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ditchy

Bmc overhaul review

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What do BMC perform like after being refurbished. I'm thinking of having mine done but Im not sure what to expect.

Should I expect a leak free engine that starts on its first compression or am i dreaming?

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That rather depends upon exactly what you mean. You use "overhauled" and "refurbished". Both words that can and are used to cover a multitude of sins.

 

If its a proper job involving a rebore, new pistons, crank grind, new main and big end bearings, checking the rods for straightness, measuring the oil pump and changing if required, changing the timing chain, changing the tensioner, measuring and replacing the camshaft & bearings as required and so on then it should be as good as new after it has been run in. However I doubt it would start on the first compression, few BMCs do but you might be lucky. This sort of reconditioning could cots a great deal, especially if much cylinder head work is required.

 

On the other hand at the other end of the scale if its a wash down and spray gun overhaul it will be no better than it is now - but might look nicer.

 

Pick whatsoever level of reconditioning you want between those two extremes and the cost will be less but the results might not be as good as one would hope.

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What do BMC perform like after being refurbished. I'm thinking of having mine done but Im not sure what to expect.

Should I expect a leak free engine that starts on its first compression or am i dreaming?

 

If you want an answer to that you'll have to be a lot more specific about what you mean by 'refurbished' in the context of an engine overhaul/repair.

 

If your engine has developed some minor oil or water leaks, and has become difficult to start, then the remedies may not be much more than some routine maintenance and repair jobs.

 

At the moment you're asking the mechanical equivalent of the length of a piece of string. Saying what your engine is either doing or not doing that makes you think it needs 'refurbishing' will help to get you a worthwhile and meaningful answer.

 

Knowing model/type, total hours run, maintenance/repair history, and current symptoms/performance would be useful information to have.

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At the moment you're asking the mechanical equivalent of the length of a piece of string

 

What kind of string?

 

I agree with the Tonys

 

Richard

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To be honest if the negine is not performing well and especially if it is smoking heavily, the realistic option is to have a complete re-build, which is what we had done to our BMC 1.5 engine a few years ago. That meant that every component that moved was either replaced, re-bored or re-ground. The result was an engine that perfomed as well as it did on the day it was originally installed, and it dstarts immediately ine the summer without pre-heating. As far as leaks are concerned, it should not leak any more than they did when new (remember the small pools of oil that sat under parked Sherpa vans?)

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Its a thornycroft engine with an unknown amount of hours. I give it a general service as it needs it filters. Oil, valve clearance, glow plugs cleaned.

Its would be just nice to know where mysterious oil leaks are coming from (which work there way onto the belts).

To stop the wetting of diesel on the top of the injector pump and of course, a more efficient start.

The engine runs fine once started. The reason for this thread is that I could start throwing a couple hundred quid here and there which instead could be better off being spent on the whole lot being dealt with.

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BMC 1.5s and probably 1.8s use Pintaux injectors. These have a small spray hole from the side of the "tit" on the nozzles. These spray mainly under cranking and direct the fuel into the hottest part of the pre-combustion chamber. When these block, as they do over time, starting does become difficult.

 

The leak on the injector pump may only need a throttle spindle O ring change or even cable adjustment to stop the lever attempting to overthrow. At least one member has changed those O rings.

 

I have no idea how even a crankshaft front oil seal can get oil on the belts but it will be thrown outwards by the pulley. Again someone here has changed one in situ but it probably requires the timing cover taking off to do it.

 

While I can understand the reluctance to try to fix each problem in turn a proper overhaul is likely to be well into four figures. Maybe £3000+.

 

At the very least take the side cover off with the breather hose on it and make sure the oil trap (may or may not have metal (rust!) in it) is clean and allows a free flow of air/gasses through it. Only 1 bolt holds the side cover on.

 

Take your injectors for overhaul. I do not trust bargains on auction sites to have the correct pintaux nozzles fitted. If they have pintle nozzles the starting will be compromised but it will run OK.

 

From your list of problems I would have thought maybe £350 should get the injectors and pump overhauled (no timing required - you can't get it wrong) and buy the parts to solve the other likely problems.

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If oil is getting onto the belt, the most likely leakage place will be either the rocker box gasket, or from the timing chain cover. Diesel wetting the top of the injector pump suggests a leak at one of the unions, and could also be ciontributing to poor starting.

 

I am sure Tony Brookes will be along soon with a much better informed assessment, but if you have tried everything without success, it may be time for you to have an experienced engineer look at your engine.

 

 

 

Edited to add: He did it! Posted at the same time!

Edited by David Schweizer

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Its a thornycroft engine with an unknown amount of hours. I give it a general service as it needs it filters. Oil, valve clearance, glow plugs cleaned.

Its would be just nice to know where mysterious oil leaks are coming from (which work there way onto the belts).

To stop the wetting of diesel on the top of the injector pump and of course, a more efficient start.

The engine runs fine once started. The reason for this thread is that I could start throwing a couple hundred quid here and there which instead could be better off being spent on the whole lot being dealt with.

 

We're still having to guess at the type/model of engine, but on the assumption that it's a BLMC 1.5 or 1.8, that you've tested the glowplugs as well as cleaning them, and as the engine runs OK once it starts, then this doesn't sound like anything much more serious than a set of service/exchange injectors, some attention/repair to a fuel leak on the pump throttle housing, and a new timing cover oil seal.

 

Depending on where you are in the Midlands, I may be able to call in and have a look at your engine on the way back home from another job.

We do carry/stock Service/Exchange injector pumps and injectors, and a common parts/spares stock for B[L]MC 1.5 /1.8, so I would almost certainly have whatever is needed with me.

Edited by Tony Dunkley

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We're still having to guess at the type/model of engine, but on the assumption that it's a BLMC 1.5 or 1.8, that you've tested the glowplugs as well as cleaning them, and as the engine runs OK once it starts, then this doesn't sound like anything much more serious than a set of service/exchange injectors, some attention/repair to a fuel leak on the pump throttle housing, and a new timing cover oil seal.

 

I agree with all of this. If the engine sounds ok in other respects I would tend to leave alone. The only thing I might do would be to check compression if there is any difficulty in starting assuming glow plugs and fuel side are all good. Excessive blow-by is an indication but not an exhaustive one.

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