Alternator alarm TAMD31a

[lynallbel]

TS31 running twin VP TAMD31A engines on shafts, VP switch panels both stations.
We have an alt light issue, and it is a weird one.

Story goes, Port engine alt light intermittent and also looses tacho, new alt fitted problem went away, on that engine at least.
Starboard engine started to show same fault, and this is where I come into the story and fit a new alternator (alt was very old, but I dont think it was 1987 old) success all works as it should, fast forward a week or two where it starts to show random alt and tacho loss on the starboard engine, but only if the Port engine is also running! owner tells me that it used to also do this with the old alternator.
Port engine volt meter shows low 13v, and Starboard shows 14v, both when running.

I am going to take a look tomorrow, and was curios is anyone has had or come across this issue before?
I did have a wiring diagram but damned if I can find it.

 

[snowbird30ds]

I get a similar on my tmd41's if been on charge overnight and sun's out (I have a solar panel), I have a Xsplit charge splitter and have a feeling it cuts the field winding entirely when the batteries are full, you can see the voltmeters on the dash drop when the tachos play up quite often.

 

[Portugeezer]

Have you checked the belt tension? Had exactly the same issue on my AD41´s, double belt setup on each engine but different tensions on each belt. Bought new belts and couldn´t get equal tension. I guess there must be a slight tolerance in belt length that´s just enough to cause the uneven tension. Out of the 8 belts I now had, managed to get 4 that were near enough equal. Problem solved.

 

[lynallbel]

I get a similar on my tmd41's if been on charge overnight and sun's out (I have a solar panel), I have a Xsplit charge splitter and have a feeling it cuts the field winding entirely when the batteries are full, you can see the voltmeters on the dash drop when the tachos play up quite often.

Weirdly the volts do not drop on the gauge/s, just the revs gauge ceases to work and the alt alarm light and buzzer sounds

 

[lynallbel]

Have you checked the belt tension? Had exactly the same issue on my AD41´s, double belt setup on each engine but different tensions on each belt. Bought new belts and couldn´t get equal tension. I guess there must be a slight tolerance in belt length that´s just enough to cause the uneven tension. Out of the 8 belts I now had, managed to get 4 that were near enough equal. Problem solved.

All new belts and they seem the have the same tension.
You can buy matched sets of belts, but I did not in this case and all 4 are nice and even, but will check again as you never know.

 

[James jameson]

Weirdly the volts do not drop on the gauge/s, just the revs gauge ceases to work and the alt alarm light and buzzer sounds

Measure the voltage at the alternator on the excite terminal see what happens to that when the rev counter stops

 

[volvopaul]

Weirdly the volts do not drop on the gauge/s, just the revs gauge ceases to work and the alt alarm light and buzzer sounds

The volts won’t drop because your getting a feed I’d guess from your other engine to the battery , I don’t know what boat you have or charging set up , that would help .
When you loose alternator charge you loose your voltage to the rev counter so it ceases to work .
On the new alternator is there 12volt positive at the yellow wire ? is the yellow wire direct to the thick red or is it wired remote from a separate supply , this system is fuses from the source possible the domestic battery if that engine is going through a split charge relay or diode block .

To make the alternator charge you need a supply to the yellow wire .
Is the new unit a genuine Volvo or valeo item , where did you buy from as certain companies sell any old rubbish that for ,any reasons are not compatible with both the Rev counter and the dashboard warning light module .

 

[lynallbel]

The volts won’t drop because your getting a feed I’d guess from your other engine to the battery , I don’t know what boat you have or charging set up , that would help .
When you loose alternator charge you loose your voltage to the rev counter so it ceases to work .
On the new alternator is there 12volt positive at the yellow wire ? is the yellow wire direct to the thick red or is it wired remote from a separate supply , this system is fuses from the source possible the domestic battery if that engine is going through a split charge relay or diode block .

