Checking and changing Comformatic gearbox oil.

[Bessy765]

Another vote for Adams morey. Our 2019 Burstner with Fiat 2.3 15 hp Comformatic. Fiat recommend or rather state the operating system fluid should be checked every 2 years changed every 4 years. we took our van to our local Fiat dealer for its first service (2 years) went to collect it told nothing to pay? Questioned this and was told the fitter said as we had only done 4500 miles it did not need servicing. So not impressed asked if he had checked the operating fluid for the comformatic he just shrugged his shoulders. When the 4 year service was due drove to Adams Morey 200 miles based on conversations with them they knew what they were talking about. Would do the same for the next service to be sure of having it done correctly. Have now covered 22600 miles trouble free.

 

[rupert]

I think that maybe a miss print in the service schedule
it states check at 48000 also check at 96000 I think it should read CHANGE at 96000

 

[dunnah01]

This thread was about changing the gearbox oil so nothing to do with the Comfortmatic system.

 

[Minxy]

This thread was about changing the gearbox oil so nothing to do with the Comfortmatic system.

Since when has any thread stayed on topic!

 

[Lenny HB]

This thread was about changing the gearbox oil so nothing to do with the Comfortmatic system.

But the gearbox oil doesn't need changing and Peter was unaware of the need to change the clutch fluid. So all very helpful to him.

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[peterc10]

This thread was about changing the gearbox oil so nothing to do with the Comfortmatic system.

My OP was about changing the oil in a Comformatic system. But I am glad that the position of the clutch fluid and its importance has been brought up by others. That seems to be more important than the oil level in the gearbox. I am going to have to put my thinking hat on.

 

[Lenny HB]

I am going to have to put my thinking hat on.

Now that could be dangerous.

 

[WESTY66]

My OP was about changing the oil in a Comformatic system. But I am glad that the position of the clutch fluid and its importance has been brought up by others. That seems to be more important than the oil level in the gearbox. I am going to have to put my thinking hat on.

Tbh I can’t see that a gearbox oil change should be that much more expensive, there’s no recalibrating to do, it’s a straight empty and refill

 

[Riverbankannie]

Another vote for Adams morey. Our 2019 Burstner with Fiat 2.3 15 hp Comformatic. Fiat recommend or rather state the operating system fluid should be checked every 2 years changed every 4 years. we took our van to our local Fiat dealer for its first service (2 years) went to collect it told nothing to pay? Questioned this and was told the fitter said as we had only done 4500 miles it did not need servicing. So not impressed asked if he had checked the operating fluid for the comformatic he just shrugged his shoulders. When the 4 year service was due drove to Adams Morey 200 miles based on conversations with them they knew what they were talking about. Would do the same for the next service to be sure of having it done correctly. Have now covered 22600 miles trouble free.

Glad you had nothing go wrong as I don’t think Fiat would honour their warranty if service schedule not met and book stamped, or a dealer record of service done.

 

[peterc10]

Tbh I can’t see that a gearbox oil change should be that much more expensive, there’s no recalibrating to do, it’s a straight empty and refill

Yes that is what my motor mechanic said, as I alluded to in my OP. My original question was posed because of some other threads in MHF which referred to the Comformatic gearbox needing more knowledge and expertise when being maintained. I did not realise that those threads were dealing with the replacement of the clutch fluid.

One other point, I cannot find any information in either the general Fiat handbook or the Comformatic handbook as to where the hydraulic clutch cylinder is on my motorhome. Any ideas please?

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[Lenny HB]

On my LHD it shares a common reservoir with the brakes, some RHD's have a small reservoir piggybacked onto to the main reservoir.

 

[WESTY66]

On my LHD it shares a common reservoir with the brakes, some RHD's have a small reservoir piggybacked onto to the main reservoir.

On my LHD I haven’t got a bleeding clue where it is

 

[Minxy]

Now that could be dangerous.

At least he's got a thinking hat ...

 

[dunnah01]

One other point, I cannot find any information in either the general Fiat handbook or the Comformatic handbook as to where the hydraulic clutch cylinder is on my motorhome. Any ideas please?

