First rebuild, 372xp, here we go!

[gafirefighter]

Let me start by saying how awesome this site is. The people that come here and post are so full of information, and that is great. I never had a desire to own as many saws as I do. Now I want more. I have already purchased two since becoming a member, and I am watching a third one.

That being said, I am ready to tackle my first rebuild. I looked around and found what I believed to be a good starting point. I purchased a 372xp off the bay almost two weeks ago and it arrived today. At first glance everything appeared to be in good shape on the outside. The saw does not appear to have had all that much use. The seller stated that the saw made a clunking sound when turned over. When it arrived I pulled the cord, and sure enough there was the clunk. So I had to investigate further. I stated taking things apart. Once I had the muffler off I took a look inside. The piston appeared gouged, but the rings were in place. So I took I down as far as my tools would let me.

Once the jug was off I took some time inspecting it. It appeared to be in great shape. There are a few minor marks in it but nothing that I can catch a fingernail on and it feels very smooth. The piston is shot. I guess I am just not sure how the piston looks like it does, and the jug is not much worse. Pretty quick I figured out what the cause of the clunk was. The piston rod is loose on the crank. There is way too much play. It is like a bearing came out. I do not see in parts to anything in the case though, so this struck me a little odd. If I am not mistaken the crank is one pressed together piece so I guess not it is trash.

Other than that minor little detail , everything else appears to be in great shape. I guess it means that I am going to have to split the case and put a new crank in it. It is a shame though, because there is no play in the crank and the bearings appear to be in great shape.

If someone can tell me what would cause this it would help quite a bit.

I would like to keep my little thread here going for a while to show the progression of my first build. I have already taken quite a few pictures, so over the course of tonight I plan to get them all up on here.

Thanks for all the help in advance, and I can not wait to see where this goes. I may just have to send it out for some porting .

Adam

 

[gafirefighter]

Here are a few more.

Adam

 

[ky-homelite]

Good luck with the rebuild and I'm looking forward to seeing the pictures as you go along. I've got a 254XP that I need to put crank bearings into this fall so it will be nice to track your progress.

 

[gafirefighter]

And a few more.

Adam

 

[blsnelling]

No loose pieces of metal anywhere in the engine? Then was there evidence the cylinder had been off. Sounds like someone knew the crank was bad since they removed the loose pieces.

 

[gafirefighter]

That is what I was thinking. This is the first saw jug that I have removed, but the bolts did seem to be quite loose.

Adam

 

[gafirefighter]

The guy who I bought it from said he was told that it would need a new piston. Maybe he meant piston and crank .

Adam

 

[PES+]

It looks like the cage let go on the big end bearing but the rollers did not fall out.

There are some marks in the top of the cylinder chamber that look like they could be from pieces of the cage and they almost certainly contributed to the piston damage.

Was there any fine saw dust/fine silt in the intake boot or inside the air horn under the air filter?

That is sometimes the cause of big end failure though usually the inside of the cases would be pretty dirty.

If the filter and carb boot are clean the likely cause is moisture from storage causing rust pits which weaken the cages.

High alcohol fuel with and oil that does not mix well with alcohol blends can be hard on cranks as well.

Flush your muffler well and blow out with compressed air several times to make sure no pieces are left in it or they will almost certainly come back to haunt you after the rebuild.

I have good used cranks if you need one.

 

[Ghillie]

I had a bad feeling about the "clunk" in the description....Tried to be optimistic though.

Sounds like you're going to need more than just a torque wrench for this one!!

I also suffer from TAD (tool acquisition disorder).

This ought to be an interesting thread, good luck Adam.

Fred

 

[gafirefighter]

Yeah I am pretty sure that I am going to need a few tools that I do not have. I guess I will be ordering a clutch removal tool and a case splitter. I really hope this is something that I can do myself. Either way, I am sure going to try.

I will clean the muffler out well, but I may just order a new one since there is a big dent in the top of this one. After I get it I will more than likely do my first muffler mod on it. I really do not want to fly through this thing. Like I said, I may even have it ported and turn it into a real runner.

The cylinder appears to me to be in pretty good shape. I hope that I can reuse it, but if not I guess it is not too big of a deal.

Adam

 

[gafirefighter]

It looks like the cage let go on the big end bearing but the rollers did not fall out.

There are some marks in the top of the cylinder chamber that look like they could be from pieces of the cage and they almost certainly contributed to the piston damage.

Was there any fine saw dust/fine silt in the intake boot or inside the air horn under the air filter?

That is sometimes the cause of big end failure though usually the inside of the cases would be pretty dirty.

If the filter and carb boot are clean the likely cause is moisture from storage causing rust pits which weaken the cages.

High alcohol fuel with and oil that does not mix well with alcohol blends can be hard on cranks as well.

Flush your muffler well and blow out with compressed air several times to make sure no pieces are left in it or they will almost certainly come back to haunt you after the rebuild.

I have good used cranks if you need one.

I did not find anything in the boot or horn. Must be moisture then. So far this seems like it will be worth doing. After the porting cost I could have had a new 372 though, but where is the fun in that.

Awesome.

Adam

 

[blsnelling]

I did not find anything in the boot or horn. Must be moisture then. So far this seems like it will be worth doing. After the porting cost I could have had a new 372 though, but where is the fun in that.

Awesome.

Adam

I can definately appreciate that. It's much more fun to build a saw than to buy a new one. Anyone can do that.

 

[gafirefighter]

I can definately appreciate that. It's much more fun to build a saw than to buy a new one. Anyone can do that.

And hopefully with the porting it will be better than new anyway.

Adam

 

[blsnelling]

And hopefully with the porting it will be better than new anyway.

Adam

Do it right and it'll beat that 395 you always wanted

 

[gafirefighter]

I guess I will have to get a 395 also to compare .

Adam

 

[husky455rancher]

hes.......gone............ theres no helping him now lol

 

[PES+]

A thread link to get you started

ttp://www.arboristsite.com/showthread.php?t=41876&highlight=371+rebuild

371 and 372 same except the chain adjuster

 

[gafirefighter]

Thank you sir, lots of reading to do over the next few days.

Adam

 

[Ghillie]

Just sent you some more...

 

[Ghillie]

Now maybe if I wasn't such a stubborn a$$hole I would have as many gold dots as you do...