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Old 10 September 2012, 11:59   #1
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Smokey Ford Sabre 250

I have got a Ford Sabre 250 in my Pac 22. I know they have a reputation for being smokey on start up and improving when they warm up. However I am not satisfied with the amount of unburnt diesel being spewed out the exhaust. I am constantly travelling in a diesel smog that is both unpleasant and probably very unhealthy to be around. I have had the injectors checked and a couple of them needed a slight tweak, but nothing that would sort this out.
The engine was supposedly reconditioned about 400 hours ago so I assume that the basics are in good shape, so the next step is the pump. The engine was a non turbo engine standard. As far as I can make out, all Sabre did was stick a good sized turbo on it and crank the pump up to give it extra fuel for the turbo to make the power. The pump is a very basic inline unit and has no boost capsule, so it just chucks fuel in depending on where the throttle lever is set. problem is that increasing the fuel at the top end to make use of the turbo also increases the fuel at the bottom end of the spectrum which I believe is contributing to the smoke problem. So my plan is to build the pump with a boost capsule that will allow adjustment at the bottom end, so at idle, the fuel being delivered will be the same as the non turbo engine, and as the boost comes up, it will open the rack up and increase the fuelling to match the turbo at the top end. This should give a nice smooth power delivery and hopefully clean it up across the power range. Has anyone on here done anything similar and how did you get on?
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Old 10 September 2012, 12:30   #2
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I haven't done this, so I don't know if it would work.
Does that help?
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Old 10 September 2012, 12:56   #3
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Smoking engines like this are either over fuelling or lack of air supply.
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Old 10 September 2012, 13:25   #4
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Quote:
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Smoking engines like this are either over fuelling or lack of air supply.
Correct but there is nothing wrong, its just the turbo doesn't do much until 1800 revs which is were the over fueling takes place. Once past 1800 revs the air fuel mix is restored by the turbo and it burns clean.

These are very old engines now, I would just use and enjoy it.

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Old 11 September 2012, 10:04   #5
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had a couple on a ranger 36 diesel smoke died down at 2000 revs but it ate oil we could only leave marina very early morning
Once went thru crinan canal neary killed everyone in the locks
there after always went round mull we fitted a engine water heater 240v that seemed to help at start up as engine was warm
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Old 11 September 2012, 12:34   #6
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What colour is the smoke, is it black?
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Old 11 September 2012, 12:55   #7
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The smoke is grey mostly when cold at idle. When the revs are increased the smoke output increases with them. Once it is under load, it does clean up some,. When the power is increased if not done gently, it will chuck out a large black cloud initially but will then clean up some.
My thoughts are that the pump has been cranked up to make the power at the top end, but by doing so the fuelling at the lower end has also been increased and the engine can't physically burn it all until the turbo kicks in.

I am hoping the pump modification (boost capsule / smoke box) will allow it to run with the correct amount of fuel off boost as it would have been in its natural non turbo spec and will richen up as the boost increases. This hopefully will clean it up some, it is unacceptable as it was.
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Old 11 September 2012, 14:44   #8
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If it is a factory Sabre 250 it should already have the boost / fuelling gear.

212c certainly does.

The smoke may simply be due to the low compression needed to run the high boost to make top end power.
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Old 11 September 2012, 17:32   #9
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Some thoughts!

Check the pump timming if its to late (retarded) you will have un-burnt fuel which is white, you could try to advance the timming and see if this helps.(mark the position of pump as it curently is and then slacken bolts and use a leaver to twist the pump round a little, do this with the engine running and you will hear the revs pick up if you are advancing the timming, or if slowing down you are going the wrong way) Not to much or it will run warm and mabe even Knock a little.

Another possibility is oil leaking past the valve stem oil seals (sitting overnight or for longer periods) and then on start up it is smokey until it burns this excess oil off. Worn valve guides is also a common fault but thats another discussion.

