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Iveco Engine Question

I was moving the bus today and noticed that the idle seemed a little lower than usual when stopped. It seemed to be fine power wise but it got progressively rough at idle to the point where it seems like the intake pipe is knocking on the cab.

It has an electric lift pump so seems to be getting fuel although the priming pump does weep, there is no unusual smoke coming from the tailpipe but it is definitely missing on one cylinder and there seems to be more blow-by out the breather vent than before.

Engine temps are fine. I put my hand on the tail pipe and it is not a steady stream of exhaust- it is missing for sure.

Seems to be a little more clatter in the top end as well

Any ideas why an Iveco would do this?

I will be away for a while but think I will start by adjusting the valves and then perhaps pull the injectors and have them cleaned and tested?

As an alternative and definitely a future project- does anyone know where I could get details/ specs on fitting a 6BT Cummins and Allison Transmission?

Thanks in advance


My bus number (if any): RM2133 (Albert Square)

Re: Iveco Engine Question

Hi Lorne - you could start with Cummins at Wellingborough as they developed the Routemaster conversions including the latest four cylinder Euro six example ?
Cummins Diesel
40-44 Rutherford Drive, Park Farm South
Northamptonshire NN8 6AN England

My bus number (if any): RML 2747

Re: Iveco Engine Question

If the priming pump weeps fuel then it can suck air in so you need to eliminate air in the system as the cause although other indications do not point to this. Fitting a 6BT and Allison is a major undertaking involving work on many systems and much structural butchery and fabrication. These symptoms are not unique to an Iveco engine.

You can start by turning engine over by hand ensuring that it CANNOT START, If coolant has entered the cylinders then hydraulic lock could occur. Check coolant level.Carry out a CO2 test- this may be steam from the breather in which case the vapour will be hot, indicating a porous liner or a blown head gasket. Short out the injectors in turn to identify which cylinder is causing the misfire. Remove rocker cover and examine valve springs and valves. Adjust valve clearances. Carry out a compression test and then a leak down test. Finally if trying to keep cost down, depending on investigations send injectors away. There will be something wrong with them almost certainly.

A Cummins C series will not fit either without considerable surgery.

Re: Iveco Engine Question

The coolant level is unchanged and the blow by does not smell like coolant. Could it be a blown heat gasket allowing pressure into an oil gallery. Do these Ivecos have a tendency to blow head gaskets? Is that why there was a set of head gaskets included with the bus?

Thanks for your help. I’d rather not have to change the engine

Re: Iveco Engine Question

Are you sure it's not just the idle stop screw had worked loose? why the electric lift pump? It could be the electric pump is sending too much fuel through, blocking or overwhelming the spill-off pipes and overflow back to the tank.

I spoke with Lionel Moss about this a few years ago after several buses abroad were fitted with electric lift pumps. the mechanical lifter works at abut 4psi, the electric pumps 40 psi. It is possible that during tick over this excess pressure is finding its way into the wrong side of the injectors.

I'd suggest you sort out the mechanical lift pump and dispose of the electric one.

My bus number (if any): RML2532

Re: Iveco Engine Question

Looking back I see that you are in Vancouver. The Iveco 0.8361 is actually a marine engine adapted for automotive use. Before you delve too deeply you will need to visit some boatyards to find a local source of parts and information. The engine is a wet liner design but similar to some '70s Renault engines because the top surface of the block is open, the liners are only located towards the bottom. The head must not be lifted straight up, it must be rotated to break the seal. Unless the liners are clamped in place then the engine must not be rotated while the head is off.

Keep it simple, check the idle screw as suggested, run the engine from a gravity feed into the injector pump, short out the injectors in turn to pinpoint a cylinder and run the engine without the rocker cover in place. If necessary run the engine minus the exhaust manifold. If you have major issues there will be clues.

I can see no relationship between it and crankcase pressure however the injection timing advance and retard is built into the front part of the timing case, a derangement of this could result in an unsteady idle.

Take sensible precautions regarding moving parts, heat, ejected fluid and gas, and insecure footing.

Re: Iveco Engine Question


I have adjusted the rocker clearances per the manual, still missing with blow by (crankcase venting) at idle ( but less when revved), pulled the injectors and have them being tested, still awaiting results. Again- it starts easily

I am trying to source out a suitable compression tester but no luck so far. I would like to do a compression test while the injectors are out

Fortunately the previous owner had a top-end gasket set so I can change a head gasket if need be.

Any more suggestions gentlemen?

My bus number (if any): RM2133 (Albert Square)

Re: Iveco Engine Question

If you have a look on Youtube you will see that the travelling Bus Grease Monkey is currently in Oregon, He may be able to help and he may not.

Re: Iveco Engine Question

Had the injectors tested and none were dripping, all had decent spray pattern and the cracking pressures were good. The shop said likely they had had some work done on them in the past.

Had them all disassembled and cleaned and set to factory specs. Still have a miss on cylinder #3 at idle which seems to go away at higher rpm.

Any chance this could be the injection pump?

Still have not found a suitable adapter for a compression test- might have to pull one and have our machine ship make a "dummy" injector ( maybe patent it and make a fortune-- ya think?)

Still open to ideas

Thanks guys


My bus number (if any): RM2133 (Albert Square)

Re: Iveco Engine Question

Make sure that you check the condition of the air cleaner and trunking before you do a compression test, it can give inaccurate results otherwise. If you cannot acquire an adapter the link from Adapt Ape details another method. You do need to take tremendous care regarding the possibility of the engine starting and also moving parts.

The second link details Blow by.

The injector pump can cause a misfire as can a worn cam lobe but neither will cause blow by. A burnt valve or cylinder damage are more likely candidates.

Re: Iveco Engine Question

Ok with only little deliberation after moving the bus to the current venue, the decision has been made to convert to a Cummins engine.

To anyone in North America I will have sundry Iveco engine bits for sale including refurbished injectors, a new water pump and whatever else would be useful.

The Gearbox works perfectly as does the unloader valve and I have a new Quill shaft for the Plessy pump I will not need now.

If there any other take off items needed just let me know.

Shout out to Simon Parle who is a BIG help and great source of information



My bus number (if any): RM2133

Re: Iveco Engine Question

OK, here is an update on this saga: I have a replacement Iveco en-route to me, I plan to pull the head on the current engine once the new one is fitted, if it is a head gasket I will see if the one I have is correct and replace it. The engine worked well before it started to miss and spew smoke out the breather and oil out the dipstick.

If the head gasket is the obvious problem I will try to sell it as a complete engine, if not I will keep all the externals for spares.

On an aside- does anyone have a contact with Absolute Charters?

My bus number (if any): RM2133

Re: Iveco Engine Question

Hi Lorne I’m not sure how long you intend to operate your bus but given the rarity of good replacement Iveco engines (possibly more in Canada) would it not be prudent to retain the old engine in case of further failure as I doubt the replacement will be a brand new engine ? Just a thought.....

My bus number (if any): RML2747

Re: Iveco Engine Question

Thanks Graham.

The replacement engine was reconditioned in 2011, we do no more than 1000 kilometers a year so am hoping it out lives me. Aside from the fact that I really have no place to store the old beast.

I think if it is truly unserviceable it will be scrap metal as it price prohibitive to try and refurbish here and costs a fortune to ship across the "pond", however I am more than happy to sell it as-is

My bus number (if any): RM2133