028 WB Diagnosis

[Rocosil]

Hi,
I’m here (new) because, although I’ve owned one or more chain saws for about forty years, I’ve never fiddled with them beyond adjusting mixture and replacing mufflers, sprockets, chains, and bars; and I now need help with a Stihl 028 WB that has cut about 300 cords of firewood over a 26-year period and has, of late, gotten harder and harder to start. Once started, after twenty or more pulls, it is difficult to keep running at a low idle. Running at high speed it cuts fine. (More about this later.)

Having exhausted my limited store of skills, I took the saw to a repairman. He checked it out and claims that the saw is “low on base compression” due to a failing seal between, or a leak in, the crank case halves. He attributed the idling problem and the fact that the saw “wouldn’t pull” under load - something I hadn’t noticed myself - to this. He also said that the saw wasn’t worth repairing. Well, I’m foolish enough to consider words like that a challenge, so I stripped the saw down to crank case, cylinder head, and flywheel, and have been unable to find any visual evidence of a leaking seal or crank case. BTW, it was also pretty clear that the repairman had not had the saw apart - he probably just did a compression test. So, before I dismantle the thing further, my questions are:
1) Does the repairman’s story make sense ?
2) Does my suspicion that it could be worn rings make sense?
3) What else could account for the phenomena I’ve described?
4) Are there any on-line Stihl repair manuals and parts catalogs?

Thanks.

 

[Mad Professor]

Pull the muffler and have a look at the piston/cyl. If it looks O.K. get the saw pressure /vac. tested for leaking seals/impulse line/carb boot. Fix any air leaks then give it a ring job.

If piston/cyl are questionable you have to consider the overall condition of the saw and if you want to invest in piston/cyl assy. If you go this route get an assy for a 028 Super, it bolts on and has the biggest bore (46 mm).

 

[adkranger]

1) Does the repairman’s story make sense ?
Not to me, but who knows.......?

2) Does my suspicion that it could be worn rings make sense?
Maybe, test compression. Though if rings are shot I'd think you'd notice it in wood.

3) What else could account for the phenomena I’ve described?
Check carb, rebuild or clean as necessary. I would start with carb if it's hard to start and go from there. Rebuild kits are relatively cheap, myself I'd just tear it apart, clean well, throw in new kit and retune. Also check/replace fuel & impulse lines as necessary. If original, I'd just replace both of those too as they are cheap and will fail eventually. Might as well do it now while apart.

4) Are there any on-line Stihl repair manuals and parts catalogs?
IPLs (illustrated Parts List) are available as are Owner's Manuals, but alas no Service(I'd be interested in one as well, if I had be more than willing to share). PM me and I'll get ya the IPL

"Not worth fixing"..........hogwash, BS or whatever else you want to call. If saw is otherwise sound the 028 it well worth fixing and keep running indefinitely. Parts are available, it's a rugged design and reputation legendary. Keep us posted with your progress and find help here whenever needed.

Good luck.

 

[adkranger]

Hey just realized (again) that you're new here. If you want to PM me just click on my user name and choose send member PM in menu.

Send me a PM with your email addy and fire off an IPL.

 

[doc874]

Hi,
I’m here (new) because, although I’ve owned one or more chain saws for about forty years, I’ve never fiddled with them beyond adjusting mixture and replacing mufflers, sprockets, chains, and bars; and I now need help with a Stihl 028 WB that has cut about 300 cords of firewood over a 26-year period and has, of late, gotten harder and harder to start. Once started, after twenty or more pulls, it is difficult to keep running at a low idle. Running at high speed it cuts fine. (More about this later.)

Having exhausted my limited store of skills, I took the saw to a repairman. He checked it out and claims that the saw is “low on base compression” due to a failing seal between, or a leak in, the crank case halves. He attributed the idling problem and the fact that the saw “wouldn’t pull” under load - something I hadn’t noticed myself - to this. He also said that the saw wasn’t worth repairing. Well, I’m foolish enough to consider words like that a challenge, so I stripped the saw down to crank case, cylinder head, and flywheel, and have been unable to find any visual evidence of a leaking seal or crank case. BTW, it was also pretty clear that the repairman had not had the saw apart - he probably just did a compression test. So, before I dismantle the thing further, my questions are:
1) Does the repairman’s story make sense ?
2) Does my suspicion that it could be worn rings make sense?
3) What else could account for the phenomena I’ve described?
4) Are there any on-line Stihl repair manuals and parts catalogs?

Thanks.

