Technodrive TM170 TM880A, TwinDisk engaging failure, low hours

[rbcoomer]

Re: port gearbox works only on reverse

Debris build up in the valve? A clean and flushing with new oil may fix, but where's the debris from? Danger in putting the good valve in is that there's a remote chance you could create a similar problem with that one! :disgust:

 

[vas]

Re: port gearbox works only on reverse

still haven't grasped how the box works, so no idea if valve is blocked, seems to be shifting air when blowing hard either way..
sure no idea what/why the debris, and tbh cannot be a good thing.
Valve is a very simple thing, I'll definitely remove the stbrd one and examine before swapping over. If it looks and behaves identically, I wont bother.

IMHO, I got to remove the whole pump/diverter assembly before deciding how to proceed.

V.

 

[rafiki_]

Re: port gearbox works only on reverse

Sorry Vas, unable to offer anything constructive on this.

 

[MapisM]

Re: port gearbox works only on reverse

Sorry Vas, unable to offer anything constructive on this.

+1, I'm afraid.

But just for better understanding:

I noticed that when I was engaging reverse on the port box while holding the oil to cooler pipes, you could feel a rush of pressurised thing through them.
On idle, when turning the lever to fwd, you felt bugger all.

What about the other one? Do you get the same feeling when engaging reverse? And when engaging fwd?

 

[vas]

Re: port gearbox works only on reverse

+1, I'm afraid.

But just for better understanding:

What about the other one? Do you get the same feeling when engaging reverse? And when engaging fwd?

+2 as far as understanding the operation and constructive comments

P, when I engage the port box with high revs I can feel some (little) pressure on the pipe, when at idle nothing on fwd.
Reverse pressure is definitely there.
On stbrd have the same feeling of pressure on both fwd and reverse (will check again today for sure, but that's what I remember from yesterday's playing around)

Mind, on the PDF link you posted (must have spent a couple of hours reading back and forth trying to figure out how these things work!) on showing the rebuilt of a box, they change plates (fine) but they also replace the diverter valve (that I feel could be the problem) with a brand sparkling new! Coincidence? maybe not!
P., I would definitely appreciate a quick search on IT sites for possible issues with the diverter assembly of these boxes!

Ofcourse someone may come back and argue that:

• box on idle has 270psi going around the box and the cooler
• on engaging, the feedback from the plates engaging, ups the pressure and that's what I feel on the flexhose going or returning to the cooler
• port box fwd clutches/plates have gone hence engaging doesn't give such a feedback that I can feel on the flexhose, hence need plates

A typical analysis of how pressure is builtup and how/when cooler is involved would be nice. I mean does oil circulate to the cooler all the time or only when engaging?
Also failed yet to comprehend how the diverter (or rather WHERE to) routes the oil and what does the by-pass valve do hidden in there.
Generally still failing to see how the oil pushes plates to engage fwd and reverse. I guess if I spend a few more hours (which I currently don't have...) I'll figure it out, cannot be rocket science...

As I said, there are two filthy and slightly rusty VDO (from my experience now) oilpressure sensors on the boxes. I've got some 300psi gauges from the Detroits (which are also VDO but much older) Will try today and wire them up and see what I get in pressure measuring (assuming I do get something and they are compatible) Not sure it's going to make any sense as for sure I got the pressure to engage reverse.

any other opinions welcomed (especially the ones that postpone removing the box from the boat


cheers

V.

 

[Portofino]

Re: port gearbox works only on reverse

Here,s the manual from Twin Disc ( similar to yours ??) -they work the same ---assuming so ------
Page 53 ---2-5. "low oil pressure " --------- feels to me a valve prob going Fwd,s
Also look @ page 23 "detent " position -I think you have checked that with the cables off ?
http://www.twindisc.com/data/en/pag...wnloads/Twin_Disc_Marine_Operators_Manual.pdf

 

[vas]

Re: port gearbox works only on reverse

Here,s the manual from Twin Disc ( similar to yours ??) -they work the same ---assuming so ------
Page 53 ---2-5. "low oil pressure " --------- feels to me a valve prob going Fwd,s
Also look @ page 23 "detent " position -I think you have checked that with the cables off ?
http://www.twindisc.com/data/en/pag...wnloads/Twin_Disc_Marine_Operators_Manual.pdf

thanks,

yep, that's the nice, cheap option I'm trying to persuade myself
will work on it (sadly not today, weather too good and rest of the family want lunch with friends...)

