Hi, i have a 1962 longshaft Century Plus with clutch which came as a back-up to the Yanmar inboard diesel on my 20ft Colvic Fisher which i bought 2 years ago. The seagull has spent the last few years locked in a cupboard and rarely used so i recently decided to clean and service it.
I found the cylinder block was cracked so changed that and fitted a new base gasket, cylinder head gasket and stainless steel head bolts. I also checked and gapped the points, changed the plug, cleaned out the carb, drained and refilled the tank with fresh 10:1(unconverted - villiers carb has no.3 needle) and drained and refilled the gearbox with 140 oil.
My Problem??? When i started the engine (2nd pull) there was a steady drip of water from the head joint so i tried smearing some gasket sealant on the metal faces which appeared to do the trick. I then took the motor for a sea trial. The motor appears to pump plenty of water in neutral but as soon as i put it in gear the water flow drops right away and i get little flow even at full throttle and the motor gets hot rapidly. Is this likely to be the impellor broken ( if so why is it ok in neutral?) or the motor height not set right( although the water is above the pinch bolt but because of the design of the transom/auxilliary bracket the motor is at an angle). I am suspicious exhaust gases are leaking past the head gasket into the waterways, this would be more pronounced in gear when the engine is under load. The cylinder head was a bit pitted but i thought was serviceable(perhaps not), the gasket was new from a local chandlery but i was surprised because it was a lot thinner than the one that came off which unfortunately was damaged and not reusable. Please help as i have now put a fair bit of time and money into this and i am getting frustrated.
Als is it normal for the engine to leak oil from the top of the crankcase below the flywheel housing or is the bearing/seal caput?
Century cooling problems
Moderators: John@sos, charlesp, Charles uk, RickUK, Petergalileo
Hello there,
cooling problems are discussed at length on the FAQ page. apologies that you might not have been able to see it for a week or so as the site had problems. Have a read of the page, I bet the impellor is Ok, but the waterways are choked, especialy if there are cracks on the outside of the block....
Regards,
John
SOS
cooling problems are discussed at length on the FAQ page. apologies that you might not have been able to see it for a week or so as the site had problems. Have a read of the page, I bet the impellor is Ok, but the waterways are choked, especialy if there are cracks on the outside of the block....
Regards,
John
SOS
Hi, thanks for the reply.
Sorry i wasn't very clear but i swapped the cracked block for a good one i bought on ebay(£15) with good threads and clean waterways. I have blown through the water pipe to make sure it's clear and backflushed the re-assembled engine and i got good waterflow out of the intake slots. When i tried the engine on the auxilliary bracket on the back of my boat it started easy, ran well and pumped water steadily but once i put it in gear the water flow decreased to almost nothing and what did come out was very hot.
Sorry i wasn't very clear but i swapped the cracked block for a good one i bought on ebay(£15) with good threads and clean waterways. I have blown through the water pipe to make sure it's clear and backflushed the re-assembled engine and i got good waterflow out of the intake slots. When i tried the engine on the auxilliary bracket on the back of my boat it started easy, ran well and pumped water steadily but once i put it in gear the water flow decreased to almost nothing and what did come out was very hot.
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hi Copers.
Your question is what we in DK calls a good one ( hard to answer ).
You don't mension, if your propeller did a good job. I wonder if your driveshaft is defect, and allmost stop spinning when it has to turn the propellor, but I have no experience in that matter, on a BS, but it is easy to try, remove the cable from the sparkplug, and see if the motor turns when you turn the prop.
Otherwise I am sure you will be recieving other Ideas.
best regards
Your question is what we in DK calls a good one ( hard to answer ).
You don't mension, if your propeller did a good job. I wonder if your driveshaft is defect, and allmost stop spinning when it has to turn the propellor, but I have no experience in that matter, on a BS, but it is easy to try, remove the cable from the sparkplug, and see if the motor turns when you turn the prop.
Otherwise I am sure you will be recieving other Ideas.
best regards
Hello Copers,
The water slowing when in gear is odd, unless you are at very low throttle openings... Seagulls do not pump well at less than 1/4 throttle.
If the flow is good, then slows as the motor warms up it normally means a leaking head gasket, or worse, a cracked block into the bore... Try back flushing it with a hose and try again, it could just be a bit of rust stuck in the waterways...
The only other possiblity I can see is if the water intake and prop are shielded by the hull, and are not getting a fair flow of water, then, as in a tank, then the prop can interfere with the pump. Site the motor in clear water.
Let us know how you get on.
Regards,
John
SOS
The water slowing when in gear is odd, unless you are at very low throttle openings... Seagulls do not pump well at less than 1/4 throttle.
If the flow is good, then slows as the motor warms up it normally means a leaking head gasket, or worse, a cracked block into the bore... Try back flushing it with a hose and try again, it could just be a bit of rust stuck in the waterways...
The only other possiblity I can see is if the water intake and prop are shielded by the hull, and are not getting a fair flow of water, then, as in a tank, then the prop can interfere with the pump. Site the motor in clear water.
Let us know how you get on.
Regards,
John
SOS
Hi, thanks for the replies chaps.
I don't think there is a driveshaft problem but i will have a look, thankyou.
I have obtained another cylinder head and gasket for a small sum off ebay so i shall fit those and check the cylinder for cracks at the same time, and also backflush the system again.
Failing that i suppose the problem must be the impellor, which seems unlikely judging by this website, or the positioning of the engine in the water. The positioning isn't ideal and the engine isn't vertical but i'll see what i can do and perhaps try the engine on my mates smaller boat and see what happens.
