GY6 50CC 4 stroke crankshaft seal replacement

[adomas]

Hi, guys!

I'm trying to replace gy6 50cc crankshaft oil seal (engine side), but I faced a problem
I've made a tool (30 mm diameter and 1 mm thickness metal tube with washer). I wanted to use this tool to evenly press the seal into the seat using the pulley nut. But when I've tried to press in seal the inner lip and the spring turned to the other side... I don't know why it happened... I know that other people are using this technique successfully... Before pressing the seal I've applied a thin layer of RTV sealant around the outer edge and a thin layer of lithium grease on the inner edge and back of the seal...

Do you have any ideas why it happened? Is the tube wall too thin or what's the problem?

Here are some photos of the case drive.google.com/drive/folders/1AiU053ScvG2EERv01gkA8iGbusOL4x_7?usp=drive_link

 

[Sparky]

On the last, photo the wall of your tool looks very thin an sharp.
Therefore i think, when you apply pressure to your tool, the tube wall acts more like a knife then a press.

 

[adomas]

On the last photo the wall of your tool looks very thin an sharp.
Therefore i think, when you apply pressure to your tool, the tube wall acts more like a knife then a press.

I know that wall is quite thin... But to find 30 mm diameter and thick wall tube is really hard. Maybe do you know any special tools that would help?

 

[Sparky]

Maybe you could spread the pressure from the tube with help of a thick washer with the outer diameter of the seal and adapt the inner diameter to the crank axle.

 

[adomas]

Maybe you could spread the pressure from the tube with help of a thick washer with the outer diameter of the seal and adapt the inner diameter to the crank axle.

Do you mean to weld a washer on the and of the tube (which presses the seal)? Let's say if seal is 30x19.8 so to find washer exact messurements and weld onto end of the tube? Do u think that tube walls are too thin?

 

[adomas]

Hello guys,

I have update. I tried to improve my diy tool by cutting it shorter and superglued old oil seal on the end. I've tried to install maybe 4 seals, but all the time seal's inner lip flips into outside...

2. What size crankshaft seal has to be on engine side? According Kymco dealership they told me 19.8x30x5, but as many of them as I try to install inner lip flips to the outside. I have no idea how tight seal should be around crankshaft sleeve (where inner lip of seal goes)… Should I be able to push it on with my fingers?
3. What tool are you guys using to install crankshaft oil seal? It’s quite tricky, because there is around 10 cm length crankshaft in the middle sticking out… I have made tool (30 mm outside diameter metal tube with superglued seal on the end. I was trying to use crankshaft nut to put even pressure and to drive seal in the place (of course I’ve lubed seal’s inner lip and packed with lithium grease where spring is to keep it in the place).

Thanks for info!

 

[C-Row]

lithium grease is not slippery enough for that soft inner lip (even a bit "sticky"): i suggest you use some fresh motor oil, same that goes into the motor.
edit: i also think that your old seal is too soft to press with. i'd look for an old bearing of that size. (just the outer ring)

 

[WEBRacing]

I don't really understand why you even made a tool. You can pretty much just push them in by hand. And if that doesn't work completely, i just lay on the old seal, and tap it in with the handle of a hammer or something. (just make sure you do it evenly, of course) It really doesn't take that much force. You certainly don't have to "press" it in.

You mean you are packing it full of grease? Or only the surface thats in contact with the crank? You can use a little grease on the surface that's in contact with the crank, apart from that, do not use grease or oil. (or sealant, its a SEAL it doesn't need sealant, come on.)

Just put it in by hand for the most part. If it doesn't go any further you can use the tool.

 

[C-Row]

good point:
packed full of grease it might even create back pressure!

 

[adomas]

I don't really understand why you even made a tool. You can pretty much just push them in by hand. And if that doesn't work completely, i just lay on the old seal, and tap it in with the handle of a hammer or something. (just make sure you do it evenly, of course) It really doesn't take that much force. You certainly don't have to "press" it in.