As mentioned compression could be down however, if it starts without to much trouble this is unlikely.
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Old 12 September 2012, 03:33   #10
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could also be dribbly injectors.(poorly atomised fuel will not burn and condenses on the piston crown, vaporising as the engine warms making white smoke) I would whip them out and get them tested first. If it was to do with overfueling because of the turbo/pump settings the smoke would be black, and then only with the hammer down and lugging to get up boost. Its may be a combination of things, stem seals, dribbly injectors, etc.
start with injectors and pump timing. then check turbo seals.
stem seals can be replaced without removing the head with a little inginuity.
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Old 12 September 2012, 05:19   #11
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The injectors should be back today, they have been checked and a couple needed servicing, but nothing much that would account for the smoke. My plabn is to refit them, check all the valve clearances whilst I am at it. I will then check the pump timing, it has been suggested to set the timing at 22 degrees BTDC to allow for backlash (book figure is 20). I will give it a run with that done and see if there is any improvement. I will then back the fuel off on the pump until it is running nicely at idle and use that as my starting point for the boost capsule mod. I considered stem seals, but the engine has only done around 400 hours since reconditioning, so I would be surprised if they are in trouble already, also I would expect to see blue smoke for oil, rather than grey/white. I have now managed to borrow a dummy injector that will allow me to do some compression checks as well.
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Old 12 September 2012, 09:57   #12
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The boost capsule or pump fuel adjustments will not account for grey/white smoke. black smoke yes. you may find without excess fuel at low rpm the turbo lag will be really bad, and it may not get up on boost at all without some "coal on the fire" white is definetley unburnt fuel/oil. if all is well with the engine and it over fuels it could make black smoke as the fuel will burn, if its not burning its because its in the ong place or at the wong time!
No amount of max fuel adjustment(fuel stop)will make any difference at tickover, the engine is off load and the fuel is entirely controlled by the govenor. the only time the fuel stop will make any differenge is when the throttle is on the bulkhead and before the engine reaches governed speed.
What happens to the smoke if you leave it revving at 2k in neutral?
is it better or worse? if its worse and the engine sounds a bit wooly it could well be timing.
you need to spill time the pump if its an inline pump, or make sure its locked at injection point if its a rotary pump or marked at injection point.
a few degrees of advance wont hurt, and may prove a point as to whether its fuel timing related or not. Worth checking the turbo tract for lube oil too, could be turbo seals or a blocked breather forcing oil into the intake?

We had a ford engined lorry, the smoke when it was cold would make your eyes water! however when warm it was fine. there was nothing wrong with that in particular and it didnt use much oil unfortunately being a DI and turbo it took a while to warm up. they were notorious for it as were the perkins 500 engines(prima) so smokey at light load you cant really use them in a river boat
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Old 12 September 2012, 10:03   #13
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Just a thought, do you have a manifold heater? They can dribble into the manifold and cause all sorts of smoke. Likewise the boost compensator on DPA pumps can leak fuel into the manifold.
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Old 12 September 2012, 10:24   #14
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I took the breather off the rocker cover with it running and it doesn't chuck anything out there, I also took the oil filler cap off and the same there, so the engine doesn't seem to be breathing much.

It doesn't have a manifold heater that I can see. All it has for cold starting is a small knob beside the stop arm that you press in for cold starts. It is all pretty agricultural stuff.
My next task is to put the rocker assembly back on (removed it to gain easier access to the injectors) and to carry out a compression test. as long as they look ok, it should make it easier to narrow down the problem. I pulled the turbo - inlet manifold connector off and had a look at the inlet side, I was expecting it to be oily as usual, surprisingly it was quite clean. So hopefully the turbo seals are in reasonable condition. The turbo ran at 1 BAR consistently once on boost.
I have also got a good size K+N filter that I am going to fit on the intake instead of the current small bell mouth with a wire mesh. The boat will spend most of its time parked in a RIB park surrounded by very fine sand, that gets in everywhere. I don't want to ingest any.

The pump timing is sounding the next best option.
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Old 12 September 2012, 11:21   #15
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Eeeek... A K+N wouldn't stop a brick getting in to your engine let alone fine sand.
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Old 12 September 2012, 13:47   #16
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Eeeek... A K+N wouldn't stop a brick getting in to your engine let alone fine sand.
What do you base that on?
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Old 12 September 2012, 14:30   #17
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Years of filtration and power testing by some of the most respected car tuners in the business.

The general consensus seems to be that they were just ok at filtering when freshly oiled but soon lost performance. When freshly oiled it was found that the oil mist/vapour coated MAF sensors and caused bad performance and even failure of the sensor.

If they are as good as they say they are then why don't the leading performance Marques like Ferrari, Porche and Aston use them?

Paper all the way!
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Old 12 September 2012, 15:12   #18
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Eeeek... A K+N wouldn't stop a brick getting in to your engine let alone fine sand.
better than a bell mouth and wire mesh though................
and you wont find any poncy MAF sensors on a Sabre
or many bricks out at sea come to think of it.
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Old 12 September 2012, 15:18   #19
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that's a minimec/simms inline pump then? you may need to spill time that.
you may also need a special splined socket to remove the delivery valve housing so you can get the delivery valve out of no one cylinder. unless some kind soul has marked injection point on the pump. probably easier to just bugger about with it and see if advancing it a bit helps!

two other things I thought of , there's not a shut off valve in the intake?
and is the oil level correct, i am sure it is on the dipstick but is it the correct one????
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Old 12 September 2012, 15:33   #20
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[QUOTE=A1an;487378]Years of filtration and power testing by some of the most respected car tuners in the business.


If they are as good as they say they are then why don't the leading performance Marques like Ferrari, Porche and Aston use them?




They do.
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