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Old 13 September 2012, 15:26   #31
DJS
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Quote:
Originally Posted by captnjack View Post
No it doesn't.

Normally unburnt diesel is dark/black.
White or grey is either water vapor or oil. Although oil is usually darker grey and slightly blueish.

Hard to tell what's going on via the internets without pictures or video...
Unburnt fuel under normal running conditions is black, however take it off the timming and its white/greyish with no power. I recently re-timed one where a guy put it one full tooth of the timming and the symptons are as described above. Water vapour is a contender and while the OP says its a recent rebuild i have seen liners drop and or poor workshipmanship lead to head gasket failure etc.

In this instance and as Captnjack says it had to tell without seeing and hearing it run. And as with all diagnostics keep it simple and check the simple things first!
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Old 13 September 2012, 16:28   #32
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My list in order at this point is as follows:
Check compressions
Check pump timing, will check marks first and then by spill method.
Fit injectors, new fuel filters and then bleed system thoroughly.
Run up and

See if my yard disappears under a grey choking smoke cloud again.
If so, try playing with pump timing, if no change, send pump off for rebuild and conversion to boost capsule setup.
try again.

i am not expecting miracles, these engines are renown for smoking from cold, but I can't believe it should be as bad as it is at the moment.
The RIB will be used as a safety boat and for towing dinghies. at the moment they would need rescuing from the fumes it kicks out.

Regarding the pump knowing what the turbo is doing question. With this current setup, the pump has no connection to the turbo, hence my desire to modify it with a boost capsule, that will increase the fuelling as the boost rises..
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Old 13 September 2012, 17:20   #33
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Are you sure it's a 250 sabre? Surely it should already have the fuelling controlled by boost pressure?

I can remember plenty of 120hp fords having a turbo bolted on with no other mods for 150hp.
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Old 13 September 2012, 19:30   #34
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I have the receipt for the reconditioned engine, and it is listed as 250 on there. It also does around 30 knots driving a Hamilton jet. I don't believe it would go at that sort of speed with much less than 225 - 250?
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Old 14 September 2012, 05:39   #35
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Quote:
Originally Posted by A1an View Post
Eeeek... A K+N wouldn't stop a brick getting in to your engine let alone fine sand.
Interestingly, the article in the latest copy of Powerboat & RIB that arrived today, has a feature on page 102 on the new GM Duramax V8 diesel and it features the identical K+N filter that I am using.
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Old 14 September 2012, 06:03   #36
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Unburnt diesel is white/grey vapour
burning engine oil is blue
diesel burned in insuffecient air is black and full of soot and normal for a diesel of this age under heavy load to a certain extent.

smoking on partial load or out of gear is nothing to do with boost compensation and you will probably be wasting your time modifying it.

Diesels have been used without compensation for years, and with an engine with such a low RPM band you can get away without it.

without compensation your engine should run very clean at displacement speeds and tickover. its only when the throttle is wide open and the engine is lugging you should get a fair plume of black, until the turbo cleans it up as the rpm climb.
I think from the smoke you describe the engine may have a big issue other than boost compensation.
In other words you should have no smoke other than black, and then only when giving it some beans.
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Old 14 September 2012, 06:20   #37
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Also there no reason why you cant screw in the rack stop screw on the back of the pump to reduce the delivered fuel(noting where it was before)
and remove the pipe from the turbo to the inlet manifold. by doing this you can eliminate over fueling as the cause by progressively reducing the fuel until it will hardly run, and see if the smoke goes away, also running without the turbo pipe connected will prove if any oil is getting in from the turbo seals.
a compression test may tell you something, but I have seen many many smokey engines with good compression. usually caused by damaged oil scraper rings or bores that are heavily worn oval at the bottom of the bore and not too bad at the top.

if the injectors and timing dont fix it I think you may neet to tear it apart.
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Old 15 September 2012, 13:22   #38
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Due to my lack of Gyneacological skills, "Fugly" has now been renamed "Frankenstein" due the large incision I have made in his forehead, which now gives me total access to the engine and gearbox. He is getting uglier by the day at the moment!
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Old 16 September 2012, 05:12   #39
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Just to set this straight...the engine is coupled to a jet, right? And there is no water based intercooler on it. What kind of exhaust sytem you have..any exhaust damperthingies added?
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Old 16 September 2012, 09:12   #40
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The engine is coupled to a Hamilton jet unit. It has several heat exchangers including an intercooler on the turbo. Now you have mentioned it, I will also check the condition of that, I guess if it was weeping, it would certainly add to grey / white smoke. Currently pulling the turbo as it has been leaking exhaust gas where the exit pipe joins the exhaust housing (gasket has disintegrated) and it appears to be leaking around the clamp where the housing attaches to the main body. Usual story of rusted bolts etc. I think I have opened the proverbial can of worms! Might be quicker to pull the entire engine assembly. At least i can give everything a good clean and paint. I can run the engine out of the boat and get that running properly and then refit the sorted lump into gleaming bilges.
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