To make the alternator charge you need a supply to the yellow wire .
Is the new unit a genuine Volvo or valeo item , where did you buy from as certain companies sell any old rubbish that for ,any reasons are not compatible with both the Rev counter and the dashboard warning light module .

I am not going down to the boat today, but will later on in the week so will check as per your suggestions then.

Pic of new port engine alternator fitted, the one that is easy to get at, I did the other much more awkward one.
Old alternator pic is the starboard engine alternator before I removed it.

 

[James jameson]

TS31 running twin VP TAMD31A engines on shafts, VP switch panels both stations.
We have an alt light issue, and it is a weird one.

Story goes, Port engine alt light intermittent and also looses tacho, new alt fitted problem went away, on that engine at least.
Starboard engine started to show same fault, and this is where I come into the story and fit a new alternator (alt was very old, but I dont think it was 1987 old) success all works as it should, fast forward a week or two where it starts to show random alt and tacho loss on the starboard engine, but only if the Port engine is also running! owner tells me that it used to also do this with the old alternator.
Port engine volt meter shows low 13v, and Starboard shows 14v, both when running.

I am going to take a look tomorrow, and was curios is anyone has had or come across this issue before?
I did have a wiring diagram but damned if I can find it.

I have exactly the same issue. Running each engine separately all good. run both and all good for a while then the port rev stops but it’s still charging but no rev. I measured the excite terminal as your image D+ this has 13 volt showing and the drops ro 12.4 then the rev counter stops. turn off the star engine and rev counter comes back up.
on mine star charges the domestics and the alt output goes straight to the domestic batts.
my port goes straight to the engine start batt
appears no links between dom and start batts,
ive checked all the earths
all the time I measure more than 14 at all batts so had given up chasing it but it’s annoying

 

[volvopaul]

I have exactly the same issue. Running each engine separately all good. run both and all good for a while then the port rev stops but it’s still charging but no rev. I measured the excite terminal as your image D+ this has 13 volt showing and the drops ro 12.4 then the rev counter stops. turn off the star engine and rev counter comes back up.
on mine star charges the domestics and the alt output goes straight to the domestic batts.
my port goes straight to the engine start batt
appears no links between dom and start batts,
ive checked all the earths
all the time I measure more than 14 at all batts so had given up chasing it but it’s annoying

Are you testing with the battery charger on ?
Overvoltage can also cause the other alt to cut out so test each one individually, ideal voltage is 14.2 and no more , also check the earths .

 

[volvopaul]

I am not going down to the boat today, but will later on in the week so will check as per your suggestions then.

Pic of new port engine alternator fitted, the one that is easy to get at, I did the other much more awkward one.
Old alternator pic is the starboard engine alternator before I removed it.

Looking at your photos the new one I assume the left pic is the new one , I’ve been here before and my hunch is Because it’s not a Valeo unit the regulator is not compatible with the dash warning module .
Some years back I thought I’d found a local company to repair my old units , they did me 2 and both worked absolutely fine on the test bed , fit them to a boat they didn’t work , after much frustration I took a near on new unit for them to check it over and do the homework on the regulator and rectifier unit , turned out they had fitted the incorrect regulator that will only work with the dash model .Another experience some years ago a client purchased a new unit from a well known Volvo parts supplier , the unit gave incorrect Rev counter voltage , they were very difficult to deal with , would not accept the unit back , I mentioned it on here and ended up with a solicitors letter from them as they said I was out of order with my comment , the moral of the story is to buy from people who know what it’s going on , there are plenty of eBay type suppliers that simply sell any old crap that just doesn’t work with Volvopenta set up , don’t forget the alternator does more than give charge to the battery, it also gives the correct calibrated voltage out put via the correct size pulley to the Rev counter.

 

[QBhoy]

If your batteries have a common earth but are arranged to be independent otherwise, I’d make sure you don’t have a short to earth somewhere. Just to rule out that being a reason.

