075 rebuild

[Joshua Tabora]

Hey everyone, I was holding out for a Husqvarna 3120 or a Stihl 880 for a while, but I've decided that the money just isn't there right now for a new powerhead. I'm trying to resurrect my Stihl 075 that failed while running an Alaskan mill. I didn't catch an airleak, and ended up scoring the OEM piston and cylinder. The saw still holds compression (less than 120 PSI) , and starts but I haven't tried to run it since I discovered the damage. I have some experience cleaning cylinders of aluminum transfer, and I still might try to salvage the OEM cylinder, but I don't want to risk having to work on the saw yet again and I've decided to try a complete rebuild.
I have a Cross Performance top end kit on the way, the HL supply gasket kit for the 075/076/TS760, a Tecomec crankshaft, new crank bearings, a new wrist pin needle bearing, and a Hutzl crank splitter on the way. I'm expecting to have everything within two weeks. I know many of these parts may be overkill, but I've had this saw apart too many times and the breakdowns have really put a dent into my milling morale and productivity. If I get into the saw and find that the OEM crank and bearings are ok, then hopefully I can just return the surplus aftermarket parts.

I have several questions going forward. Firstly, am I missing anything from the order that should be replaced? I thought to order an impulse line replacement, but don't know what kind of fuel line to source. I'm also on the fence about using a sealer on the crankcase. If I go that route, what sealer do you all recommend? Secondly, come time for reassembly, I plan to use the hot/cold method to drop the new bearings/crankshaft in. Are there any potential problems with this particular model that I should expect to run into? There seem to be a plethora of methods when it comes to installing the bearings and the crankshaft, and I need all the help I can get. How would you go about it?

 

[Ted Jenkins]

Since I am a long time motor cycle guy I have always used Yamabond. The hot and cold method works well. I have a 075, but it still runs OK. It is tough to send surplus items back to sender so it is best to keep all parts. There are tons of threads here on how to assemble every little detail. I do not think that you will be disappointed. Why not get a 070 for milling and possibly put a 090 cylinder since they are very inexpensive. Thanks

 

[alexcagle]

+1 Yamabond 4
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The OEM exhaust and intake gaskets are way less susceptible to loosening up down the road. "PM" me. I have a whole bunch of each in stock.
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The aftermarket crankcase gasket should be fine to install without any sealer. Just make sure to use a flat file lightly to remove any stubborn old gasket material. Don't get too agressive with a razor blade, you can gouge a surface, creating a potential leak. I'm not real sure about some of composition of the early gaskets, but if they were asbestos, try not to file them into a dust. Usually a green gasket indicates a safe "non-asbestos" material.
*
During removal, or final assembly, I recommend a spacer between the crank counterweights to aide in preventing a potential bent crankshaft. Not too tight, just enough for support from the stress of assembly.
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Check your throttle shaft for play. It is a common source of an unstable idle. There were two types used on Tillotson carbs, if you need to order one.
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I use red 660 loctite, or similar, on the exhaust flange screws. It helps keep them from coming loose. The exhaust heat will keep them from becoming un-removable.
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Unless your impulse hose has become brittle, it should be fine. An R3 hose from Stihl should be fine. Check that the port isn't clogged up while your in there.
Although rare, I've seen one or two get clogged before.
My two cents.....

 

[Ted Jenkins]

Well outlined Alex. Thanks

 

[Joshua Tabora]

+1 Yamabond 4
*
The OEM exhaust and intake gaskets are way less susceptible to loosening up down the road. "PM" me. I have a whole bunch of each in stock.
*
The aftermarket crankcase gasket should be fine to install without any sealer. Just make sure to use a flat file lightly to remove any stubborn old gasket material. Don't get too agressive with a razor blade, you can gouge a surface, creating a potential leak. I'm not real sure about some of composition of the early gaskets, but if they were asbestos, try not to file them into a dust. Usually a green gasket indicates a safe "non-asbestos" material.
*
During removal, or final assembly, I recommend a spacer between the crank counterweights to aide in preventing a potential bent crankshaft. Not too tight, just enough for support from the stress of assembly.
*
Check your throttle shaft for play. It is a common source of an unstable idle. There were two types used on Tillotson carbs, if you need to order one.
*
I use red 660 loctite, or similar, on the exhaust flange screws. It helps keep them from coming loose. The exhaust heat will keep them from becoming un-removable.
*
Unless your impulse hose has become brittle, it should be fine. An R3 hose from Stihl should be fine. Check that the port isn't clogged up while your in there.
Although rare, I've seen one or two get clogged before.
My two cents.....

Alex, thanks for the input. I've read some of your posts on the 075 family in the past and I'm grateful to have your advice. To be clear, are you generally endorsing yamabond, but saying that it isn't neccesary in this case? Also, should I shim the crankshaft counterweight, in addition to placing a spacer between them?

 

[ThackMan]

For what it’s worth this stuff is pretty awesome.

