Stihl 025 Could use some advice on replacing bearing and seals.

[Roy Hockett]

I have a Stihl 025 that had a bad idle so I tried a new carb. That did not work so I took it in to Stihl and they told me I had a leak on seals most likely. Took home and did a pressure check with a vac and psi. Bad. Leak on chain side. I have torn the unit down and have ordered new bearing and seals from Red barn on Ebay. At this time I am waiting on parts. The local Stihl parts store wanted about $24 for each bearing and each seal. Another one was $16 each for seals and $9. for each bearing. So thought I would go online instead.
My questions are several at this time since I have never done this before. Have watched a few videos on You Tube. I guess a product for high temp silicone would be Dirko and maybe something called Yamabond 4 to put on seals after seals are installed. I still have to get the old bearing off of the crankshaft I was going to try some dry ice at $1.25 lb from the grocery store to cool down the shaft so the bearing will slide off and off. Would I be better off sanding down the crank slightly to get bearing off and on I was wondering about lubing up the seals before installing them into the case over the shaft. I have checked this Yamabond 4 and it is a high temp silicone too. Does it matter which one I use? I wanted to put a seal something on top of seal edges also. Which one of this two products would be better to use for base gasket since the 025 has no gasket. Does anyone know where I can download a Stihl 025 repair manual? I appreciate any help you guys can supply. I am retired at 71 and a retired refrig mechanic but have always had rough time on carbs. Trying dry ice because have experience with liquid nitrogen temps, use to produce the stuff years ago.
thanks Roy H

 

[drf255]

It's been a while for me and the 025, but I believe you can pop the seals out and replace without splitting the case.

I'd personally split it and make sure it's done right.

Don't sand the crank. Use a 2 jaw puller to take the bearings off. You can carefully hit them with a propane torch to heat them and tap them off as well.

Then toss the crank in the freezer for an hour and heat the bearings up to 300* in a toaster oven. They will slip right on.

Dirko, Hondabond and yamabond will all work. Make sure you put some in the seal pockets before you push the seal into the head and also in the crankcase cap pockets.

 

[backhoelover]

There are two types of seal
1. Soft seal just pulling seals and replacing
2. Hard seal if you pull the sump and crank (complete tear down) give @ray benson a shout he can send u a service manual

 

[Totembear]

Put a very thin coat of sealant around where the seals sit in the case and top and bottom of the bases. The 025 is a clamshell engine. You dont want to put gobs of the stuff on there and have it all over the place and possibly blocking up an impulse line. The clamshell when it is tight naturally puts a clamp on the seals, the sealant is an insurance policy.

 

[ray benson]

Hi Roy, check your inbox for an ipl and service manual.

 

[Roy Hockett]

It's been a while for me and the 025, but I believe you can pop the seals out and replace without splitting the case.

I'd personally split it and make sure it's done right.

Don't sand the crank. Use a 2 jaw puller to take the bearings off. You can carefully hit them with a propane torch to heat them and tap them off as well.

Then toss the crank in the freezer for an hour and heat the bearings up to 300* in a toaster oven. They will slip right on.

Dirko, Hondabond and yamabond will all work. Make sure you put some in the seal pockets before you push the seal into the head and also in the crankcase cap pockets.

I was not planning on splitting the case but where I am finding an issue now is the oil unit. I need to put the cylinder together and have it inside the case with it bolted tight on the bottom. The issue is not sure how to get the oil unit out so I can tap in the seal on the chain side. I have not got the bearing yet so just waiting for mail. Issue I have taken the small screw out of the oil pump on the bottom but not sure how to get the little white oil pump out of the way or out of the case without breaking it. Any sugggestions?

Make sure you put some in the seal pockets before you push the seal into the head and also in the crankcase cap pockets.[/QUOTE]
What do you mean by the seal pockets and the crackcase cap pockets? Are you talking about the little seam that goes around the bottom cap of the cylinder on the flat surface? Hate to seem like a dummy on this one but could use a little more explanation of these pockets.
Thank you for you come back on this issue

 

[Totembear]

Some people leave the bottom half of the ckamshell in, me I pull the whole engine. If its like a 290 which I think it is, the back bar bolt has got to come out. Read the manual Ray sent you then it will all make sense. I think the oil pump lifts out if I remember correctly

 

[Roy Hockett]

There are two types of seal
1. Soft seal just pulling seals and replacing
2. Hard seal if you pull the sump and crank (complete tear down) give @ray benson a shout he can send u a service manual

It's been a while for me and the 025, but I believe you can pop the seals out and replace without splitting the case.

