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Ford Lehman fuel consumption

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    Evening all

    In Crosshaven Ireland preparing my NC33 number 1000 (purchased blind in March because of Covid) for trip to Portugal I hope starting mid May. I have searched the forum and not found any valuable info on fuel consumption for 1985 Ford Lehman 90hp engine – anyone studied the subject or has direct records would be a great help. The NC manual gives values which look way too high but it is a old system engine! Need the info to gauge fuel to take on deck ….
    Dick Smith


    Additional forgot!!!! Are these bow cleats standard and has anyone a spare as mine is missing one port side?


    Work on 5 litres per hour @ 1400rpm.


    Thanks James thats three times a suggestion made today by another 🤔. do you have any practical experience of these engines??


    My Ford Lehman 90 ( not Turbo) does about 3 litres per hour at 7 knots. I have those very similar cleats which I fitted 2 years ago on my 1990 Nauticat 33 mk 2 no. 1092. I had no centre cleats as standard and fitted one each side


    Further to my reply, these are reliable workhorse engines but use a lot of oil, so keep a regular check on oil consumption. Also keep a spare relay, the one that ensures both steering positions are in neutral before you can start the engine. ( Sorry, technical terms have evaded me) mine has failed twice, but once was a connection working loose.


    Thanks for most helpful comments any idea where I might locate the neutral relay as so far only been aboard for a week and learning curve on the vertical – photo would be great value if possible but cant imagine finding one in this quiet Irish village! Will see if a cleat turns up as like to have original if possible.


    My NC33 is burning between 2,5 and 4 litres /h at 1400-1600 rpm, always 6 knots.

    David Babsky

    Our 1989(?) Ford Lehman uses about 5 litres an hour at 1600rpm, giving us a constant 7 knots. Unlike Rose-Anne – above – we never seem to burn any oil! (But I do keep several spare gallon cans of engine oil and gearbox oil – different substances! – down beside the engine ..just in case! AND spare fan belts. And make sure that you know the correct mark for the engine oil level on your dipstick!)

    Regarding the “..spare relay, the one that ensures both steering positions are in neutral before you can start the engine..” I think this means (well, it does on ours, anyway) the elaborate metal ‘skeleton’ arrangement of sliding metal plates, down beside the front-left of the engine, into which the ‘Morse’ or ‘Teleflex’ cables run from the throttle / gearstick lever. As Rose-Anne mentions, BOTH (internal and outdoor ‘poop-deck’) gear levers need to be in the central ‘neutral’ position before the engine can be started. But perhaps Rose-Anne means a separate small electrical relay box which is connected to that metal skeleton, and which also connects to the boat’s starter switch: I don’t know about that, as we’ve never had any trouble with ours, and I’ve never even thought about there being one till just now!

    Dip the gearbox (there’s a built in awkward-to-reach extractable dip stick) to make sure that it’s full up to the mark, and if you see any white ‘margarine’ in there, that means that water’s leaking into the gearbox via a cracked gearbox oil cooler (strapped onto the rear of the engine: one’s a roller for the engine oil; one’s a cooler for the gearbox oil).

    If the engine hasn’t been run for a while, ‘prime’ the fuel pump by squeezing the rubber cover on the fuel pump, which is about three-quarters the way back from the front of the motor on the right-hand side. That assumes that you’ve first turned ON the fuel ..on ours, it’s with a three way tap under the steps down to the back cabin: centre position OFF, left position PORT tank, right position STARBOARD tank (or is it the other way round?) ..anyway: centre OFF; one way or the other, one or the other tank.

    If the engine hasn’t been run for a while – or even if it has – check (and maintain spares of) the FUEL FILTERS! Very important. On a rough passage, if the boat’s been standing for months, there’ll likely be messy deposits in the bottoms of the tanks, which will get stirred up as the vessel rolls and pitches, and can then clog the fuel filters. Replace the filter elements in the main fuel pipe AND in the filters attached to the engine.

    If you can reach them, open the small taps at the bottom of each tank FIRST, to drain off any sludge from the bottom of the tanks, and add ‘Marine 16’ diesel-bug killer (available from most chandleries) to both tanks.

    If the boat hasn’t been used for a while, DO A SHORT SHAKEDOWN JOURNEY FIRST before going from Ireland to Portugal, to find out what doesn’t work, and what’s just about to fail. Check that the anchor chain really is fastened to the boat! Carry seacock bungs, a WORKING radio, and be sure that the fuel gauges are ACCURATE! (I replaced ours – the mechanisms in the tanks – as the originals were (invisibly) cracked and showed false readings on the wheelhouse dials.) When the gauges show that two thirds has been used ..i.e; there’s a third of a tank left.. REFUEL as soon as poss, because ‘one third left’ in a flat calm sea can mean that the fuel pump sucks just air when the boat is heeling!

    And when the boat is heeling (over to port, I think) the seawater inlet may be out of the water(!) so if you’re motor-sailing and heeled over, do make sure that cooling water is still coming out of the starboard ‘tell-tale’ pipe and the rear exhaust pipe!

    All the best!

    David Babsky

    ..On second thoughts ..maybe all the way over to the left is OFF for the fuel switch, and maybe upright is PORT tank, and all the way right is STARB’D tank. I’m not on the boat right now, and can’t quite remember!


    A bit off topic, but the cruising rpms cited above are much lower than I was led to believe to be best for the engine.
    My Ford Lehman 90 runs at 3200 rpm wide open throttle. Cruising speed is 80% WOT, or ~2500 rpm. This yields optimum speed. Temp and pressure and fuel usage(4l/h)the same as if running at 1800 rpm.
    Or am I doing it wrong?
    The Boat of Laughter and Forgetting
    1989 NC 33 #1072

    Nicholas Muir

    This is very interesting – p.42 of the post Apr 1984 NC33 Boat Manual (see attached) has a table and comments some of which is obviously ‘fictitious’ but I find it amazing that running at 2500 rpm is a good advice. I tend to chug around at 1600 @ 6.5knts, all good with fuel consumption around 5 l/hr. I think I should up the revs a bit maybe.


    Well caused some interesting thoughts and data thanks to all I understand the comment about the suggestion that you should run at higher revs for the good of the engine what I do if running for a long time I up the revs for an hour or so then drop back – as a final comment I must make note we do have a sailing boat performance to factor in, wind permitting, and that should also pull the revs back I have about 1350 miles to run for Portimao Portugal so with sail full tanks and say 100lts on the deck I can comfortably get into a re fuel early down the Portugal cost but I do plan to be well off shore. I am also retired and can wait for wind – I once sat waiting for wind on a return trip from the Azores for 5 days bit boring but interesting wild life watching!!!! Thanks all

    David Babsky

    This is a reply to Bruce Goldman:

    How weird; we run generally at 1600rpm, and that gives us 7 knots in still (-ish) water, and 9 knots with a following tide.

    2500rpm seems excessively high ..and must generate a lot of noise, I’d have thought (and use a lot of fuel). Perhaps you have a non-standard prop (..or a damaged prop?..) which needs higher revs to push the boat along ..could that be it? Or for some reason you have a different gearbox or reduction drive?

    The fastest I’ve driven ours is about 2100rpm to push forward in a head-on sea, but that almost doubles our hourly fuel consumption!

    2500rpm seems – I have to say it again – incredibly high if for a different engine entirely.

    – David.


    Hi David

    I have no experience of this craft until launching next week but I agree I have never run any of my cruising boats up at those revs and where you are I would hope to be from noise and consumption points of view. Whats your consumption may I ask please at 1600 rpm? Sounds a comfortable speed – naturally I will look for some contribution by the sails hopefully!!

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