Novice Request

[Big_Al]

Hello All,
Would appreciate some feedback on a problem with one of my Volvo AQD 40's Just purchased boat and noticed smoke coming out of breather filter when running at cruising revs (3000). Local mechanic suggested head off and possible new lining/piston required Compression test on survey was good, engines have just been serviced. Any comments/advice appreciated.

Also to push my luck, can anyone tell me how to enter data on an old Nasa Video Navtex?

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[BarryH]

More than likely blow-by. How many hours on the engine also what type of running has it had over its life. Has it pottered on a river or had a blast out at sea.
Not a serious serious complaint, its just showing its age. On the downside, it will build up sludgey deposits quicker than would be normal, so ger into a habit of changing the oil on a regular basis.

Why would the mechanic suggest a new liner/piston. If the comp test showed reasonable results then the wear is not that bad that it needs doing. At the worst its a rebore and pistons/rings at best it could just be a hone and new rings. Is it a wet liner block, Don't think it is but I've not had a head off one.

Does the engine use oil to noticeably drop the level n the dipstick. Is the exhaust very smokey with a blue tinge to it. Are the crank case breathers clear. Just a few things to check. On the compression test were all the results with the same area or was one or two drastically different from the others.

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[Will_M]

Good morning Big_Al.........

The old 40's do smoke alittle from the breather filters, if the compression results were good then you may not have too much to worry about.

A better test, seeing as you have had a compression test, would be a cylinder leakage test.

An example of this test. I forget what the engines, I think they were 60's maybe 61's, but the compression test indicated all was ok however the reality of the engine running suggested otherwise.

So cyl leak test done, basically involves use of small compressor and various fittings etc, in effect you pump air in & see were it exits.

For these engines the test was confirming compression test results all ok until one, and then some more, cylinders checked and the dipstick blew out of the side of engine!!!!

Result = Needing new set of piston rings..

Dont know nothing about an old Nasa Video Navtex!

 

[Dave_Snelson]

Reading Barry's post below, he makes a very good point re compression testing. Not only do you need readings within manufacturers spec, but all cyls should be within 5% of each other at worst. Large differences = trouble.

<hr width=100% size=1>Madoc Yacht Club
<A target="_blank" HREF=http://www.madocyachtclub.co.uk>http://www.madocyachtclub.co.uk</A>

 

[tcm]

Hiya Al.

I agree with others.

The smoke genrally seen as is a bit of the burnt gases sneaking past the piston rings and then getting pumped out of the breather. If it's only a bit, then not too much worry. As barry says, if the comp test was ok and if the compressions matched mostly - it's okay. Of course, a rebore would solve it and make it sparkly new (how much?) but then so might just a good cleanout and the rings are gummy from lack of use, specially if the boat has not been used much.

If the rebore sounds a bit £££ i woulkd consider changing the oil - and flushing the thing with flushing oil - Pela pumps allow you to change oil yourself, then refil with flushing oil (or any cheapy thin engine oil will do really) run it for a ten mins or so, not much above tickover, then empty that. Then change filter and refill with new oil of correct spec. There are piston ring degumming additives and if you are a chemical addict like me you could lob some of that in. Praps lob it in to start if oil change is recent.



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[Big_Al]

Thanks for the advice. I feel much better knowing (probably!!) that the condition of "Heavy Breathing" isn't terminal. Compression tests were all between 380-390. Engines approx. 1600hours, both start/run sweet as a nut. Type of use unknown, last few years apparently on Windermere. Both engines have had very little use recently. On start up smoke is blue/grey clearing to very slight blue/grey smoke. Oil pressure 70psi at 2000 revs. Will flush out system as advised although oil is only a few weeks old. (who knows when changed previously) Haven't run long enough to notice drop in oil level.

Can rings/honing be done without removing engines?

Also, anyone recommend any good mechanics in the SW?

On a social note, I'm in Dartmouth couple of w/e's per month if anyone local wants to meet up.

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[itsonlymoney]

If it's been on Windermere it probably has the "I am going to ruin all your boating fun" virus, and presumably is having a technical breakdown in anticipation of being forced to do 10mph. Having retained a degree of its facultys it upsticked and beggerd off to more fun destinations (as will lots of others no doubt and see what that does to local economy) give it time to sort it's head out.

Not bitter or twisted about impending doom on the last remaining haven for power boats Ian

<hr width=100% size=1>I'd rather have a bad day boatin, than a good day workin ! ! !

 

[BarryH]

Regarding the sticky rings bit. Good point to use a bit of oilio addative. Best one that I've found, and works, is Wynns hydraulic valve and tappit stuff. Dunno what it does, dunno how it does it, but it does exactly as it says on the bottle. Cost is about 4 quid a bottle. One bottle will treat upto 8 ltrs of oil.

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[Plan_B]

Hi Al

We're in Torbay. If you want a dealer service try Marine Engineering Looe at Galmpton (Dartside) 01803-844777. or Darthaven Marina 01803-752242 both are Volvo dealers. We use Darthaven. Engineer costs about £35 per hour.

Everyones a bit busy now though - winterising, repairs etc.

Hope this helps.

Dave D

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