston available. If its already bored to the max its an expensive bore out and liners job.

I have found its cheaper to buy pistons than ring sets, crazy.

[Momac]

On 02/09/2017 at 15:50, alan_fincher said:

The BMC 1.8 was I think first produced in the early 1970s, so many are still going strong after at least 40 years. 

But are they all like Triggers broom?

 

[TNLI]

2 hours ago, Alan de Enfield said:

 

It must be very upsetting, when your crusie liner has hit an iceberg and is sinking and you decamp to the Lifeboats, to then find that what is supposedly your life-saver, itself sinks. Presumably at that point you need to rely on the 3rd line of defence - your lifejacket - and hope that it has been maintained, serviced and functions correctly.

 

To sink one boat is bad luck, to have two sink is exceedingly careless.

Hull up project, the previous owner forgot to close the engine seacock and the nearby filter unit was leaking. Bilge pump kaput, no watertight bulkheads or floatation, so it sank on its mooring before I bought it for one pound. Alas the engine was already trashed beyond all hope of a rebuild.  Never sunk more than a rubber duck before.

[TNLI]

2 hours ago, Tracy D'arth said:

Before you get too involved, measure the bores. As far as I can remember +60 thou is the biggest oversize piston available. If its already bored to the max its an expensive bore out and liners job.

I have found its cheaper to buy pistons than ring sets, crazy.

Thanks, no time to get involved in a rebuild, so leaving it to Purbeck Marine Ltd in Cobbs Quay marina Hamworthy, the natives seem to think they are the best around for restoring, parts and installation of any marine diesel. Main dealers for most. Oddly enough I'm more concerned about trouble with the gearbox bearings. The BMC manuals don't seem to cover that part and they can be fitted with 3 different 2:1 boxes.

[TNLI]

3 hours ago, Tony Brooks said:

I can't agree that a Hurth box is more reliable than a hydraulic box if the hydraulic box is a Borg Warner or PRM. TMPs were a bit suspect though. Hurths have a poor reputation in the inland world. ZF is a too general term in respect of reliability, if its a ZF owned Hurth designs then they are no better than pre-take over Hurths but other ZF designs have a better reputation.

 

As BMC 1.5s are simple engines and in most respects easy to work on, I would suggest a rebuild would be less trouble than trying to fit a different engine. That way you know the state of the internal parts. You might even find after careful inspection and measurements glaze busting the bores, new rings shells and gaskets are all that is needed.

 

Have you sorted your torsion bar problem yet and done a compression check yet?

 

No chance to do anything other than run the engine. The rest is not my problem. I will ask Purbeck marine about the gearbox options, although I hate to drag a 3 bladed prop and not be able to use all the drag to generate some power, so I'm inclined towards fitting a recon manual box.

 

 

 

 

[Alan de Enfield]

2 minutes ago, TNLI said:

Thanks, no time to get involved in a rebuild, so leaving it to Purbeck Marine Ltd in Cobbs Quay marina Hamworthy, the natives seem to think they are the best around for restoring, parts and installation of any marine diesel. Main dealers for most. Oddly enough I'm more concerned about trouble with the gearbox bearings. The BMC manuals don't seem to cover that part and they can be fitted with 3 different 2:1 boxes.

 

You wouldn't really expect an engine manual to cover the gearbox, 

Marinisation of engines did not involve the gearbox and the choice of gearbox would be left to the installer, and a variety of adapter plates were commonly available.

You know the make / model of the gearbox so try and find the relevant maual

[Tony Brooks]

30 minutes ago, TNLI said:

Thanks, no time to get involved in a rebuild, so leaving it to Purbeck Marine Ltd in Cobbs Quay marina Hamworthy, the natives seem to think they are the best around for restoring, parts and installation of any marine diesel. Main dealers for most. Oddly enough I'm more concerned about trouble with the gearbox bearings. The BMC manuals don't seem to cover that part and they can be fitted with 3 different 2:1 boxes.

 

Once again duff information. The gearbox would normally be installed by the mariniser so they can supply the whole power unit and BMC 1.5s have been fitted with TMP hydraulic boxes, PRM hydraulic boxes, Borg-Warner hydraulic boxes, PRM mechanical boxes, Hurth mechanical boxes and Technodrive boxes. That is without the BMC/Parsons A and or B type mechanical boxes that you really do not want to get involved with these days. I make that at least six different boxes and all would have been available with a variety of reduction ratios.