You mean you are packing it full of grease? Or only the surface thats in contact with the crank? You can use a little grease on the surface that's in contact with the crank, apart from that, do not use grease or oil. (or sealant, its a SEAL it doesn't need sealant, come on.)

Just put it in by hand for the most part. If it doesn't go any further you can use the tool.

I've seen in the video they said that if I put grease on the spring it will stay better in the place and won't pop out... Also, I've put some sealer on the crankcase oil seal seat side, because I've made there some scratches (marked spots red on the screenshot)... I'm definitely not able to push seal with a hand or tap it in with a hammer (I make sure it is aligned properly), but the inner lip flips outside... I wrote email to dealership, they suggested for me to heat up engine block and freeze seal... Not sure if it is a good idea... What do you think guys?

Post automatically merged: 24 July 2023

good point:
packed full of grease it might even create back pressure!

I've seen in the video they said that if I put grease on the spring it will stay better in the place and won't pop out... Don't you think that it is good idea?

 

[WEBRacing]

Putting in seals really shouldn't be this difficult.

The spring is not going to pop out. No I don't think its a good idea, it's completely unnecessary. (and will contaminate the engine oil)

Ahhh look. Now we are getting a better image. Clean up the edge of the case, it looks like there are huge lips on the edges. I don't even really understand how you managed to do that, but I have the feeling it has something to do with the tool.

The surface behind that looks pretty clean. A little ding on the side isn't going to make it leak. But if you have damage on the whole edge, then yeah, i would probably put in some sealant too.

 

[C-Row]

WHAT have you done to it? if the damage on the axle will be where the seal sits, it will not seal for very long! the damage will eat the seal inner lip.
the hole in the crank case should be cleaned/resurfaced, preferably without getting filings or grains of sandpaper in the bearing behind there! (would try waterproof, very fine)

 

[adomas]

Putting in seals really shouldn't be this difficult.

The spring is not going to pop out. No I don't think its a good idea, it's completely unnecessary. (and will contaminate the engine oil)

Ahhh look. Now we are getting a better image. Clean up the edge of the case, it looks like there are huge lips on the edges. I don't even really understand how you managed to do that, but I have the feeling it has something to do with the tool.

The surface behind that looks pretty clean. A little ding on the side isn't going to make it leak. But if you have damage on the whole edge, then yeah, i would probably put in some sealant too.

This picture is not actual my crankshaft, I just took it from online and marked spots where I have scratches...

WHAT have you done to it? if the damage on the axle will be where the seal sits, it will not seal for very long! the damage will eat the seal inner lip.
the hole in the crank case should be cleaned/resurfaced, preferably without getting filings or grains of sandpaper in the bearing behind there! (would try waterproof, very fine)

Yes crankshaft has some scratches... Is there any replacement sleeves or something like that? Or do I have then to replace the whole crankshaft?...

 

[C-Row]

This picture is not actual my crankshaft, I just took it from online and marked spots where I have scratches...

Yes crankshaft has some scratches... Is there any replacement sleeves or something like that? Or do I have then to replace the whole crankshaft?...

i've heard of sleeves (my second moped ever, a 1973 Kreidler Florett, had some pit corrosion on the axle where a seal didn't quite seal, luckily this was on an axle that barely moved (pedal axle) and i sought for them back in the nineties, but was not able to find any.. hope you will succeed..

 

[adomas]

i've heard of sleeves (my second moped ever, a 1973 Kreidler Florett, had some pit corrosion on the axle where a seal didn't quite seal, luckily this was on an axle that barely moved (pedal axle) and i sought for them back in the nineties, but was not able to find any.. hope you will succeed..

Thanks anyway

 

[C-Row]

Thanks anyway

something entirely different: i recently had to cut an impeller off the driveshaft of one of my outboards (was rusted on) and knicked the driveshaft, exactly where an oil seal is.. i filled the cut with a drop of superglue and i don't see any big oil leaks in the water when i use that old outboard .. there are two seals opposite in this case: one to keep oil in (where the cut is) and one to keep water out of the gearcase.. the final test will be after this season, if water comes into the gearcase, i'll have to find a sleeve or replace the drive shaft.