Bukh cold start/electrics

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RobBrown

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Just put the 20DV engine back after a refurb, but on refitting, the retrofit glow plug cold start on the air intake and the sound alarm on the engine panel now not working. I suspect the large green solenoid on the cold start circuit likely to have gone as the cover came off in the engine removal and possibly damaged as a consequence. I think it is a Lucas solenoid, but that is all I know. I guess Bukh may be able to supply, but anyone aware of suitable replacement units?

Buzzer unit has definitely gone. It is a little round disc designed to fit in a round grill in the instrument panel. Again any one know of any sources of replacement units, if not Bukh?

Ta muchly
 
I have one to fit mine are they good for cold starting?
Don't suppose yiu have the fitting instructions by any chance?

Bob
 
I remember the little buzzer well from my old Bukh. It used to become detatched from the rear of the panel but always worked.

It was a small flat circular buzzer and looked very much like a piezo transducer that Maplin sell for £0.99. So probably worth trying one of those as they are so cheap. I think they'll work up to 30V.

Only problem is that they need to be fed a square wave signal so plain 12V won't work. However, it looks very similar so good chance the panel produces this already for the existing buzzer.

If it doesn't work then buy another from Maplin with a built in oscillating circuit (£1.99). You'll only have wasted £0.99.

http://www.maplin.co.uk/components/component-loudspeakers/buzzers-and-sounders
 
Look at the connections to the alarm sender unit. Try reversing the wires by memory I thing the yellow is the inner one.
If these are the wrong way around the alarm will not come on when hey first turned, also when running up to temp the alarm will gradually sound louder and louder.
Hope that helps.

Ps

the sender unit on the engine
 
Thanks chaps.

As no further info on the cold start electrics box, I rang Bukh and they will get back to me with a price, as don't normally sell it separately. It is evidently a relay, not a solenoid.

They do sell the whole cold start as a retrofit kit- I think around £200.

The Sond alert buzzer is £33.20 + VAT from Bukh, so I will give the Maplins unit a go first! From Mistroma's link, that looks a possible as a round disc like the original, so I'll pop nto Maplins to look at sizes to see if likely to fit. Worth a punt for a couple of quid. I will go for the 12 v one with the built in circuit. Electronics & I don't get on very well!
 
RobBrown said:
The Sond alert buzzer is £33.20 + VAT from Bukh, so I will give the Maplins unit a go first! From Mistroma's link, that looks a possible as a round disc like the original, so I'll pop nto Maplins to look at sizes to see if likely to fit. Worth a punt for a couple of quid. I will go for the 12 v one with the built in circuit. Electronics & I don't get on very well!
Click to expand...

There is certainly no waveform generator on the BUKH panel. Any sounder which simply needs 12v to sound should be OK. Someone earlier mentioned the temperature sender...... just for info, if the sender has two terminals, the smaller one is the alarm terminal. The larger one is a thermistor for a temperature gauge.
 
I used to have the full workshop manual but it went with the boat when she was sold. I can't be 100% certain but do remember a small circuit board behind the BUKH logo on the panel. It wasn't very complex but could easily have been a basic flip-flop circuit (couple of resistors, transistors, capacitors and a few resistors). Probably worth checking if the "buzzer" feed comes from this circuit board.

The alternatives would seem to be:

a) No flip-flop circuit and so the "buzzer" can be replaced by one with a built-in oscillator

b) Flip-flop circuit exists and works so "buzzer" can just be replaced by a piezo transducer

c) Flip-flop circut exists but doesn't work and is the source of the fault. Either fix flip-flop or connect a buzzer with built-in ocsillator to the input side of the circuit board.

a) & b) are easy enough as it is just a matter of swithing components.

c) Requires some work in finding the 12V output that feeds the buzzer (via the flip-flop).

I hope that this helps and doesn't confuse. The more I think about it the more certain I am that the fault can be repaired for a few pounds (instead of ~£40 for BUKH parts).

Perhaps VicS can confirm the purpose of the circuit board I remeber seeing. I'd never really thought much about it before now.
 
Mistroma said:
I can't be 100% certain but do remember a small circuit board behind the BUKH logo on the panel.
Click to expand...

