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Reluctant to start - doesn't idle correctly

Guest plesbit

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Not sure anyone here will have seen one of these engines close up but anyway....

Volvo Penta AD41 - it's a little reluctant to start. There's no pre-heat, apparently that's normal for these, turn the key and for about 3-5 seconds all you get is the starter. Then the engine begins to splutter and you have about a further 10 secs of it slowly spluttering into life before it can run by itself. It then remains pretty lumpy for about another 20 seconds before it really becomes smooth. It's also pretty smokey at this stage. After a decent run the engine is smooth as you like but becomes quite smokey when left to idle for a bit. Tickover is stupidly high - I'd say around 1100-1200rpm. Something clearly is not right there. But what?

I was advised to expect an AD41 to start almost instantly which blatantly it doesn't. But a diesel with no pre-heat? How quickly is one of those ever likely to start when it hasn't run for a week? I was surprised at the smokiness, both on start up and on idling later on - but then it was blowing a F8, very misty, and with vicious driving rain. Potentially these conditions would make it difficult to judge the smokiness or otherwise of the exhaust?

Despite this, there's no doubt the engine delivers the punch it promises on the box.

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Well, it's a Volvo, it will smoke a bit even when warm, provided it's not too much then not an issue, the start problem is another matter, is the smoke on start a whitish grey or black, blue?. Could be anything from dragging a bit of air in to Injectors or pump (the idle speed is almost certainly pump related) and could be anything from something as simple as not returning fully to it's stop to more complex internal issues. Is there a film of unburned fuel on the water at ay time?

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The problem with the smoke is very hard to judge. Firstly, my colour vision is very poor, secondly it was blowing a horrendous gale with driving rain and significant mist. As you can imagine the air was very damp indeed and I don't know if this would make the problem seem worse than it really is. There is no doubt, for example, that the engines deliver the grunt you'd expect from them. I would say the smoke was mostly grey but it also looked slightly bluer than I get with Silver Dream - and she's not exactly shy of using oil. However, I haven't seen Silver Dream's engines running in such awful conditions for many months. Practically everything, including the crew and passengers, had a bluey grey colour cast to them in that light! It certainly wasn't black anyway. I didn't look for evidence of unburned fuel in the water but I doubt any would have been obvious in those conditions anyway. The boat is not moored in a marina but a creek with a quickly rising tide.

Injector issues were my first thought and another friend suggested the FIP would be involved with the incorrect tickover. Whenever people venture to suggest problems with an FIP I start to get nervous. The engine was revved repeatedly in neutral to see if it would settle back to its proper tickover but it did not.

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Having been based at Broom for while smoking engines were a hazard of life with some of the older models.

You would hear the engines cranking and then they would fire up with a huge cloud of White smoke which I was told by an owner was perfectly normal. Evidently Volvo fitted an exhaust break solenoid on elbow to try and keep smoking down, if that was keeping it down lord knows what it would be like without :o

I am pretty sure HLB on MBM forum has these fitted in his Princess 35 which he nicknamed 'Mucky farter' the smoke it exuded on start up is evidently legendary.

Smoke colour is a good start point but understand your problem; was anyone else with you that could differentiate colours? Or you could look at having an Oil analysis done.


Diesel engine exhausts should be clear with the possible exceptions of:

# Sudden acceleration or extra loading. The engine may give off a little black smoke for a second or two until it settles down.

# Idling or running under low loads. The fuel pump may have problems metering out the minute quantities of fuel needed, resulting in an uneven idle and a little smoke. Diesels should not be idled or run at low loads for prolonged periods, as they tend to carbon up. If the engine must be used for battery charging, calorifer heating at anchor or dockside, buy a high-output alternator to keep the time to a minimum and, if possible, switch in other loads (e.g. refrigeration) or put the engine in gear. Give the engine some work to do.

Generally, any other smoke is a sure sign of problems. The colour of the smoke is a useful guide to the source of the trouble.

Black Smoke

Black smoke results from inadequate combustion of the injected diesel. This can arise from a restricted air flow through the engine. (plugged air filter, defective turbocharger, or blocked exhaust);too much fuel injected (generally due to overloading-the governor responds by opening up the fuel rack and pumping in more fuel). Or improper fuel injection (an injector fails to atomise the fuel correctly, dribbles fuel into a cylinder after the main injection pulse, or injects to late).

