Engine Problem

[mickp]

My engine a Thorneycroft / BMC 1500 38Hp starts and runs very well and also delivers plenty of power to propel the boat. Problem is it chucks outs lots of white smoke ? Oil presssure and temperature all ok. Also got smoke coming from rocker cover. Can I run my engine continuously without damage or is there a problem that needs sorting ? Can any experts point me in the right direction to resolving this ?

 

[Buck]

Sounds like water is getting into the cylinder head, with liquid cooled engines this could be head gasket or warped head, get it sorted rapidly or risk catastophic failure.

Buck

Is more than one octopus, octopi or octopussies?

 

[HenryB]

Well I'm not an expert, nor do I know your engine but white smoke is water (steam) and as you also have smoke (is it white?) from the rocker box then it sounds like a cylinder gasket leak which is allowing water into the combustion chamber and also compressed gases into your sump and hence out of the rocker box.

If this is the case then you may also find that your sump oil contains water in suspension giving it a lighter colour and frothy look. If the sump oil confirms the problem then it is unwise to continue running the engine.

If the rocker box smoke is minimal and the sump oil is OK then the problem might simply be that there is a reduced flow of cooling water through the exhaust which is making it flow at higher than normal temperature, thus producing steam. In which case check that the sea water input filter is clear and that your impellor is sound, also the sea water pump belt is tight.

Hpe this helps,

Regards,

 

[mtb]

Re: different white smokes !!

Normaly its due to over injection of fuel ,could be a blocked nozzle on one of the injectors.
The fact that you mention white smoke from the rocker cover !!!
you see blow by gases that are passed through broken or worn rings dont normaly come out as white more a grey colour .Back pressure would show up if you pull the breather pipe of the side of the block then look for gases pumping out as you lightly rev the engine,one other point these breathers do get blocked so check its clear .
Steam well again its more steam than white smoke
I would get it compression tested before any thing else , also check the oil mind you I imagine the oil is ok or you would have said something re that.
I would not run it untill the actual fault is sorted because if the head gasket has gone you could end up causing a cracked head because of over heating.
Mick

http://homepage.ntlworld.com/boats
I want a big steel ex trawler / tug v/cheep or swap for tug

 

[Chris_Stannard]

It's a pity I don't know where you are, if you are near Cowes try Neil 07855640561, he is a very good machanic, works for himself so is very reasonable.

Good Luck

Chris Stannard

 

[jfkal]

Squids

 

[PeteMcK]

White?

Or very light blue? I wouldn't worry about a small amount of blow-by from the rocker cover. Light blue from the exhaust is unburnt/partially burnt fuel which could be down to something as simple as incorrect (retarded) injection timing or a dribbling injector. Alternatively, it could be the result of poor compression in one or more cylinders (fault in gasket or valves or pistons/rings) in which case it will probably run a bit rough. If the exhaust really is white, then it's only steam being produced due to insufficient flow in the sea-water feed. You might find your sea-water circuit has a leak on the suction side, or the pump impeller need replaced, inlet strainer blocked, heat exchanger tubes need cleaned and so on. As a quick check, disconnect the sea-water hose from the nozzle on the exhaust, spin the engine on the starter and watch: you should get a noticeable flow (rather than a trickle) within a few seconds. Finally, where's your exhaust? A large number of boats fitted with this engine have the exhaust under the transom (submerged when the stern sits down): it's inevitable that you're followed by a small cloud of steam with this arrangement!