Crankcase seal - 40 Plus

[dartmoor]

Hi, Haven't posted on here as I was Seagull free for a while - now like an addict in relapse I have bought a couple of 40's!

One is in really good nick and seems well looked after - starts and runs fine, but there is a weep of fuel from the join of the two halves of the crankcase. Checked the bolts - very tight. No visible damage either.

So, does the crankcase weep matter too much, or will it be terminal? I know from other engines, poor crankcase seal = doesn't start, as not enough compression to pull in fuel. But this seagull has no problem pulling in fuel - and starts completely normally?

Any ideas? Also sounds a tad more whiney than normal - its a 10:1 model - maybe it has been run too leanly in the past and worn the bearings a bit?

[Keith.P]

Definitely not terminal, but you would have to pull the motor apart to fix the problem and at the same time you could see what the condition is of the internal parts.
Its normally worn crank bushes that will course more of a problem with starting and running.
Its up to you if you wish to live with it or fix it, but its not a major problem.

[Stelios_Rjk]

Hello,

Well yes, as Keith said you better fix it.
Spanners out! What? Were you expecting to reenter the word of Seagulls without grease in the hands?

[dartmoor]

Definitely not terminal, but you would have to pull the motor apart to fix the problem and at the same time you could see what the condition is of the internal parts.
Its normally worn crank bushes that will course more of a problem with starting and running.
Its up to you if you wish to live with it or fix it, but its not a major problem.

Thanks for the reply. I have acquired two 40's - one looks very tatty - but when I did get it started, it sounds and runs great. The other one looks the part - cosmetically well looked after - but I think there is major wear there - untypically whiney, and the crankcase leak.

Probably what I will do is look for a complete powerhead and crankcase in one and do a swop over - as this one has all the signs of being very worn.

[headdownarseup]

hi dartmoor
when you were "testing" your motor were you running it in a bin. if yes (and maybe you had the prop still attached which won't do it many favours) the winey noises could be coming from the gearbox? just have a quick look to see if its got any oil in there? a "dry" gearbox will and can sound horrible, especially in a test bin! that's where your noise might be coming from! the powerhead does't usually give much trouble unless its really oosing a lot of oil from the crankcase which would suggest worn crank and/or crank bushes with a leak somewhere(usually out of the top crank bush but not uncommon from the bottom crank bush either)
first things first, make sure its got oil in the gearbox and report back. if its still noisey and whiney, then it might need a strip down. plenty of advice available on here.
regards jon

[Collector Inspector]

Yes

A whine is usually the gears down below and yes, in a bin the sound is amplified.

I might just mention that an old engine , any OLD engine or mechanical device has a "Song" when everything is correct. I think that is where the term "On Song" actually comes from regarding something "Humming Along".......................anyone else experienced that with old nicely running machinery?

It is very satisfying sound that just makes itself known to the trained ear. If you have actually rebuilt the thing it is an awesome feeling when it happens.

I can listen to the "Singing" of anything I have all day.

Silly Old Me.

B

[dartmoor]

hi dartmoor
when you were "testing" your motor were you running it in a bin. if yes (and maybe you had the prop still attached which won't do it many favours) the winey noises could be coming from the gearbox? just have a quick look to see if its got any oil in there? a "dry" gearbox will and can sound horrible, especially in a test bin! that's where your noise might be coming from! the powerhead does't usually give much trouble unless its really oosing a lot of oil from the crankcase which would suggest worn crank and/or crank bushes with a leak somewhere(usually out of the top crank bush but not uncommon from the bottom crank bush either)
first things first, make sure its got oil in the gearbox and report back. if its still noisey and whiney, then it might need a strip down. plenty of advice available on here.
regards jon

Sadly not the gearbox oil - I had checked that. Sounds very much like over worn bearings. The two stroke oil is green - so the leak of green fuel is coming from the crankcase join is very noticeable. You wipe it away with a tissue when its running, and more is immediately oozing out, and also from the join of the bottom of the crankcase to the leg. I guess it could be re-built - but easier just to get a complete swap on the powerhead and crankcase if I can find a good one? If the crankshaft has been badly worn, chances are someone has run it on not enough oil - and so rings and cylinder will probably also be worn.