Check the air filter first. If the engine has a turbocharger, check all the ducting for air tightness. Remove an inspection cover and check the compressor assembly for carbon build up. If you find build up, clean the assembly, making sure it spins freely with no binding. Open up the exhaust line for any kinks or other restrictions.

If the air flow is deemed adequate, what about overloading? Is a line wrapped around the propeller? Are you powering hard into a head wind. Has any extra load been placed on the engine recently, such as belt driven auxiliaries equipment, a high output alternator, or a new propeller?

In the case of faulty fuel injection, remove the defective injectors and send them in for servicing. Make no attempt to work on the injectors yourself.

Blue Smoke.

Blue smoke comes from burning oil. There are only a few paths by which oil can find its way into the combustion chambers-up past the piston rings; down valve stems; through defective turbocharger seals; and out of crankcase ventilators, where there is high crank case pressure as a result of defective piston rings.

White Smoke

White smoke is indicative of one or more cylinders misfiring, water or air in the fuel, or water in the cylinders (most likely from a blown head gasket or cracked cylinder head). If the smoke occurs on start up and at light loads but clears when the engine warms, it maybe due to condensation or water vapour formed in combustion and is acceptable, but then again one or more cylinders also may have a compression problem and be failing to reach ignition temperatures until the engine warms up. If the smoke develops during normal operating, generally accompanied by erratic misfiring, the engine is running out of diesel or has water in the fuel.


Most diesels run unevenly at idle speeds, even though not “missing†with a fair amount of knocking and clattering. This is normal. Under load however, the engine should run smoothly. Rhythmical misfiring indicates one or more cylinders missing all the time; erratic and random misfiring, a generalized engine problem. If the missing is more pronounced at high loads, the fuel filters are probably plugged; if it is accompanied with black smoke, the air filter is also likely to be plugged.

In the case of rhythmical misfiring, the offending cylinder(s) can be isolated by loosening the injector nuts in turn (with the engine running) until fuel spurts out. If the engine slows or changes its note, this cylinder is ok. If no change occurs (or no fuel comes out) this cylinder is missing. NOTE: Don’t do this with a Detroit Diesel; fuel will flood out

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Smoke colour is a good start point but understand your problem; was anyone else with you that could differentiate colours?

Sadly not. The owners were on deck completing the mooring. It was not really possible to look out the back as the canopy was down but whilst they were mooring up the side was off which afforded the opportunity to have a proper look around at the smoke. The boat is potentially a very good deal and I'd hate to walk away without a good reason but anything which involves the FIP makes me nervous as the costs can be very high indeed and without further information it's a big risk. However I'd expect any serious injector / FIP issues to manifest themselves in performance and as I said, she performed faultlessly so perhaps the smoke had more to do with the weather than anything else. The reluctant start and the high tickover, however, are a different matter. Really I'd like to go and have another look at her in decent weather and have a better chance to investigate these issues but with her based in Cornwall that doesn't seem feasible. I've even looked at the option of flying down to Exeter and hiring a car from there but the return flight would be a Monday afternoon and with no more annual leave to take that simply isn't possible so I'm pretty much out of options! :(

There are only three other diesel Sealine 285's that I can find. One is in the RoI, one in Northern Ireland and one in Scotland so compared to them even Cornwall is close! They seem to be like rocking horse dung and I've been looking out for one we could afford for over a year so it's only with the utmost reluctance I would walk away now having finally found one. Am I really going to have to start looking at paraffin burners? They aren't in short supply and there are several within a couple of hours drive but that really isn't a route I want to go down. Perhaps I should start stock piling fire extinguishers now....

I am open to suggestions. And whilst on the subject, what information could I expect from an oil analysis if I was to get one done? Could it help point any fingers with the smoke / slow start / high idling issues?

