3 saws to repair, 2 Stihls & 1 Poulan

[Sub-arctic]

I'm looking to get 3 saws running that I kind of inherited, maintenance-wise anyway. I'm a mechanic, but I haven't messed with small
2 strokes much. I'm looking for some recommendations or pointers on where to get good information on working on these things......... videos, reading material (preferably on-line), or what ever else.

1 saw is a Stihl 025 that I know has had problems for many years. The owner took it to a shop at least a couple of times, it would run okay for a while and then start
having problems again. I tried to use it recently, it seemed to cut okay, but the longer I ran it, the less it would idle.

Another saw is a Stihl 023. I don't know any history on it. I tried to use it recently, I didn't even get it started.

The 3rd saw is a Poulan Pro PP4218AVX. I don't know the history on this one either. I tried to use it as well, it would start and run, but didn't cut worth a darn, and would quit after a few minutes. The chain seemed to be getting very little oil, if any. I did a little file work on the chain, I may not have gotten it very sharp. I will try to check the oil pump and passage ways on this one.
If the chain wasn't getting oil, would it bind up and make the engine quit? The chain didn't seem to be getting bound up.

Hopefully, you guys can point me to some good educational material. I'll start with cleaning the saws up and doing basics that I know I should do, like testing compression, spark, air an fuel filters, and whatever else I can think of, or find out about on my own.

Thanks,
Brett

 

[J D]

Start with compression test, or better yet pull mufflers & check cylinder & piston for scoring. If you use a tester make sure its suitable for small engines (short hose with schrader valve in the end). You need at least 120psi to run but really want +150psi.
Assuming C/P are good they probably all want new lines, fuel filter, carb cleaning out & possibly a carb kit. Sitting with stale/old/bad gas is the cause of an awful lot of issues. After that, if they don't tune & run right you need to be checking for air leaks... older saws often need the crank seals replaced. Clutch side usually goes first. Ideally a pressure/vac test would be done but you can also use a can of carb cleaner or something similar sprayed around the saw while idling to identify leaks

 

[Sub-arctic]

Start with compression test, or better yet pull mufflers & check cylinder & piston for scoring. If you use a tester make sure its suitable for small engines (short hose with schrader valve in the end). You need at least 120psi to run but really want +150psi.
Assuming C/P are good they probably all want new lines, fuel filter, carb cleaning out & possibly a carb kit. Sitting with stale/old/bad gas is the cause of an awful lot of issues. After that, if they don't tune & run right you need to be checking for air leaks... older saws often need the crank seals replaced. Clutch side usually goes first. Ideally a pressure/vac test would be done but you can also use a can of carb cleaner or something similar sprayed around the saw while idling to identify leaks

Thanks for the reply.
I did compression tests, but the only tester I have has an automotive type with an 8" hose that screws into the spark plug hole. A 12" hose plugs into that via a QD fitting. Schrader valve on the aluminum fitting that the gauge screws into. I got 100 on the 025, 110 on the 023, and 125 on the Poulan. I could see one score mark through the spark plug hole on the 025. The spark plug on the 025 was very black with carbon. The spark plug on the 023 was light gray, the spark plug on the Poulan was a darker brown. There was quite a bit of crud on the air filter of the 025. I wouldn't think enough to choke it much if at all, but maybe.
I cleaned out the oil passage on the Poulan with a piece of wire. I haven't figured out for sure where the oil pump is, but I'm guessing I have to remove the clutch and dig deeper to get to that. I might try running it again since I cleaned the passage.
That was as far as I got tonight.
I thought about old gas after I initially posted. That might explain some of the problems now, but at one time the 025 was used fairly regularly, and I think it always had problems.

 

[J D]

If you can do a compression test on a known good saw of a similar size that will give you an idea of what your tester should read on a saw that should run.
At this point in time I'd probably focus on the Poulan as that seems likely to be the most straightforward. I wouldn't go poking wire down the oil lines, that's more likely to do harm than good. Remove the pump & check the drive gear, blow air through the passages, clean the oil tank out with kero or diesel, & clean or replace the oil pickup strainer. The pumps are a pretty simple piston design but it doesn't take much to restrict the flow. More often than not it's just crud built up in the bar rail or blocking the oiler hole in the bar. Check the bar is correct for the saw too.
Personally I'd worry about the fuel side of things & getting the saw running properly (carb cleaned/kitted, fuel lines, filter, etc) before I got too involved in fixing the oiling

 

[Michael E]

Stihl 023 and 025 are basically the same saw, just with different displacement. Most parts should be interchangeable. That gives you the opportunity to exchange carburator, coil, etc. and see if that fixes the problem. I still recommend an systematical approach. Your two stroke engine needs fuel, spark, compression and impulse. Check those systematically.

I would also recommend to take off the exhaust first. If there is a spark arrestor, it may be plugged. A look into the engine will tell you a lot about the condition of piston and cylinder.

