Thornecroft Engine Replcaement ?.

[Jim@sea]

I am considering an old boat with a Thornecroft Engine. BMC 4 cylinder Diesel. 38hp ?
Has any one experience in what would go straight in as a replacement.
ie, Bukh, Beta,Yanmar. The boat is a Colvic and I particually remember helping a friend who had bought a New Hull (1979) to fit a second hand (but reconditioned) engine, as did many people who bought a Colvic.

 

[Tranona]

Beta or Nanni 35 or 38 would be good replacements. Same basic Kubota engine slightly different marinisation, good choice of gearboxes.

 

[macd]

My last boat had a BMC/Thorneycroft 1500, which I replaced about nine years ago with a Beta 28.
Assuming it's like mine, your BMC will be much wider across the bearers than anything you're likely to replace it with. And quite possibly one cylinder longer.

Of course several manufacturers will make special feet to your drawings so that the new engine can slot straight in. I didn't go that route through fear of vibration being set up in the large overhangs and bonded in new bearers, instead. I did it myself and it's not terrible difficult if you're used to messing with grp, but it was not a small job. I can probably send you chapter and verse if you PM me.

An alternative might be to bolt and bond substantial timbers inside the old bearers, which wouldn't be half so much work.

Many Moodys were fitted with BMC engines as standard: you might get some useful info from the owners' association (although I did hear, how correctly I don't know, that this costs money).

 

[galeus]

Unless you know this engine is u/s why rush to spend your money. I'm 13 years into enjoying a Thornycroft 1.5 BMC diesel and the oil pressure is perfect and about 4,050 hours on.

 

[Jim@sea]

Unless you know this engine is u/s why rush to spend your money. I'm 13 years into enjoying a Thornycroft 1.5 BMC diesel and the oil pressure is perfect and about 4,050 hours on.

The boat is a 1983 and I will be delighted if the engine runs OK. The engine though is still a BMC, and having had various farm machinery which had the same engine, I am not impressed. Certainly early JCB's had the same engine fitted and they were known to have overheating problems, which was resolved by removing the thermostat. And having bought and sold perhaps 50 BMC J4 Diesel Vans in the 1970,s with the same 1500cc Diesel Engine I ended up giving every buyer a can of Easy Start as I knew they would not be able to start it the following morning.
Mind you these vans had done over 200,000 miles and I never had to do any repairs.
Perhaps if I buy the boat I could find a scrap engine and have it overhauled. I wont say regardless of cost, but I have been quoted £9000 for a new Nanni which is more than I am paying for the Boat. Mind you if it was a Moody 33 worth £25,000 it would be worth it.

 

[charles_reed]

The boat is a 1983 and I will be delighted if the engine runs OK. The engine though is still a BMC, and having had various farm machinery which had the same engine, I am not impressed. Certainly early JCB's had the same engine fitted and they were known to have overheating problems, which was resolved by removing the thermostat. And having bought and sold perhaps 50 BMC J4 Diesel Vans in the 1970,s with the same 1500cc Diesel Engine I ended up giving every buyer a can of Easy Start as I knew they would not be able to start it the following morning.
Mind you these vans had done over 200,000 miles and I never had to do any repairs.
Perhaps if I buy the boat I could find a scrap engine and have it overhauled. I wont say regardless of cost, but I have been quoted £9000 for a new Nanni which is more than I am paying for the Boat. Mind you if it was a Moody 33 worth £25,000 it would be worth it.

Nothing much wrong with the Tnorneycroft, if an archiac, bulky and heavy design, providing it's in good order.
AS you point out re-engining will doule the cost of the boat - certainly give you lower fuel consumption but probably no greater reliability.
In cost/benefit terms a non-starter.

However, if you're sure the engine is clapped out - put a compression tester on it and confirm.

 

[Jim@sea]

I asked a local boatyard who have serviced the engine about doing a compression test and they seemed to think I should go for a sea trial and see if it runs smoothly and not do a compression test on this engine as being 30 years old things can break off in it.
But in the real world where people run out of diesel and have to quickly bleed an engine I need to have "loosened" things up.
Perhaps a new Impeller. New Starter Motor (if the one is an original "Lucas" ) etc.
In any case on my last boat (1986 Iveco Diesel 2400 hours) It was not starting properly and removed the Injectors for servicing and fitted new Glow Plugs. The problem was a Glow plug.
And on this boat I would not go to sea without having the Injectors Serviced, the Filter to the Injector cleaned and the tank inspected internelly as on my last boat the tank had a kilo of sediment.

 

[Boo2]

I am considering an old boat with a Thornecroft Engine. BMC 4 cylinder Diesel. 38hp ?
Has any one experience in what would go straight in as a replacement.
ie, Bukh, Beta,Yanmar. The boat is a Colvic and I particually remember helping a friend who had bought a New Hull (1979) to fit a second hand (but reconditioned) engine, as did many people who bought a Colvic.

I've sprung for a Nanni N.38 which has the identical power, rpm, direction and torque as the Thornycroft 90 so will take the same prop. But it has been sitting in its crate at the bows of my boat ever since delivery a year ago so I'm half wishing I'd gone for a rebuilt Thornycroft from these guys : http://www.pbmechanical.co.uk/engines/index_bmc.htm

If the rest of your sterngear is in OK condition then £3300 for an exchange power unit will save you a bomb and should be good for another 30 years.