As stated earlier "not worth repairing??" LOADS OF BS!! Even if the piston is scored, an aftermarket one would be well worth the money ( If the cylinder is ok or can be sanded lightly and honed) I just did my 028. These saws are great and hold-up very well. Most dealers will of course wish to sell you a new one and offer a trade-in-value on your old one ( They are just trying to stay alive in a competitive business.) Good you came here, there are enough people to help you totally rebuild your saw without you leaving your workshop. Have it pressure tested as stated and replace the oil seals if needed, usually its the clutch side one that goes first. If the pressure test is good replace the rings ( dependent on piston condition. ) it may be just as well to replace the piston ( check at Curt baileys here he has after market kits for cheap). Either way, let us know how you make out and don't let the saw go. Welcome to the site.:greenchainsaw:

 

[lesorubcheek]

He also said that the saw wasn’t worth repairing.

May not be worth what he would charge you to do the work, but its very likely worth fixing if you can do it yourself. I don't know what tools are available for ya, but I'd definitely do a compression test and a case vaccuum/pressure test. If there's a leak around the cylinder base, you'll know for sure. If not, you can go back and tell the guy he's full of it. Do some searching on here and you can find all kind of suggestions for making up a nice vaccuum/pressure test kit. Also plenty of reccomendations for good compression testers for saws.

Dan

 

[Rocosil]

Thanks, guys, for the input and the encouragement. I've rebuilt the engines, carbs, and transmissions of several old Volvos, so I should be able to tackle this. I should have thought of doing the compression test before I took the saw apart, but since the repair guy specifically said that the saw was low on "base compression" and mentioned failing seals, I'm assuming he did the standard cylinder compression test and found it to be o.k. I'll pull the flywheel and clutch to see if the crankshaft seals give me a clue, and I'll look further here for what I can find out about crank case compression and vacuum testing. What, BTW, would be acceptable compression values? My owners manual is, of course, silent on the subject.

Thanks again,

Bob

 

[Fish]

Do a search, your saw has, or had points, look there first, before you throw a lot of time and money at it.

Do a search, Fish/points/028/etc

I may be wrong................................................................

 

[Fish]

throw in a 030, in the search, you never know................................


You guys complete me...................................................................

well most of you.........................................................................

 

[Zodiac45]

Pull the muffler and have a look at the piston/cyl. If it looks O.K. get the saw pressure /vac. tested for leaking seals/impulse line/carb boot. Fix any air leaks then give it a ring job.

If piston/cyl are questionable you have to consider the overall condition of the saw and if you want to invest in piston/cyl assy. If you go this route get an assy for a 028 Super, it bolts on and has the biggest bore (46 mm).

+1 Do the leakdown, Vacume/Pressure If that's good. Piston and rings.

 

[Fish]

Yes, the puppet is likely right......................

 

[adkranger]

Thanks, guys, for the input and the encouragement. I've rebuilt the engines, carbs, and transmissions of several old Volvos, so I should be able to tackle this. I should have thought of doing the compression test before I took the saw apart, but since the repair guy specifically said that the saw was low on "base compression" and mentioned failing seals, I'm assuming he did the standard cylinder compression test and found it to be o.k. I'll pull the flywheel and clutch to see if the crankshaft seals give me a clue, and I'll look further here for what I can find out about crank case compression and vacuum testing. What, BTW, would be acceptable compression values? My owners manual is, of course, silent on the subject.

Thanks again,

Bob

Oh, it's started now. First you'll acquire the knowledge and ambition to repair your own saw next thing you know you'll be dumpster diving at your local saw dealers and picking up old saws at auctions/tag sales..........you'll be done for. Full blown CAD will be just around the corner, you'll feel the "need" to fill the 4, 6 or 12 saw plan and have at least two saws torn apart on your work bench at any given time. Run away now while you can...:hmm3grin2orange:





On a serious side, compression 155-165 very good, 145-150 mid-life, below 130 rebuild time, roughly anyways as everyone's compression guage seems to very a bit. Saws really are very simple animals, if you've rebuild Volvos you'll not encounter anything you can't handle here. Do some research here first using the search function, print out some of the more pertinent posts(like some guys' sweet vaccum tester setups and procedures). Lakeside for one has posted some really good info on vaccum/pressure testing crankcases, others too. When you get stuck, post again and someone will help you out.

Good luck.

 

[Fish]

And you might want to check the spark........................................

