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BMC 1.5 new fuel leak near fuel lever


ThornyCroft T-90

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Hi all!

Just joined the group-

I have a ThornyCroft T-90 in my home...a 1983 Moody 34.

Just found a bad fuel leak...on the starboard side near the fuel lift/fuel lever area...

anyone have a similar problem? I just want to get more education before I call a mechanic here...especially since maybe in the States they are not so familiar with the BMC 1.5

Thanks so much for any input!

 

-Vin

 

my channel:

Sailing Nervous

 

 

 

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I assume that you are talking about the lift pump.

 

If it just appeared with no work being done in that area its probably a split lift pump diaphragm. In the UK you can get a repair kit or a new pump. If you recently cleaned the strainer that is under the domed cap (on most 1.5s) then the soft washer around the bolt may be broken, the rubber sealing ring be misplaced or excess spannering may have distorted the domed cover.  Also carefully inspect the two fuel pipe unions but if they have not been disturbed they are far less likely to be the source of the leak.

 

If it is the diaphragm check the engine oil level, leaking fuel can get inside the engine so its probably bets to change the oil as well.

 

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Thank you so much for replying. We are stuck here and still trying to assess where the fuel is spilling from. Here are some pictures from where the spill seems to be generally located. It started all of a sudden...the first day there was maybe a cup after 6 hours of journeying....then yesterday much more after only 1 hour so we turned around and are stuck here at a marina.

Anyway, here are the pics of the general area--thanks for looking at the pictures and I certainly welcome your help in problem-solving. Once I can figure out what is wrong...then I can maybe fix it myself or look for a mechanic but we are in the middle of nowhere in an isolated part of the region:

 

IMG_5411.jpg

IMG_5410.jpg

IMG_5409.jpg

IMG_5407.jpg

IMG_5406.jpg

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So on the wrong side of the engine to the lift pump but definitely around the injector pump.

 

My guess the most likely culprit is the rubber O ring that seals the stop or throttle lever spindles.

 

First  and third photo suggest stop lever spindle, fourth and fifth the throttle lever spindle. These are will know leak points, especially if the throttle cable is badly adjusted and over moving the throttle lever on idle. It is unlikely that both would be leaking but if the US has gone to ultra low sulphur diesel they may well be. They are on opposite sides of the pump so as you photo both sides it may indicate a leak from else where. make sure the "turret" the two levers are fitted to is not loose on the pump body and is not leaking from its base.

 

The second photo with the arrow shows one of the high pressure injector pipe unions and to me the nut looks very far down the thread. This may indicate the olive on the end of the pipe has been squashed so it now won't seal. If you undo that nut and find a sharp disk has formed around the olive above where it meets the union on the pump you probably need a new injector pipe or pipes. This may apply to the other pipes as well.

 

In the last photo the red arrow points to the joint between the pump mounting adaptor plate and engine block. This is sealed by a gasket that rarely leaks and if it did it would be engine oil. The arrow may also indicate the pump flange to adaptor plate join and this shows signs of a damaged gasket but again it would be an engine oil leak, not a diesel leak.

 

In the top photo if you look to the left of the clamp around the injector pipes you can just about make out the idle damper and bleed screw. Make sure the 8mm AF bleed screw is not loose. If the leak is around the hexagons below this come back.

 

I think you need to dry it all off and run the engine while dabbing likely areas with tissue, that should soon show what is leaking.

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Tony,

I will run the engine and dab and report back-

Your reply jogged my memory which may help in diagnosis:

Everything was fine - about a year ago I had a mechanic install a new gearbox and new cables. He did not adjust the cable to the gearbox properly...he clearly was not experienced. I also noticed that the cable to the throttle lever kept making the throttle by the helm 'pull back' to idle whereas before he installed the new cables when you pushed the helm throttle forward it would stay wherever you pushed it to once you took your hand away. But after his job I had to hang a pound of heavy rope on the end of my helm throttle to keep it in place so as to keep it at whatever RPM I wanted to run it at.