Perhaps if I buy the boat I could find a scrap engine and have it overhauled. I wont say regardless of cost, but I have been quoted £9000 for a new Nanni which is more than I am paying for the Boat. Mind you if it was a Moody 33 worth £25,000 it would be worth it.

Is that the installed cost ? You should be able to get a new N.38 for around £5k5, rest of the cost is up to you to an extent but £3k5 should be enough even in a boatyard.

Boo2

 

[Hugh Foulis]

If you do take it out can I have it?

 

[cryan]

I asked a local boatyard who have serviced the engine about doing a compression test and they seemed to think I should go for a sea trial and see if it runs smoothly and not do a compression test on this engine as being 30 years old things can break off in it.
But in the real world where people run out of diesel and have to quickly bleed an engine I need to have "loosened" things up.

What do they expect to break off? And why do they expect it to break off?

 

[Jim@sea]

What do they expect to break off? And why do they expect it to break off?

The problem is that I was not listening properly. I think it related to changing the Glow Plugs or perhaps the Injectors.
Obvously if I was going to take these bits out I would have run the engine so that it is hot then try and "tease" the bits out.
What I should do really is get a workshop manual for the basic engine and see where things are.
Although I did look at the engine the other day and the chrome rocker cover looked a bit battered and realised that the original one would have probably had "Morris" written on it.

 

[Otter]

You can buy a new one, same size and spec for £3k as said but even less if you reuse parts like the starter etc. The quality and frequency of the servicing combined with lots of high rev motoring has waaaaaaaaaay more effect on an engine than mere 'age'. Short runs in and out of a marina will do lots of damage to an engine.

 

[maxi77]

The problem is that I was not listening properly. I think it related to changing the Glow Plugs or perhaps the Injectors.
Obvously if I was going to take these bits out I would have run the engine so that it is hot then try and "tease" the bits out.
What I should do really is get a workshop manual for the basic engine and see where things are.
Although I did look at the engine the other day and the chrome rocker cover looked a bit battered and realised that the original one would have probably had "Morris" written on it.

The B series engine actually came out of the Austin drawing office but the company was BMC by the time it appeared in it's earliest form. In general they are unremarkable but reliable engines with a decent supply of spares as they were very widely used in both road vehicles, tractors yachts and canal boats. If it starts easily it is likely to keep going well, they like to be used and are reasonable on fuel. I managed to get a spin on oil filter kit for mine which was a big improvement. They were fitted with a wide range of raw water pumps but impellers seem to be available for all of them. There are people who will sell uprated alternators but in the end I found for me the 35 amp one was OK.

 

[Caer Urfa]

Hi Jim

You say the boat is a Colvic and I am guessing a Colvic Watson.

As a side line I have done Pre Buying Inspection visits for many years for new buyers of dozens of Colvic Watsons of all sizes and as already said many were built with a BMC/Thornycroft engine.

In a sentance most are 'bullet proof' and I would have no reservations about a CW with an old or original BMC/Thornycroft engine fitted in it, spare are available no problem from various sources and if in the worst case I would have it reconditioned.

If your considering buying the boat surely you have run the engine, How does it start from 'cold', lots of blue smoke? but does the smoke clear as the engine warms up?

Also look at what gearbox is fitted Hurth, ZF, PRM ? and check the forward/reverse engine controls to the gearbox!!

If I can help further send a PM

Mike

 

[Otter]

One thing chaps, there's no such thing as a Thornecroft or Thorneycroft, only a Thornycroft. Not being pedantic, just helping when you try to Google search for info and manuals. Lovely simple engines, cheap spares and straightforward to work on.

 

[Pasarell]

I have a Moody 33 with 36 year old Thornycroft T90, the BMC 1500 engine. Boat was out of the water when I bought it with no opportunity to run the engine. It looked rather tatty so my offer price allowed for replacement. When she went in the water the engine started first time and has carried on like that ever since. Runs smoothly and is reasonable on fuel. They do need quite a bit of heat before starting. 30 seconds seems typical. Last winter I replaced the fuel lift pump and the glow plugs. Other than that just regular oil and filter changes.

 

[CarlBarnett]

I have searched a bit and the engine you have chosen is pretty great. Go with that.
I have received some great reviews of it.

 

[The Dogs Pollacks Brother]

We have a BMC 1.5 in our Colvic 21. This engine has been excellent in the 3 years we have had it although we have just had the origional Lucas starter servived after it gave up. This engine has been half submerged so had to be drained and "pickled" then after a weekend of flushing and putting back together it started first time and has done ever since. Needs about 30 seconds of heat though as mentioned above. Fuel usage is never mentioned as it seems to chug along forever on a tank....we do about 10 or 12 fishing trips a year with an average of 2-3 hours motoring per trip and get through about 75 litres of red a season!
A little noisy compared to more modern engines but a steady old lump!

 

[maxi77]

We have a BMC 1.5 in our Colvic 21. This engine has been excellent in the 3 years we have had it although we have just had the origional Lucas starter servived after it gave up. This engine has been half submerged so had to be drained and "pickled" then after a weekend of flushing and putting back together it started first time and has done ever since. Needs about 30 seconds of heat though as mentioned above. Fuel usage is never mentioned as it seems to chug along forever on a tank....we do about 10 or 12 fishing trips a year with an average of 2-3 hours motoring per trip and get through about 75 litres of red a season!
A little noisy compared to more modern engines but a steady old lump!

The original handbook does say 30 seconds, but after changing to a decent car type starter battery and a couple of 12 hour runs she started with no heat at all in warm conditions and 10 seconds otherwise.