The Poulan is not worth a lot of money. From the economic side, it makes no sense to put a lot of time and money into it. It's still fun, though.

 

[Sub-arctic]

Stihl 023 and 025 are basically the same saw, just with different displacement. Most parts should be interchangeable. That gives you the opportunity to exchange carburator, coil, etc. and see if that fixes the problem. I still recommend an systematical approach. Your two stroke engine needs fuel, spark, compression and impulse. Check those systematically.

I would also recommend to take off the exhaust first. If there is a spark arrestor, it may be plugged. A look into the engine will tell you a lot about the condition of piston and cylinder.

The Poulan is not worth a lot of money. From the economic side, it makes no sense to put a lot of time and money into it. It's still fun, though.

I read that the 023 and 025 were built on the same chassis(?), and had thought a little about exchanging parts. I hadn't gotten too far on that thought yet though, I'm glad you suggested it. I did test the 023 for spark, and it looked like it was working pretty well to me. The air filter looked pretty clean, so it would seem to be a fuel problem. Last night I started trying to find out if it has a fuel pump. I'm guessing it does, maybe a diaphragm type? I hadn't found an answer yet. I supposed the carb could be gummed up with bad gas too. I have no idea how long it's been since it ran.
I had to look up impulse, I was not familiar with that term relating to engines. I infer from that, that it does have a diaphragm type fuel pump that runs off of impulse? I am familiar with those type of pumps.
I will remove the exhausts soon, and inspect what I can.
I've read that the Poulan is not a very good quality saw, but it has the best compression of the 3. I will put some time into it, if nothing else I will probably learn something from it.

 

[Sub-arctic]

If you can do a compression test on a known good saw of a similar size that will give you an idea of what your tester should read on a saw that should run.
At this point in time I'd probably focus on the Poulan as that seems likely to be the most straightforward. I wouldn't go poking wire down the oil lines, that's more likely to do harm than good. Remove the pump & check the drive gear, blow air through the passages, clean the oil tank out with kero or diesel, & clean or replace the oil pickup strainer. The pumps are a pretty simple piston design but it doesn't take much to restrict the flow. More often than not it's just crud built up in the bar rail or blocking the oiler hole in the bar. Check the bar is correct for the saw too.
Personally I'd worry about the fuel side of things & getting the saw running properly (carb cleaned/kitted, fuel lines, filter, etc) before I got too involved in fixing the oiling

I haven't found out for sure how to get to the oil pump. Do I need to remove the clutch?
Your point about getting the saw running right before worrying about oiling is a good one, but if I can test the oil pump early on, I would like to. If it's a diaphragm type, I would think I should be able to test it by blowing / sucking on the ports. I don't know what the availability of parts is around here, if I have to order parts, I might want to order everything at once.

 

[Sub-arctic]

If you can do a compression test on a known good saw of a similar size that will give you an idea of what your tester should read on a saw that should run.
At this point in time I'd probably focus on the Poulan as that seems likely to be the most straightforward. I wouldn't go poking wire down the oil lines, that's more likely to do harm than good. Remove the pump & check the drive gear, blow air through the passages, clean the oil tank out with kero or diesel, & clean or replace the oil pickup strainer. The pumps are a pretty simple piston design but it doesn't take much to restrict the flow. More often than not it's just crud built up in the bar rail or blocking the oiler hole in the bar. Check the bar is correct for the saw too.
Personally I'd worry about the fuel side of things & getting the saw running properly (carb cleaned/kitted, fuel lines, filter, etc) before I got too involved in fixing the oiling

I found another thread on this site that gave a description of how the oil pump works, and where it is, so I'm good on that. It also gave some other good information, such as priming the oil system.
I think I've got enough information to keep things going for now.

 

[cdahl383]

I'm relatively new to the chainsaw hobby as well. Here's what I've learned so far as I've picked up about 10 vintage saws and got 7 running so far (only 1 ran when I got it).

1.) Compression test (verify the model saw you have does not have an auto decompression feature as it will read low when it's fine)
2.) Pull muffler and inspect piston and cylinder. Should be clean, shiny, etc. If it's scored up bad, will need additional work.
3.) Verify the saw has spark (pull plug while on plug wire and ground out against muffler or other metal surface)
4.) Inspect fuel tank and clean if necessary (Berryman Chem Dip works great on metal tanks, not sure on plastic tanks)
5.) Inspect fuel lines and replace if necessary
6.) Inspect and/or replace fuel filter
7.) Clean air filter
8.) Replace spark plug if it looks bad
9.) If saw will not start, remove carburetor and order carb kit for specific model.
10.) Inspect oiler and verify it works properly

That's sort of what I do at first when I get a new saw. The first thing I do is clean the saw thoroughly though so I can see what I'm working with and to avoid dirt/sawdust from getting into places it shouldn't. Most of my saws that are healthy have around 130-150psi compression. Some are a little lower (110-120psi) but they still run great and the piston/cylinder look fine. The one saw I have that has a scored piston only has 60psi so it's clearly shot.

