XE valve guides

[StewartG]

I have a coscast XE head which leaks oil down one valve stem, this results in an oil fouled plug, puff of oil (large) on start up and oil consumption.

The obvious thing was to change the valve stem seal but this didn't cure the problem.

I'm now wondering if the bronze valve guide is worn or could I have a slightly bent or undersize valve stem?

Is DIY changing of valve guides possible?

If so how?

Are all XE valve guides the same size/fitment? obviously some are bronze and some aren't .

Anyone played this game already and fallen down the holes?

Thanks

Stewart

[Peter T]

If you only have one guide that is showing signs of leakage and has no wear then it is possible to replace just one guide. But it is not worth removing the head for one only. It really is not a DIY job as it takes several tonnes of pressure to remove them and install them, if you try and use a hammer and drift you will end up distorting the guide, which results in rapid valve wear.

Have you checked all the valve stem sizes to assertain that the guides are worn ?

Valve stems also wear, especially when run in harder steel guides as opposed to the bronze variety. Having small amounts of oil pass down the guide is not really anything to worry about, but if you say that it is beginning to foul a plug, i suspect that you have a problem elswhere, maybe in the piston/ring area, you need to check that your symptoms are pinpointed correctly, as one giude in a head would not wear that rapidly causing said. It is also not cost effective changing one guide, might aswell have them all checked and changed.

There are several sizes and types of guides available for this head.

 

 

Carbon Components from K9 Composites

 

[StewartG]

Thanks for the info Peter.

I know it's a guide problem as I've replaced the head with another one and the problem has gone away. I'm assuming this tells me the rings, bore and piston are OK and the problem lies with the head.

I can also see that oil has leaked down the guide and onto the back of that valve.

So I guess I need to find someone to check out the valve and maybe renew the guide.

[oilyhands]

You could always have the guide K-lined, a K-line is a tubular insert that is pressed into the centre of the guides to reclaim it, the material is excellent, concentricity is pretty much guaranteed and there is no risk of damage to the guide bore in the head. Lubricity is better too.

 

If you do decide to press the guide out, bear in mind that there is a circlip on the spring side, so push it out away from the combustion chamber. Coscast guides arw a different size from the GM / Mahle heads, you can get Colsibro ones from Paul Ivey, it shouldnt be a problem to repalce just one, but you will need to recut the seat and re-lap the valve.

 

Oily