Valve stem seals

Afternoon all,

It would seem my old XJ550 is about to return to me (my mate who took it off my hands no longer has the space for it).

The main thing that was wrong with it was worn valve stem seals. Its blowing oil past the valves like a bastard.

I've been searching around for some info regarding whats involved with this. It's not a job I've done before on any bike, however I'm still willing to give it a go.
The service manual seems to gloss over this very briefly.

Is some one able to point me at a how-to, or at least give me the nutshell version of what needs doing?

Cheers,
Lurch

 

Nutshell.

Remove cams and then cylinder head, keeping chain hooked up.

Use a valve spring compressor to remove the valve springs and take the valves out.

Using pliers pull off the valve stem seals.

While they're off, check the valves are seating right with engineer's blue. ( A sort of blue dye paste - you rub it on and twist it a little and pull the valve out - if it gets rubbed off continuously all the way round the idea is that the valve is closing. If there are gaps, then it is not. Good advice is to clean and polish everything while it is apart and lap the valves in again while it's apart, but then you will certainly need to reshim the valves.

The absolute minimum while it is apart is to check that the valve has no worn to a loose fit in the slide, as if it has you won't get a good seal. You can change valve guides, but it is a pain and a replacement cylinder head will probably be easier (I reckon a few of us have spares...)

Anway - will a scrupulously clean valve, coat in in oil and reinsert it into the cylinder head. You then push the valve guide seal over the end and slide it down. You will then need to find a suitable tool to just push it onto the seat. A piece of tube with no sharp edges or possibly the outside of a pen. Some thing like that.

Then use the valve spring compressor to refit the valve springs and collets (have some tweezers available) and be careful you don't lose them - they're fiddly. It can be easiest to fit them as you wind back on the compressor. And put the top end back together.

It's a cheap job if you can re-use the gaskets, but if you buy new ones you are more likely to have to do the job only once. Your choice.

 

Thanks mate - the info is much appreciated.

 

I can almost guarantee you that you won't have an issue with the valve guides. They are almost NEVER a problem unless you have major malfunctions and/or a rusty cylinder/valve that pulled loads of garbage up into the stem guide.

You can check them if you want to, but I wouldn't waste my time.

Dave F

 

@ Hogfiddles

They're pretty long lasting, but the bikes are 30 years old and he does say it's his 'old XJ550'. It doesn't hurt to hold the valve head and see if it rocks slightly while it is apart. I wouldn't bother measuring the guides unless I could feel noticeable play.

If they're rattling I'd use another head. I know you have low mileage XJs (judging by comments here) over there, but here they've all been round the block a few times.

 

Well, 24,000mi, 32,000 mi and 39,000 mi for my main three xj's.

dave

 

Yes - that's low mileage isn't it ?

That's why there's a good market for second hand imports from the states into the UK - keep them coming

 

The odometer on mine says 12,xxx - but i have a funny feeling thats 112,xxx

 

I've lost track - I'm on my third speedo. One was smashed in a crash. One wore out and the third was wearing out, but some lubrication in time seems to have saved it. Twenty years ago it was around 130-140,000 or more but I've done much less mileage on it since then. I'm pretty sure I haven't reached 200,00 miles yet.

Mind you, not everything is original...

 

With some patience, headwork on these is pretty easy. Don't be intimidated just because you've never done it before.