What about the oil seeping from the crankcase top joint(underneath the flywheel) amongst a couple of other places, is that normal. I know the 10:1 mix is bound to leave oil residue in the exhaust , etc., but i expected the crankcase to be oiltight although as the engine seems to start and run ok apart from the cooling problems i guess there can't be much wrong.
I don't think there is a driveshaft problem but i will have a look, thankyou.
I have obtained another cylinder head and gasket for a small sum off ebay so i shall fit those and check the cylinder for cracks at the same time, and also backflush the system again.
Failing that i suppose the problem must be the impellor, which seems unlikely judging by this website, or the positioning of the engine in the water. The positioning isn't ideal and the engine isn't vertical but i'll see what i can do and perhaps try the engine on my mates smaller boat and see what happens.
What about the oil seeping from the crankcase top joint(underneath the flywheel) amongst a couple of other places, is that normal. I know the 10:1 mix is bound to leave oil residue in the exhaust , etc., but i expected the crankcase to be oiltight although as the engine seems to start and run ok apart from the cooling problems i guess there can't be much wrong.
Thanks john@sos, the way it's going i'll have changed the complete top end soon.
My replacement head and gasket arrived through the post and both were in excellent condition so i duly fitted them to my seagull century. I am now fairly confident the cylinder head is gas and water tight. I then tried the engine on the auxilliary bracket of my boat whilst having an evening cruise on the River Tamar. I have now sussed out that the engine is not pumping water in gear because it is not revving high enough , even on full throttle the engine is not revving high and i'm only getting a trickle of very hot water from the outlet. The engine revs freely and pumps plenty of water in neutral.
So why the loss of power in gear?? The seagull is attempting to push my 20ft colvic which is a fairly heavy displacement hull but i understand the seagull century should be able to cope but at a slow rate of knots. Surely if the boat was too big for the outboard the engine would still rev but speed would be very slow. I am able to turn the engine easily by hand whilst in gear so there can't be any transmission problems. I recently regapped the points so if i had set them incorrectly would that cause the engine to lose power under load? When i fitted the replacement barrel i noticed it was slightly different to the original - the ports were machined differently and the carburretor mounting was slightly higher but i just assumed the barrel was off an earlier or later model and didn't worry too much as it went straight on and the engine ran ok(in neutral). Are the barrels of the century 100s, plusses, etc., all interchangeable? I know the silver century block has the carburretor on the other side.
Assuming that the points and barrel are ok then i guess we're looking at poor compression . Any ideas would be much appreciated !!!
My replacement head and gasket arrived through the post and both were in excellent condition so i duly fitted them to my seagull century. I am now fairly confident the cylinder head is gas and water tight. I then tried the engine on the auxilliary bracket of my boat whilst having an evening cruise on the River Tamar. I have now sussed out that the engine is not pumping water in gear because it is not revving high enough , even on full throttle the engine is not revving high and i'm only getting a trickle of very hot water from the outlet. The engine revs freely and pumps plenty of water in neutral.
So why the loss of power in gear?? The seagull is attempting to push my 20ft colvic which is a fairly heavy displacement hull but i understand the seagull century should be able to cope but at a slow rate of knots. Surely if the boat was too big for the outboard the engine would still rev but speed would be very slow. I am able to turn the engine easily by hand whilst in gear so there can't be any transmission problems. I recently regapped the points so if i had set them incorrectly would that cause the engine to lose power under load? When i fitted the replacement barrel i noticed it was slightly different to the original - the ports were machined differently and the carburretor mounting was slightly higher but i just assumed the barrel was off an earlier or later model and didn't worry too much as it went straight on and the engine ran ok(in neutral). Are the barrels of the century 100s, plusses, etc., all interchangeable? I know the silver century block has the carburretor on the other side.
Assuming that the points and barrel are ok then i guess we're looking at poor compression . Any ideas would be much appreciated !!!
Hello Coper, the barrels were all slightly different over the years, but are interchangable. Cast by different foundries.... Some later ones had Amal 2 jet carbs and produced an extra .5 hp...
If the motor is having pronlems reving in gear the prop might be slightly too coarse a pitch, try taking the prop off and checking to see if all the blades are at the same angle. If over pitched it will slow the motor. You could even try shaving half an inch off the prop blades... the early Century plus's only had 4 blade props instead of the later 5 blade, because they produced slightly less power... Worth a thought. Spare props £10.00 S/H if you want to experiment.
Saegull cut the tips off the blades and sold them as 'Trolling' props !!
At the powerhead end, if the points are not right, the revs are effected, as it can retard the spark, if they are wrong. 20thou.
More things to play with!
Regards,
John
SOS
If the motor is having pronlems reving in gear the prop might be slightly too coarse a pitch, try taking the prop off and checking to see if all the blades are at the same angle. If over pitched it will slow the motor. You could even try shaving half an inch off the prop blades... the early Century plus's only had 4 blade props instead of the later 5 blade, because they produced slightly less power... Worth a thought. Spare props £10.00 S/H if you want to experiment.
Saegull cut the tips off the blades and sold them as 'Trolling' props !!
At the powerhead end, if the points are not right, the revs are effected, as it can retard the spark, if they are wrong. 20thou.
More things to play with!
Regards,
John
SOS
Hi John@sos, my century plus is a 1962 model apparently and has an earlier four bladed prop with CPC stamped on it, the blades all look to be in good order.
Unfortunately the engine came with the boat and i have never used it, neither did the previous owner, so i don't know if the engine was working ok before i changed the block, regapped the points , etc., but i'll keep playing and let you know if i sort it out or throw it over the side in frustration.
Unfortunately the engine came with the boat and i have never used it, neither did the previous owner, so i don't know if the engine was working ok before i changed the block, regapped the points , etc., but i'll keep playing and let you know if i sort it out or throw it over the side in frustration.