Another good idea is to run a pressure/vacuum test to verify the crank seals are good and there are no air leaks. I have yet to do this as I just bought a Mity-Vac kit and am still learning stuff.

 

[J D]

Carbs have an impulse driven fuel pump that uses a diaphragm & valve system to pump fuel. There's also a metering diaphragm. Sitting with old fuel can cause lots of different carb issues so pulling the carb apart to clean & evaluate it is probably your best starting point. Tom @Vintage Engine Repairs has some good youtube videos that would be worth a watch. As mentioned, the Poulan is probably the least valuable & sounds like it will be the most straightforward saw to get going so I'd be starting with that

 

[cdahl383]

I try to take the carb apart and lay out the parts in the order they came apart. Then replace with new parts from the carb kit in reverse order. I take pictures sometimes too just in case I forget something.

 

[ZeroJunk]

There are three 8 mm nuts that hold the muffler on. Take the muffler off and look at it with a flashlight.
If there are vertical scratches on the piston then the saw is not likely worth repair unless you are sentimental about it for some reason.

If the lateral tooling marks are clear then there is no problem there. Compression testers are of little use on small displacement engines. Waste of time really, unless you are trying to sell it to some sucker.

If the piston is clean, replace the fuel lines and buy a new carb.

Save you a bunch of time.

 

[Vintage Engine Repairs]

Carbs have an impulse driven fuel pump that uses a diaphragm & valve system to pump fuel. There's also a metering diaphragm. Sitting with old fuel can cause lots of different carb issues so pulling the carb apart to clean & evaluate it is probably your best starting point. Tom @Vintage Engine Repairs has some good youtube videos that would be worth a watch. As mentioned, the Poulan is probably the least valuable & sounds like it will be the most straightforward saw to get going so I'd be starting with that

Thanks for the shoutout JD!

 

[Sub-arctic]

Thanks for the replies. I think I've gotten some pretty good advice.

 

[stihltech]

When checking 10, 15, 20+ year old saws. the vacuum and pressure test is high on the list. These saws have set who knows how long with fuel in them. Seals dry out, sealant loses its its ability to seal, etc. Follow all that has been said here for diagnosis, but lack of the vacuum and pressure test has had many a person pulling out there hair when it won't run right.

 

[dav2no1]

I'm new too..and like you.. have mechanical skills, but just started to learn about saws. This forum has tons of experienced members with lots of great suggestions. I picked up an 024 from a friend and like you I'm in the beginning learning stages and parts gathering. Luckily I have a local dealer with any parts I need. I forgot a few things and will pick them up this weekend before I start to tear it apart.

I've found YouTube to be a great source. You can search anything. For example I also wasn't familiar with the impulse line. So I searched, "024 replace impulse line". It easier for me to see the parts and steps before diving in. I don't like surprises.

 

[Sub-arctic]

When checking 10, 15, 20+ year old saws. the vacuum and pressure test is high on the list. These saws have set who knows how long with fuel in them. Seals dry out, sealant loses its its ability to seal, etc. Follow all that has been said here for diagnosis, but lack of the vacuum and pressure test has had many a person pulling out there hair when it won't run right.

I had to look up vacuum and pressure tests, found a video that I thought was pretty good. A crankcase leak is something I hadn't considered. I also thought it was interesting that the guy had a hand operated tool that could either pressurize or pull a vacuum. I don't recall ever seeing one of those. I have one that only pulls vacuum, that's all I've ever seen. Thanks.

 

[dboyd351]

The Poulan is not worth a lot of money. From the economic side, it makes no sense to put a lot of time and money into it. It's still fun, though.

The poulan is not worth a lot of money but parts are likely both cheap and available. Stihl parts are very expensive - if you use OEM parts and you're having to replace things like the piston and cylinder, it's likely the parts are going to cost you more than the saw is worth.

It sounds like the Poulan is a lot closer to running right now, so for my money, I would start to learn on that instead of throwing a lot of expensive parts at the Stihls.

You have gotten some good advice here to get you started.

 

[Sub-arctic]

I cleaned the Poulan up, especially the bar oil passages. It's oiling now. I also turned the idle speed up a little bit. It seemed to be running okay, so I tried to cut some wood with it. It didn't cut worth a darn, but the chain looks to be in pretty bad shape to my untrained eye, so I ordered a chain.
The bar is discolored along the bottom, near the back. It obviously got hot. I suppose that bar is no good, or soon will be due to the temper being taken out of it?

 

[ZeroJunk]

I cleaned the Poulan up, especially the bar oil passages. It's oiling now. I also turned the idle speed up a little bit. It seemed to be running okay, so I tried to cut some wood with it. It didn't cut worth a darn, but the chain looks to be in pretty bad shape to my untrained eye, so I ordered a chain.
The bar is discolored along the bottom, near the back. It obviously got hot. I suppose that bar is no good, or soon will be due to the temper being taken out of it?

Flip it upside down.