There are two types of clutch fluid reservoir, either the separate eggcup type attached to the side of the hydraulic reservoir or a common reservoir shared with the brakes.

The eggcup type looks like this



The clutch fluid in either type of reservoir could becomes contaminated by the hydraulic fluid so if yours is a shared reservoir with the brakes then you'll need to get the brake fluid (including the fluid in the brake lines and calipers) changed at the same time as the clutch fluid to ensure that the braking system doesn't get contaminatd.

I've been trying to source a larger reservoir to replace the eggcup type but so far with no luck. The logic is that with a bigger reservoir any contamination is more diluted so buys a lot of time to get the fluid changed as a maintenance item. The reservoir shared with the brakes is already significantly larger than the eggcup reservoir so already has a better window for fluid replacement but the consequences of severe contamination are then a braking issue aswell.

 

[rupert]

The op asked where the clutch cylinder was …not the reservoir.
The clutch slave cylinder is concentric in the bell housing ..the master cylinder is on the outside of the bellhousing amongst the pump and accumulator etc.

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[jockaneezer]

Can anyone explain how you get this cross contamination from the two fluids, at what point in the system are they in a position to contaminate one another ?
I've no experience of any Comformatic, (never heard of them till I came on here !) but I am curious as to how they work.
So far I'm under the impression that the Dexron fluid side of things works some actuators (mini hydraulic rams ?) via an hydraulic pump an solenoids that moves the gear linkage, but the clutch operation I'm not so sure of unless it's a two stage hydraulic cylinder with Dexron pushing one end and clutch fluid getting squeezed out the other that then operates the concentric slave cylinder ? If this is the case, it makes sense that the oils could combine here, but that also implies a seal is on it's way out to allow them to mix ?
There's been mention of "dirty oil" when stripping out the concentric cylinder, this (in my experience of hydraulics) is usually a sign of a seal or O ring breaking down, which lets tiny particles of rubber (other sealing compounds are available!) mix in with the oil ?

 

[dunnah01]

The op asked where the clutch cylinder was …not the reservoir.
The clutch slave cylinder is concentric in the bell housing ..the master cylinder is on the outside of the bellhousing amongst the pump and accumulator etc.

Strictly speaking the Comfortmatic Master/Slave unit is remote from the clutch and under the hydraulic reservoir for the Comfortmatic system with the standard concentric slave cylinder in the bell-housing .

 

[rupert]

I can’t give the link but i have read the pressures involved from the pump are, or can be in excess of 50 bar .the same article sugests 90% of contamination problems originate from the pump seal
I haven’t had mine in bits (yet) so I can’t confirm any of this .. but souds plausible
Alan

Can anyone explain how you get this cross contamination from the two fluids, at what point in the system are they in a position to contaminate one another ?
I've no experience of any Comformatic, (never heard of them till I came on here !) but I am curious as to how they work.
So far I'm under the impression that the Dexron fluid side of things works some actuators (mini hydraulic rams ?) via an hydraulic pump an solenoids that moves the gear linkage, but the clutch operation I'm not so sure of unless it's a two stage hydraulic cylinder with Dexron pushing one end and clutch fluid getting squeezed out the other that then operates the concentric slave cylinder ? If this is the case, it makes sense that the oils could combine here, but that also implies a seal is on it's way out to allow them to mix ?
There's been mention of "dirty oil" when stripping out the concentric cylinder, this (in my experience of hydraulics) is usually a sign of a seal or O ring breaking down, which lets tiny particles of rubber (other sealing compounds are available!) mix in with the oil ?

