Valve guide replacement

[ROGER A. BROWN]

I think I need to replace the valve guides on my TO20. I have a fouling problem in the #3 cylinder and I think the valve guide is worn and letting in the excess oil. Anyone have an idea on how difficult this replacement is? I saw one post, but all it mentioned was removing the spark plug and having a spring compressor. Thanks in advance.

 

[Matt L]

Its easy to do. just need a air hammer with the right bit.
Only problem is u'll need to have a valve job done so the valve seals again.


Not all new guides are perfectly centered when installed.

 

[Anonymous-0]

You have to REMOVE the HEAD guides can be drove out ,I think you would have to take the head to a repair shop as most people dont have the tools to do this job sounds like it may need rings

 

[Jerry/MT]

Why do you think it"s the guides? It could be loss of oil control on the rings.

If you get smoke at idle, than it"s a valve guide oil problem because the intake valve is subject to high vacuum that pulls oil down from the head through the guide and into the cylinder. Usually you get a lot of smoke under load from loss of ring oil control.

The guides are usually pressed out and pressed in though they can be driven out with the correct tool. The guides may also be able to be knurled to control oil. Why a

 

[Don Hooks*]

some parts companies used to sell a guide kit with a properly sized mandrel to drive the guides in and out. I don"t know if those are available still. I used a home-built arbor press and the only problem was that the first one popped loose shaking the work bench and giving me a scare because I thought something had broken. The rest popped also but I wasn"t surprised then. Re-installation was easier than removal with setting the correct depth for the guides the only concern (exhaust and intake depths are different).

 

[gshadel]

as other guys have mentioned, you have to remove the head to replace the guides, the guides are pressed out from the top of the head. I think the manual references using the new guide as the mandrel to press out the old, so the new guide goes in and it pushes the old guide out the bottom of the head. I don't recall off the top of my head if the manual lists tolerences for the ID of the guide. It does have tolerence for the valve stem diameter. I would measure and inspect vs. just replacing, my experience is that guides wear very slowly compared to rings. The piston rings my be worn, broken, or just gunked-up with carbon. The intake seals get smashed and brittle and fail.
The first recommendations I would make is to soak your pistons with Marvel Mystery Oil, Sea Foam, ATF fluid, or your favorite snake oil to loosen-up the build-up in the rings. Many guys simply pour the snake oil thru the s. plug hole, let soak overnight, crank the engine by hand slowly a few time to work the pistons, Be careful, make sure the piston has either drained down, or the spark plug is out so that you don"t hydraulically lock-up your engine!, soak overnight again, do that for a few days. Change your crankcase oil. Start the engine and let it run a while.
If that does not help, pull the valve cover, pull the intake valve spring and keepers and replace the O-ring seals on the intake valve. You will need to keep the valve UP when you do that. There is an attachment that lets you screw an air fitting into the spark plug hole to keep the cylinder under pressure and keep the valve in place. If the valve drops in, you will be pulling the head, so be careful.
If those 2 suggestions fail to resolve the problem, pulling the head, and maybe the piston are the next most time consuming step.
George

 

[bigdad390]

From someone with 30+ years of engine repair, listen to gshadel.

 

[supergrumpy]

excellent coverage of the things to do

 

[Duner Wi]

When I use air to hold the valves up I like to have the piston near top dead center. Then I make sure engine does not rotate from the air pressure. It will rotate if enough pressure. But if piston is near TDC I don't think you can loose a valve into cylinder .