BMC 1.5 litre diesel - "what to do?"

Kukri

Kukri

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There will be a thread or three on this I am sure but the forum search function denies it!

Am looking at a boat fitted with one of these...

Engine spins like a top on one battery, but not at all interested in starting..

Can of ether suspiciously close to engine...

Engine hours around 3,400...

Amateur diagnosis - low compression.

Need expert advice, here..

Chuck it, or buy/ part ex a reconditioned one?
 
Often poor starters. Try a squirt of Easystart. Getting on in years now, but bits are available to rebuild. However a Nanni or Beta 35 makes a very good replacement!
 
Found my BMC1.5 a right awkward sod to start, but found that priming by manually operating the fuel lift pump solved this and it started easily after 30 seconds on the glow plugs with a good amount of throttle.
This was 2 years ago before I lifted the boat out of the water due to a severe lack of time for boat, I will get eveything sorted and get some sailing done. Sometime. Honest. Then I can start finding out why the engine occasionally revs up of its own accord, although pretty sure that checking fuel suction piping will sort this out!
 
'Spinning like a top' sounds suspicious. Try turning the engine over by hand using a socket spanner. It should be quite difficult to bar it over top dead centre. If this seems too easy, spin it over again while squirting oil into the inlet and try again. A marked difference when oiled shows rings or bores to be in poor condition.

My BMC 2.2 is pretty clapped out and needs 15 seconds on the glow plugs but then usually starts on most cylinders with clouds of grey smoke.
 
Try searching for Thornycroft T90 as that may well be what it is.
I sold mine a couple of months ago (in the boat) at 40 years old and it was still running nicely. They are notorious for needing lots of preheating and I found priming with the fuel lift pump made a big difference too. So 30 seconds preheat and about 20 pumps and mine usually started quite easily. The old owner left a couple of part used cans of easystart in the spares locker but in 6 years I never used it.
 
My friend had one of these engines on his MacWester. It was always difficult to start and there was an anxious few minutes whilst he worked his magic. We concluded that part of the problem was the lift pump, the other cause was lack of heat from the glow plugs. The lift pump was overhauled and a Thermostart installed as fitted to several of the Thorneycroft engines. This improved things significantly.
 
Thank you all very much.

Will now have a Think, in the manner of Winnie the Pooh, as I am a Bear of Little Brain where engines are concerned.

On a boat that I would expect to sail by myself for much of the time, an engine that requires manual priming and squirts of ether is not ideal...
 
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There was a reconditioned one that popped up for sale on one of the facebook selling groups yesterday for £500.00
I know absolutely nothing about it, I didn't pay much attention to the ad in all honesty, but if it's of interest let me know and I'll see if I can find the post/ad and forward it on to you.
 
Murv said:
There was a reconditioned one that popped up for sale on one of the facebook selling groups yesterday for £500.00
I know absolutely nothing about it, I didn't pay much attention to the ad in all honesty, but if it's of interest let me know and I'll see if I can find the post/ad and forward it on to you.
Click to expand...

Thanks; please do.
 
Do as Vyv suggests in post #4. That will or will not eliminate what is probably the most expensive fault to put right. If nothing untoward shows on those tests, suspect glow plugs or possibly fuelling. Glow plugs are pretty easy to test if the seller lets you.
I had a simiar engine a decade or so ago: from cold it started reliably, but only after about 15 seconds of pre-heating. When warm, starting was almost instant.
 
The glow plugs must be good, and used for at least 30 seconds. It's best to have the throttle down at first and increased as the engine turns. If it doesn't catch, leave it for a couple of minutes before trying again.
 
For 8 years, mine was a real b.... to start despite all tried methods already suggested. I needed 2x 100 ah batteries + 1 min heater to get 1 cyclinder to fire first for 10 secs for the others to come in in later.

All transformed just before I had to sell = I advanced the timing a midge and then it started on all 4 pots without needing heat within 15 secs

Flood it first with full throttle for 5 secs. - wait 2 secs - then back off to mid range and hit the starter again

Old story - if only I know now - what a lot of trouble I would have missed
 
We used to find that the glow plug holes into the pre combustion chambers blocked ,effectively insulating the plugs. We used to remove the glow plugs, and I had a 3mm ? Drill welded to a piece do 3mm welding rod with a Tee handle. We would grease the drill, hopefully to catch the grot ! Drilled through the. Carbon, check the plugs word before refitting.
The 3 MM ? Is the same dia as the glow plug end.
 
My T90 is 32 years old, runs smoothly and starts within 10 seconds every time (instant if warm). When I first bought my boat 11 years ago I had a long chat with Mike Bamford (thorneycroft man) about the engine. The main wisdom and my routine is this:
- engine runs for ages if well maintained
- DO NOT under any circumstances put modern oil in it. It must be 20/50 NOT thinner. It needs the thicker oil to build compression. I use Comma Xflow mineral 20/50
- Carbon in the glow plug holes is an issue (see other post on here) Google or Moody owners website give the exact imperial drill to use to clean out the hole - easy
- Start on full throttle, then ease off immediately it fires.
- With this routine I have never used more than 10 seconds glow even for first frosty start after winter lay up.

I would suggest that this is what you should expect from a healthy engine, otherwise you have fuel supply or compression problems. Good luck.
 
Mine was always a b***** to start - spent about £500 getting head off and 2 broken off heater plugs machined out, new fuel pipes etc etc. It took 20 secs of heat and it would eventually start with clouds of smoke and would leave the marina leaving a smoke screen behind me. It had apparently been 'reconditioned' 7 years earlier but when I attempted to change the oil it was like tar and I suspect it had never been changed for years. Fortunately I had an unexpected inheritence the following year and fitted a new Beta engine and sold the BMC on ebay - the best investment I ever made!
ps a lot of spares now come from India and of very poor quality ...
 
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Had my 1.5 reconditioned by Calcutt boats about 7 years ago and it still runs very nicely and starts easily. Best thing to do with a poor starter is take out the glow plugs and use a drill bit to remove the carbon build up, these engines won't start from cold without the heaters. Then 20 to 30 seconds of heat, open the throttle and start.
 
PaulJS said:
Found my BMC1.5 a right awkward sod to start, but found that priming by manually operating the fuel lift pump solved this and it started easily after 30 seconds on the glow plugs with a good amount of throttle.
This was 2 years ago before I lifted the boat out of the water due to a severe lack of time for boat, I will get eveything sorted and get some sailing done. Sometime. Honest. Then I can start finding out why the engine occasionally revs up of its own accord, although pretty sure that checking fuel suction piping will sort this out!
Click to expand...

These engines rev up if they are starved of fuel, you probably have air getting in or dirty filters. I've had this issue myself and it was caused by air.
 
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