 

[Rocosil]

O.K., so far so good. Well, sort of. I gave all the parts a good cleaning yesterday, peeked through the exhaust and intake ports and saw a smooth piston without any discoloration and intact rings. I put the saw back together again to the point where I could do a compression test which gave me 150lbs dry and 155lbs with a few drops of light oil on the piston. That was the good part, now for the bad. I plugged the brass pulse nipple on the crankcase with 1/3 of a round toothpick to keep the dirt out. Between the washing with mineral spirits and blowing dry with compressed air, the toothpick-bit slipped all the way into the nipple. I tried to get it out with tweezers, but there wasn't enough sticking out to grab, and it slipped in further. Question: does that nipple fit into a straight, unobstructed hole in the crankcase, or does it go into some twisted passage? If a straight hole, I could twirl a tiny drill bit in there to grind up the wood. I did a little of that already, and with a hose I'm able to suck some air through, but I don't dare to clean it out further for fear of doing more damage. I'd just as soon avoid having to separate the crankcase halves to take a look at the situation in there.

I've been going through the archives here looking for the other information I need, i.e., how to do a crankcase compression/vacuum test, how to rebuild the carburetter, how to replace oils seals, how to pull flywheel and the clutch assembly. I'm confident it's all there, but I keep running into all sorts of other fascinating stuff, and that slows down my search.

I'm absolutely delighted I found this forum - great information and lots of kind, helpful people.

Cheers,

Bob

 

[adkranger]

That nipple for the impulse line is a direct shot into the crankcase(straight hole). You are going to want to get rid of that pick-piece and not into the crankcase. Worst case scenerio is to pull the jug off and slowly push that tooth pick piece until there's enough showing inside to grab with a pair of surgical forcepts, or fine needle nose pliers.

Jug removal not a big deal, plus it gives you an opportunity to give it a close inspection, thorough cleaning, polish up that exhaust port, clean up combustion chamber, etc.... You'll be able to get an up close and personal look at the piston.

Don't worry, we've all done things like this before.:censored:

Edit: just thought of something I've done in a similar situation. What about a decent sized sewing needle, try to work it into the pick piece w/o pushing it further in, see if you can generate enough friction needle-pick to overcome the pick-nipple friction, if you follow my "logic". Just a thought.

 

[Fish]

Push the little piece of wood on in, and don't worry about it, you are not working on the space shuttle, don't stick any metal in there though.

Have you even considered checking the spark/points???????????

You have good compression, but it has progressively become harder to start???? HHHMMMMMMMMM........................
If it was an air leak, it would act so. Have you even opened the carb??
You need to check the simple first..........Look inside the fuel filter, see if the foam insert is still in there.

Keep it simple......
Now that you have given a good bath in mineral spirits, you will probably have to clean and adjust the points anyway. ..........................

Does everyone have me on the "ignore" list?????
I will let it drop now, and not bother anymore............

 

[Rocosil]

Fish,
Got you: points, fuel pickup, carb and KISS. Makes sense - will do. Took the jug off and got the piece of wood out that way.

Thanks for the input.

Bob

 

[Fish]

Sorry, get kind of testy............... Several years back, Stihltech and Andy
came along, and when they did, they usually beat me to the correct diagnosis

So I never jumped in, because I didn't want to crimp their shorts, nor be
redundant. So I became the "arboristsite" ..........................

OK


"Silly boy"............................................

So I have no respect..................................................





But a dam good lookin, "SILLY BOY"!!!!!!!!!!!!!!!!!!!!!!!!!!!

But you new posters have to realize that I do not invent this poop, I actually
work on the junk you like talking about, for a living, but you have no way
of realizing this. The sad part is, if another member would actually log
on and agree with me, you might actually listen to me, but I guess not.

But I digress.....................................................................................

 

[mechaniacal]

I just installed an aftermarket coil/solid state ignition in my old 028wb.
Equivalent to Stihl Part #0000 400 1300

I could always get it to run and idle, but wouldn't always rev.
Sometimes feathering the throttle just right would get it to rev.
Looking back, I think it was more heat related. It had gradually gotten worse and the saw hasn't run to it's full potential in a long, long time.
It would run well cold and for small jobs it would be problem free. It would start to bog and act up after extended use. Then whatever repair I did would "fix it" because the saw would have a chance to cool. "cleaning" a perfectly clean carb would "fix it" and I'd think there must have been something in it. Bead blasting and re-gaping a slightly blackened plug would "fix it". Blowing out the intake screen with compressed air would "fix it". Adjusting the H/L settings was more effective when I had to walk from the woods to the house to get the screwdriver and less effective when I had brought the screwdriver out with the saw at the start of the job.

I never put all that together. This winter I decided to get to the bottom of it. Found this site. Pressure/ vac tested the case. Went over the saw. Finally I put a spark tester on it and found spark was intermitent. Based on advice here I went with the replacement coil rather than trying to clean and properly set the points. I just installed the new ignition and the saw seems to be running better than I ever remember. I was surprised to see how far in I had the idle speed screw to compensate. I could cut at the speed it was revving, where the clutch was not engaging the chain with the old ignition.

mech

 

[mechaniacal]

long-winded and a double post.

mech