Yanmar 6LP tick over issues

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Corvette320

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Advice, please. I have a boat with two Yanmar 6LP diesels, 430 hours and have had a Main Agent strip intercoolers, after coolers send away for a full service both fuel pumps and service fully each engine, including timing belts etc. In other words having purchased the boat I have had it gone through fully.

Strangely, the engines on cold tick over are at about 600rpm each, warming up to 750rpm. The manufacturer's hand book says tick over should be 750rpm +/- 25rpm.

The agents have returned to adjust the tick overs, telling me that this variation cold to warm is normal and that on Volvos the same thing happens.

I am sceptical, having had many boats with diesels (Volvos, Sabre and Cummins) and all of these engines have been "rock steady" with a constant cold/warm tick over.

Am I being over sensitive, or are the fuel pumps nit doing their job properly of governing the idle speed?

Advice would be welcome, thanks.
 
If both engines are doing the same thing does that not suggest it is quite normal ?
 
I have received confirmation from the Technical Services Team of EP Barrus, the UK importers of Yanmar that the tick overs should be 750rpm cold or warm and therefore the fuel pump govenors are not doing their job. So much for a four figure bill and specialist rebuilding of the fuel pumps.
 
My mate had one of those, it strangled itself by breathing it's own foul air from the rocker cover straight into the air intake, via that breather pipe, (daft idea) that's why your main agent had to clean your intercoolers out. Divert the breather pipes away from air filters and then see how they run.
 
Pretty certain my Volvo engines started at a higher revs and then dropped back 50 or 100 Rpm after warming up ?
 
Hi, I can understand the slight rpm drop on Volvos, but clearly the fuel pump governors on my engines are not working as they should. Hopefully the Yanmar ?Agents will act properly.
 
Corvette320 said:
Advice, please. I have a boat with two Yanmar 6LP diesels, 430 hours and have had a Main Agent strip intercoolers, after coolers send away for a full service both fuel pumps and service fully each engine, including timing belts etc. In other words having purchased the boat I have had it gone through fully.

Strangely, the engines on cold tick over are at about 600rpm each, warming up to 750rpm. The manufacturer's hand book says tick over should be 750rpm +/- 25rpm.

The agents have returned to adjust the tick overs, telling me that this variation cold to warm is normal and that on Volvos the same thing happens.

I am sceptical, having had many boats with diesels (Volvos, Sabre and Cummins) and all of these engines have been "rock steady" with a constant cold/warm tick over.

Am I being over sensitive, or are the fuel pumps nit doing their job properly of governing the idle speed?

Advice would be welcome, thanks.
Click to expand...

Sounds to me that your dealer hasn't a clue what to do apart from taking your money if the situation is still the same.
Are you saying it's hunting i.e. Revs up and down on its own or it starts up and then increases or decreases its stable rpm?
Any mechanically governed engine wil increase its idle speed a few minutes after a cold start up.

The 6lp on both 12 and 24 valve versions suffered from metal particles breaking up inside the injection pump traveling to the injector nozzle and partially blocking the nozzle giving poor performance and smoke, didnthey mention this at all, I'd find out which pump shop they went to for overhaul as over the years I've used many different pump shops before I found one I can trust and that have the knowledge required on marine engines requirements.
 
Thanks for the helpful advice. I would expect some engines to rev a little higher on cold start up, but here the opposite is the case. On start up they are at least equal following the re visit by the agent. However, they start at 600 rpm, gradually reaching 750 on warm up. During the warm up process the engine tick over revs vary up and down between 600-750rpm and manoeuvring on tick over therefore requires constant adjustment of one or both throttles to get equal revs. In essence at low speed the tick overs are all over the place. I await the response of the agent.
 
Further response from Barrus Technical Services is that the revs would be down on cold start as the alternators are working hard to supply the heater plugs and the extra load this puts on the alternators recharging the batteries.

Sounds logical, but I have never experienced low tick overs on cold start with Yanmar, Cummins, Sabre and Volvos before.

Looks like I will live with it and thanks for the helpful replies.
 
A friend has Yanmar engines in his Broom 38 and I think possibly the same engines (are they 250 BHP ?) or similar so will ask him at the weekend if I see him.
I can’t say I have noticed this sort of thing with my Volvo Penta engines but they don’t have heater plugs .
 
if your engines are STE 24 valve versions they have heater elements in the inlet manifold controlled by a relay , when this is operating on cold start it draws about 60 amps until the engine warms up and then switches off automatically . To disprove Barrus theory disconnect the relay plug located on the top port side of the engine , that deactivates the relay and try your idle speed again . I have mine disconnected permanently as they are not needed with our climate . I am not sure but I think the DTE 12 valve version has the same arrangement . Sounds more like governor adjustment to me especially as you have just had them rebuilt and not noticed the fault before . They might settle down with a few hours on them , I would run them for a few hours and then reassess the situation .
 
I met the above mentioned Broom (and Yanmar 6LP) owner today and he does not recognise the variable tickover symptoms you describe.
 
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