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Thornycroft T154 and BMC 2.5D compatibility


Jozzah

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hi All,

 

new to this forum but after been reading the first 10 pages i am confident i will find the experts here!!

couldnt find any older topic on this matter, i have a t154 in my motorsailer,  which runs fine (knock wood!) i do love these old "simple" engines with no computers, so much easier to troubleshoot!

i, recently, was able to buy a similar which i  want to overhaul and keep in reserve.

after taking off the cylinderhead, i noticed the head was cracked, 2 minor cracks between the valves.

finding a replacement head seems to be very difficult.

i am now offered a BMC 2.5D, seller claims they are identical, 

they do look identical but for one extra hole in the thornycroft head, pic 1. an array of 5 holes on the right hand side, where the bmc has only 4, pic 2 and 3.

 

Any thoughts on this matter??

thnx in advance!

Jos

(from the Netherlands.....)

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Its not the same engine.  I can't remember which has the extra head stud. There are 2.4 and 2.5 BMC engines, very similar.

 

Cracks between the valves is common, a good engineer will be able to stitch them and fit valve seats.

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I think they are the same engine. Found a site in Dorset listing them as the same base engine.  there never was a BMC 2.4 diesel, on;y a 1.3  and then a 2.5 and then a jump to 3.X.

 

I think the glow plugs on the bottom head makes it likely that its a BMC 2.2 so not the same as a 2.5. I think the 2.5 used 12 pin type plugs.

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Many thnx already for your replies!

pic 1-2 are from the T154, the 3rd from the BMC, wil try tomorrow to get a pic of the typenr. 

 

Tracy D'arth

could you explain in  leeman terms how the stitching is done?? and is it a reliable solution for say the  next 10 yrs?

never heard of that before, ( but then again, l'm not an engineer....)

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Can't tell from the lower photo which engine it is, 2.2 or 2.5 but as it has a dynamo I guess a 2.2. It also looks more like a direct raw water cooled exhaust manifold so again more likely a 2.2. What type of injector pump is fitted. if its an inline one then its definitely a 2.2 and an early one at that. If its a DPA its no help in identifying the engine but those glow plugs are a give away.

 

Stitching is where a crack is chain drilled so you have a series of small holes. Then a special soft metal strip is pressed into the holes. On a long crack a cross shaped piece is inserted. Then the soft metal is peened flush with the original surface.

 

In your case its more likely that the valve seats would be cut out and  seal insert press fitted into the recesses so produced. That on its own may well sort the cracks.

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3 minutes ago, Tracy D'arth said:

See Metalock.

 

If it is a 2.2D, its the same base engine as the old JCB. Can't think why I said 2.4.

Cracks there seldom go into the waterway.

 which is why I suggested valve inserts would do the job.

 

If it is an inline pump 2.2 then there was a weak area on the block behind the injector pump. They needed stitching.

Edited by Tony Brooks
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It's an inline injector pump so definitely an early  2.2.

 

For information. Those glow plugs are 2V each in series so you need a hefty resistor in series with them to run off 12V, I think you can now get 12v plugs to fit.

 

Check the block for cracks behind the injector pump.

 

If you can get it fitted into your boat I doubt you will notice the loss of power caused by the 300cc less capacity but that engine is probably 60 years old so is likely to be well-worn.

 

The name Commander was applied to both the BMC 2.2 and 2.5 official marinisations but this one looks like a bitza to me.

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hi Tony,

many thnx for your feedback, priceless!

unfortunately, i have not been clear, i assume because english is not my native language,

last pic is of the BMC commander, of which the cylinder head was removed, just to be put on the blue T`154, which head had the 2 cracks. (labeled troostwijk 309)

am sure other parts of the Commender are for sale if anyone needs parts

at this moment i think i will opt for the "stitching" method of the original T154 head, since it will be a spare engine anyway

 

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Just now, Jozzah said:

hi Tony,

many thnx for your feedback, priceless!

unfortunately, i have not been clear, i assume because english is not my native language,

last pic is of the BMC commander, of which the cylinder head was removed, just to be put on the blue T`154, which head had the 2 cracks. (labeled troostwijk 309)

am sure other parts of the Commender are for sale if anyone needs parts

at this moment i think i will opt for the "stitching" method of the original T154 head, since it will be a spare engine anyway

 

 

The blue engine is a BMC 2.5 marinised by a company called Thorneycroft.

 

The grey engine is a BMC 2.2 marinised by the official BMC mariniser who was probably Newage at that time but might have been Tempest. Who marinised it does not matter cylinder head wise.

 

The name Commander was applied to the official marinisations of the 2.2 and 2.5 so its best to stick with the engine capacity (2.2 or 2.5) to avoid confusion.

 

The grey engine looks to me as if its been marinised by parts from other engines so is unlikely to be an official marinisation.

 

In my view the 2.2 and 2.5 heads should not be interchanged even if they fit. A 2.2 head on a 2.5 block may well mess up the cooling flow.

 

I am sure that you have companies that do engine machining in Holland so my advice would be to clean the 2.5 head up and take it to one and ask for advice because as I said and sort of confirmed by Tracy new valve seal inserts will probably solve the cracks without paying for stitching. If you have it stitched you will probably still need inserts fitting so you get a good valve seat.

 

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hi Tony, (and all)

after dived into this for 4 days now, i am convinced that there are no 2 identical inboards in the whole world!! haha, 

every engine seems to be constructed using bits and pieces that were accidnetly available at the time....haha,

but on a serious note,

yes, i will get my cracked head fixed with inserts, i found a professional company this morning, (even pretty nearby) and the assured me they can do the job!

so will go with that, ( and decline on the offer for the BMC head)

all thanks for your advice and the final post will be the picture of the repaired head, promise!!

jos

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