Craftsman 3.7/Poulan 3700 Cylinder and Ring Replacement

[GBertolet]

Trying a rebuild on my Craftsman 3.7 from the mid 1980's. 358.354831 w/18 inch bar. Very low compression, tore it down, and found the cylinder was scored badly. Piston does not look too good either. I am in the market for a cylinder/piston combo. I might have a couple of leads. If anyone has any, please let me know. Unfortunately they are all used parts. I love this saw. Unfortunately they are not made like this anymore.

I noticed that there are no clips holding the wrist pin in place. Looks like it may be a press fit, on bearings. Can this wrist pin be practically removed without tearing the crankcase apart to remove the crankshaft?

Here are two pictures of the bad news. Any tips on rebuilding this would be appreciated.

 

[Stevetheboatguy]

There are a few ways to remove the piston pin. On the 3.4 & 3.7 I usually heat the small end of the rod with a butane torch and the pin slides right out.


Steven

 

[GBertolet]

Do the needle bearings come out with the pin, or are they stay with the piston? I do see that a tool set is available to remove the wrist pin, but I can't see spending $30 for a one time use. I am hoping to remove the pin without removing the crankshaft.

 

[Stevetheboatguy]

The bearings stay in the piston.

No need to pull the crank out of the bottom end.


Steven

 

[GBertolet]

So the journal of the connecting rod is the main impediment to getting the pin out. If I then heat that journal up with a propane touch, expanding it slightly, the pin should come out with minimal effort, leaving the bearings still in the piston. Correct?

 

[Stevetheboatguy]

So the journal of the connecting rod is the main impediment to getting the pin out. If I then heat that journal up with a propane touch, expanding it slightly, the pin should come out with minimal effort, leaving the bearings still in the piston. Correct?

Bingo.



Steven

 

[legdelimber]

If I'm not losing my mind (iffy matter there...), I thought one of our sponsors was working up a top end for this series of the Poulans.
Just can't recall who it was. argh.
Anyone else remeber it?

 

[Stevetheboatguy]

Possibly @Duke Thieroff ?


Steven

 

[GBertolet]

I got the wrist pin out. I heated the connecting rod, flipped the saw over on it's side, supported the piston with a block of wood, and drove the pin out. It didn't come out that easy, but once I got it moving, all was well. I was ready to buy a cylinder and piston from a parted out saw, to get this project moving. If you have a forum sponsor that has what I need, I will consider it. Let me know, soon.

 

[Lightning Performance]

If your interested in whole 3.7 Craftsmen or one with a smashed rear handle PM me.
I don't think those new Duke kits are on the market yet.

 

[Duke Thieroff]

I got the wrist pin out. I heated the connecting rod, flipped the saw over on it's side, supported the piston with a block of wood, and drove the pin out. It didn't come out that easy, but once I got it moving, all was well. I was ready to buy a cylinder and piston from a parted out saw, to get this project moving. If you have a forum sponsor that has what I need, I will consider it. Let me know, soon.

 

[Duke Thieroff]

If your interested in whole 3.7 Craftsmen or one with a smashed rear handle PM me.
I don't think those new Duke kits are on the market yet.

Yep---haven't been moving on it at all lately....

 

[Dub11]

Yep---haven't been moving on it at all lately....

I got a minty 3800 that could use one.

 

[GBertolet]

I have located 2 potential replacement cylinder/piston assemblies. One Poulan assembly, that the seller claims to have had 150 lbs compression on, for $50 + shipping, and the other, a Poulan cylinder for $25 + shipping, adding a Lil Red Barn piston for 35 + shipping. Photo's of both cylinders look good, it's just the matter of the pistons, new vs used. Any experience with the Lil Red Barn pistons?

 

[fossil]

Trying a rebuild on my Craftsman 3.7 from the mid 1980's. 358.354831 w/18 inch bar. Very low compression, tore it down, and found the cylinder was scored badly. Piston does not look too good either. I am in the market for a cylinder/piston combo. I might have a couple of leads. If anyone has any, please let me know. Unfortunately they are all used parts. I love this saw. Unfortunately they are not made like this anymore.

I noticed that there are no clips holding the wrist pin in place. Looks like it may be a press fit, on bearings. Can this wrist pin be practically removed without tearing the crankcase apart to remove the crankshaft?

Here are two pictures of the bad news. Any tips on rebuilding this would be appreciated. View attachment 255712 View attachment 255713

That's a 3800 top end on your saw. You'll like the 3700 top end better once you get it. The 3400 and 3800 have a bare cylinder bore and a chrome plated piston and thick cast iron rings. The 3700 and 4000 have a plated cylinder and bare piston with thin rings.

I've attached a service manual for that series of saws. and a pic of the different rings in the pistons.

