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I bought a Spanish 200 engine, complete and original some time ago with the intention of using it to learn more. I am fairly handy with a spanner and have done basic stuff on my lambretta, replace clutch, top-end, replace stator, etc etc. But never built an engine from a bare casing.
Stripped the engine I bought, had it cleaned, and fitted new seals and bearings etc, 12 volt stator and re-built the whole thing. Dropped the engine out of my sx150 and put the newly built engine in. Took a bit of starting but start it did and ran well, but within minutes started pouring out white smoke. Bollocks!! I must have damaged the drive side oil seal.
Stripped it all down and rebuilt it, started 2nd kick - excellent! Round the block and through the gears, all looking and sounding good. Then bloody white smoke again!!!

I'm clearly doing something wrong but don't understand what?? On reading up again the only thing I haven't done is use sealent on the halite washer. Is this absolutely necessary? Before I strip it and try for what will be the 3rd (and final) time, is there anything obvious I could be doing wrong and how can I spot what's wrong when I strip it?
Cheers steve

I have never ever used sealant on the washer/gasket in question and never had a drive side seal fail as a result. Something is wrong with the parts (no lead-in on crank lip) or the you're damaging the seal lip when fitting crank.

Although not related to this issue if you are still managing to turn the crank by hand (firm pressure by hand or light spanner use) after assembly of crank and mag housing, I have come across a number of halite washers being too thick and not allowing the drive side plate to seat correctly, which in turn causes the crank to lock up when the mag if fitted. Whilst this should not be related to drive side seal failure, it is something to watch out for.

Another issue is that I recently swapped out a crank on an otherwise fine motor (change of configuration) and found that the seal's spring had broken and was not doing its job of applying pressure to the seal. Frustratingly, this was the best seal (according to price and theory) that money could buy and had only been in the motor for a max of 2-3K miles.

Adam

Are you putting the seals in the right way round ?

Is it an old (oily) exhaust ?

Is the gearbox oil noticeably down ?

have you pressure tested it ?

have you ran it for 10 minutes or more ?

Thanks........

its a used Indian clubman that I got off eBay so could be oily inside, I did think of swapping that first before I strip again but don't hold out much hope.
No didn't do a leak test, would that show the problem?
Yep ran it for more than 10 mins but will try again now.
Not checked the oil but will do

Cheers

I also know a mate who stripped his motor twice because of billowing white smoke, which turned out to be an issue with the fuel that he had recently bought.

Adam

Just tried it again now, and the smokes there immediately so can't be crap burning in the exhaust which is still cool.

Pretty sure it's the seal, doesn't immediately die when I block the exhaust. I just can't figure out what I've done wrong.

I'll look carefully at the seal when I strip it, and use gasket sealant on the replacement.

(Fuels ok, no problem with the sx150 engine smoking when I mot'd it the other month)


Thanks

I'd leak test it before you strip it. The leak test should show if a seal is leaking. It will also show any air leaks which may not be an issue now but could be later. When leak testing squirt soapy water over the breather, this will show if the seals gone in the drive side.

Another "test" is to block the exhaust when running (hand and cloth) the engine should die but if there's a leak or seal gone it will still run......in theory

Stevepshipley wrote:
Pretty sure it's the seal, doesn't immediately die when I block the exhaust.

But it does die? How long does this take if so?

After about 5 -10 seconds on tickover

Could it STILL be the lubes I used when building it?

Sealant is not needed for this gasket but you can smear a little grease to hold it in place whilst fitting the retaining plate. Greasing of paper gaskets is advantage in a lot of instances ans helps a paper gasket to slide to find its best seating position.

Sealant really shouldn't be needed and I'd imagine that it is counter productive as far as getting any on the seal or bearing is concerned. Personally, I'd advise against it.

Adam

Hi Mate
Frustrating I know - I personally had a similar problem with an Indian engine and found the bearing retaining plate ( 4 pins with seal in) was distorted and not seating allowing oil to pass,thus white smoke.
Is plate an aluminium one if so dump at purchase a steel one. If steel check it is perfectly flat and seating correctly
Worth a check. - jono

are you renewing the drive seal after each strip?
also use a sealed for life drive side bearing, think they're 6305-2RS (might have the first 4 digits wrong)
are you impact driving the 4 screws in place too?

Might be a stupid suggestion but i will say it anyway have you checked your oil breather for a blackage.

Fiveo

sorry should have said blockage.

hullygully wrote:are you renewing the drive seal after each strip?
also use a sealed for life drive side bearing, think they're 6305-2RS (might have the first 4 digits wrong)
are you impact driving the 4 screws in place too?

If you're using a bearing with two seals in it, you must remove the seal on the chain side of the bearing so that it can be lubricated. You still have the seal on the crank side.

Just a thought and I have not noticed it in your post but which drive side seal type are you using? I always use Rolf seals and so far have not had an issue. I have a friend who had a similar issue when using viton seals - every time he fitted, the seal would fail - changed to a Rolf seal and no issue. it seems that the viton seals he was using were too hard and would 'catch' when fitting the crank causing immediate failure.

Cheers
humble

Last play today, checked breather all ok. Drained oil smoking stopped.
Looks like strip and re-build. I used Viton seals so will try Rolf
Just ordered bits to make a leak test kit, will test before I strip it then see what I can find.
Thanks very much all for your inputs, much appreciated
Cheers
Steve

Stevepshipley wrote: bloody white smoke again!!!
Before I strip it and try for what will be the 3rd (and final) time, is there anything obvious I could be doing wrong and how can I spot what's wrong when I strip it?
Cheers steve

one thing that hasn't been mentioned is contaminated petrol or 2 stroke oil ? I may be way off base but just thinking aloud. Your spark plug should tell you what is going on in your engine

With a water cooled 4 stroke if water gets combusted in the engine ,with say a leaking head gasket ,that always gives lots of white smoke .

Why not try run the engine on a seperate fuel supply from a plastic bottle or something and use new 2xstroke oil and fresh petrol .
Give the scoot a good long run to thoroughly burn any residues in the exhaust and see what happens.

^... by Adam_Winstone » Sun Jul 17, 2016 2:13 pm

I also know a mate who stripped his motor twice because of billowing white smoke, which turned out to be an issue with the fuel that he had recently bought.

Adam

... let's hope that he did pay attention to this comment as poor fuel, burning white, cost a mate £1000 before he changed the fuel and cured the issue.

The engine I took out ran clean on the fuel in the tank. However I'll try fresh tomorrow just to make sure.

Again, many thanks