The little PCB in the middle of the panel has a tag-strip on the front and some very basic resistor-diode logic circuitry on the rear. This is only concerned with when the alarm sounds. (It is also very vulnerable to corrosion which causes false or inactive alarms).

Vic(M)
 
Thanks for that VicM (sorry for confusing you with VicS). I knew it was a simple circuit related to the alarm but couldn't remember any detail. I probably last looked at it around 10 years ago.

Just had a brainstorm as I write. A picture of the circuit popped up in my mind and it matched something that I saw in the garage last week. I never throw anything out and have a faint memory of having a spare when I bought the boat in 1986.

I'll go out and have a look.
 
It is deffo the buzzer unit that has failed- it & temp sender was working when engine re-connected, as raw water intake was blocked in process of first re-start & alarm triggered! But it then was sounding intermittently and unit fell apart when looking for cause and stopped sounding at all.

Not sure if there is a separate circuit board, but will check when down to boat @ the w/end to try out the two Maplins units I bought this evening. Just the simple ones @ the mo- 2 diff frequencies to try out.
 
I found the board, it might be of some use to OP but don't know if it is functional (though there isn't much to it). Perhaps VicM will recognize it as a BUKH part. No idea what else it might be but a pretty big coincidence finding it so recently if it is from the BUKH.
 
Mistroma said:
I found the board, it might be of some use to OP but don't know if it is functional (though there isn't much to it). Perhaps VicM will recognize it as a BUKH part. No idea what else it might be but a pretty big coincidence finding it so recently if it is from the BUKH.
Click to expand...

Yep, that's the one. As I said it's pretty simple!. I did draw out the circuit a long time ago, and could probably recreate it if I really wanted to. I have long since rewired my panel in a more straightforward manner to avoid erroneous alarms.
 
Mistroma

I don't recall seeing anything like that by the buzzer unit itself. Just two leads going to soldered terminals on the unit. Might be further up the wiring. I'll look on Saturday.
 
Update

Just thought I'd report back on the Bukh buzzer issue for the possible info of others. No joy with just fitting the basic piezo from Maplin to the original buzzer, so went back to Maplins and bought a complete 12v buzzer unit for about £3 and glued this to the fascia part of the original buzzer, so that it could still fit the hole in the instrument panel. The alarm worked when engine first started and for the ignition off-switch alarm, but it did not cancel once water flow got underway as the original did. Couldn't identify the cause, so assume it is because it lacks some electronics installed in the original buzzer. In the end, I located the original manufacturer in the US- Sonalert by Mallory Inc & ordered a unit via Digi-Corp supplier for a total of £22 inc postage to UK.Ordered online Mon lunchtime, delivered Wed afternoon! Trying this out next weekend.

Can also confirm the board that Mistroma has is the unit the pos and neg leads from the alarm go to on the Bukh instrument panel.
 
RobBrown said:
but it did not cancel once water flow got underway as the original did.
Click to expand...

Sorry you are still having problems. However 'water flow' when you start the engine is irrelevant. The temperature sensor is open-circuit unless the temperature becomes excessive, at which point it should sound the alarm.

The factors involved when you start the engine are a) the oil pressure switch opening when the oil pressure builds; and b) the voltage rising on the alternator warning light terminal.

I have described the normal sequence before, and it doesn't sound from your description that your panel ever worked 'normally'.
 
Thanks for that Vic. With the old alarm, it always used to sound when the ignition was turned on, but would stop after the engine was actually started, which I why I assumed it was as a result of water flow, but I was obviously incorrect. Equally the alarm would sound if the ignition key remained in the left stop position after the engine stopped. The new buzzer sounds as soon as the ignition is on and does not stop when then engine starts,so something new is (or is not) happening! As I have already purchased a replacement original alarm, I will try that & see what happens.
 
Sorry to hear you are still having problems. I think my alarm stuck on once and I had to replace the oil pressure switch.

I'm dubious that the correct buzzer will solve the problem. Best to check the oil pressure switch anyway. It's easy enough, just disconnect the wire and clip a meter (set to Ohms) to the tag and to an earth on the block. The meter should show low resistance with engine off and jump to open circuit soon after starting. If the reading stays constant then I'd consider replacing the pressure switch.
 
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