3cylinder lazy diesel engines- anyone any experience on here?

[JimK]

compact tractor, 3 cyl diesel, starts ok (bit black smoke soon clears) but v. lazy to rev and v. low powered, nearly conks on slight incline?!

any ideas/pointers plse?

Cheers JimK

[NT]

from experience on petrol engines I'd check compression.

NT

[The Natural Philosopher]

bad comp generally makes smoke

I'd say blocked air intake

Prolly air filter full of rats nest etc.

[Bill Taylor]

Had a similar problem, turned out to be a clogged fuel filter.

Bill

[dennis]

Or fuel filter if it has one.

[The Natural Philosopher]

Yup. that's a definite pissobolity.

[JimK]

Thanks for replies so far..

could it be something =A3=A3=A3=A3=A3 expensive?

I don't know - fuel/injector pump, injectors or something else?

or does the fact it starts, runs and "tries" (without any unusual smoke) bode well for something simple (and cheaper:>) ?

Cheers JimK

[The Natural Philosopher]

yes.

change fuel and air filters, and go again.

costs very little, may completely solve the problem.

Poor compression normally means dire starting.

Its starved of air, fuel, or both, not worn out.

[Steve Firth]

I have a 3 cylinder diseasel tractor (Fiat) and there are a number of possible problems.

1. Check the air filter.
2. Check the throttle linkage and make sure it is properly adjusted and that you are getting full movement.
3. Check the separator bowl and drain off water, if any.
4. Check the fuel filter.
5. Check the fuel and make sure it hasn't got full of water over winter.
6. May be injectors blocked by gunge.

It may be unique to mine, but I would also check the state of the bolts securing both mechanical fuel pumps to the block. The lift pump bolts worked loose on mine which led to a loss of power. I've also had the high-pressure pump bolts work loose which led to a loss of power. Both solved by re-torqueing the bolts after applying a thread locking compund.

I'd also check for leaks in the high pressure circuit.

However general gunge, clag and nastiness is the best bet particularly if it's a tractor that gets laid up for several months over winter. Bugs grow in diesel and clog up the filters.

[JimK]

which question was the "yes" for?

it ain't mine yet... ;>)

anything I can easily check to confirm how dire it could be *before* I purchase? (and ideally without fixing it for the vendor? :>))))

Cheers JimK

[andrew]

If it starts easily without chugging out white smoke before it fires then I'd go along with clagged fuel filter. The black smoke may indicate bad air filter but it could just be the slight over fueling before the governor cuts the delivery back.

Check also that there isn't a blocked, gelled or collapsed sock filter in the tank attacked to a fuel tap.

I've had a spate of problems with water (presumably condensation) in the tank in which a bacteria lived and caused a jelly deposit on the tank filter to restrict fuel. Solved by adding an expensive marine biocide and dewatering additive. I have wondered about just adding neat 95% methanol to sort this, remembering from school days how we added methanol to dry out retorts.

AJH

[JimK]

thanks for input andrew:-

what would white smoke signify ? (and how much white smoke we talking about here?)

......there may have been a whiff of white whilst first starting it up

- tho it seemed to "catch" quite quick for a 20yr old, blow abit of black smoke ("clearing its lungs") then largely smokefree but feeble...

Cheers JimK

[Steve Walker]

Sounds like restriction of fuel or air supply, as discussed above. If it runs smoothly then it's structurally OK, sounds like a good bargain if the price reflects the current state.

[andrew]

Unburnt atomised fuel, which generally means poor compression, if one cylinder starts firing it goes grey. It can also be poor injector pattern but not that frequent an occurrence compared with worn rings or bores.

Generally the engine will crank over and white smoke emanate from the exhaust then gradually it will start firing on one, then the next undsoweiter. A worn engine will genrally tickover with a blue smoke (from partially burnt oil) and clear when put under load and higher rpm. Much the same symptoms from an engine that has regularly been left idling (glazed bore). Look also for water vapour from the breather, this is also a symptom of an underworked (or worn) engine, assuming it hasn't a fundemantal problem like blown gasket or leaking liner.

I still think it's most likely a fuel problem, has the injector pump a separate oil level? Still 20 year old tractors are a bit modern for me!

AJH

[Fredxx]

An air restriction would make a very smoky exhaust on any sizeable throttle/pedal.

[Steve Walker]

If it's the air filter, you should be able to see if it's clogged or to be certain just remove it and try running it without (short term it won't do any harm).

SteveW

[JimK]

er...pass sorry

so given that

1) it starts from cold (after 30 secs glow plugs) 2) ticks over ok, 3) will pick up revs "leisurely" in neutral, but 4) in 1st (high) gear cannot climb even a gentle incline (when you try the engine fairly quickly (5secs) loses revs (in a controlled gradual decline manner) and you typically press the clutch just before it conks)

necessarily suggest poor compression (worn rings, bores)?

*if so* what other symptoms would I expect to see? or what other simple tests could I do to confirm ? NB no blue smoke whatever, that I recall....

or if a fuelling problem a simple supply prob?, or worst =A3=A3=A3 case injectors / pump?

Put another way if it's the injectors and/.or pump thats shagd, am I seeing enough "correct" symptoms to confirm it? what else can I check simply to confirm/dispel?

Cheers JimK

[Andrew Mawson]

talking

bores.

er...pass sorry

so given that

1) it starts from cold (after 30 secs glow plugs) 2) ticks over ok, 3) will pick up revs "leisurely" in neutral, but 4) in 1st (high) gear cannot climb even a gentle incline (when you try the engine fairly quickly (5secs) loses revs (in a controlled gradual decline manner) and you typically press the clutch just before it conks)

necessarily suggest poor compression (worn rings, bores)?

*if so* what other symptoms would I expect to see? or what other simple tests could I do to confirm ? NB no blue smoke whatever, that I recall....

or if a fuelling problem a simple supply prob?, or worst £££ case injectors / pump?

Put another way if it's the injectors and/.or pump thats shagd, am I seeing enough "correct" symptoms to confirm it? what else can I check simply to confirm/dispel?

Cheers JimK

Classic fuel starvation - change the fuel filter, clear the sediment bowl, and check the lift pump diaphragm.

AWEM

[JimK]

fuel tank is actually above engine so would it have a "lift pump" or just an injector pump?

if just injector pump would there be a diaphragm in it to check? (ISTR they are precision engineered bits not worthy of tinkering?)

cheers JimK

[Dave Liquorice]

Does it have a pull/handle start facility? Try turning it over by hand without operating the decompression lever(*). It should be almost like tuning it into a solid stop on each compression stroke and not creep if you hold it compressed hard. You might *just* be able to take it through compression by hand.

If it is as easy as a petrol engine to turn over, it ain't right... With the decompression lever active it'll spin easy.

(*) Beware that it might fire and run... a pull start mechanism shouldn't bite you but a handle might. As with all starting handles don't grip the handle between you fingers and thumb. Use your palm and fingers only, your thumb staying the same side of the handle as your fingers.