diesel fuel injectors

Don thats kind of a loaded question. Depends on a lot of factors. Clean fuel, engine hrs, age, mechanical or electronic ? Farm tractors or over the road tractors/trucks. A lot of times the injectors can have the pop pressure reset and itll make A LOT of difference. Sometimes some injectors will need more work done to them then that. Some its cheaper to buy new. Others its the other way around. Cheaper to rebuild them then buy new. Are you having problems with a tractor not starting like it used to ? Or are you curious as I am and want to know ? Theres SO MUCH info about injectors on the NET its not even funny. But DONT beleive EVERYTHING you read on the net!!!!! Hope others will chime in too.
 
X 2 what husker said, it varies. Some injector bodies have replaceable nozzle tips, sometimes the complete assembly is cheaper than the tips are. Pencil type can be cleaned, reset and resealed, but if bad they must be replaced as even the builder stopped repairing them.
 
What issue are you trying to deal with?

Typically, quality name-brand diesel injectors fed with good fuel last a LLLOOONNNGGG time.
 
I have no experience with diesel engines. I'm considering buying a tractor with 4,000 hours on it. It is a little hard starting. Owner thinks the cause may be the injectors. Is it normal to have to replace injectors after 4,000 hours?
 
You'd have to define what "last' means. I've pulled Stanadyne pencil injectors out of Deere engines with over 10,000 hours on them and they still worked. Poor spray pattern though. They'd test as "bad" if the usual test protocol was used. Also had to replace a few that plugged with less then 1000 hours. Note - not worn out - just plugged shut.
I just pulled the injectors out of my 1994 IDI Ford truck as "routine maintenance." It has 278,000 miles on it and was running perfect when I pulled them out. I tested them and they checked near as good as the new ones. But as I said - "routine maintenance." New fuel injector nozzle tips cost $7 each. Near as cheap as spark plugs in a gas engine. So I replaced them.
With pencil injectors - usually a cylinder goes dead when they plug since they rely on small orifices that plug. There is NO rebuilt process that I know of for pencil injectors. A few on this forum will claim there is (like Lavoy). Maybe so. I've never come across one that is cost effective. No good way to recut and narrow the valve and seat. Clean up and reset if not too worn -yes. I don't call that "rebuilt."
In regard to pintle injectors? The ones I've dealt with just degrade over time and when really bad, cause engine knocking at cold starts. Since they can be fitted with brand new nozzle tips cheap - it makes no sense to me to try to clean up old nozzles. That is - unless you cannot get new ones anymore. I've had to lap and reuse many a Bendix injector in older Deere engines when new ones were not available.
 
The main issue is the tractor starts hard. Was wondering if the injectors could be the cause? Tractor has 4,000 hours on it. Also, what problems do worn injectors usually cause?
 
4000 hours with all fuel injectors worn out is not common unless the fuel used has low lube or the filter system is poor. They consist of close-fitting hardened metal parts and life depends on clean fuel with adequate lube (that some ultra-low diesel fuels do not have). The filter system has a lot to do with it. A system that does a great job of filtering out small particles helps injectors last longer, but also plugs up more - especially in cold weather.
By the way - I don't know what model or make tractor you're looking at. I've worked on a lot of diesel tractors with poor cold starting complaints and have yet to see the injectors be the cause. I've worked on engines with injectors that tested as "worn out" that still started fine. My opinion is - if the tractor runs well when warmed up, but starts lousy - it has problems other then injectors.
 
Don,
It would help to have a little more background info, what tractor and engine? What is the ambient temperature out? What type of service has this machine saw? Is 4000 hrs accurate? I've seen Farmall 560's that needed to be glow plugged on a 90°F day that were stalled at operating temperature to start.

I overhauled a Cat 3406B with a million miles on it which worked out to be about 19,000 engine hours, only one injector was bad and that was most likely due to the bad plunger on that cylinder. It started well at 50°F but not at 20°F.
 
I've had good luck with mine on diesel tractors. Over 7000 hours on two Case tractors and all original injectors. Had them cleaned on the Magnum 7130 about 12 years ago but the 2090 has never had them out. It is 34 years old. Starts, runs great.
 
It is an AC 7010 with a 301 cu. inch engine. The
ambient outside temp. was 50 to 60 degrees and the
tractor had been outside for a couple of days. I
believe the 4,000 hours is accurate, but I don't
know the service history of it.
 
The tractor does run well after it starts. Takes a bit of cranking to get it started and it makes a lot of black smoke initially when it starts, but it soon clears out and runs smooth with no smoke. Almost no blow by.

What are more likely causes of the hard starting?
 
Like a lot of things, more injection nozzles are damaged from taking them apart when not needed than ever cause problems with starting, smoking or not running correctly. Sure, some crap out, but I have seen way too many mistreated to try to put an hour basis for cleaning or repairing them. IH put a 600 hr cleaning interval on I believe the 806 when it came out and that was just plain stupid. The dealership I left in disgust and disrespect for new management had a policy of pulling the injection nozzles out of Magnums upon doing inspections. Just one of their misguided ways of getting work for service department.
 
I have an AC 7000 301 that has 5000 hours, runs well, pulls rated power on the dyno, and starts hard too. The only AC 301s I've heard start good are the ones with the higher compression sleeve assemblies installed. Of all the diesels I've seen the 301 did not impress me on cold starts, even though they run and pull well. But I think all diesel engine builders have some that start well, and some that do not. I just know to preheat the intake on the 7000 and it will start.
 
The quickest and most reliable way to contaminate a diesel fuel system is to open it up. Never remove lines, pumps, injectors, etc unless all your troubleshooting indicates a failed component.

Hard starting and smoke at start-up indicates to me low compression or incorrect injection timing. It's highly unlikely that all 4, 6, 8 injectors all fail at the same time. Usually they go one at a time unless you have a catastrophic upstream failure that loaded the whole system with debris. Classic symptoms of failed mechanical injectors are either hot or cold cylinders from over or underfueling (respectively) combined with smoke that won't go away as it warms up indicating more fuel than can be burned or poor injector spray pattern.

Newer injection systems are electronic and you'll usually get an engine code on your ECM as part of the on board diagnostics.
 
One of our forklifts has a 200 cubic inch Allis engine, basically a 4 cylinder version of the 301. Same thing, starts hard, not sure if it low on compression or the injection pump is lazy at cranking speed.

A guy near us runs a bunch of AC's, years ago we had got him some engine kits for his 301's, he wanted the the high headland piston with top ring right on top, said they would fire right up in the winter time with little or no help. It was an old M&W design that Herschal carried under the Pow'r Seal brand name.
 
yes, timing could also cause this and smoke. I would think that gear wear would be the cause of slow timing.
 

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