I'd personally split it and make sure it's done right.

Don't sand the crank. Use a 2 jaw puller to take the bearings off. You can carefully hit them with a propane torch to heat them and tap them off as well.

Then toss the crank in the freezer for an hour and heat the bearings up to 300* in a toaster oven. They will slip right on.

Dirko, Hondabond and yamabond will all work. Make sure you put some in the seal pockets before you push the seal into the head and also in the crankcase cap pockets.

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I am in the process of trying to find these products in Des Moines, Iowa and looks like most auto parts stores do not carry them so I may order them online. The heating up and freezer would be easier than the CO2 or dry ice.

How much do you put into the seal pockets or just a thin coat on the edges where the seal slides into the casting? I was going to add a little on the top edge after seal is in place also. Are you talking about add some into the area around the crank. Not sure what you mean as seal pocket?
Thank you for the help on this project.
Roy Hockett

 

[HarleyT]

I was not planning on splitting the case

Huhhhh?

 

[Roy Hockett]

Huhhhh?

What do you mean by a double taper? I took the case off in one piece. Why is it necessary to split it up?

Thank you
Roy Hockett

 

[HarleyT]

Are you suggesting that you can split the plastic crankcase/tanks?

 

[HarleyT]

Just trying to figure out how you can replace the bearings by not removing and splitting the "block". This is a clamshell type saw, the plastic crankcase is one piece.

 

[HarleyT]

Just a difference in phraseology............

 

[ericm979]

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I am in the process of trying to find these products in Des Moines, Iowa and looks like most auto parts stores do not carry them so I may order them online. The heating up and freezer would be easier than the CO2 or dry ice.

How much do you put into the seal pockets or just a thin coat on the edges where the seal slides into the casting? I was going to add a little on the top edge after seal is in place also. Are you talking about add some into the area around the crank. Not sure what you mean as seal pocket?
Thank you for the help on this project.
Roy Hockett

You can get Yamabond at a Yamaha dealer. Yamabond #4 is the stuff to use for two stroke cases. I have used it for many two stroke motorcycle engines and have used #4 and #5 to make vintage Triumphs (that normally leak like a sieve) oil tight. Make sure the surfaces you use it on are completely clean of oil. Yamabond does not stick to oily surfaces. I use carb cleaner to get the oil off and then alcohol or acetone to get the carb cleaner residue off.

If you're replacing the bearing(s) anyhow you can pull them off with a puller. I prefer three jaw pullers if I can get one on the part. If you are using temperature to make it easier, heat the bearing to get it off the crank. Heating expands the bearing and even though there is good heat transfer between the crank and bearing the bearing will expand more.

Do not sand the crank. Sealant glopped on the outside of anything just makes a mess. It's not effective for sealing. If the seals are a tight fit in the case they don't need sealant but a small smear on the outer rim is insurance. Don't use a lot of sealant on the surfaces. If it oozes out on the outside it's oozing out on the inside. That stuff will break off and go through the motor. It may just go out the exhaust if you are lucky or it may go into a bearing and damage it.

 

[TheTone]

If you take the engine out you don't need to fool with the oil pump. It's less work to take the engine out and remove the pan than to try and replace the seals with the engine in, and they'll work better too. Clamshells are easy to rebuild, and when you have it apart, you can check and clean the other components as well, such as crank bearings, rod bearings, and rings. Also, it's not uncommon to have air leaks in the flat mating surfaces of the pan and cylinder, especially on an abused saw, even on clamshells with separate pan bolts and housing bolts.

 

[Totembear]

Read the manual Ray sent you. It will clear up most of your questions. that's what they are meant for. Pictures tell a lot.

 

[Roy Hockett]

You can get Yamabond at a Yamaha dealer. Yamabond #4 is the stuff to use for two stroke cases. I have used it for many two stroke motorcycle engines and have used #4 and #5 to make vintage Triumphs (that normally leak like a sieve) oil tight. Make sure the surfaces you use it on are completely clean of oil. Yamabond does not stick to oily surfaces. I use carb cleaner to get the oil off and then alcohol or acetone to get the carb cleaner residue off.