Still would be nice to understand the oil flow within the box.

BTW, seems that mine looks VERY similar to TwinDisk MG-502 box (at least externally, will try to find specs and exploded views on that as well)
Also, I thought that box needed ATF oil, turns out it needs SAE20/30 or 15W/40. Thank god levels were OK and hadn't a chance to up it.

Ah, I should also mention that I'm no single morse controls which means that none could unwillingly force engaging the box with high revs (which is a no-no.

cheers

V.

 

[superheat6k]

Re: port gearbox works only on reverse

Link to MG502 service manual here ...

https://www.dropbox.com/s/qumix80nun5wy8j/Twin Disc MG502 Service Manual.pdf?dl=0

 

[vas]

Re: port gearbox works only on reverse

Link to MG502 service manual here ...

https://www.dropbox.com/s/qumix80nun5wy8j/Twin Disc MG502 Service Manual.pdf?dl=0

thanks!

this is much more analytical, shows how things rotate and engage and generally will help me understand better the whole thing.

cheers

V.

 

[MapisM]

Re: port gearbox works only on reverse

P., I would definitely appreciate a quick search on IT sites for possible issues with the diverter assembly of these boxes!

Sorry V, I just made it, but couldn't find anything relevant.

Fwiw, judging by your description of the stbd behaviour, I would definitely think/hope it's just a valve problem, but don't take this as more than an educated guess.

Besides, re. your Q on whether oil circulates to the cooler only while engaging, I positively don't think so!
I mean, the g/box heat generation while engaging is close to nothing, compared to when it runs for hours transmitting power/torque to the shafts.
If the oil wouldn't need to be cooled while operating, I suppose they could as well not have fitted a cooler at all.....

PS: Doh!, Sorry, maybe you meant if the oil circulates also while no gear is engaged at all? This question makes much more sense, but I'm not sure about the answer.
I would think it's a useless complication to have valves controlling/closing the cooler recirculation when the gear is not engaged, but I really don't know.

 

[vas]

Re: port gearbox works only on reverse

Sorry V, I just made it, but couldn't find anything relevant.

Fwiw, judging by your description of the stbd behaviour, I would definitely think/hope it's just a valve problem, but don't take this as more than an educated guess.

that's good news, if it was a known fault/failure, I'm sure we'd find some references.

PS: Doh!, Sorry, maybe you meant if the oil circulates also while no gear is engaged at all? This question makes much more sense, but I'm not sure about the answer.
I would think it's a useless complication to have valves controlling/closing the cooler recirculation when the gear is not engaged, but I really don't know.

yep, that's what I meant, mainly due to the fact that I could feel a change of conditions once gear was engaged and shaft was rotating

Maybe it's as simple as route the oil to the cooler before or (most likely) after it goes to the plates and does it's job. Not difficult and wont involve any extra valves/routes and complication. Haven't had the time to digest the new manual that sh posted but it may make things clearer.

anyway, will wait for more ideas and attack the box when I have some time.

cheers

V.

 

[vas]

Re: port gearbox works only on reverse

confused even further !

bought a nice ss WIKA 550psi glycerin pressure gauge with an adapter and fitted it on both engines (one at a time...) at the place where the VDO 25bar pressure sensor lives (on the pipe returning from the heat exchanger)
Started engine, on idle pressure zero, nil, zilch. Engaged gear everything works except for fwd on port engine, On BOTH engines, NO PRESSURE registers at all.

Was so puzzled that I got the gauge to Alekos' paint shop and tested it with their pressure tank and nozzle. Gauge is fine, works, needle moves, SO,


anyone care to explain HOW on idle by moving the lever, gears engage, shaft rotates but pressure gauge registers NOTHING, no pressure
Service manual mentions 300psi.

I'm afraid it's not feasible to try same thing at higher revs whilst MiToS is moored med way and holds on the 15kg bruce and 60m of chain on the bow...

