Partially Blocked Exhaust Volvo 2003?

wragges

wragges

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www.minstercomputers.com
Hi All,

Anyone know what symptoms to expect in diagnosis of a partially blocked exhaust (elbow).

I have a Volvo 2003 that revs fine when out of gear (3200+rpm), but will only get to 2100 rpm in-gear. I originally suspected the prop, but this appears to be original and correct size for the boat.

The only tell-tails I have observed are: anti-syphon is a emitting a little more continuous flow than I would expect as "normal", and also the engine is very sluggish to start the first time each day...takes 20-30 seconds of turning over (and yes I do know the correct cold-start procedure).

No smoke to speak of (either hot/cold black/white). Good (but intermittant flow of water from exaust).

Have changed both fuel filters, given it nice clean/fresh diesel, Soltron etc. not sure what else is worth checking...am sort of thinking it might be the exhaust elbow but no real clues...any advice appreciated.

Cheers,
 
Steve,
the 2003 on our Duo is also sluggish to start from cold on first start of the day. I use the cold start procedure, but turn the engine over on decompression for about 5 secs, and then reset everything for cold start but with compression engaged. It still takes about 5 to 10 secs to get going even then. I suspect the valves need looking at, as I had the injectors serviced last winter, and they came up OK.

I think you may be right about the water/exhaust injection being a bit blocked. If you are getting more water from the piddler outlet, and less from the exhaust....may be time to have a look at the exhaust/injection pipe.

I now get less revs than before I fitted a water trap. Previously, and since launch in '86 (we bought her in '03) there had been a straight through exhaust - no water trap and no silencer. What a noise it made!! Now very little noise, but a bit down on top revs - although we rarely go flat out on the engine, usually about 2500.
 
Do you mean blocked for the exhaust gas or the cooling water? My 2001 had a build up of scale in the elbow reducing the diameter of the water inlet significantly. The effect was overheating of the engine at higher revs. The best improvement to starting came from reseating the valves and a new injector. You can easily check the valve timing.
 
I've had similar thing that turned out to be very small airleakages in the fuel system in the part between the fuel-feed pump and the three high-pressure pumps mounted on the side of the engine. It was resolved by renewing all the seals of the pipe fittings and the two rubber pipes between the three pumps.
The reason for this is that it is not uncommon to loosen these fuel lines to get the air out of the system, this however results in sealing rings becoming devective after a few times.

Hope this helps,

Arno
 
have you checked the lift pump strainer ?

lack of black smoke would suggest it is not getting excess fuel as previous post you may need to change washers in fuel lines as they can work harden over time
 
Possibilities

Blocked exhaust, but this is often accompanied by black smoke. Failure to clear exhaust is the same as a partially blocked inlet - poor breathing.

Air leak on suction side of fuel supply, but this is often characterised by uneven running - appearing to faulter or die then recovering.

Blocked fuel supply, fits your description well.

Gearbox / propshaft problem. Can you turn the shaft by hand with engine off, and with engine on bu in neutral?

Ancilliary problem. Very flat batteries can take a couple of hp if the alternator is big enough, though this is usually most apparent in making an engine lazy to get up to 1500 rpm where charging hits max.

Tend to favour looking at fuel supply for air leaks and filtration for blockage and pump for wear.
 
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