[Donkman]

ok I'll admit it, I have never done a de-carb on my 446 tractors. Anyone up to the task of laying out a step by step procedure. I sure wouldn't want to tear apart a running Onan engine without a clue on what to do? :shock:

 

[99flhr]

Order new graphoil gaskets from ONANPARTS.
Sit down on a milkcrate.
Remove the side tins.
Remove the cyl heads.
Plastic or wooden "scraper" to remove carbon after rotating the piston to the "top"
Install new gaskets.
Torque head bolts per manual.
Replace tin. This is the only part requiring any finesse, it helps to pay attention during removal ( tab A, slot B etc)

 

[BushBoneYard]

This might make a good topic to ad to the FAQ's in the tech area.

 

[Donkman]

Order new graphoil gaskets from ONANPARTS.
Sit down on a milkcrate.
Remove the side tins.
Remove the cyl heads.
Plastic or wooden "scraper" to remove carbon after rotating the piston to the "top"
Install new gaskets.
Torque head bolts per manual.
Replace tin. This is the only part requiring any finesse, it helps to pay attention during removal ( tab A, slot B etc)

Ok, after using a wooden / plastic scraper, how clean is clean enough? Do I dare to use emery or anything else to remove loose particles?

 

[99flhr]

I would not try to make it bare metal, just remove the "crustacations"


Perhaps run Seafoam before and after the decarb.
Prior will loosen the crud and after will get any thing left behind

I would NOT introduce anything with GRIT
JMO

EDIT: use your shop vac to remove particles as you clean.

 

[CASE 220/4]

I will be doing this to my 446 this summer and will make a step by step thread about it with pics to help others out. Just give me a month or two to get other things done.

 

[Donkman]

1. Order (2) new 110-3181 graphoil gaskets from
http://onanparts.com/index.php?main_pag ... ucts_id=17
2. Sit down on a milkcrate.
3. Remove the side tins.
4. Remove the cyl heads.
5. Use plastic or wooden "scraper" to remove carbon after rotating the piston to the "top"
(a) Do not try to make it bare metal, just remove the "crustacations"
(b) Perhaps run Seafoam before and after the decarb. Prior will loosen the crud and after will get any thing left behind
(c) DO NOT introduce anything with GRIT
(d) Use your shop vac to remove particles as you clean.
6. Install new gaskets.
7. Torque head bolts per manual. (16-18 ft/lbs)
8. Replace tin. This is the only part requiring any finesse, it helps to pay attention during removal ( tab A, slot B etc)

 

[99flhr]

^ That covers it, figure 1.5 hrs on a Sat afternoon.

You may wish to insert
"Quaff a frosty beverage" after items # 2,#5,#8
Your consumption may vary with time, temperature and individual style

 

[Donkman]

99flhr Thanks for the help. I'm going to wait till it warms up a little in Michigan, I hate working with gloves on! :trink:

I look forward to your post Case 220/4

 

[boomers_influence]

O.K.
you guys ALL missed this.
valve grind/carbon removal gasket kit #168-0189 (from onan parts.com)

you have the tin off already, this is the time to adjust the valves.
(i actually remove and clean and lap mine,i have seen some valves SO
full of crud that the engine barley ran)
thank you. boomer

 

[Donkman]

Sounds like this could get real messy. Thanks boomer

 

[JerseyJim]

I knew it sounded too easy :wink:

Thanks for that Boomer.

Is there anything else to do during this because its easier with the heads off?

Best,
Jim

 

[Donkman]

How about a step by step for cleaning / lapping / adjusting the valves.

 

[99flhr]

Sounds like this could get real messy. Thanks boomer

Only gets "messy" if one of the head bolts snaps off flush with the cyl deck. LOL

 

[glc]

One other thing that helps is to use spray on gasket remover on the carbon deposits. When I used that they almost wiped off with a damp rag, far easier to remove than just scraping. Caution I only did this on the heads so I could be sure I didn't get any of the solvent were it might contaminate the oil. Some autoparts stores still carry out but around here most don't but our local CASE IH dealer carries the stuff and I thought Napa did too.