Temp Alarms but all ok

[Dimjim]

Hi All,
I have KAMD43 and have alarm coming up for tempreture ... But the gauge reads normal 85c.
The alarm comes and goes .... Where's the best place to look first.

The other engine has a battery alarm and the Rev counter drops to zero .. This is also intermittent and hard to find as only dose it when under way ...

Thanks in advance

 

[superheat6k]

1st engine Does the temp alarm sound the buzzer, or just the lamp. Former suggests dodgy sender, but check the actual temperature by the sender with an infrared thermometer when it is happening, latter the alternator field is requiring exciting. Is the gen / alt light coming on as well, and does the Gen / alt light work normally otherwise, e.g. on when engine is off, then goes out as engine revs.

Only the temp sender makes the alarm sound, but the temp bulb also feeds the alternator field circuit via a diode to back up the normal Alt field light.

2nd engine Dodgy alternator connection, or alternator diodes dodgy, or possibly slipping belts.

These would be the areas I would start with.

 

[volvopaul]

Overheat alarm switch faulty . Common issue.

 

[Dimjim]

Thank you both for the quick response,
The first engine only did it twice in half an hour for about 10 seconds each time.. The temp light came on and the alarm went off... Is there 2 temp senders as the temp was normal on the dash.

Second engine sounds alarm and alternator light comes on a lot , Rev counter drops to zero sometimes when this is happening but not all the time. Someone said check The yellow wire, Rev counter signal but it seems ok.
Need to sort this as alarms are making the Missis jumpy ha ha

 

[Rickard]

My friend had the same problem on his KAD43 and two weeks ago I replaced the alarm sender 873066. No alarms after that
It´s placed on the engine block(front) under the thermostat housing. Not the easist access but it´s possible to change it without taking other parts apart
The cable goes normally between the the thermostat housing and the valve cover. Just follow it

 

[Dimjim]

Thanks for the reply, il have a look when over there next... Am I right in saying there is two senders .. One for the temp gauge and one for the alarm and light ? .....

 

[superheat6k]

Thanks for the reply, il have a look when over there next... Am I right in saying there is two senders .. One for the temp gauge and one for the alarm and light ? .....

Yes two senders. They are not the same - one is a switch the other a transducer (gauge).

The earlier modules did not sound the alarm if the alternator was playing up, but I understand the later ones do. I would check the alternator connections are all clean and tight, and if it persists then it might be an internal issue such as dodgy field diodes. This would need an expert to test for.

 

[Montemar]

I had the same problem on a TAMD41B last weekend. Should receive new overheat sender switch on 7th and will report back after sea trial.

 

[Dimjim]

Thanks for the info guys ,,, the more I gather the more chance I have sorting it quickly on my next visit

 

[Montemar]

Hope to do sea trial today however I brought the original sensor home on Thursday and tested it in water which I brought to the boil. It tripped at just over 70 degrees and did not switch back until just under 40 degrees. It should trip at 93 +/- 3 degrees! It was a bit rough and ready ( new use for the egg pan ) but made the point. Also the second time the sensor went off on the boat the alarm continued to sound for ages afterwards whenever the ignition was turned back on. It did not do this the first time it went off so suggests that it is disintegrating internally.

 

[volvopaul]

Hh

Hope to do sea trial today however I brought the original sensor home on Thursday and tested it in water which I brought to the boil. It tripped at just over 70 degrees and did not switch back until just under 40 degrees. It should trip at 93 +/- 3 degrees! It was a bit rough and ready ( new use for the egg pan ) but made the point. Also the second time the sensor went off on the boat the alarm continued to sound for ages afterwards whenever the ignition was turned back on. It did not do this the first time it went off so suggests that it is disintegrating internally.

A great explanation and way of testing, to say these are made by VDO for VP there not up to the job at all . The location on the KAD 32 is a real joke, anyway I hope this is the end of the ghost overheat , see you for the injectors soon.