One could argue that that oil goes through the cooler at a lower pressure, which then defies the point of having ORIGINALLY a 25bar VDO sensor on this pipe
And yes, I don't have the gauges for these sensors, never had.

cheers

V.

 

[superheat6k]

Re: port gearbox works only on reverse

Is the pressure access point closed somehow - what was the VDO sensor showing ?

If the access point is a tapered valve, like a car brake bleed valve it has to be cracked off to open the port. If the clutches are engaging there must be hydraulic pressure to push the clutch packs into engagement.

 

[vas]

Re: port gearbox works only on reverse

Is the pressure access point closed somehow - what was the VDO sensor showing ?

If the access point is a tapered valve, like a car brake bleed valve it has to be cracked off to open the port. If the clutches are engaging there must be hydraulic pressure to push the clutch packs into engagement.

Tried to undo the gauge whilst engine was running in idle. Oil tried to escape (very leisurely I may add...) so no access is not blocked. Not like the car brake bleed valves at all.
A simple adapter between the gearbox block and the flex hose to the heat exchanger with a hole on the side and threads to bolt the sensor (or gauge in my testing)

Sensors were on the boxes when I got the boat, no gauges were installed, no wiring is present.

Two questions:

• Does it make sense to have 300psi oil turning from box to heat exchanger? Sounds stupid to me, oil would rush that quickly around that wouldn't have the chance to cool down...
• how would you have a low pressure to turn oil around to the heat exchanger and keep the high pressure built-up just inside the box for the plate engaging?

If the answer to these Qs is that low pressure makes sense for the cooling system, then I'm afraid that the main Greek IVECO dealer and their certified installer have done something very silly fitting these gauges there. Maybe this threaded hole is for an oil temp sensor and not an oil pressure one and they happened not to have a couple of temp sensors lying around

Will search the manuals a bit more.

For the record, I revved the engines up to 2K rpm, no pressure registers. Further, engaging fwd on the port box and revving up to 1.8K prop rotates at the level and force that it does on stbrd box at idle.

So box is not really dead on fwd, just slips badly due to lack of pressure (at least I hope for my wallet's sake...)

any further ideas?

cheers

V.

 

[superheat6k]

Re: port gearbox works only on reverse

Tried to undo the gauge whilst engine was running in idle. Oil tried to escape (very leisurely I may add...) so no access is not blocked. Not like the car brake bleed valves at all.
A simple adapter between the gearbox block and the flex hose to the heat exchanger with a hole on the side and threads to bolt the sensor (or gauge in my testing)

Sensors were on the boxes when I got the boat, no gauges were installed, no wiring is present.

Two questions:

• Does it make sense to have 300psi oil turning from box to heat exchanger? Sounds stupid to me, oil would rush that quickly around that wouldn't have the chance to cool down...
• how would you have a low pressure to turn oil around to the heat exchanger and keep the high pressure built-up just inside the box for the plate engaging?

V.

Oil at 300 psi does not escape 'leisurely'.

You are confusing oil pressure with flow. Flow is the result of pressure differential, not pressure per se. The pressure is required to operate against the resistance of the clutch springs holding the clutch plates apart. If you measured pressure in to and out of the cooler there would barely be any difference.

The fact you are not picking up pressure of around 200 - 300 psi suggest the tapping you are using is not open to the main pressure you need to be measuring, which is why I asked how the access port was connected.

Do not be chasing a red herring here. Clearly if the hydraulic pressure was at zero everywhere you would have nil propulsion from either box. The clutches will not close (drive) without this significant oil pressure. You are just not measuring in the right place.

When things start getting complicated go back to the simple. You have to have the necessary pressure to operate the gearbox clutches. You need to work out where to pick this up, and then why the Stbd fwd is not engaging hence possibly a different pressure.

They cannot all be zero. If the fitting you are using is not showing pressure then you need to look where the pressure will definitely be present, e.g the hose connections to the gearboxes. An adaptor between the hose and its normal fitting with a suitable tee access point would provide this, but you will need someone who can work out the adaptor thread and coupling profiles and with a suitable side access point.