I am hundreds of miles away now from that mechanic so he cant adjust it-

Now, there was no leaking for about 25 hours of engine use but three days ago I noticed that when I started the engine the RPM's went super high whereas normally when I bring the throttle to neutral the idle seed is about 5-6,000 rpm's. I also noticed that enroute the throttle did stay in place -- it just felt 'screwy'- I am certain now that the mechanic did not adjust the new cable correctly as he did a very sloppy job on the gearbox cable which i called him and had him come over to fix which he did....but I did not notice the poorly adjusted cable on the fuel lever until many hours away and many states away-

Tonight I will re-run the engine and see if we cant pinpoint more specifically where the leak is originating.

 

Thanks again for your input- it is invaluable

-Vin

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OK, may well be the throttle cable.

 

You seem to have a ball and socket fitting on the pump throttle lever so on those you pull the outer sleeve upwards (in your case) and this allows you to lift the cable end fitting away from the lever and off the ball. Set the control to idle in the neutral position and with one hand (actually you have a throttle return spring so you may not need to) hold the lever on the pump against the idle stop. Now offer the cable end up to the ball and see if you need to loosen the locknut on the end of the cable and screw the end fitting onto or off the cable a bit more (I suspect onto) so the ball just enters the fitting but the throttle does not open. You will have to pull thee sleeve back to get the ball back into the fitting. That may be all it needs if you are very lucky.  If you run out of adjustment at the engine end of the cable there should be more inside the control where the cable connects to the lever.

 

If you are now running on low sulphur diesel you are likely to find all the "rubber" seals in the pump start to leak eventually, especially the main shaft seal so it may be a good idea to start investigating where in the USA you can get that pump overhauled and have new compatible seals fitted.

 

If the cable adjustment does not cure any leak from the spindle(s0 changing the seal may be a DIY job for a tolerably handy person. There are instructions on this site. Just observe absolute cleanliness because you will be getting inside the injector pump in an area where dirt or water can stop it working..

 

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I just pulled out the original 'ThornyCroft Operations Repair manual' which I 'inherited' when I bought the boat 3 years ago....this notation would have been written at least ten (10) years ago. Note it says 'seems to be leaking past 89  needs 15/15" wrench'

IMG_5415.jpg

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Im going to start the engine up after work today and spend some time with a white tissue dabbing to see exactly where it all is coming from- i will post the pics later tonight - you are 4.5 hours ahead of us...so 7:00 pm our time is 11:30 pm your time-

Im also going to see if I can follow your post #7 so I will have alot to report back-

Thanks again-

 

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Update:

1.) I read the instructions on adjusting the throttle lever but do not have the aptitude to make the adjustment as I had difficulty in separating the cable unit from attachment point and did not want to screw it up. I do not know how to adjust the throttle cable and may need a mechanic on site because: 

 

A.) (Note: the Shut Off Lever which normally has a cable from the helm instrument panel to shut off the engine from the cockpit is now shut off directly by hand on the engine as the shut off cable was damaged and removed)

 

The Shut Off (fuel) Lever seems to be moving downwards to the 'on' position on its own more readily compared to before when you pulled the lever back to cut off the fuel it would seem 'stiffer' and stay in the 'off' position. I still push it down all the way before starting the engine it just seems 'looser' and more prone to want to be in the 'on' position. (Note: the fuel cut-off cable from the instrument panel was removed and the fuel lever to start the engine is moved 'UP' position directly by hand now)

 

B.) Normally, 'idle' is when the throttle at the helm is in the upright position. I have noticed that when starting the engine by giving it fuel/ pushing the helm throttle forward....the engine receives fuel in a greater amount as it quickly revs up as if alot more forward push of helm throttle....I have to quickly pull it back to the neutral position but even then it does not idle at the usual 6,000 rpm but it idles at 8-9,000 rpm's even when the helm throttle is pulled back into the full- upright' clicked 'neutral position. Thus it appears to be a cable adjustment which I dont seem to be able to do-

