Thornycroft T90 questions

Boo2

Well-known member
Joined
13 Jan 2010
Messages
8,581
Visit site
Hi,

I'm considering buying a yacht fitted with a Thornycroft T90 35hp diesel auxiliary engine and would be looking to re-engine her if I go ahead. I'm trying to investigate what would be required in terms of engine mounts, control gear etc and have drawn a bit of a blank in terms of finding drawings of the T90 so I can suss out space and mounting arrangements etc.

I have searched on the web and found a file called Thornycroft90-108.pdf but the several copies of this I have found don't seem to give the dimensions of the mount to output centreline or the size or the location of protrusions etc so I was wondering if anyone knows where relevant drawings of this engine can be found ?

Thanks,

Boo2
 

Pasarell

Well-known member
Joined
18 Jan 2007
Messages
1,324
Location
Greece
Visit site
T90

I bought a boat this time last year with an original 34 year old T90 engine. The boat was out of the water on a rickety yard trailer so we couldn't start the engine at survey etc. I got a very good price, partly because I factored in re-engining. Launched her exactly a year ago and the engine started first turn of the key. Since then it has run faultlessly. Quiet and smooth, doesn't burn oil etc. Money for the new engine is still in the bank so I advise checking it properly before committing to a big expense
 

maxi77

Active member
Joined
11 Nov 2007
Messages
6,084
Location
Kingdom of Fife
Visit site
Did some 300 hours last year with a T90, apart from needing a good dosing with radflush it was brilliant. It still starts with less preheat and throtle than recomended in the handbook. I would only change the engine for a morepowerful one to obvercome the loss of speed with a head sea/wind. Basically the T90 is a good engine, it will run for ever, it is quite ecconomical and if you buy the conversion to replace the CAV oil filter ( wich to be honest is a lunatic design) with the Thorneycroft spin on replacement the engine is asgood as anything else
 

Boo2

Well-known member
Joined
13 Jan 2010
Messages
8,581
Visit site
Thanks to all for the interest and replies. However I am really only looking for drawings for the T90 here (I am pursuing other options as well, seperately...)

I have asked the Thornycroft parts site but have not had an answer yet so if anyone does know where I can find a drawing of the engine with mounting dimensions then I would be very grateful...

Thanks again,

Boo2
 

Colvic Watson

Well-known member
Joined
23 Nov 2004
Messages
10,862
Location
Norfolk
Visit site
Try the Colvic Watson owners group on Yahoo groups, you will have to join (v easy) but they have scans of the original brochures and installation plans etc for almost all Thornycrofts as they were the engine of choice for all CW's. I'll add my voice to those saying how good the engine is, it must be really knackered to be needing replacement.
 

maxi77

Active member
Joined
11 Nov 2007
Messages
6,084
Location
Kingdom of Fife
Visit site
Thanks to all for the interest and replies. However I am really only looking for drawings for the T90 here (I am pursuing other options as well, seperately...)

I have asked the Thornycroft parts site but have not had an answer yet so if anyone does know where I can find a drawing of the engine with mounting dimensions then I would be very grateful...

Thanks again,

Boo2
then

Though I believe most T90s had the same mounts that does not mean yours has standard mounts. If you add to that the reality that there were several gearbox options many with varying output alignments then using 'standard' drawings as gospel for your boat would be dangerous.

Most respectable engine suppliers can match previous installation geometries so perhaps you are worrying too much at present. At the end of the day the bearers are but steel fabrications.
 

Tranona

Well-known member
Joined
10 Nov 2007
Messages
41,194
Visit site
Hi,

I'm considering buying a yacht fitted with a Thornycroft T90 35hp diesel auxiliary engine and would be looking to re-engine her if I go ahead. I'm trying to investigate what would be required in terms of engine mounts, control gear etc and have drawn a bit of a blank in terms of finding drawings of the T90 so I can suss out space and mounting arrangements etc.

I have searched on the web and found a file called Thornycroft90-108.pdf but the several copies of this I have found don't seem to give the dimensions of the mount to output centreline or the size or the location of protrusions etc so I was wondering if anyone knows where relevant drawings of this engine can be found ?

Thanks,

Boo2

It really is rather irrelevant what the current arrangement is. All the old BMC based engines have mounts far wider spaced than any modern engine - as well as being longer, taller and heavier. If you are intending fitting a modern engine you will need complete new bearers and probably modified beds to suit the narrower footprint. The only dimension that you need to know is the centre of the prop shaft as it is almost impossible to change. When designing your new installation you start from that datum point, and every dimension from that is to suit your new engine.

Some engine suppliers such as Beta can make the bearers to suit your beds, but it is just as easy to build a dimensioned mock up of the new engine and design your own arrangements. I have done that twice, first from a Stuart Turner to a Yanmar (big difference) and then to a Nanni just using the installation drawings from the manufacturer and some ply and a 1"dowell. Same was done when the Yanmar went into another boat in place of a Petter.

Hope this helps.
 
Top