jd6820
Well-known member
Hi folks,
Think a bit of a rant to start off with as I'm that annoyed with local specialist repair firms. I'm currently trying to troubleshoot a smoking Isuzu 4LE2 engine in a 2012 JCB 8085ECO, at first I sent the injectors away for refurbishment as the chap had a run of dodgy fuel and the machine was down on power and smoking (blue) from memory? The problem has been ongoing since just before covid. Ended up with refurbished injectors, the machine started on the button and ran well apart from black smoking, worse under load or using the hydraulics. Engine runs nice and smooth no missing or oil burn, tracking along ends up with a column of black smoke out the exhaust, engine rpm makes no difference. Maybe just more smoke with more rpm? Spoke to the diesel repair firm and they advised to remove pumps and inspect. Apparently they were amazed the machine ran with the fuel pumps like they were. So they would source the parts and repair. The firm couldn't source the parts though as Bosch didn't have any on the shelf and covid had halted production. Fast forward 18 months/2yrs I've still got this digger in my yard and no pumps due to parts supply. Having tried to source new parts myself I gave up and looked for new pumps. Only three sources: JCB (only had one and needed four @ £1600 each), Alibaba (£450 but questionable quality) and Genuine Isuzu (£1800 each), so contacted a mate who sales diesel engines and parts, very good at his job, found me 4 new genuine pumps from Isuzu abroad, shipped them to me for £590 each, still expensive but worth it to cure the fault. Got the diesel shop to check the injectors again to make sure spray pattern correct and re-installed the injectors and pumps, changed all filters again and renewed all the fuel lines. Checked lift pump was working and the correct shims were replaced in same locations for the pumps to set the timing. Guess what, over £2400 later and the digger is no better. Hell I'm mad! All I want is for people to tell me if something is actually broken not just replace stuff because it brings them business. Next I check boost pressure with an adapter on the inlet manifold as I suspected the turbo wasn't provding boost, it was but maybe slightly lower than I'd expect (8-9psi), manual states apprximately 10psi. So removed turbo and only issue I could find was maybe a slightly tight impeller, but no movement or damage to the vanes. Just didn't freewheel like im used to. No end float or wobble to indicate wear. Took it off and sent to a local turbo rebuild specialist. They identified it had been leaking oil in the past and carboned up the piston ring seal and that was my issue. The core needed replacing and they could do it for £350 plus Vat, so I asked to confirm would that cause the impeller to be tighter than im used to or is that normal for that particular turbo. They said yes carbon buildup could affect the running of the turbo. I collected the new part days later to find the impeller to take the same effort to turn, a bit worried I refit the turbo in the hope the fault is cured guess what. Nope identical to before only now I have another unnecessary part. Why can't people just be honest and say I can't find anything significant here that could cause the symptoms you describe? Starting to think I should start learning about diesel systems and turbos myself to make it another job I dont sub out. I like to do things right, once rather than chase round the houses but I don't know diesel pumps and turbos intricately so rely on other expertise.
Hopefully one of you guys has any idea what the issue may be, here is what I've checked so far.
EGR valve operation, blanked off to prove its not adding exhaust gases and check solenoid is operating under correct parameters.
Compression check, tested all four cylinders against manufacturers specs, new spec 401psi. Spec on ours 400psi on every cylinder.
Turbo boost pressure at the intake manifold, 8 psi under load.
Air filter restriction, all intake pipework checked for collapsed plugged hoses, bypassed the intercooler also checked flow through the intercooler all fine. Checked exhaust side too, had the exhaust box removed just incase junk was plugging the exhaust system. No change.
Like I mentioned earlier fuel system has been gone through, all new lines and filters lift pump changed not longer before the injectors and still providing good pressure.
Things left still to check....
Spill time the injection pumps, not done sooner as the other pumps appeared to be original and the timing I'm fairly sure is set by the shims used under the pump to alter contact height in relation to camshaft driving the pumps. I'm leaning towards the timing being advanced? Hence the black smoke, but it starts really well and no diesel knock from advanced timing.
Valve stem seals, although no blow by in crankcase or blue smoke?
Valve timing or valve lash, but will check that next I think, but doesn't fit the symptoms in my eyes? Not like the engine has been messed with when replacing injectors, not ruling out that the digger hasn't been messed with previous to this persons ownership. Although everything looks untouched.
Sorry for the long post, but I'm thousands into this job along with lots of time, both waiting for parts/diagnostics and no nearer to curing the fault. Anybody have any ideas before I take a match to the dam thing.