No one ever said hydraulic engineering was simple. The difficulty for you is having someone explain to you via a forum where you need to look and just how to look, but we will get there.

Can you take some more photos of your gearboxes and place them on the forum or PM me and I will see if / how I can help further.

 

[vas]

Re: port gearbox works only on reverse

Oil at 300 psi does not escape 'leisurely'.

You are confusing oil pressure with flow. Flow is the result of pressure differential, not pressure per se. The pressure is required to operate against the resistance of the clutch springs holding the clutch plates apart. If you measured pressure in to and out of the cooler there would barely be any difference.

The fact you are not picking up pressure of around 200 - 300 psi suggest the tapping you are using is not open to the main pressure you need to be measuring, which is why I asked how the access port was connected.

me again...

Last few days I spent a good 2-3 h reading the manuals of the TM170/A/880A as well as the Twindisk MG502 which is very similar to mine.

First of all, yes I agree 300psi and escaping leasurely is a contradiction hence me asking.

Yes, first thought is that something's wrong and the tapping is on the wrong place. However studying the manuals and following the description of oil flow through the system it looks like everything is normal:

First page of the manual as posted by MapisM http://allpa.nl/media/manuals/Techno...0TM 880A.pdf shows the route of the oil to the cooler and back. On my setup, where it enters back there's a 1/4NPTF tap for the sensor as seen on the following pic (as I said, please excuse the dirt it's much cleaner now):

Reading the TwinDisk MG502 Service Manual http://fos.prd.uth.gr/vas/crafts/mitos/rebuilt6/Twin_Disc_MG502.pdf on page 10 (pdf page 14) it mentions exactly where you tap for the oil pressure sensor and shows all oil pressures at 600 and 1800rpm on fwd/idle/rev.
However, here it mentions that taping in on the outlet from the pump to the oilcooler whereas on mine it's on the return from the oil cooler!
Considering that there's enough oil to be pumped about by the oil pump, there should really be no difference if it's on the inlet or outlet, but open to ideas.

The TD MG502 manual on the general hydraulic system description on page 13 (pdf page 17) explains that there's a tap already on the diverter (also mentioned as control) valve cover where you connect the sensor (that's again the return pipe from the cooler).
I do have that tap visible to the left of the sensor on the above pic, got to see if it's an allen or torx or whatever and see if I can remove it and fit the sensor there.

Finally, to complicate things a bit more, on Troubleshooting page 17 (pdf page 21) it again mentions to "attach an 0-500 psi range pressure gauge to the (3/8-18 NPTF dryseal) selector valve inlet from the heat exchanger"
That is where i'm fitting the gauge, means I've got the connections right.

Concluding, it is fair to say that something's wrong on my testing methodology as I must stress I also get zero pressure on the stbrd box that works just fine!

So, I think we should try to address that one first, may I explain my testing:

Start both engines (probably irrelevant) run them a couple of minutes in idle, leave them there at approx 650rpm while I go down to the engine bay where I'm in front of the two gbox levers disconnected from the morse controls, just sitting there free.
STBRD ENGINE: I turn the lever to fwd, axle immediately starts turning (and boat tries to MOVE!). Since I'm moored the med way, I just do that for a second or two and then back to neutral. Throughout this process the 400psi brand new (and tested on compressed air) glycerine filled WIKA ss gauge that is bolted on the tapping where the 25bar VDO sensor is bolted on the above pic does bugger all. Needle doesn't move AT ALL.
Undid it and looked carefully at the threads and the oil path. It is nice and clean and I can see the whole shiny oil route at the end of the threads, so not blocked at all.
Same happens on reverse but also on the port engine.
Going astern on the PORT ENGINE, does nothing. Axle doesn't feel like turning, however if I up the revs I get it to turn to a much lower speed than the stbrd on idle.

I've not tried leaving the good box engaged on idle for more time to see what's happening as I'm afraid of boat shifting to port and I'm usually alone on these tests (should bring the son along next time...) but the twindisk manual clearly states that oil pressure is there even on idle and neutral 290psi!

I have some v.old vdo gbox gauges form 40yrs ago that came with the detroit diesels that MiToS was originally fitted. I'll try them one evening this week and see If get them to register something.

