I have a caterpillar d6n serial number cck00666 it's very hard to start even when it's warm I change both fuel filters when you crank it there's a lot of white smoke coming out of the exhaust once it gets started it seems to run fine couple days ago it bogged down for a minute or two we assumed it was a bad fuel filter hasn't done it since after I changed the fuel filters I let it idle for about 15 minutes shut it off went to start at about an hour later won't start again you have to crank it for over a minute to get it to start
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Caterpillar d6n very hard to start
- Thread starter KWhauling
- Start date
I had to guess on punctuation to clear up the thoughts in my head. I don't have any guess after all, but maybe the punctuation will make it easier for somebody to understand. Correct me if I got anything out of place. Or edit your original post, you have one hour from posting, then it's locked from editing.
Sorry I talked to my phone I don't type that's why there's no punctuation
Nige
Senior Member
Did the symptoms come on suddenly, or has it been getting worse for a while.?
Have you tried pumping up the fuel pressure with the priming pump before attemtping to start.? Does it make any difference.?
You've changed fuel filters (both of them I hope). What else have you done to the fuel system.? Below are a few thoughts/suggestions........
Remove the head for the water separator and check each fitting and passage in the head for obstruction. There are more dark corners in that head than you can shake a stick at.
Replace all the seals on the water separator and the gaskets on the priming pump if you haven't already done so.
Drain water and sediment from fuel tank.
Check fuel suction line for blockages between the fuel tank and the priming pump by blowing back to the tank with compressed air.
Have you tried pumping up the fuel pressure with the priming pump before attemtping to start.? Does it make any difference.?
You've changed fuel filters (both of them I hope). What else have you done to the fuel system.? Below are a few thoughts/suggestions........
Remove the head for the water separator and check each fitting and passage in the head for obstruction. There are more dark corners in that head than you can shake a stick at.
Replace all the seals on the water separator and the gaskets on the priming pump if you haven't already done so.
Drain water and sediment from fuel tank.
Check fuel suction line for blockages between the fuel tank and the priming pump by blowing back to the tank with compressed air.
Do you have access to Cat ET? I would be looking at the injection actuation pressure and seeing if actual matches desired. Definitely need to do what Nige has suggested first as good fuel supply is a must. If youre not getting good actuation pressure, watch closely the engine oil pressure because if the engine oil pump is getting weak, it will not supply the HEUI pump which will cause slow building actuation pressure.
BigWrench55
Senior Member
Another way to check if you are losing actuation pressure. Is to remove the valve cover and have a helper crank the engine. If you see little guisers of oil coming out around injector bore. Then you have blown orings. Thus you can't build enough oil actuation pressure to open the injectors. This sounds like this is your problem. Extended cranking can eventually get you there, but it's a good way to burn up a starter.
It's been a little hard starting in the morning but it was single digits or teens I did give it a shot of either I was just assuming it was because of cold we would start it and run it all day I think it came on quick . One thing I did notice there was fuel coming out the primer when I pumped it. It never gets hard when pumping I honestly never used the primer as I always filled the filters but the one on engine is upside down so you can't fill it I'm going to mess with it alittle but tomorrow I have a mechanic coming next next if I don't figure it out I just thought I'd ask here for a couple things to look for first thanks
Nige
Senior Member
If the priming pump is not getting hard try clamping a set of vise grips on the fuel return line and then pump it. What happens then.? If the pump goes hard then your fuel pressure regulator (#7 below, and #2 in the 2nd illustration) could be on the fritz.
As mentioned by ahart above, once you've got the basics of fuel supply and filtration sorted as per my suggestions above then it's time to crank out ET and see what the HEUI system is doing.
My suggestion of the day - Don't EVER pre-fill fuel filters on an engine like this that only survives on super-clean fuel. It's the quickest way I know to kill expensive fuel system components. That's what the priming pump is for.
As mentioned by ahart above, once you've got the basics of fuel supply and filtration sorted as per my suggestions above then it's time to crank out ET and see what the HEUI system is doing.
My suggestion of the day - Don't EVER pre-fill fuel filters on an engine like this that only survives on super-clean fuel. It's the quickest way I know to kill expensive fuel system components. That's what the priming pump is for.
Nige,I know this is a daft question,but why?
