Hydraulic Lock from 2 stoke oil

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Laurence
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Joined: Fri Aug 01, 2014 3:57 pm
Location: West Sussex

Hydraulic Lock from 2 stoke oil

Post by Laurence »

Hi Folks
It's been a few years since I have been on the forum but life just got in the way of bikes . Anyway I need some help and advice . I recently re commissioned my GT380a often being dried stored for around a year and a half due to house move etc. Anyway did all the usual prep before attempting to fire her up but got a nasty clunk when I kicked her over and noticed a spray of fluid from the centre cylinder head gasket.
I took out the centre cylinder crankshaft drain plug and it was literally full of neat 2 stroke oil . Fearing the worst (a bent Conrod ) I have taken the head and barrels off and luckily the centre piston has hairline cracks on the outside and underneath around the gudgeon pin supports but no noticeable damage to the Conrod. It looks like the piston took the brunt of it and luckily the head gasket seal gave way . My problem is how did that quantity of oil end up in the crankcase. I have checked the oil pump over and found a few issues the actuator leaver had not returned to the neutral position so was like the throttle was partially open . The spring was not returning the lever properly but have now sorted this and it seems to spring back ok well at least with the pump off the bike. Now the bike has always smoked quite a lot and I think (hope) I may have found the reason for this. The actuator shaft was not turned fully clockwise before the leaver was placed on which I understand means that at idle it was delivering maximum oil and at maximum throttle minimum oil :o .
So could these two things cause the oil to pool over time or is there something else that would have caused this ?
Normally the bike is only dry stored for about 5 months max .
One other question how do I tell what size piston to order the I removed is a Suzuki genuine and has the markings ART on the back of the skirt one side and what looks like 16 on the other ?
Any help or advice would be appreciated :)
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Laurence
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Joined: Fri Aug 01, 2014 3:57 pm
Location: West Sussex

Re: Hydraulic Lock from 2 stoke oil

Post by Laurence »

Some Photos
Centre conrod
Centre conrod
Piston damage
Piston damage
Piston damage
Piston damage
Oil pump hopefully sorted ?
Oil pump hopefully sorted ?
barney01
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Location: Prestatyn.Wales

Re: Hydraulic Lock from 2 stoke oil

Post by barney01 »

Hi
Firstly the oil pump arm only returns to zero every 65 revolutions of the engine so forcing it to off will damage it. This is why Suzuki put a cover on it to stop owners doing so. If you store the bike for any length of time it is advisable to empty the oil tank as oil can, and usually will, creep through the banjo's on the end of the oil pipes collecting in the crankcase. The damage is done when the piston is forced down onto the oil which has no escape. And the conrod bends under pressure. You were lucky it seems. The piston cracks are minor considering what has happened.
The piston crown should have the size on it i.e. 05 for first over. These can be hard to read if they are old and worn. The only other way is to measure it.
NO SMOKE .......NO POKE
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Laurence
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Joined: Fri Aug 01, 2014 3:57 pm
Location: West Sussex

Re: Hydraulic Lock from 2 stoke oil

Post by Laurence »

Hi Barney
Thanks for the information.
I was rotating the pump drive as if the engine was running as I was trying to reseat the spring and yes it did seem to free up , but your explanation makes it clear what really happened.
I will decoke the top of the piston to see if there are markings on it , as at the moment all I can see is the arrow indicating the front .
Yes it makes sense to drain the oil tank prior to a lay up , or if not at least check the crankshaft drain bolts before trying to start . I had thought about fitting an in line fuel tap in the oil line but I guess the danger there is that you forget about it after a winter lay up, so perhaps not a good idea .
Should I get new rings as well as the piston, gudgeon pin, circlips and of course new barrel and head gaskets ?
Cheers
Laurence
barney01
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Joined: Wed Sep 26, 2012 7:33 pm
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Re: Hydraulic Lock from 2 stoke oil

Post by barney01 »

Is the cylinder bore damaged ? You are right to replace everything. False economy not to. :D
I think if the piston has no number stamped on it at all, it is standard bore. See photo for mark location
This is a relevant read for you
http://suzukigt380j.blogspot.com/2012/0 ... .html?m=16
Attachments
This is a first ovee
This is a first ovee
NO SMOKE .......NO POKE
teazer
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Re: Hydraulic Lock from 2 stoke oil

Post by teazer »

Barney is correct. Oil seeps past the one way check vales to fill one or more crankcase chambers and that's all it takes. That would also explain the excess oil consumption and smoke.

He is also correct that the pump doesn't "close" all the time. Just kick it over a few times and the actuating arm should spring back to the fully closed position. The actuating arm is unlikely to 180 degrees out (well the arm is correct but the shaft may be 180 out), but that's unlikely. The easiest way to be sure is to pop the top off but you need to order a top gasket and I think that GT Reiner is one of the few people selling them. Check with Astrax and see if he supplies them.
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canaletto5
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Re: Hydraulic Lock from 2 stoke oil

Post by canaletto5 »

barney01 wrote: Mon Apr 19, 2021 5:27 pm Hi
Firstly the oil pump arm only returns to zero every 65 revolutions of the engine so forcing it to off will damage it. This is why Suzuki put a cover on it to stop owners doing so. If you store the bike for any length of time it is advisable to empty the oil tank as oil can, and usually will, creep through the banjo's on the end of the oil pipes collecting in the crankcase. The damage is done when the piston is forced down onto the oil which has no escape. And the conrod bends under pressure. You were lucky it seems. The piston cracks are minor considering what has happened.
The piston crown should have the size on it i.e. 05 for first over. These can be hard to read if they are old and worn. The only other way is to measure it.
If I'm laying up my bikes for any length of time, I pop the oil tank cover off and mark the oil level with a Sharpie. Never had a leak yet but it tells you straight away if you have.
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Laurence
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Location: West Sussex

Re: Hydraulic Lock from 2 stoke oil

Post by Laurence »

Hi Guys

Thanks for the feedback it's very much appreciated.

Cleaned piston crown up and there is no number so it must be a standard bore.
There does not seem to be any damage to the bore so that's good.
Barney Thanks for the link to that article .

Will try Reiner and Astrax for the pump top gasket as I have already had the top off.
Genuine head gaskets £35 each from Robinsons Foundry is a bit steep has anyone reused these with any success ?

Cheers
Laurence
barney01
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Joined: Wed Sep 26, 2012 7:33 pm
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Re: Hydraulic Lock from 2 stoke oil

Post by barney01 »

NO SMOKE .......NO POKE
Kettletimes3
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Re: Hydraulic Lock from 2 stoke oil

Post by Kettletimes3 »

Laurence wrote: Tue Apr 20, 2021 3:43 pm Hi Guys

Thanks for the feedback it's very much appreciated.

Cleaned piston crown up and there is no number so it must be a standard bore.
There does not seem to be any damage to the bore so that's good.
Barney Thanks for the link to that article .

Will try Reiner and Astrax for the pump top gasket as I have already had the top off.
Genuine head gaskets £35 each from Robinsons Foundry is a bit steep has anyone reused these with any success ?

Cheers
Laurence


That sounds cheap considering it’s a genuine gasket.
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