 

I am not sure why you are concerned with the gearbox bearings on anything other than planet gear boxes like the A and/or B type (not sure about the TMP) because the rest will throw oil around inside when the output or input shaft is turning.

 

I do appreciate that you may want a mechanical box so you can lock the prop when sailing without having to install a shaft brake but please, for long life, forget Hurth. I would use a mechanical PRM and ideally one of the larger ones.

 

You also seem fixated with Thorneycroft. By the time they were marinising 1.5s they had little to do with the original Thorneycroft company and were just marinisers. Other marnisers were J G Meaks, Newage, Tempest, AMC, Lancing Marine plus  a host of hire fleets and Freds in Sheds doing one offs. I susepect there were more up on the Broads.

[TNLI]

10 hours ago, Tony Brooks said:

 

Once again duff information. The gearbox would normally be installed by the mariniser so they can supply the whole power unit and BMC 1.5s have been fitted with TMP hydraulic boxes, PRM hydraulic boxes, Borg-Warner hydraulic boxes, PRM mechanical boxes, Hurth mechanical boxes and Technodrive boxes. That is without the BMC/Parsons A and or B type mechanical boxes that you really do not want to get involved with these days. I make that at least six different boxes and all would have been available with a variety of reduction ratios.

 

I am not sure why you are concerned with the gearbox bearings on anything other than planet gear boxes like the A and/or B type (not sure about the TMP) because the rest will throw oil around inside when the output or input shaft is turning.

 

I do appreciate that you may want a mechanical box so you can lock the prop when sailing without having to install a shaft brake but please, for long life, forget Hurth. I would use a mechanical PRM and ideally one of the larger ones.

 

You also seem fixated with Thorneycroft. By the time they were marinising 1.5s they had little to do with the original Thorneycroft company and were just marinisers. Other marnisers were J G Meaks, Newage, Tempest, AMC, Lancing Marine plus  a host of hire fleets and Freds in Sheds doing one offs. I susepect there were more up on the Broads.

The reason I'm chasing a Thornycroft BMC 1.5, rather than any other version, is that it was selected by the RNLI as the best company to supply their 37ft Rother class, BUT just to confuse things those engines were the keel cooled version as far as I'm aware. In reality I'm just as happy with any other BMC 1.5 marinised version, but might need to think about changing it to a keel cooled version. It's not difficult to do that and far less expensive than fitting an extra pump and heat exchanger. The other real big reason for chasing a Thornycroft, is that both the BBC 2 documentary concepts folks and myself think that it looks drop dead gorgeous sitting on the restored, (Blasted and powder coated), signal red frames. Red and a sort of slightly metallic version of Royal blue look cool in an engine bay with see through fire glass side plates, (The cheap wire mesh ones).

 

The engine I'm looking at buying is fitted with a hydraulic box, but I do not know which exact type, the one I want is the one fitted to the engine in the picture, as that restoration was done by the new Thornycroft dealer, Marine Enterprises Ltd. 

 

Fingers and toes crossed the test run on Thursday is OK, or I'm right back looking around Apollo Duck and Fleabay again. Fallback engine is a less powerful BUKH 24, (The 36 is too heavy). 

 

I do seem to have a cash deal, BUT it all depends 

[TNLI]

12 hours ago, Alan de Enfield said:

 

You wouldn't really expect an engine manual to cover the gearbox, 

Marinisation of engines did not involve the gearbox and the choice of gearbox would be left to the installer, and a variety of adapter plates were commonly available.

You know the make / model of the gearbox so try and find the relevant maual

My 3 previous boats had a Yanmar 2GM, Volvo Penta 150 and a Vetus M310 diesel, and all of the engine manuals covered the gearbox. Alas that is not true of Thornycroft or other BMC 1.5's due to multiple options, although the boats they were fitted to sometimes had a seperate manual for the gearbox. 

 

Drifting off topic, but just glaced through BBC news:

Two men and a dog chasing an Arctic dream in a lifeboat - BBC News

Edited July 18, 2021 by TNLI
new ending