For years I allways used to fill my fuel filters first from the tank tap before fitting to my older D8’s D6’s etc of 1970/80’s vintage.It wasn’t until I bought my first (relatively new) D5H that I noticed the operators manual in the cab.It was a young tractor and I kept it right enough by the book.It told me never to pre-fill fuel filters,so I never have done since,but I figured the fuel still flows from the tank into the top of the filter before going through to the pump.Does the slower process of priming it simply allow it to sit in the filter longer?
For years I allways used to fill my fuel filters first from the tank tap before fitting to my older D8’s D6’s etc of 1970/80’s vintage.It wasn’t until I bought my first (relatively new) D5H that I noticed the operators manual in the cab.It was a young tractor and I kept it right enough by the book.It told me never to pre-fill fuel filters,so I never have done since,but I figured the fuel still flows from the tank into the top of the filter before going through to the pump.Does the slower process of priming it simply allow it to sit in the filter longer?
Nige
Senior Member
On older tractors with much more forgiving fuel systems in terms of contamination it's no major issue.
The latest generation of fuel systems are filtered to something around 2 microns, maybe even less in some cases, as emissions controls get tighter and tighter.
Fuel flow through the filter is from the outside (red arrow) to the inside (blue arrow), so by pre-filling the filter through the big hole in the centre that gob of fuel (often from a less than clean container) is going to be sucked straight to the FIP/injectors/whatever and will never be filtered in any way before it gets there.
The admittedly small quantity of unfiltered fuel heading off to some extremely expensive fuel system parts to potentially cause issues is not a chance most people want to take which is why manuals for newer machines usually state quite clearly not to do it. It's also why a large percentage of modern equipment is fitted with electric fuel priming pumps, instead of the hand priming pumps of yesteryear, to encourage installing filters dry and then filling them the proper way by sucking all the fuel through the filter media.
The latest generation of fuel systems are filtered to something around 2 microns, maybe even less in some cases, as emissions controls get tighter and tighter.
Fuel flow through the filter is from the outside (red arrow) to the inside (blue arrow), so by pre-filling the filter through the big hole in the centre that gob of fuel (often from a less than clean container) is going to be sucked straight to the FIP/injectors/whatever and will never be filtered in any way before it gets there.
The admittedly small quantity of unfiltered fuel heading off to some extremely expensive fuel system parts to potentially cause issues is not a chance most people want to take which is why manuals for newer machines usually state quite clearly not to do it. It's also why a large percentage of modern equipment is fitted with electric fuel priming pumps, instead of the hand priming pumps of yesteryear, to encourage installing filters dry and then filling them the proper way by sucking all the fuel through the filter media.
Someone should have told Mack/Volvo about the electric priming pump on the granite trucks with the MP8 engines. They have a tiny little hand primer pump that probably takes 100 or more strokes to fill the filters. Definitely doesn’t encourage the practice of installing filters dry I can tell you that.
Honestly, there are a lot of manufacturers who still use mechanical hand pumps. I would say that CAT and AGCO group tractors are the only ones I can name that use electric pumps mostly. From experience, yes, after changing filters or running out of fuel, pumping is unnecessary suffering.
Thanks for the explanation Nige.It’s quite obvious from your arrows.
I never fill them since the D5 days and use the electronic pumps on the D8 and D9 to prime them.Keeps the place cleaner too.
Now for an engine oil filter………It would go against my gut though to not put half a gallon of oil in those big spin on filters at oil change time.I know I shouldn’t,but I cringe at the thought.
I never fill them since the D5 days and use the electronic pumps on the D8 and D9 to prime them.Keeps the place cleaner too.
Now for an engine oil filter………It would go against my gut though to not put half a gallon of oil in those big spin on filters at oil change time.I know I shouldn’t,but I cringe at the thought.
Nige
Senior Member
Crank the engine over for 10-15 seconds with the emergency stop switch activated. That ought to be plenty to fill the filter and get the oil pressure up. TBH if the oil is changed while the engine is hot it won’t do it any harm to crank it on an empty oil filter while it’s building oil pressure. My opinion (*other opinions are available).
If you ever saw an engine oil filter blow off of a 3508 in a D11 and see 50 gallons of oil get pumped out in about 12 seconds, you wouldn’t see a need in filling that filter first…unbelievable how much oil those oil pumps move per second really.
Would you happen to have part number for pressure relief valve? Thanks
Nige
Senior Member
The valve is 369-6662
You will also require a 6V-5049 and a 214-7568 O-Ring.
You will also require a 6V-5049 and a 214-7568 O-Ring.
Thank you