Onan CCK Rebuilding FAQ

[OnanParts]

The oil pump. The heart of any infernal combustion engine. If your Onan has the oil filter option odds are very good that your oil pump is in good shape and will not have to be replaced. No oil filter? Inside of that pump may not look so good.

Two bolts hold the cover on. Remove those and carefully take the pump cover off. Slowly...you want the gears to stay put, OK one gear is retained in place with a very small C clip. You want to carefully wipe the oil off them so you can use a permanent marker on both gears so they can go right back exactly where you found them. This goes for any parts that mate or move together that you will not replace. Always mark, bag and tag parts so they get put back in the same place.

[OnanParts]

If the gear faces look nice without any ugly wear pattern then in most cases you can put it back together replacing the only part that typically shows any real wear and that's the woodruff key. Before removing the small oil pump gear that is retained by the C clip hold the big drive gear and then see how much "play" or slop the small gear has when you try to turn it back and forth.

Very little play the key is ok. Lots of play it's tired and you will see that when you remove the gear. With the gear off.....don't lose that little C clip...you can check the drive gear shaft for play in the housing. A little is OK but a lot with obvious wear on the shaft means it's toast. Part number for a new pump is 120-0491. If all is good time to re-assemble it. A new woodruff key if needed and gasket kit # 120-0161 that will come with three different thickness gaskets. .005" .007" & .009".

Don't use a metal scraper or screwdriver to clean the gasket surface! I use really fine scotch brite and some solvent on both the cover and body. Put any nasty scratches here and you may as well give it up and get a new pump. Some of that spray gasket remover stuff comes in handy here if the gasket won't let go without a fight.

Oil up that big shim washer that goes back on the drive gear shaft first, then put it back in the housing. New key, it may not want to go back in the shaft slot. NO metal tools here! A small wood dowel to get the key seated works best. Hit the dowel with a small hammer but not the key! Install small pump gear and make sure the C clip has the "rough" edge side facing away from the gear.

Be certain the C clip is actually fully seated on the shaft. It will click on and appear to be all the way there but most likely it will need a second little push.
Triple check the C clip!

Set the other gear in place with the marks you made lined up. Now comes the fun part. You want to use the thinnest gasket possible that allows the pump to turn freely. Start with the thickest gasket, typically the white one and put the cover on and just finger tighten the bolts. You will need to move the cover around a bit while turning the drive gear to find a position that has no resistance or binding.

Play with it until you have the pump turning smoothly with one finger turning it. Now try the next size thinner gasket, the yellowish one. same deal. Still moving freely? ok go for the Blue one and try for some smooth action.

Remember, finger tight only on the cover bolts when doing this. You have to be able to move the cover but have it stay put at the same time. When you feel confident the pump is turning smooth and not binding at all carefully tighten the cover bolts one side then the other, repeat. Back and forth nice and easy and keep checking the pump for smooth turning. Tighten some more, still smooth? Snug them up some more, still smooth? About 10 foot pounds is good for a final torque but good and tight works too. Just don't put your weight into it!

If it bound up as you were tightening the cover you probably need to go to the next thicker gasket. When all is good put some oil down the pickup/inlet and see how it feels. Still smooth? A little resistance is ok as it is now squishing the oil you put in there. Put some more oil in and keep turning the gear counter-clockwise as you are facing it. The oil should start to come out the feed hole.

Final test is screw on the pickup tube and drop the pickup in some fresh oil and turn that drive gear until oil is coming out the feed hole really nice. Cover the feed hole with your finger and see if you get some pressure.

[OnanParts]

Got some pressure? You're done! Always replace the oil pressure by pass spring with a new one as part of the rebuild process. Part number 120-0140.

[OnanParts]

Since we are talking about oil pumps might as well shed some light on the oil bypass spring and valve.

First pic is fixed pressure bolt, second pic adjustable pressure bolt & locknut.

The oil bypass valve and spring are what regulates the oil pressure. The bolt or bolt and nut used on early engines is removed and the spring will typically fall out after you turn the block upside down. Sometimes the bypass valve will come out with it, sometimes not.

If not use a small magnetic pickup tool or spray some carb cleaner down the hole to breakup the oil that is holding it in place. If using compressed air to launch it out of the block and you don't put a rag over the opening to catch it and hours later it's still hiding someplace you will never find it.....Part number is 120-0398.

The valves hold up well but it's always a good idea to replace the spring, part number 120-0140 when rebuilding.

When putting it back in the "flat" end goes in first. The smaller rounded end on the top is what keeps the spring centered. Oil up the valve before installing it, drop it in the hole and then put the spring in. The copper washer can be reused if annealed. Heat it up cherry red and drop it into some water.

What? You lost the bolt too? It's a 3/8-24 X 7/8. The length is what sets the oil pressure. Torque it to 10 foot pounds. Don't over tighten or you risk cracking the block.

