A Volvo TMD41B difficulty.

[Jegs]

Greetings,

I have tried to search the forum under headings such as "engine misfire, Volvo misfire, diesel hunting, lumpy tickover & fail to reach max revs." The last produced a thread entitled "Man in 80's shot dead in Reigate," so my searching incompetence has forced me to bother the forum.

V. TMD41B, 1993 3000 hours; problem lumpy/uneven/misfiring tickover & max revs 3200 in neutral & forward, including operating lever on injection pump, rather than specified 3800/3900. Boat: steel displacement.

The only smoke is a slight blue output on startup.

Unsecuring oil filler cap merely results in a wobble at tickover - no UFOs visible.

The fuel & air filters have been [unnecessarily] changed.

The tappet clearances have been checked [feeler gauge] & valves appear to function normally.

Only oil visible on dipstick & no sludge on filler cap or anywhere visible.

Finger 'test' on turbo - no play detected & spins freely.

Oil pressure & temperatures remain within manufacturer's specs.

Engine filter bled whilst engine ticking over - clean diesel only.

Feed from tank to lift pump - gushing if you forget to close stopcock on tank - no prizes offered.

[Confident of hull cleanliness & hopeful of prop condition although suspect neither would affect tickover.]


The nearest engineer does everything, paint, woodwork, electrics, generators, propulsion engines etc; jack of all trades & lacking Volvo special tools?

Please assure me that a new lift pump [groans of derision from the stalls] will solve the problem or...............?

Hopeful thanks,

John G

 

[[2068]]

When's the last time the injectors were checked / tested?

 

[Ragnahex]

it does like of sound like it is having difficulty getting enough diesel through to achieve stable tickover. I have no idea about volvo engines though i have had this problem on a different diesel engine and it was a restricted fuel pipe (awful little fuel bleed nut got a piece of what looked like grass stuck in it)

 

[scottie]

Could the engine be a derated commercial spec engine governed to 3000 rpm

Check engine spec number with Volvo dealer?

 

[oldgit]

Is there an internal filter inside lift pump,one of those mini white plastic jobbies hidden away in fuel pipe banjo union or mesh inside removable cap on pump ?

 

[Jegs]

My thanks to all of you.

Scottie - no, reached higher revs earlier this season.

FlowerPower - probably never [if it works leave alone?].

Ragnahex - feed to lift pump copious & fuel spurts from pipes if opened where connected to injectors.

OldGit - Dunno, it's a sealed unit but fuel at entry to injectors & not much required on tickover.

ATB,

John G

 

[oldgit]

Injector.Bit dribbly at tickover when injectors virtually closed but spray pattern OK when more throttle applied ?

 

[A_8]

If the injectors have not been replaced or refurbished I think you should absolutely do that, I believe they are at 1000h service intervals and the tip of the injector can break leaving metal parts where you don't want them.

 

[Divemaster1]

KIS first of all....

Exhaust bend clogged up with corrosion...

Fuel pick-up gauze on tank clogged

Air leak somewhere in the fuel system... (think these engines are self priming... are they not?)

De-laminated fuel pipes..

Once the simple things are eliminated, you go to the more complex and costlier...

 

[Jegs]

KIS first of all....

Exhaust bend clogged up with corrosion...

Fuel pick-up gauze on tank clogged

Air leak somewhere in the fuel system... (think these engines are self priming... are they not?)

De-laminated fuel pipes..

Once the simple things are eliminated, you go to the more complex and costlier...

Thank you, Alf.

Corrosion in exhaust, hadn't thought of that but would it affect tickover? Fuel gushes from disconnected feed pipe to lift pump so think blockage in tank unlikely. Copper piping from tank to approx. 30 cm of lift pump & another 15 cm flex twixt that & injection pump then steel [I believe] from inj. pump to injectors. I'll start again tomorrow - damaged index finger making things awkward.

ATB,

John G

 

[Divemaster1]

Did this happen before or after filter change?

Had 40A's once... and became a pig to start... would not rev... completely blocked exhaust bend... replaced and all became A1... surprised you get same rpm in gear as not which would not be the case if you had fuel restrictions.

Sorry on bad network in S Italy with small device so short replies... Good luck!

 

[Jegs]

Did this happen before or after filter change?

Had 40A's once... and became a pig to start... would not rev... completely blocked exhaust bend... replaced and all became A1... surprised you get same rpm in gear as not which would not be the case if you had fuel restrictions.

Sorry on bad network in S Italy with small device so short replies... Good luck!

Happened before change & was replaced [as well as air] in hope that would solve the problem. My first thought was slippage in linkage, but all tight & operating lever on pump gives same result.

Thank you for your time.

John G

 

[Jegs]

Is there an internal filter inside lift pump,one of those mini white plastic jobbies hidden away in fuel pipe banjo union or mesh inside removable cap on pump ?

Apologies for the delay, I am unable to find anything like that in any of the exploded diagrams of the six listed pumps on the marinepartseurope web site. There is something that looks like, but not labelled as, a bleed screw; not plucked the courage to try it yet! Nearest V agent >100 miles &, having dealt with them, I'd sooner vote for "gorgeous George."

Thanks,

John G