 

[dunnah01]

That

Can anyone explain how you get this cross contamination from the two fluids, at what point in the system are they in a position to contaminate one another ?
I've no experience of any Comformatic, (never heard of them till I came on here !) but I am curious as to how they work.
So far I'm under the impression that the Dexron fluid side of things works some actuators (mini hydraulic rams ?) via an hydraulic pump an solenoids that moves the gear linkage, but the clutch operation I'm not so sure of unless it's a two stage hydraulic cylinder with Dexron pushing one end and clutch fluid getting squeezed out the other that then operates the concentric slave cylinder ? If this is the case, it makes sense that the oils could combine here, but that also implies a seal is on it's way out to allow them to mix ?
There's been mention of "dirty oil" when stripping out the concentric cylinder, this (in my experience of hydraulics) is usually a sign of a seal or O ring breaking down, which lets tiny particles of rubber (other sealing compounds are available!) mix in with the oil ?

That's pretty much how it works and the Comfortmatic Master/Slave unit is the component that uses a Dexron powered ram to push a DOT4 powered clutch release system.
The internal seals for the Master/Slave unit are where the cross contamination occurs, possibly due to the extra return pressure on the Master/Slave unit piston from the clutch diaphragm spring overcoming the Dexron side hydraulic seal, but just speculating.

 

[rupert]

the dextrin fluid is recirculated back into the reservoir cap via flexible pipe so good idea to check for any oily deposits around it

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[rupert]

it would be nice if it could have been designed to use the same fluid for both

 

[dunnah01]

the dextrin fluid is recirculated back into the reservoir cap via flexible pipe so good idea to check for any oily deposits around it

Only the Dexron fluid lost to the gear change solenoids is recirculated. The clutch activation solenoid isn't recirculated and will weep into the Master/Slave unit and eventually into the DOT4 clutch system.

 

[peterc10]

Thanks for all the help.

But I must say .............................................................................. MY BRAIN HURTS

 

[Minxy]

Thanks for all the help.

But I must say .............................................................................. MY BRAIN HURTS

Mine's just given notice and is leaving!

 

[Bessy765]

Glad you had nothing go wrong as I don’t think Fiat would honour their warranty if service schedule not met and book stamped, or a dealer record of service done.

Sorry forgot to. Add took the van back to our local dealer the next day for the 2 years service to comply with the Fiat Schedule. When we bought out van new in Sept 2019, no one told us about the extended warranty available. By the time we found out fiat told us it was too late, but stated that as long as the van is serviced in accordance with their schedule they may look favourably on any issues that would have been covered by them up to six years.

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[peterc10]

OK I have a plan.

We will not be using the motorhome until the new year at the earliest because Angela will be having her second hip operation soon. In addition our daughter and Son in Law are coming over for Xmas, so no Benidorm at Christmas. So in October I will take the motorhome to our local mechanic and get him to do a full service including changing the gearbox oil and MOT. l will not get him to touch the Hydraulic clutch fluid or the clutch fluid. I will book a separate visit to a specialist in comformatic gearboxes and who can recalibrate the clutch mechanism.

We are in West Kent so it's quite a long drive the Adams Morley in Pompey. Does anybody know any other garage nearer to us that could be able to do this properly? Our nearest Fiat Pro dealer, Northern Commercials in Sevenoaks, is slapdash and expensive, so don't want to use them

 

[peterc10]

There are two types of clutch fluid reservoir, either the separate eggcup type attached to the side of the hydraulic reservoir or a common reservoir shared with the brakes.

The eggcup type looks like this

View attachment 811106

The clutch fluid in either type of reservoir could becomes contaminated by the hydraulic fluid so if yours is a shared reservoir with the brakes then you'll need to get the brake fluid (including the fluid in the brake lines and calipers) changed at the same time as the clutch fluid to ensure that the braking system doesn't get contaminatd.

I've been trying to source a larger reservoir to replace the eggcup type but so far with no luck. The logic is that with a bigger reservoir any contamination is more diluted so buys a lot of time to get the fluid changed as a maintenance item. The reservoir shared with the brakes is already significantly larger than the eggcup reservoir so already has a better window for fluid replacement but the consequences of severe contamination are then a braking issue aswell.