 

As for identifying the source of the leaking fuel:

The process I did:

 

1.) I started the engine up the leak appeared once the rpm's hit 2,000:

(see above schematic)

 

Number 48 'screw for cover' over the 'adjusting hole cover ' (46) of the Pump Housing (44) was leaking fuel. The wire that normally runs through it was broken off and the 'screw for cover' was extremely loose and exuding fuel. I used a 5/16'  wrench and was surprised that it tightened over a full revolution. It was very loose.

I then started the engine again....and let it run at 2,000 rpm's for a while.......no more leaking.

 

However, there was still a scant fuel leak, minimal, between the Shut Off Lever (82) and the Shut Off Shaft but 98% or more of the leaking fuel was coming from the Screw For Cover (48) over the Pump Housing, but nowhere near the amount that was flowing out by the 'Screw for Cover) #48 over the Pump Housing.

Also---the wire that used to go through the screw has been broken off....

Upon running the engine at 2,000 rpm's after tightening that 'Screw for Cover' (48) no more fuel leak-

however, i did notice that when i pulled the helm throttle back to neutral.....the engine was idling at 8-9000 rpm's whereas before the new throttle cable was installed in the same position at the help at neutral the engine idles at 6,000 rpm's.

 

here are some pics:

IMG_5462.jpeg

IMG_5454.jpeg

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First that wire. It has nothing to do with screw 48, that screw is just used as an anchor for the wire. The wire is supposed to hold the long aluminium anti-tamper shroud around the maximum speed stop screw in place. Apart from keeping idle or idiot hands away from the throttle maximum speed stop the shroud has no purpose4 so the wire and shroud can be discarded as long as you do not ever mess with the screw under the shroud - if you do the engine might throw a connecting rod out of the side.

 

Normal practice is to push the stop control back to run as soon as the engine has stopped, this prevents anyone who does not know what you do ruining the starter/battery by trying to start with the control set to stop. I don't see the looseness of the stop lever as a problem. The sealing O ring may be a bit warn but as long as its not leaking leave it alone, the spring in the governor will tend to try to move it to the run position.

 

cableballjpoint.jpg.95bc22f0b7afe347f5b6f2ab48d391d9.jpg

 

It sounds to me as if the cable outer is loose in one or both clamps. One will be bolted to the bracket that is above the pump. The other is inside the control head/Morse control head.  Make sure those are both tight first.

 

Now the cable adjustment. B above is the body of a ball joint connection. A is a sleeve that can be slid upwards (in the photo). If you do this the the sleeve will come clear of the ball itself so the whole assembly can be pushed to the left so the body B hangs free on the end of the cable. If you can't do this simply undo the nut on the right of the lever and take the ball joint out of the lever.

 

Once you have done that set the Morse control to idle in neutral and make sure the lever on the pump is set to idle. The body should now (with the sleeve raised) push straight onto the ball without needing to move either lever. If it wont the loosen the hexagon nut immediately above B (the lock nut) and screw B up or down the cable until the ball will just drop into the body. Then tighten the lock nut. If there is not enough adjustment at the pump end you will find more inside the control but with a different cable end piece.

 

The long set screw and locknut on the extreme right of the photo is the idle stop screw. If this has been maladjusted so it holds the lever too far open you can loosen the locknut and adjust it to get the correct idle but its best to do that with a warm engine and the cable disconnected. Readjust the cable when done.

 

If none of that gets the correct idle I would suspect something is jambing the governor inside the pump, even a blob of water can cause problems here or small pieces of muck but although I would remove the whole of item 60 (the turret), levers and all to allow me to swill and flush the whole thing out in clean diesel I can't advise you to try it.

 

PS - we assume you mean 900 rpm, not 9000 - the BMC would explode at that speed

Edited by Tony Brooks
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