Genuine Toyota Fluid 00295-00103 Formed-in-Place Oil Pan Gasket - 3 oz. Tube https://www.amazon.com/dp/B000EDDTV0/ref=cm_sw_r_cp_api_i_0tcaDbSW561X9


Sent from my iPhone using Tapatalk

 

[alexcagle]

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Yamabond 4 is the bomb.
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No, just something between the counterweights to keep it from compressing any. Not both.

 

[Joshua Tabora]

Noticing a huge gradation in 075 bearing prices, from the farmertecs that I have ($10), with lil red barn bearings costing $35 and OEM coming in at $75 on EBay. Can I stick with the ones I have coming or should I bite the bullet and buy the OEM?

 

[Ted Jenkins]

Each OP has their own way of conducting their system. For me I almost always go with the cheaper route on all my saw equipment. For one to me important reason. One time I rebuilt a saw with the best of every thing and spent plenty of time to get every thing perfect. I was coming back from a project with my splitter in tow and several saws when it was getting dark. Very tired I unloaded most of my stuff and went to bed. During the night it snowed a couple of feet and a couple more the next day. It was a month latter I finally found the saw and yes it needed a full rebuild. Then I bought three pro saws with in a month one of them was stolen. Then I bought a $1,800 Stihl and had a newbie drop a tree on it with the second tank full of fuel. So my opinion is when possible buy what seems reasonable and hope you can wear every thing out. Thanks

 

[Mad Professor]

If you can salvage the OEM cylinder and find a quality piston I'd go with that. Chi-Com stuff you may spend a lot of time getting things to fit/work right.

Instead of a file for cleaning gasket surfaces use a large honing stone w/oil or kerosene. Surface will be smooth without gouges. Years ago I wrenched at a motorcycle dealership and that is the best way I found to get stuck gasket material off.

I'd pull it down to inspect the used OEM crank assy. Again I'd reuse OEM rather than Chi-Com stuff. Same with seals/gasket set if available

 

[Joshua Tabora]

If you can salvage the OEM cylinder and find a quality piston I'd go with that. Chi-Com stuff you may spend a lot of time getting things to fit/work right.

Instead of a file for cleaning gasket surfaces use a large honing stone w/oil or kerosene. Surface will be smooth without gouges. Years ago I wrenched at a motorcycle dealership and that is the best way I found to get stuck gasket material off.

I'd pull it down to inspect the used OEM crank assy. Again I'd reuse OEM rather than Chi-Com stuff. Same with seals/gasket set if available

I normally feel that way about the aftermarket stuff, but I've read good things about the cross performance kit specific to the 075. I definitely like the honing stone idea. The connecting rod looked fine the last time I had the saw apart, but I'm worried about the needle cage bearing being damaged by floating aluminum/ iron particles. The Tecomec cranks are Italian and supposedly as good as OEM quality. I've had the saw apart a bunch of times, and every time I go to run it, some other OEM piece is breaking, or rattling itself loose, or needs replaced. First it was the carb, then the clutch, then the decomp valve, then the oil seals . I use locktite and routinely service the saw, it just gets beat to hell pulling a mill. This is the last time I want to have this saw this far torn down, and I'm trying to make things as 'new' as possible, to ward off future repairs. Like I said, I'm still on the fence about the crank, though.

Each OP has their own way of conducting their system. For me I almost always go with the cheaper route on all my saw equipment. For one to me important reason. One time I rebuilt a saw with the best of every thing and spent plenty of time to get every thing perfect. I was coming back from a project with my splitter in tow and several saws when it was getting dark. Very tired I unloaded most of my stuff and went to bed. During the night it snowed a couple of feet and a couple more the next day. It was a month latter I finally found the saw and yes it needed a full rebuild. Then I bought three pro saws with in a month one of them was stolen. Then I bought a $1,800 Stihl and had a newbie drop a tree on it with the second tank full of fuel. So my opinion is when possible buy what seems reasonable and hope you can wear every thing out. Thanks

Definitely hear that. Sorry to hear about your misfortune! I just can't find $1000+ for a new 880 or 3120, and I have to make this one last until some time next year. I have a pile of board feet just sitting waiting to be milled, and I'm going to lose access to a good chunk of that if I keep my mill out of operation for that long. Some of it is very wide, walnut (48"+). I doubt I'll wear down even aftermarket bearings, but you never know, especially with the toll that milling takes on these saws. I'm into it about $250 with this repair, and I might try to get the magnesium powder coated if things work out right. May seem like an 'over-investment' but I definitely don't want to cut corners on something like bearings. I'd pay the difference in a heartbeat if it meant no more repairs!

 

[Mad Professor]

How bad is your P/C? Unless the cyl plating came off a little aluminum transfer is not going to trash the crank bearings. Pictures?

Yes your saw is old, but how long did those OEM parts last and why?

Are you sure the Tecomec crank is still made in Italy?