I don't suppose David wants an all expenses paid weekend in Cornwall? :lol:

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If it were October perhaps Simon :-D , frankly it would be a lot cheaper to invest a few quid with the local Volvo guys and get an inspection and report done, if you're serious then it will be money well spent whatever the result. I'm sure some of the Cornish denizens on MBM could point you to somebody good. An oil analysis will give some indication of wear state from the presence of suspended solids and any fuel in the lube.

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Yes good point. Engineers tests were originally on the agenda but got put to one side. We had them done with Silver Dream and they found both the fuel supply problems and the blown head gaskets so it was money well spent then too. However the method of testing was fairly crude - welly the engines as much as you can and see if they break. Well we've already done that with this one and there was an initial problem with one of the engines (it had been overfilled with oil). Some oil was removed and the engines thrashed again without issue. And, albeit briefly, they were again pushed to their limit on Saturday without incident so I'd want to be sure anyone we hire in Cornwall is going to be a bit more scientific about it because I don't think we'll learn anything if they simply repeat what was done in Brundall (by the Volvo dealer). After all, we've already done that ourselves.

I'll make some phone calls and maybe even make my way over to MBM. Not only will there be some Cornwall locals but there must be some that actually own some AD41's who can perhaps offer an owner's perspective on them. In the meantime if you have any other thoughts I am all ears....

[Edit to add - engine hours are around the 1000hr mark, so hardly worn at all]

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"Edit to add - engine hours are around the 1000hr mark, so hardly worn at all"

Engine hours are an indication of how many hours the engines have done, nothing more and have far less bearing on the actual engine condition that is often percieved.

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Engine hour meters are no indication of the state of the engine Simon, all they tell you is how many hours they've done, in fact worse than that, all they tell you is how many hours the meters read and often more is better. :naughty::naughty:

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Boss man at Marine Engineering Looe is Robert Newton, been in the business for years and very knowledgable.

Contact at Challanger is John Langan, also a good guy.

AD41's are known to be a little on the smokey side and as long as properly serviced they are fairly bullet proof but it definitely needs checking, the same block eventually put out 285hp.

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I have spoken to Adrian at Challenger Marine (thanks Perry for the link) - this particular engineer had already been recommended to me by the existing owner as he has worked on those engines in the past.

I discussed the issues I've outlined here and he said the following (paraphrased because I didn't completely understand all of it):

1. Apparently the AD41's come in various forms as there were some radical changes to some aspects of the fuel system during their life time. He didn't denote which variant these are and I failed to ask the question (though he didn't actually seem sure anyway). Some have pre-heat, some don't, some like a bit of throttle to start, others don't (depending on variant). They are all known for a smokey start up and generally are known for smoking at idle - a "bluish haze is very common" he said. Doubtless in the weather of Saturday evening any bluish haze would have looked even worse. But here's the scary bit - he would fully expect the AD41's to smoke more significantly at idle than the AQD32's in Silver Dream - gulp! They should be clear under load though (I didn't check).

2. The high speed idling is due to a corroded lever (on what I didn't catch). It could be fixed with about 20 mins work and the engine should idle normally. He doesn't think the FIP's have a problem.

3. He agrees that the injectors do need attention. He thinks that proper cleaning / replacement nozzles would cut the smokiness quite a bit. However the cost of getting this done would be around £700 - plus the labour to remove and refit them and probably plus VAT as well. Ouch.

4. Oil analysis would cost around £500 per engine. What??? I was expecting it to be about £40 (I'm sure someone on here told me that). So I am afraid that is out of the question.

He's going to get back to me with some idea of costs for engineers tests. I think progress may be being made so please keep the ideas coming....

Ooh - just seen Neil's response.... seems to back up what I am hearing from elsewhere. Neil, what it is it with Volvo's and smoke? Don't you lot know that smoking in public places is frowned on these days. :lol:

Further to that, I understand the engines have a lot in common with KAD42's - slight capacity difference in bore and stroke and no supercharger but largely the same engine otherwise.

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How much for Oil Analysis :o Must be a Volvo price.

I am sure there are Oil Analysis and Oil Analysis but probably no substitute for a competent Dealer inspection report.

From Insight (Steve Truss)


Oil Analysis Tests:

Engine oil analysis is not new and a lot of you may be using it to try and understand what is happening to your engine.

