Hello Everyone. I am new to the group so please be kind.

DUCATO 3.0 based motorhome 50,000 miles.
Cruising above 2000 rpm engine stutters and judders. This happens briefly then all is good. It can happen 4 or 5 times in quick succession or just the odd occasion then be OK for many more miles before happening again.
No fault codes. No smoke or other indications.
Replaced air and fuel filter.
Only clue is only seems to happen after it was discovered that the engine had no thermostat fitted and was running cool. New housing and stat fitted by motorhome supplying dealer.

It could be a coincidence that it happens after new stat fitted as I had only driven 200 miles or so during my ownership before this.
I even phoned previous owner who said he never had a problem but he also says he noticed the temperature gauge sometimes never moved much. He had the vehicle from new.

Just wondering where to start as it is driving me loopy worrying what might be wrong.

Hi and welcome

Is this temperature related.. only doing it when warm?

Or only when cooler..


Crank angle sensor is often doubted at this point.. it seldom throws an error code.. and temperatures can have an effect

However.. its probably the opposite end of the engine from the thermostat

(No cambelt.. or waterpump work??)

Do check the electric fittings around battery all look secure.. thermostat work probably involves moving all of this around

Charlie

Thanks for the response.
I can't say if it happens when its cold as by the time I can get in any fast moving traffic the engine is hot and temperature normal.
One other thing I forgot to mention is a very slight vibration from the engine I noticed while holding a steady 1800 rpm while stationary. Not sure if this is normal or even related to my other problem.

I thought I would post an update.

ECU sent for testing at ecurepairs.com. They said my ECU was faulty and unrepairable and offered to dispose of it. Long story short, they had wrecked my ECU and they ended up paying for a new replacement.

Sent to repairers who charged me for 15 hours labour, replaced EGR valve and mass air flow sensor and inlet manifold gasket.

Problem still not resolved.

Chris McGlinchey said:

I thought I would post an update.

ECU sent for testing at ecurepairs.com. They said my ECU was faulty and unrepairable and offered to dispose of it. Long story short, they had wrecked my ECU and they ended up paying for a new replacement.

Sent to repairers who charged me for 15 hours labour, replaced EGR valve and mass air flow sensor and inlet manifold gasket.

Problem still not resolved.

Click to expand...

Was that 15 hours of ECU work.. or a load of mechanical parts swapping ?

I take it the thermostat housing has electrical connectors on it?

Charlie

What a saga..

Hi Chris

The absence of fault codes suggests that your problem is occuring after the electronic fuel injection has done its job.


It's rather unusual to discover a missing thermostat. Rather unlikely to be missing from the factory, though I guess it could have been built on a Friday afternoon ! More likely to have been removed at some stage by "someone" trying to solve an overheating problem. If so, this is a "bodge" as a properly functioning thermostat won't cause overheating. With no thermostat the warm-up will be tediously slow and the low running temperature in cool weather will increase engine wear.


I'm just wondering if there is some problem with the head gasket which is causing coolant leakage into the cylinders, maybe only when the engine is properly warm ? This could lead to a misfire which won't generate a fault code.

Does the coolant level hold steady ? Is there any sign of an oil film on the coolant in the expansion vessel, or water in the oil ? It's not easy to do a compression check as this involves removing an injector to attach the test equipment, and injector removal can be a fraught business.

I might be barking up the wrong tree, but it does seem possible that the missing thermostat and the engine misbehaviour could be linked. If you do eventually find head gasket leakage, mild cases can respond to the addition of a product like k-seal to the coolant. It's my understanding that this contains tiny fibres which are drawn into and lodge in small cracks.

Apologies in advance for jumpoing in - cannot find many answers about 3.0 HDi engine. I have a 2009 3.0L and want to clarify the turbo boost sensor part number - have code P0235.
The one on my engine is italian and part no not easy to read.
Hoping someone could help.
Thanks

Hello Charlie,
It was just a combination of labour for numerous road tests etc as fault is intermittent. They did say they were positive the fault was on the air side and nothing to do with fuel delivery but I remain sceptical about their level of skill when diagnosing this problem.

Well its finally fixed. The thermostat housing is part blanked off and covering a port on the engine that is linked to the inlet side of the manifold.
The housing is slightly warped letting hot coolant into the manifold and causing intermittent juddering.
Who would have thought....

Hi Chris

Well, I was right about coolant getting into the cylinders. But that particular route would never have occurred to me !