I have a RHD Hymer, but can't find anything like that on my motorhome on the right hand side. Maybe it is because it has the Iveco 3 litre turbo diesel engine?
I have found what looks like a brake fluid reservoir, to the right side of the coolant tank (looking from the front). Can't find any other brake fluid reservoir, so I guess that the tank is being shared with the clutch fluid. And to the left side of the coolant tank, and above the windscreen top up tank, there is what looks to be a hydraulic tank, which the handbook says is the power steering fluid. Would that also be for the clutch activation as well? If not I can't see anything else that looks like it needs topping up (other

Here is a photo of all the tanks I can find. That are all on the offside (RHD) of the engine bay

 

[dunnah01]

I have a RHD Hymer, but can't find anything like that on my motorhome on the right hand side. Maybe it is because it has the Iveco 3 litre turbo diesel engine?
I have found what looks like a brake fluid reservoir, to the right side of the coolant tank (looking from the front). Can't find any other brake fluid reservoir, so I guess that the tank is being shared with the clutch fluid. And to the left side of the coolant tank, and above the windscreen top up tank, there is what looks to be a hydraulic tank, which the handbook says is the power steering fluid. Would that also be for the clutch activation as well? If not I can't see anything else that looks like it needs topping up (other

Here is a photo of all the tanks I can find. That are all on the offside (RHD) of the engine bay

View attachment 812358

The reservoir(s) are on the left hand side above the gearbox (RHD nearside ). It may only be the rectangular tank but I also have the 3.0l Iveco lump and mine has the small eggcup reservoir attached to the rectangular hydraulic reservoir

 

[dunnah01]

They lo

I have a RHD Hymer, but can't find anything like that on my motorhome on the right hand side. Maybe it is because it has the Iveco 3 litre turbo diesel engine?
I have found what looks like a brake fluid reservoir, to the right side of the coolant tank (looking from the front). Can't find any other brake fluid reservoir, so I guess that the tank is being shared with the clutch fluid. And to the left side of the coolant tank, and above the windscreen top up tank, there is what looks to be a hydraulic tank, which the handbook says is the power steering fluid. Would that also be for the clutch activation as well? If not I can't see anything else that looks like it needs topping up (other

Here is a photo of all the tanks I can find. That are all on the offside (RHD) of the engine bay

View attachment 812358

They look like washer fluid, power steering, coolant and brake reservoirs so there should be a couple hidden away on the other side of the engine bay behind the air filter on top of the gearbox

 

[Freo]

There are two types of clutch fluid reservoir, either the separate eggcup type attached to the side of the hydraulic reservoir or a common reservoir shared with the brakes.

The eggcup type looks like this

View attachment 811106

The clutch fluid in either type of reservoir could becomes contaminated by the hydraulic fluid so if yours is a shared reservoir with the brakes then you'll need to get the brake fluid (including the fluid in the brake lines and calipers) changed at the same time as the clutch fluid to ensure that the braking system doesn't get contaminatd.

I've been trying to source a larger reservoir to replace the eggcup type but so far with no luck. The logic is that with a bigger reservoir any contamination is more diluted so buys a lot of time to get the fluid changed as a maintenance item. The reservoir shared with the brakes is already significantly larger than the eggcup reservoir so already has a better window for fluid replacement but the consequences of severe contamination are then a braking issue aswell.

To those of us, like myself, who have been a bit bamboozled by some of this subject, IMHO this is an excellent explanation of the Comfortmatic system. Many thanks for posting this.

My current understanding, and please, correct me if I’m wrong, is that there are 3 separate fluids to consider.
1. Gearbox Oil - which will outlast the clutch and so will not need changing until the clutch needs replacing.
2. Hydraulic Oil (Dexron) - which does not normally need replacing.
3. Hydraulic Clutch Fluid (DOT 4) - which does need replacing every 2 years, although recommended for annual replacement by Adams Morey, Portsmouth.

I think that for those of us who are less knowledgeable on this, there is confusion between the 3 different fluids. Also, the differing terminologies used by people over the various threads on this subject to describe fluids 2 and 3 above only adds to the confusion. Or maybe it’s just an age thing.

Once again, superb post. Many thanks for the clarification it brings.

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