If you're replacing the bearing(s) anyhow you can pull them off with a puller. I prefer three jaw pullers if I can get one on the part. If you are using temperature to make it easier, heat the bearing to get it off the crank. Heating expands the bearing and even though there is good heat transfer between the crank and bearing the bearing will expand more.

Do not sand the crank. Sealant glopped on the outside of anything just makes a mess. It's not effective for sealing. If the seals are a tight fit in the case they don't need sealant but a small smear on the outer rim is insurance. Don't use a lot of sealant on the surfaces. If it oozes out on the outside it's oozing out on the inside. That stuff will break off and go through the motor. It may just go out the exhaust if you are lucky or it may go into a bearing and damage it.

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I went up and got Hondabond 4 at a local Honda shop verse of waiting for Ebay or Amazon to deliever. Still waiting for bearing and seals to arrive.
I will try the heat or temperature approach method. I have a few pullers so will see how that works out. Not going to start till parts are all here. I will take your advice on the seal sealant. I though a thin coat might be ok but will at least give it a small outer coat anyway. I saw a few guys on You Tube sanding shafts but thought it might be questionable. Thank you for the advice on this.
Roy Hockett

 

[Roy Hockett]

If you take the engine out you don't need to fool with the oil pump. It's less work to take the engine out and remove the pan than to try and replace the seals with the engine in, and they'll work better too. Clamshells are easy to rebuild, and when you have it apart, you can check and clean the other components as well, such as crank bearings, rod bearings, and rings. Also, it's not uncommon to have air leaks in the flat mating surfaces of the pan and cylinder, especially on an abused saw, even on clamshells with separate pan bolts and housing bolts.

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"]If you take the engine out you don't need to fool with the oil pump

I have the total cylinder out. I guess I need to go through the manual carefully. It looks like I can put in the bearing and then fasten in the cylinder or motor to the base of the case with the long bolts. But were I am getting confused is I did not want to install seals and not have the long bolts attaching through the plastic saw case. Logically it looks like I need to install bearing then attach the motor to the case itself. After the cylinder is attached tight into the saw case, then I can install seals. But the oil pump would be in the way for the chain side. I need to look at the manual and go through it in detail.

Harley T indicted I have to split the case up but it is one piece now. Not sure why the case has to be split up. I will try and take some picture tomorrow and try to find out how to up load them. You guys understand these 025 more and this is my first time of tearing down a chainsaw.
thanks for being patient with this old guy.
Roy H

 

[Roy Hockett]

You can get Yamabond at a Yamaha dealer. Yamabond #4 is the stuff to use for two stroke cases. I have used it for many two stroke motorcycle engines and have used #4 and #5 to make vintage Triumphs (that normally leak like a sieve) oil tight. Make sure the surfaces you use it on are completely clean of oil. Yamabond does not stick to oily surfaces. I use carb cleaner to get the oil off and then alcohol or acetone to get the carb cleaner residue off.

If you're replacing the bearing(s) anyhow you can pull them off with a puller. I prefer three jaw pullers if I can get one on the part. If you are using temperature to make it easier, heat the bearing to get it off the crank. Heating expands the bearing and even though there is good heat transfer between the crank and bearing the bearing will expand more.

Do not sand the crank. Sealant glopped on the outside of anything just makes a mess. It's not effective for sealing. If the seals are a tight fit in the case they don't need sealant but a small smear on the outer rim is insurance. Don't use a lot of sealant on the surfaces. If it oozes out on the outside it's oozing out on the inside. That stuff will break off and go through the motor. It may just go out the exhaust if you are lucky or it may go into a bearing and damage it.

 

[Roy Hockett]

I know I have messed up with the photo downloads. What I am not understanding is the statement of not having to remove oiler to get the seals in after the motor is in place and bolted together with the Stihl case. I might be able to work around the oiler but I do not think it is a good idea. Need to get a full circle or socket to tap seal evenly into place. This is for chain side of case only. Clutch side is no problem. Hope the picture help a little. Concerned about breaking the oiler but I am going to check out manual for details.
Thank you guys for all your help.
Roy Hockett