The system that has been developed and currently used by transport operators is now being made available to the leisure boat industry. In the past the oil analysis was used in more of a ‘knee jerk’ reaction, you took a sample and when you got the results back from the labs with all the different amounts of metals and pre set type comment, did you fully understand the information and implications, and have you really had value for money.

The way oil analysis is being driven now is extensively as a long term prediction tool. With the old adage of 'knowledge is power' the wear trends of your engine can be plotted and measured, feed in to this information on the amount of oil top up you are using along with the amounts of fuel being consumed a very detailed picture can be built up of the condition of what is a very expensive asset. With the pending changes in fuel costs this service could help towards covering the extra costs. 'How much of your fuel ends up in the engine sump' because of excessive idling or poor fuel injection.

If you instruct Insight Marine Surveys Ltd to carry out an oil analysis test on the vessels engine, it could highlight potential engine and equipment problems before any serious damage is done to the unit and provide added security to those purchasing a vessel.

Once I have taken the oil sample, the turn around time from receiving the sample to you obtaining your report should be 48 hours. This report can be e-mail posted.

Having an Oil Analysis Test can give you peace of mind.

Oil analysis can:

* Identify at early stages mechanical problems, which may in future cause engine or equipment damage and failure leaving you with a failed boat and expensive bills.

* Help with warranty claims.

* Provide added value to any boat sales by giving the clients engine condition on top of any service details.

* Oil Analysis may help prevent expensive repair bills.

The service Insight Marine Surveys Ltd is offering is set around taking an oil sample from the boat you are considering buying and then providing a detailed analysis, which will allow the owner to take remedial action before any damage takes place. The in-depth analysis identifies all the different metals and place them in groups to understand if there are bearings, piston and liners or valve gear problems. If the engine is repeatedly showing amounts of metals that are above average then action can be taken to avoid an expensive repair. A monitor on the oil additives and viscosity from the sample add to the information.

The data and information will be supplied in the form of a confidential report to the customer in the form of an e-mail or by post. The basic cost of a sample would be £90:00 this will include VAT and all handling.

The analysis will also show:

* The actual wear pattern of the equipment.

* The condition of the fuel injection equipment.

* How well the maintenance has been carried out.

* In a twin-engine set-up we can run a comparison between the two Installations.

In addition to preventing damage and expensive repairs by taking early action, a clean bill of health via oil analysis would also add value to any customer wanting to buy or sell a boat. A report maybe used to demonstrate that the boat has no long-term problems or any nasty surprises months after purchase.

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The basic cost of a sample would be £90:00 this will include VAT and all handling.

That's a bit more like it Perry - and I would certainly value anything Mr Truss has to say. But unfortunately I can't get him to do the sample so I would need to find someone else, though not someone charging £500. Scary stuff!

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  • 2 weeks later...

heres a cheat for you remove the injector pipes from the injectors pull them back to acess the injectors remove them from the cyl head taking care not to lose the copper washers that go on the ends now reconnect them back onto the injector pipes now taking care not to have anyones hands near the buisness end of the injectors as they can inject diesel through the skin if in close contact and crank the engine over as normal watching how they inject a fine mist is what you are looking for any poor ammounts or single jets are bad and meaning they need attention if they seem ok the problem is elsewhere

could be contaminated diesel disconnect the rubber fuel pipe wherever you can closest to the lift pump use a 5 litre fuel can and run a rubber fuel hose to the lift pump from the fuel can that you know has good clean fuel in it prime it through and try starting again see if theres any difference

im also guessing the fuel filter has been changed

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We looked at a few 305's with AD41's so I have done a bit of digging over on the big boys site.

Basically the comments back were that they are pretty much bullit proof but basic, they all smoke and are well known for it, the a's are the worst then Volvo had a couple of attempts at making it less on the b's and then the KAD 42s.

of the ones we looked at the smoke cleared in about 10 mins on the boats that had been used at sea a lot but never cleared on those that had been on the river all the time, remember these engines are pushing 20 years old so a major rebuild could be on the cards regardless of hours, it was one of the plus points we put to petrols in that they were much, much cheaper to replace if neccesary.

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