JCB 3CIII - Misfire/Blacksmoke/loss of power (movement & hydraulic) help?

[philwheelton]

A few years ago I had a customer with a 3C11 with a misfire on striping the top of the engine the oil feed to the rocker shaft had blocked to one way and the valve springs had rusted and not returning the valves causing a misfire through loss of compression .

[Jeremy Rowland]

Hi,

good points and warnings - I've heard that testing injectors can prove lethal. Couple of things before I try testing each one - if the head gasket has gone between no 1 and 2 would this have caused the failure of the injectors ie; from coolant? Would, if the gasket was blown cause detrimental problems in the short term ie: so long as I didn't run the engine for long, and if the head gasket was blown, is this a relatively easy job to replace without masses of specialised tools, specialised knowledge and specialised resetting of cams/timing etc?

Also mentioned that all 4 injectors would need servicing, i saw some cav injectors advertised on ebay as new ex military stock for bedfords, surely these would match?

steve

Steve if the head gasket is at fault then your injectors should be okay; as for the job it should be relatively simple the only two tools you will need to check that you have access to is a torque wrench and a pair of feeler gauges to set the valve clearances after the job is complete.

Top tip use a digital camera as you remove the parts so you know how it all goes back together again when you come to re-assemble it. If the head gasket has blown the make sure that you clean the face of the head and the cylinder block with some emery cloth, make sure that you don't get bits of the abrasive down the cylinder bores!

Jeremy

[essexpete]

If it is head gasket I would also check that the rad core is clean, not always obvious when hidden behind cowling and coolers.

Another thing to ask because I can't remember can the liners drop in these engines?

[stevejcb]

Hi, and thanks all for the comments.

I removed number 2 injector and discovered lots of muck and carbon (I took a picture but my camera is playing up and the pictures were to grainy). Their condition was so bad that there was little point in connecting it upside down to see if it worked - number 1 was equally as bad. I cleaned out the sleeves as best I could, so now the next step, is to source alternatives or have them serviced.

On the head gasket side, there's no doubt in my mind it has failed, but it's whether I can keep it going until I've completed a task. one assumes if I keep it only running for short periods and ensure it doesn't boil, damage will be limited.

steve.

[Stormin]

Not much point having your injectors overhauled if the head gasket has gone.
If it's not getting sufficient compression to fire properly it'll just coat your injectors in unburnt diesel deposits and you'll end up having to overhaul them again.
Think you're going to have to bite the bullet and do it properly, or muddle through on part power for a while.

[stevejcb]

Hi,

Yes I agree. Replacement injectors are on there way - hopefully i'll get something out of them before tackling the biggy and then i'll need all the help i can get.

steve

[philwheelton]

if you said where in the world you are maybe someone could have a look at it for you.

[stevejcb]

Hi again,

Yes, I am based just to the south of Loch ness - (As Fraser once said from Dad's army - a wild and lonely place...) no, its getting more built-up like everywhere, but certainly not as much as where I originally came from.
V- nice area though with good caravan and camping place nearby on the shore - possible? any help welcome.

Update - I purchased 2 used injectors from Vicary plant, which where identical and in GWO. These were put in and the engine restarted - less black smoke but still present, engine reluctant to rev. The supply unions were then slackened in turn - this produced on no. 1 & 2 the same response as before ie:- plenty of spray fuel but no engine stop. I then decided to invert them as suggested and test these to ensure they were functioning (see pics). The Injectors produced the atomised spray as they should - having stood well back. This then as discussed, indicates that everything is fine, but the engine is not firing in the cylinder ports, due to possible compression problem from blown head gasket.

Aside - When hard revving, more black smoke, though this did turn paler, and it pushed water from the radiator. Also, although I've only ran it for a short period since the new oil/filter change, I checked it for discolouration - traces of brown soup.

If no one disagrees or can suggest any alternative, it looks as though then that the replacement of the head gasket is the solution - so will need to progress with this.

As I have said in other topic, I'm not a mechanic, but willing, with your advice, to have a go (not that i have much choice - unless i intend to dig everything by handd have a heart attack. )

So, I'm going to order a Headgasket, get hold of some A/F sockets for the main head bolts - is there anything else that I need to get in preparation? (fortunately, I have a torquewrench and feeler gauges - hope there sufficient)


thanks guys.

[Jeremy Rowland]

Steve it does sound more and more like you have a blown head gasket; don't forget to make sure that you clean up the block and head surface with emery cloth by where the old gasket was blowing before you put the lot back together again; in fact you need to clean all of the block and head faces off with emery cloth, just be sure that you don't let any of the grit or crap get down the bores, some rag will usually take care of that.

Jeremy

[agrimax]

Yer even running her on derv? Don't see much colour in those fuel pipes!

Don't forget to disconnect the oil feed pipe from the block to the head. It can be easily overlooked and then you wonder why the head won't lift off.