Engine, gearbox and prop questions

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rockingh
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Engine, gearbox and prop questions

Post by rockingh »

Hi all. We are restoring a 30 foot wooden fishing boat built in 1900 and we are a charity. We are at the painting stage and are now getting to engine and electrics.
It was fitted with this Thornycroft LT120 120HP (Ford based), Gearbox Borgwarner 2:1.5 (we think) and would like some info from your members collected knowledge.
We have had the engine running and you can see lots of detail on http://www.floatourboat.co.uk.
Picture links, https://drive.google.com/drive/folders/ ... sp=sharing
Looking at the first picture a we aren’t sure what these drain pipes marked A and B are for, they come out into a union and are a very thin tube going down in to drip tray. A comes out of the injector pump and B from the side of cylinder head.
Also in the side of the engine is a wooden plug C which goes into a hole with a dog in the bottom. If it was a petrol engine I would have said a distributor but obviously not? Two more pics as well.
Gearbox
We think this is hydraulic drive because you can turn outlet flange without engine. We know it needs an oil cooler and assume it goes to the two sockets marked a and b, does this cooler normally go in the external water feed before the engine oil cooler and engine heat exchanger? Or are there air radiator coolers?
With this sort of gearbox does it matter whether the prop rotation is left or right as long as the gear lever is mounted correct way? I assume the gearing is the same forward and reverse.
Anymore comments or information on this would be much appreciated.
Chris

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Alacrity
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Re: Engine, gearbox and prop questions

Post by Alacrity »

I am not familiar with the engine so can't comment on that, but I can help with the gearbox.

You are correct in that it is a hydraulic gearbox & yes it does need an oil cooler (heat exchanger) fitted. The raw (sea) water would normally pass through this before it goes anywhere else. The union with the 'a' next to it is the feed to the cooler but 'b' (with the yellow cap - which should be removed before use) is shown next to the gearbox breather. The cooler return to the gearbox goes into to the maincase at the front lower corner on the starboard side. You can run the gearbox either way (as in engine rotation) but you will need to check the pump is mounted correctly (on the very front of the gearbox). The are two arrows cast into the casting 180 degrees apart, the one at the top should be the same as engine rotation. If it is incorrect then remove the 4 retaining bolts & rotate it 180 degrees until it is.

You CANNOT run the gearbox in astern to get the prop shaft rotating the right way for the prop. The lever MUST move to the forward position for ahead & to the rear for astern, if the shaft is then rotating the wrong way for the prop you need to either change the prop for the correct rotation or change the gearbox for one that has the correct rotation output. You will wreck the gearbox if you ignore this. They do these transmissions with the output rotating the same as engine in ahead or reverse rotation in ahead. In the pictures the gearbox selector lever is shown in the ahead position.
Mercs are like women, no 2 are exactly alike. That's what testing is about. In general it is safer to test motors and props than women!

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solitaire
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Re: Engine, gearbox and prop questions

Post by solitaire »

You seem to have a ford 2700 series engine. Ford made tens of thousand of them in various guises 70,s and 80's 4 and 6 cylinder - turbocharged and normally aspirated with power ranges from 80 to over 400HP, (about 6.0 litre, also know as the Ford Dorset Engine) - went on with enhancements and a bit bigger 6.2 litre - still a 2700 series and also known as a Ford Dover engine.

Fitted to Ford Cargo trucks , and tractors - but many thousands designated "Industrial engines" were sold to companies (like Thornycroft, Mermaid, Lehman etc) who fitted some, in house and some off the shelf marine conversion parts, and they were sold as marine engines.
They are extremely reliable, but very basic units, just like a big Ford Cortina engine, so maintenance is very simple and spare parts cheap and abundant.

One of these little pink Ford 2700 series books. http://www.ebay.co.uk/itm/FORD-2700-RAN ... SwYIxYAnNd will cover all of your servicing and maintenance requirements. Ford original pink workshop manuals are also on FleaBay for around £30-£40

The pipe from the back of the cylinder head B is the fuel leak off, from the injectors (quite a lot of fuel is leaked off) and needs to go back to the top of the fuel tank,
The pipe A on the side of the Simms injection pump is also a fuel leak off/overflow, in a truck this often is let to spill onto the road (its onlyan overflow if the pump is in poor condition) but in a boat it should be tee'd into the same return to the top of the tank (but please double check in the manual when you get it on this one).

The wooden bung is covering the gear that is driven off the camshaft to turn the oil pump in the sump. The plate usually has a drive adaptor for a Tachometer, and the little pink book is good enough to have a parts list which will show the tacho drive and plate and parts required.

They are good lumps and in non turbo form, very under-stressed, and quiet economical. (Fishermen love them) . We fitted the Lehman conversions in Grand banks cruisers, many of which cruise world wide and trans Atlantic -

A couple of word's of warning, they are dirty internally and need frequent oil and filter changes, the fuel injectors are fitted UNDER the rocker cover, so when you do get it running - just let it idle with the cover removed and check there are no fuel leaks from the injectors (high pressure and leak off pipes), if you get a leak or breakage here - fuel will leak into the sump, diluting the oil and wreck the engine very quickly - A daily dipstick oil level check will also indicate a problem here.

Alactity is the gearbox expert - and it's a shame the build plate is missing, can you find any numbers on the G/Box? - I'm sure Ford never build a counter-rotating 2700 engine. so the engine should turn clockwise from the front, ie counter-clockwise when viewed from aft, But like Alacrity says, - the gearbox could be counter-rotating - If you find the g/box serial number I could tell you what direction it left the factory as, and obviously you need to know the output flange rotation when in Forward gear before you can select a propeller l/H or R/H.

rockingh
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Re: Engine, gearbox and prop questions

Post by rockingh »

Many, many thanks to both of you for great info. I'm sure there may be more questions :giggle: Chris

rockingh
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Re: Engine, gearbox and prop questions

Post by rockingh »

Can someone (alacrity?) confirm the gearbox oil cooler connections to the velvet drive please.
We know the outlet is on top with a 1/4" BSP male connection and we think the return is on starboard bottom with a double socket as seen in the photo attached.
We thin that is 3/8" BSP female.
https://drive.google.com/file/d/0B3dgQH ... sp=sharing
Thanks Chris

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Alacrity
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Re: Engine, gearbox and prop questions

Post by Alacrity »

Both cooler unions are the same size, the square headed bung will serve as a pattern as I am not sure of the size. You have one union that looks correct (the outlet), you just need another.

I am slightly concerned that it appears to have been run without a cooler as the return looks to have been permanently blocked by the painted bung. :hmmm:
Mercs are like women, no 2 are exactly alike. That's what testing is about. In general it is safer to test motors and props than women!

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