Dexta Newbie

[russelm]

Hi All

I have just aquired a little dexta to compliment the large diesel loco I work on so thought I would introduce myself.

She is a 1959 Standard Dexta that has been in pieces at the Nottingham Transport Heritage Centre for around 8 years (inside).

I have started to strip and clean the top end to complete a full engine re-build.

Problems so far:

1) The former owner cant find one of the pistons and rods
2) The lost piston/rod assembly has the wrong big end cap on.....so I am currently down 2 rods effectively (he guarantees me that he has it though!)
3) The head has a crack around No2 exhaust valve seat so thats scrap!....new head on order from Agriline

Other than that, all is good so far!

I will post a few pics as I continue.

As a first question, anything to watch when pressing out and in new little end bushes?

[YorkshireDextaMan]

Hi fella, I don't think these engines are difficult to put right but they can have a few issues that need a bit of thought, I would first wonder why the engine is in bits in the first place, and if you have a cracked head you should check for cracks in the block.
As you have gone for a new head , you seem to mean business and you could find new parts quiet expensive, you can't miss match things like conrods and big end caps. In answer to your first question about the small ends , easy enough if you have use of a press but they will need to be bored to fit the Gudgeon pin. Jim

[russelm]

Thanks Jim

The head was removed due to poor starting after it had been treated to a re-furb pump and injectors which made no difference to the starting fault (all by the previous owner)

I removed all the ancillaries from the head and stripped the valves out etc. There was some play in the guides on the exhaust valves and following the clean up, the crack was found and hence the need to replace.

Thankfuly, Agriline heads are a very competitive price and not far off what it would cost for guides, valves etc plus guide fitting, reaming and seat re-furb.

I have access to a large machine shop with press, millers, laiths etc so fitting and boring them wont be a problem.

I plan to get her running and then trundle around with her in order to find and list all the other niggles.

Once they are sorted she can have a full re-paint (although anything I work on in order to get her running will be painted as I go).

Once the head arrives I will check it over and reassemble the top end parts before removing the engine in order to check and re-furb the bottom end.

Well, thats the plan anyway

Thanks

Mark

[russelm]

Good news, Agriline have delivered my nice shiney new head plus a few other bits so I can get the top end sorted before sorting the bottom end out.

I checked the block out and there are no signs of cracks, I will check it very closely once its in the garage and cobble together a pressure test arrangement.

Any recommendations for painting the cast items....do they need a good primer (I have some very zinc rich expensive etch stuff I used on the locomotive)

[roromac]

Welcome
The common reason for poor starting on Dextas is that the original cold start mechanism - diesel injection into the manifold onto a glowing coil will probably have failed years ago and the pipe sealed off. This often leads to use of cold start spray which then leads to multiple shattered rings and severe loss of compression so continued poor starting. It's a viscious circle.
Rob

[russelm]

Some good news, the 'lost' conrod and piston assembly turned up today

[russelm]

Heres a quick pic of her as she is today

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