Ford Lehmann 80; Blue smoke

[peterhodson]

I have a Nauticat 33 with marinised Ford Lehmann, circa 1980. Engine runs well with little smoke until load is suddenly increased (throttle increased) when a large plume of blue smoke appears. Compression is good and it doesn't smoke more than expected for its age when running at constant speed.
Any suggestions?

 

[FF]

FORGETABOUTIT.

A rapid movement of the throttle asks the engine to respond rapidly which requires more fuel.

The engine gets a bit more fuel than it can instantly burn , so you see some smoke.

Push the throttle up slowly and I would guess there will not be any excess smoke.

 

[what_barnacles]

And for a complete 180 (its the internet where there can be no agreement allowed)

This what perkins says about it.

Fast facts

• Blue smoke is mainly caused by oil being burnt within the combustion process

https://www.perkins.com/en_GB/resources/useful-information/blue-smoke.html

 

[FF]

"The possible sources of blue smoke are:" (from Perkins)

• Worn valves or guide seals
• Failure to change your oil or oil filter regularly enough
• Damage or wear to pistons
• Turbocharger issues

These might all cause smoke at a steady state of operation .


Sudden throttle movement seems to cause the OP smoke.

 

[Xsbank]

Does your engine run well at wot? That is the acid test and you should do that occasionally. Its noisy.

 

[what_barnacles]

Well if I was going to venture a guess, I would say the injector pump is full, too full. Drain it, and put fresh oil in it. If you get a lot more from draining it than it takes to refill it then the seals are leaking fuel into it's "crankcase" (for lack of a better word).

 

[Ski in NC]

A bunch of smoke when power is increased suddenly is somewhat norm on these old engines. Especially if engine has been run at light load where gunk builds up. As long as it burns clean at steady state operation, no worries.

 

[Xsbank]

I agree. That info about the Simms pump, if that's what you have, is mostly correct. You have to drain and change the oil in it at 50 hours. British engineering. You haven't told us much, really, but if the engine is running well and it passes the wot test, just keep doing the regular maintenance, sooner or later you should have the injectors renovated, but just run the bag off it. The old jerk-injection engines are only efficient and therefore smoke free at a very narrow load and rpm so just live with it and enjoy the reliability.

Also, make sure the crankcase is not overfilled and check that the water jacket is properly bled. There is lots of info on here if you search.