[Collector Inspector]

"Probably Also"

Man Up and get into it!

Pics. We like pics.

B

[headdownarseup]

sounds like its time to get the spanners out?
re whiney gears, have you had the rear cover off yet to make sure its got the thrust washer fitted. good time to look at those gears as well. if you can see noticeable wear on the gears ie. not flat any more(should be slightly cone shaped if that makes sense) and without any teeth missing, then probably gears are worn.sometimes gearboxes need a little bit more of a "closer" fit to quieten them down. in otherwords the THICK thrust washer and a series of THINNER washers to set them up properly. worn bushes in the box wont help either.
good time to strip the crankcase apart also to sort out the leak. you probably dont need replacement crankcases yet unless there is a lot of for/aft movement in the crank itself. easiest to see when the magneto is removed.
what i do with the crankcase is this.
remove the cylinder by undoing the 2 bolts at the cylinder base. DONT REMOVE THE HEAD UNLESS YOU ABSOLUTLEY HAVE TO?
with the crankcase,con rod and piston as one assembly you will be able to see if there's any play in the crank bushes.
with the leak i would split the cases apart, remove the crank assembly and put to one side. next put the cases back together "empty" to see if you can see a gap between the faces. if there is a gap then carefully and gently "reface" both surfaces of the cases by rubbing them on a piece of wet and dry something like 800-1200 grit should work well. ideally you need a good flat surface to do this. on reassembly use a light smear of rtv silicone or similar on the joint surfaces. new base gasket with a little rtv on the cylinder base and crankcase end and put it together. with a bit of luck, no more leak.

or you could buy a workshop manual from john. these are a must if your going to play with these motors. they can explain things far better than i can and they've got loads of pictures which makes things easier.

jon

[Charles uk]

Only use RTV on the cylinder side of the crankcase / cylinder gasket, bolt it up medium tight, leave for 24 hours, undo & clean away all the RTV snots, oil the clean side of the gasket, then fully reassemble the powerhead, this way you only need cut or buy one of these gaskets!

[headdownarseup]

that's a neat little trick!
i'll have to try that next time.
easy to come apart as well.

j

[Hugz]

Haven't I read somewhere in the past that the factory used to use a metal punch and tap the metal either side of the leak thus stretching the metal to seal the problem. (Bit more than a tap I would imagine).

[dartmoor]

May all come down to price - I would think the cost of the new gasket, new rings and any other parts might exceed the cost of buying replacement power head/crank/crank case complete.

It does seem as is buying a complete engine from ebay is actually the cheapest way of sourcing parts, as the individual second hand parts seem to go for more in some cases! So much so, that I notice on ebay more and more engines being broken up to realise a better value in the individual parts. So I am tempted to get one that comes up locally and make one good engine out of two.

For example - most 40's on auctions rather than buy it nows seem to be fetching from £30 to £60 on average. Just a base plate seems to sell for £30.

[Stelios_Rjk]

A base plate is trying to sell for £30 I would say. New gasket why? OK the correct is to replace it but you could also anneal and reuse it. It also depends on the condition.
New rings, yes if they are worn enough. Measure the gap at first. But some honing in most cases increases the compression. Search on the forum about flex hone

search.php?keywords=flex+hone

In general it's a lot cheaper to get an engine than an engine in parts.

For me removing the head in an newly acquired engine is not an option. It's obligatory. You never know what's underneath!

Pics. We like pics.

Indeed!



Have fun
S

[headdownarseup]

hi dartmoor.
if the engine was running fairly well (albeit with a leak from the crankcase and whiney gears) before all this discussion of going to the expense of sourcing replacement blocks etc. just use what you've got. you'll be surprised just how easy these little motors are to fix! they are fairly tough little things and have stood the test of time (and owner abuse).
if you're that worried about the noisey box, i can sell you one CHEAP that's been overhauled.
the powerhead is really quite simple to sort out. refer to previous post for advice or pm if you get stuck.
i'm not a million miles away from you.

jon