Thanks in advance,
Matt
Think a bit of a rant to start off with as I'm that annoyed with local specialist repair firms. I'm currently trying to troubleshoot a smoking Isuzu 4LE2 engine in a 2012 JCB 8085ECO, at first I sent the injectors away for refurbishment as the chap had a run of dodgy fuel and the machine was down on power and smoking (blue) from memory? The problem has been ongoing since just before covid. Ended up with refurbished injectors, the machine started on the button and ran well apart from black smoking, worse under load or using the hydraulics. Engine runs nice and smooth no missing or oil burn, tracking along ends up with a column of black smoke out the exhaust, engine rpm makes no difference. Maybe just more smoke with more rpm? Spoke to the diesel repair firm and they advised to remove pumps and inspect. Apparently they were amazed the machine ran with the fuel pumps like they were. So they would source the parts and repair. The firm couldn't source the parts though as Bosch didn't have any on the shelf and covid had halted production. Fast forward 18 months/2yrs I've still got this digger in my yard and no pumps due to parts supply. Having tried to source new parts myself I gave up and looked for new pumps. Only three sources: JCB (only had one and needed four @ £1600 each), Alibaba (£450 but questionable quality) and Genuine Isuzu (£1800 each), so contacted a mate who sales diesel engines and parts, very good at his job, found me 4 new genuine pumps from Isuzu abroad, shipped them to me for £590 each, still expensive but worth it to cure the fault. Got the diesel shop to check the injectors again to make sure spray pattern correct and re-installed the injectors and pumps, changed all filters again and renewed all the fuel lines. Checked lift pump was working and the correct shims were replaced in same locations for the pumps to set the timing. Guess what, over £2400 later and the digger is no better. Hell I'm mad! All I want is for people to tell me if something is actually broken not just replace stuff because it brings them business. Next I check boost pressure with an adapter on the inlet manifold as I suspected the turbo wasn't provding boost, it was but maybe slightly lower than I'd expect (8-9psi), manual states apprximately 10psi. So removed turbo and only issue I could find was maybe a slightly tight impeller, but no movement or damage to the vanes. Just didn't freewheel like im used to. No end float or wobble to indicate wear. Took it off and sent to a local turbo rebuild specialist. They identified it had been leaking oil in the past and carboned up the piston ring seal and that was my issue. The core needed replacing and they could do it for £350 plus Vat, so I asked to confirm would that cause the impeller to be tighter than im used to or is that normal for that particular turbo. They said yes carbon buildup could affect the running of the turbo. I collected the new part days later to find the impeller to take the same effort to turn, a bit worried I refit the turbo in the hope the fault is cured guess what. Nope identical to before only now I have another unnecessary part. Why can't people just be honest and say I can't find anything significant here that could cause the symptoms you describe? Starting to think I should start learning about diesel systems and turbos myself to make it another job I dont sub out. I like to do things right, once rather than chase round the houses but I don't know diesel pumps and turbos intricately so rely on other expertise.
Hopefully one of you guys has any idea what the issue may be, here is what I've checked so far.
EGR valve operation, blanked off to prove its not adding exhaust gases and check solenoid is operating under correct parameters.
Compression check, tested all four cylinders against manufacturers specs, new spec 401psi. Spec on ours 400psi on every cylinder.
Turbo boost pressure at the intake manifold, 8 psi under load.
Air filter restriction, all intake pipework checked for collapsed plugged hoses, bypassed the intercooler also checked flow through the intercooler all fine. Checked exhaust side too, had the exhaust box removed just incase junk was plugging the exhaust system. No change.
Like I mentioned earlier fuel system has been gone through, all new lines and filters lift pump changed not longer before the injectors and still providing good pressure.
Things left still to check....
Spill time the injection pumps, not done sooner as the other pumps appeared to be original and the timing I'm fairly sure is set by the shims used under the pump to alter contact height in relation to camshaft driving the pumps. I'm leaning towards the timing being advanced? Hence the black smoke, but it starts really well and no diesel knock from advanced timing.
Valve stem seals, although no blow by in crankcase or blue smoke?
Valve timing or valve lash, but will check that next I think, but doesn't fit the symptoms in my eyes? Not like the engine has been messed with when replacing injectors, not ruling out that the digger hasn't been messed with previous to this persons ownership. Although everything looks untouched.
Sorry for the long post, but I'm thousands into this job along with lots of time, both waiting for parts/diagnostics and no nearer to curing the fault. Anybody have any ideas before I take a match to the dam thing.
Thanks in advance,
Matt