A couple years ago I was in contact with the Tilton/Total rep who used to be the USA importer for Tecomec. He said the P/C production was all now Chi-Com, and not the quality of the Italian production. Lil Red Barn said the same.

Their old P/C assys were beautiful and OEM quality. I have a spare for my 038M saws. Have a look at the quality of the casting, plating, and port chamfers. I don't see that in Chi-Com stuff unless things have gotten much better. Most you have to grind the ports if you don't want to hang a ring and casting/plating quality is fugly



there is a little roughness on the intake casting, but the chamfers are flawless

 

[Joshua Tabora]

How bad is your P/C? Unless the cyl plating came off a little aluminum transfer is not going to trash the crank bearings. Pictures?

Yes your saw is old, but how long did those OEM parts last and why?

Are you sure the Tecomec crank is still made in Italy?

A couple years ago I was in contact with the Tilton/Total rep who used to be the USA importer for Tecomec. He said the P/C production was all now Chi-Com, and not the quality of the Italian production. Lil Red Barn said the same.

Their old P/C assys were beautiful and OEM quality. I have a spare for my 038M saws. Have a look at the quality of the casting, plating, and port chamfers. I don't see that in Chi-Com stuff unless things have gotten much better. Most you have to grind the ports if you don't want to hang a ring and casting/plating quality is fugly

View attachment 740969 View attachment 740970 View attachment 740971

there is a little roughness on the intake casting, but the chamfers are flawless

Thank you for scrutinizing, it's always good to hear an opposing voice. I'm certain that the crank is Italian, as per Hlsupply's description below:

I do plan to inspect the OEM parts for wear, and I'll post my findings once I have everything apart. The cylinder is most likely usable, I've only looked at the piston via the exhaust ports. In addition, both the tapped holes for the muffler bolt were stripped when I got the saw, and I kind of boogered the helicoil job. They work ok now, but it isn't perfect. I'd consider repairing it, the decision was made due to the fact that I can drop in an aftermarket at the same price as an OEM piston, and that isn't even counting the time to clean the original cylinder. I'm mostly skeptical of the integrity of parts exposed to a lean running motor over a relatively long cut (7+ minutes).

 

[Mad Professor]

Thank you for scrutinizing, it's always good to hear an opposing voice. I'm certain that the crank is Italian, as per Hlsupply's description below:
View attachment 740974
I do plan to inspect the OEM parts for wear, and I'll post my findings once I have everything apart. The cylinder is most likely usable, I've only looked at the piston via the exhaust ports. In addition, both the tapped holes for the muffler bolt were stripped when I got the saw, and I kind of boogered the helicoil job. They work ok now, but it isn't perfect. I'd consider repairing it, the decision was made due to the fact that I can drop in an aftermarket at the same price as an OEM piston, and that isn't even counting the time to clean the original cylinder. I'm mostly skeptical of the integrity of parts exposed to a lean running motor over a relatively long cut (7+ minutes).

Lets see your P/C. If you can salvage the cylinder (nikasil don't really wear , as long as the plating is there) a OEM piston would be best.

Not sure about the helicoils, but installed properly they are stronger than aluminum threads.

Here is a picture of a 036 piston, the cylinder completely cleaned up.



It will give you something to do tonight while you watch the Bruins beat the Blues.........

P.S. how long might you spend fixing the port chamfers on the aftermarket P/C so you don't hang a ring?

 

[Joshua Tabora]

Lets see your P/C. If you can salvage the cylinder (nikasil don't really wear , as long as the plating is there) a OEM piston would be best.

Not sure about the helicoils, but installed properly they are stronger than aluminum threads.

Here is a picture of a 036 piston, the cylinder completely cleaned up.View attachment 740981



It will give you something to do tonight while you watch the Bruins beat the Blues.........

P.S. how long might you spend fixing the port chamfers on the aftermarket P/C so you don't hang a ring?

Just got the flywheel removal tool j. The mail and removed the flywheel and clutch. Can't seem to find the air leak. Am I plugged into the right line? I am using a vaccum tester and soapy water and looking for bubbles, with t
the exhaust and carb plugged with innertube.

 

[Mad Professor]

I think so. Is your intake/exhaust blocked off? Plugged the decomp valve?

 

[pioneerguy600]

You won`t get any bubbles pulling vac, you need to apply pressure to get bubbles with soapy water. All ports or holes to the engine must be plugged air tight, you can pull vac or apply pressure through the impulse nipple. The vac will suck in oil applied around the suspect areas,it appears you can only apply vac with that tool.

 

[Joshua Tabora]

Just got my case split. Can't seem to get the oiler assembly out. It looks gunked up with some kind of melted plastic, but the cap looked fully intact when I removed it. Also, any tips for removing the old oil seals?

 

[Joshua Tabora]

Is the flywheel bearing supposed to sit proud of the races of the crankcase? It isn't sitting flush against the snap ring, if that helps.