 

[GBertolet]

Thank you, that manual will really come in handy! What about the Lil Red Barn piston. It is a small ring. Would that make it a better choice? Here are my current options.

https://www.ebay.com/itm/Poulan-3700-Craftsman-3-7-48mm-Piston-and-Cylinder/283970581287?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20131231084308%26meid%3D63dab6f854104858bd1db321c5e7cd9f%26pid%3D100010%26rk%3D5%26rkt%3D12%26sd%3D224060899824%26itm%3D283970581287%26pmt%3D0%26noa%3D1%26pg%3D2047675%26algv%3DDefaultOrganic%26brand%3DPoulan&_trksid=p2047675.c100010.m2109


https://www.ebay.com/itm/Craftsman-3-4-3-7-Chainsaw-Poulan-3400-3700-3800-Chainsaw-Engine-Cylinder/224060899824?_trkparms=aid=1110006&algo=HOMESPLICE.SIM&ao=1&asc=20131231084308&meid=1ec7ba94acb747db9f390d369d244bea&pid=100010&rk=2&rkt=12&sd=192828103501&itm=224060899824&pmt=0&noa=1&pg=2047675&algv=DefaultOrganic&brand=Poulan&_trksid=p2047675.c100010.m2109

https://www.ebay.com/itm/POULAN-370...264642?hash=item2a53113b42:g:aO0AAOSwjVVViHcc

 

[fossil]

I have located 2 potential replacement cylinder/piston assemblies. One Poulan assembly, that the seller claims to have had 150 lbs compression on, for $50 + shipping, and the other, a Poulan cylinder for $25 + shipping, adding a Lil Red Barn piston for 35 + shipping. Photo's of both cylinders look good, it's just the matter of the pistons, new vs used. Any experience with the Lil Red Barn pistons?

Someone on here tried a red barn piston and the wrist pin was not a press fit. I believed they used the old pin but it was for a 3400 which uses a plated piston and it was bare AL. The saw didn't last long. I don't think they are paying attention to what they're selling.

If I were you I would choose the used OEM unit if your budget allows.

There were very few red 3.7 Craftsman saws with 3800 top ends. Most of them were grey.

 

[fossil]

Thank you, that manual will really come in handy! What about the Lil Red Barn piston. It is a small ring. Would that make it a better choice? Here are my current options.

https://www.ebay.com/itm/Poulan-3700-Craftsman-3-7-48mm-Piston-and-Cylinder/283970581287?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20131231084308%26meid%3D63dab6f854104858bd1db321c5e7cd9f%26pid%3D100010%26rk%3D5%26rkt%3D12%26sd%3D224060899824%26itm%3D283970581287%26pmt%3D0%26noa%3D1%26pg%3D2047675%26algv%3DDefaultOrganic%26brand%3DPoulan&_trksid=p2047675.c100010.m2109


https://www.ebay.com/itm/Craftsman-3-4-3-7-Chainsaw-Poulan-3400-3700-3800-Chainsaw-Engine-Cylinder/224060899824?_trkparms=aid=1110006&algo=HOMESPLICE.SIM&ao=1&asc=20131231084308&meid=1ec7ba94acb747db9f390d369d244bea&pid=100010&rk=2&rkt=12&sd=192828103501&itm=224060899824&pmt=0&noa=1&pg=2047675&algv=DefaultOrganic&brand=Poulan&_trksid=p2047675.c100010.m2109

https://www.ebay.com/itm/POULAN-370...264642?hash=item2a53113b42:g:aO0AAOSwjVVViHcc

The complete one for $50 (SOLD now) is a 3800 P&C. If you bought it it's a good price.

The second one, cylinder only, doesn't state what cylinder it is. It might be a 3400 cylinder which would be a big step down as far as performance goes.

Ask the guy what the bore is on the cylinder without the piston. He can measure it with calipers.

3400 1.810"

3700" 1.875

3800 1.880"

4000 1.935"

If it's a 3400 or 3800 the red barn piston isn't plated so that piston won't work.

Unless you know what caused the scoring on the first place, you need to figure that out. It's very likely it was caused by running too lean or the crank seals need replacing.

The seals are the same both sides and direct subs are National 253747 and SKF CR6119 or CR6120

 

[fossil]

Yep---haven't been moving on it at all lately....

If you don't mind me asking, how did your trials go on the 4000 P&C?

 

[GBertolet]

I am the one that bought it. Although it might not be used too much, I purchased the wrist pin removal kit, from Saw Salvage Co. https://www.sawsalvage.co/products/...ch-press-fit-wrist-pin-extractor-removal-tool

I may be getting ahead of myself, but does anyone know where I can get a complete oil pump assembly for the 3.7. It hasn't worked for the last 20 years or so. The part # is 530010639. I have been having to squirt my oil can on the chain periodically to get by. I am getting rather tired of doing this, and while I have the saw torn apart, now would be a good time to address this issue.