 

[James jameson]

Any progress ? Keen to know what you find

 

[lynallbel]

Well I have been down there for 5 hours today, and my poor brain is frazzled.
Much faffing I traced the wire (Grey) down to the alternator, and it is the same, ie start engine and after about 5 seconds the power just vanishes as the tacho needle drops to zero.
I even disconnected the volvo connector box so eliminating the upper helm, leaving just the lower helm, still faults.

We have noticed the port engine has no oil warning light (unsure if that was the case before) port engine warning lights are amber, starboard ones are red.
Start starboard engine and it will either fault within 5 seconds or happily run for ages with no apparent issues, then turn on port ignition but not start it, and the port warning lights start to flicker, start the port engine and again it will somehow mess up the starboard side and the tacho will drop to zero, then every now and then both port and starboard tachos will drop to zero, but both side volt gauges remain at 14 volts

Another thing we have noticed is the starboard side smoke limiter solenoid makes a loud click, but could not hear the port one making any noise, and tbh I even forgot to check if it was moving as my brain is not with it.

I can wiggle all the dash looms with engine on or off and nothing flickers/changes.

I have unplugged everything, both ign switches had black spade terminals, which I cleaned and also nipped up the female side to make them nice and snug, no difference.
So we decided enough is enough and I put it all back together, and would you know it the bloody thing is working perfectly both sides, aaagghh!

I hope it is not as VolvoPaul suggests and the alternators are duff.

 

[volvopaul]

Well I have been down there for 5 hours today, and my poor brain is frazzled.
Much faffing I traced the wire (Grey) down to the alternator, and it is the same, ie start engine and after about 5 seconds the power just vanishes as the tacho needle drops to zero.
I even disconnected the volvo connector box so eliminating the upper helm, leaving just the lower helm, still faults.

We have noticed the port engine has no oil warning light (unsure if that was the case before) port engine warning lights are amber, starboard ones are red.
Start starboard engine and it will either fault within 5 seconds or happily run for ages with no apparent issues, then turn on port ignition but not start it, and the port warning lights start to flicker, start the port engine and again it will somehow mess up the starboard side and the tacho will drop to zero, then every now and then both port and starboard tachos will drop to zero, but both side volt gauges remain at 14 volts

Another thing we have noticed is the starboard side smoke limiter solenoid makes a loud click, but could not hear the port one making any noise, and tbh I even forgot to check if it was moving as my brain is not with it.

I can wiggle all the dash looms with engine on or off and nothing flickers/changes.

I have unplugged everything, both ign switches had black spade terminals, which I cleaned and also nipped up the female side to make them nice and snug, no difference.
So we decided enough is enough and I put it all back together, and would you know it the bloody thing is working perfectly both sides, aaagghh!

I hope it is not as VolvoPaul suggests and the alternators are duff.

Right you have exactly the same problem I had after having a couple of units refurbished by a local company, as I said they fitted the incorrect regulator that was not compatible with the dash warning module hence it charged fir a few seconds then failed , I’d swap the alternator over from the good engine to the bad and try that .

 

[lynallbel]

Apparently electrician booked for later this week, will report back with findings.

 

[lynallbel]

Electrician came and checked everything, engine ran for ages with zero issues, did not fault once.
Then today owner starts engine and pop she faults again!

 

[lynallbel]

Well it appears to be fixed.
I started from scratch and worked my way along.
Problem was with port engine, even though it was the starboard that showed the symptons.
Kind of suspicious that there is a further issue waiting to surprise us.
But I will take it as a win for now.

 

[Mr Googler]

Well it appears to be fixed.
I started from scratch and worked my way along.
Problem was with port engine, even though it was the starboard that showed the symptons.
Kind of suspicious that there is a further issue waiting to surprise us.
But I will take it as a win for now.

Good work! What was the fault?

 

[James jameson]

Hi. I still have the same issue and paused looking through frustration !

What did you find that sorted the problem ?