If you have the early adjustable style it's about 18 turns with the washer installed. If you have an oil pressure gauge you can dial in the pressure to about 30 psi before fully tightening the locknut. Snug the locknut just a bit before adjusting or you will have some "extra" oil seeping out.

[Gary Reif]

I am working on a CCKB48M. A friend bought it as a basket case to replace the engine he had. The box of parts he got included a new cam and cam gear. Which he needed because his engine has stripped the teeth off the cam gear. The basket case engine had the same problem. Is this a common problem?
Now the main reason I'm posting here is after checking the interference fit between the new gear and cam I feel that it has an excessive amount. Are these normally pressed on or do they need to be heated to be installed.
Thanks
Gary

[OnanParts]

Rare to find stripped cam gears. The fit is VERY tight. Don't use any heat on the gear unless you remove the plastic ball separator first. Some come off using all your fingers on one hand and twisting it left/right while pulling on it.

Some do not want to come off..... Early gears have a metal separator, later ones plastic. The metal ones are more likely to fail than the plastic ones.

[Gary Reif]

onanparts thanks for your reply. This gear has a metal ball separator. Do I need to try to remove it first or can I warm up the gear with it on? I'm worried about not getting it all the way on and getting stuck. It seems like a lot of press for somethig that small. I pressed one of the old ones I have here off and it only had half the press that the new one has. I know it may have stretched some but not that much. The seperator in the old gear is metal and looks in good shape. Will probably use the old cone and spool over the balls. Am open to any advise.
Thanks again
Gary

[vitormotor]

hello
i am from portugal

you have the manual parts of this motor cck

send for mi

tks

[cbt1124]

Originally Posted by onanparts

Onan valve guides hold up really well but at some point they will need to be replaced.

For those of you that are going to replace them here are the part numbers, specs and how to remove and replace.

B series: B43E, B43G, B43M, B48G, B48M etc.

Intake guide: Part # 110-3161. Takes intake seal 110-3604
Exhaust guide: Part # 110-1935 This # supersedes 110-1807

P series: P216G, P218G & P220G.

Intake guide: Part # 110-3526. Takes intake seal 509-0289
Exhaust guide: Part # 110-3527

B & P series Intake valve clearance (stem to guide) 0.0010-0.0025

B series exhaust valve clearance (stem to guide) 0.0025-0.0040

P series exhaust clearance (stem to guide) 0.0020-0.0035

See previous post for CCK numbers. Stem to guide clearance is the same as a B series.

First part is removing the old guides.

Tools required: Hammer and a stepped punch that will fit down the guide bore.
No stepped punch in the toolbox? No problem. Use a long bolt with a nut threaded at least an inch up with a small washer as a shoulder and drive the guides into the valve box. Lifters need to be removed before attempting this!
You should be able to see the guide around your punch/homemade driver. You don't want to scar up the guide bore here!

Put a small rag in the valve box to catch the guide and prevent damage to the lifter bore. A couple of good whacks to get the guide moving and then easy tap tap tap until it falls into the valve box.

Intake guides have the raised shoulder for the stem seal and the intake valve/guide is always at the rear end of the block. Exhaust valve/guide always at the flywheel end of block. Intakes valves are larger than the exhaust.

First pic is of my home made copy of the factory stepped seat guide tool with some 1/4" all thread and washers. Use a lock nut at one end with correct size washers built up for intake or exhaust seat for the do it yourself super cheap tool. Don't go oversize because you want the washer to rest on the seat shoulder not the block. Seats and guides are at an angle compared to the head gasket surface and you want the guide to be pulled in nice and easy.

Small washer with oversize nut and regular nut for the guide or valve box end. Second pic is of the all washer cheap tool. Washers work fine if you pay attention to the next part. Put some clean engine oil on the outside of the new guide before installing.

When you are turning the locknut/all thread go easy and keep it centered so you don't mess up the inside of the new guide with the all thread. You may or may not have to put a wrench on the nut inside the valve box.

Some CCK/CCKA/CCKB series intake guides use a thin rubber gasket, new part # 110-3136. Old # 110-0068.

Third pic ready to start pulling the guide in.

I am working on a NHC , could not find any part numbers for the ehaust valve guides. I was hoping that you could provide me with the correct number and also where to purchase them. onanparts.com does not even list them. Thank You in advance for your assistance.

[OnanParts]

Originally Posted by cbt1124

I am working on a NHC , could not find any part numbers for the ehaust valve guides. I was hoping that you could provide me with the correct number and also where to purchase them. onanparts.com does not even list them. Thank You in advance for your assistance.

110-3167 is the exhaust valve guide for an NHC. They are listed on onanparts.com

The 110-3167 is also the intake guide on Some N series engines without intake guide seals.
110-3168 is the intake guide for some N series engines that do use guide seals.