Open to ideas!

cheers

V.

 

[Portofino]

Re: port gearbox works only on reverse

They need oil pressure a lot to engage , the discs .
I have oil G-box pressure guages on my boat .A pipe split (just entering the marina ) and I saw the guage over 1-2 mins drop from 300 (or what ever ) to zero -it slipped into neutral .
Easy fix new pipes -replaced all 4 -as all same age .+ oil or course
The Oil pressure does drop when in neutral /idling and goes up and stays up when over 600 rpm gradually to 300 psi -plateau,s out at 1500 rpm -ie does not go any further from 1500-2000

Back to your prob -have you changed /swapped over the "diverter " valves -there in could be prob ?
Or there is a blockage or leaky union in the internal pipe to the device that pushes the relevant disc .

 

[superheat6k]

Re: port gearbox works only on reverse

I can't explain why you are not measuring pressure where you are tapping in, unless the port is somehow closed. The fact it engages astern but not ahead suggests it is a diverter issue. If the ahead clutch had failed it would gradually fail and slip first, not just not drive at all.

I would do as Portofino suggests and withdraw the selector valve and inspect it. Make sure every where around is clean, and be thorough with cleaning any muck off before you put it back in. You might need new seals as these may swell up.

Just a thought have you removed the oil strainer and checked this is clean - large plug at bottom of box below the oil pump. This will drain the oil, so collect this and check for any metallic debris.

Your box is certainly very similar to the MG502.

 

[vas]

Re: port gearbox works only on reverse

They need oil pressure a lot to engage , the discs .
I have oil G-box pressure guages on my boat .A pipe split (just entering the marina ) and I saw the guage over 1-2 mins drop from 300 (or what ever ) to zero -it slipped into neutral .
Easy fix new pipes -replaced all 4 -as all same age .+ oil or course
The Oil pressure does drop when in neutral /idling and goes up and stays up when over 600 rpm gradually to 300 psi -plateau,s out at 1500 rpm -ie does not go any further from 1500-2000

Back to your prob -have you changed /swapped over the "diverter " valves -there in could be prob ?
Or there is a blockage or leaky union in the internal pipe to the device that pushes the Reverese disc .

yes I understand that, what I'm trying to do now step by step is establish that I'm on the right path to troubleshooting..
So, unless I get my analogue gauge to show pressure on the stbrd box (that works fine!), I'm not doing anything more.
Hence my asking if I'm doing something wrong in only engaging astern for a couple of seconds (or max 5-6 turns of the axle) and if that's enough to built up pressure. Which anyway contradicts with the manual saying I should have 270psi on idle anyway and it's against what happens on my mate's P45 with CATs.
Easiest thing to do without getting dirty today is to engage astern on the stbrd box for 1 min and see if pressure builts up (and how my stern lines fare...).
Next easiest is to try and wire the existing sensors to my 40yo VDO gauges and see if they for some odd reason register pressure. That will mean that the WIKA doesn't work (But it does...) or is unhappy with 20-30 grade oil, which I cannot believe tbh.

Swapping the diverter valve is relatively straight forward although I'd like to understand EXACTLY how the thing works first:
It's a shaft with various cuts and holes that routes oil differently as it rotates (approx. 45deg each side)
But under it is another valve that sockets in it and can easily slide out of it.
You cannot see through the hole along this valve, but you can blow through it (not easily as in a whistle, but with a bit of effort.
If this is the pressure regulator of the system (as vaguely implied in the pdfs I've been reading) I can safely assume it's buggered, but I'd expect something more complicated and serious than that tbh and anyway would struggle to justify it only failing on one side.

Something blocked seems more interesting, we shall see.

cheers

V.

 

[Portofino]

Re: port gearbox works only on reverse

Swapping parts is luxury with a twin engined outfit -like a boat -and use full in diagnosis .A luxury not afforded in say a car ?
You don,t necessarily need to know how they (parts) work .

Another Q have you manually moved the shift lever after its disconnected ?
This is to eliminate "detent" position .ie the attached cable is preventing the valve fully clicking /engaging .
So when you rev up some oil squeezes through the partially engaged /lined up valves ?-leading to the shaft starting to turn