MF35, starting & diesel quality?

I purchased my MF35 4 cylinder diesel knowing these things generally have starting issues. It was a hard starter when I picked it up, but when I got it home I filled it up with a fresh tank of diesel and it has started first go without a problem ever since. I only use the tractor on weekends so that tank has lasted a couple of months. I've just re-filled the tank now and its back to being very difficult to start again. The only thing I can think that has changed is the fuel?

I've read about varying cetane levels in diesel, but can this account for such a dramatic difference in starting from one tank to another?

I guess I'll try adding a cetane booster and see if that helps - but was just wondering if anyone else has experienced this with just fuel?

Does your tractor have cylinder preheaters.
Are your air and fuel filters in good order?

How old is your battery, you may want to buy a battery
maintainer and keep it hooked up to the battery during the
week. The battery must be in top condition.
What weight oil do you have in the motor.
check with your dealer there may be a injector cleaner you
can add to the fuel.
If you use starting fluid be sure to check with your dealer an
insure you follow their procedures. As you can ruin your
motor with this stuff.

(quoted from post at 10:20:31 03/25/13) Does your tractor have cylinder preheaters.
Are your air and fuel filters in good order?

How old is your battery, you may want to buy a battery
maintainer and keep it hooked up to the battery during the
week. The battery must be in top condition.
What weight oil do you have in the motor.
check with your dealer there may be a injector cleaner you
can add to the fuel.
If you use starting fluid be sure to check with your dealer an
insure you follow their procedures. As you can ruin your
motor with this stuff.

Click to expand...

Thanks for the reply Wellmax99. It has two heater plugs in the intake manifold, the manifold gets hot, I can even hear a flame front some times when I'm preheating the intake so I know its working. I was told that's how this system works, it introduces diesel and heat to start a small fire in the intake manifold to aid in starting.

Air filter is the oil bath type which I cleaned out and put fresh oil in when I got it(it was in poor condition before this). Haven't checked the fuel filters but the previous owner said all the filters were fresh.

The battery is good, its a truck battery. I keep it on a solar trickle/maintenance charger during the week. It has no trouble cranking the engine over for many minutes if its being difficult to start.

I put 20w50 oil in it as the engine is a little tired, but it has had this oil in it for weeks and has been starting fine with it. I don't use starting fluid - haven't needed to as it was starting first go until the last fuel up.

The only thing I can isolate as having changed is the fuel? Was originally a pig to start, put some fresh fuel in and it was starting fine, now all of a sudden another new tank of fuel and its being a pig again! I'm in Australia and we're in Autumn but the temperatures are still warm (20C+). The fuel was purchased a couple of months apart from different sources.

I doubt fuel quality is the problem here but adding fuel to the tank can stir up any crud in there and cause problems.
AT 20°C, it should start easy but since it is most likely a Standard 23C diesel they are notorious for being hard starters. Does pre-heating help? If it doesn"t and the engine is in reasonable mechanical condition(good compression, good valves, etc) I"d suspect the fuel delivery. While I"m not familiar with your specific intallation, the fuel delivery system includes the tank, a shutoff valve/strainer fuel line to the filter filter to pump fuel line and a return to tank line from the injector pump to the tank.
Check for full flow through the filter by removing the fuel connection to the pump and checking on the flow. An unrestricted fuel system from tank through to the filter should allow a CONTINUOUS gush of fuel. If it dosn"t, then suspect a restricted filter or a clogged strainer in the tank bottom, and make sure the tank vent is not clogged. Check all your fittings for tightness so they cannot suck air. Throughly bleed the fuel sytem starting at the fuel filter, through the pump and to the injectors. See if that helps.

No worries, I'll go through the fuel system and make sure its all clean and clear. I would have thought any obstruction there though would also show symptoms once the engine was running? Once I get it started it runs fine, throttles up ok and gains revs with no hesitation. Maybe dirty injectors?

If you want get serious about fixing the starting problems with these old girls, you might like to ponder removing the head, and attacking it with a die-grinder.(see before and after pics).
The secret is to open up the narrow port from the pre-combustion chamber. This allows the ignited fuel to pass from the pre-combustion chamber into the cylinder more easily and quickly.
The pics show one I did some time back, with very good results. A friend of mine removed more material than I did when he attacked his, and, in his words,.."Starts like a 3 cylinder Perk now!!"
But DO NOT take any material away from the area close to where the head gasket sits, for obvious reasons! In the pic, I have scribed a line where the edge of the gasket would sit.
Let us know how you get on,
Evan.

Great pictures Evan! I had heard of that mod, but hadn't seen pictures explaining it as well as those. It's something I plan to do when I get to doing a rebuild on the engine.

This problem just has me perplexed as for the last 2 or 3 months it has started straight away every time, so I know it can start well 'as is' - just not sure why its suddenly changed.

Only other thing I can think is maybe cranking speed? The battery appears to last a while whilst cranking the engine over but maybe it has lost a little 'oomph' and not cranking as fast it has been?