Valve stem seals

[RaceDiagnostics]

I started on this job yesterday and thought I would try out both the rope trick as well as air.

The rope went fine.

But ran in to coupling problems with the air.

I used this hose from my compression tester.

Connected up, but air was leaking from the coupling at the end of the blue hose.

This was the issue....

....the coupling on the end of the black hose was some sort of mini Euro connector, not the normal size, I will either need to get an adapter or cut it off and fit a standard size.

 

[gaz_moose]

if its only temporary then can you not just wrap it in PTFE tape?
or just put the rubber air line directly onto it with no female coupler.

 

[Cobbler]

I had one like that on something, couldn't change the coupling as the thread was odd as well, pushed the pipe over the coupling & put a Jubilee clip on. It worked fine.

 

[graffian]

The connector on your compression gauge tail is a type 23 or 310.
The connector on your airline is a type 25.

 

[Farside]

I plan to use rope rather than air just in case I run into problems and it takes me days to finish the job.

Used rope a few times for that. It does the job.

 

[RaceDiagnostics]

I did the other bank of cylinders today however on cylinder 1 I got more than I bargained for. The entire valve guide came out with the seal.

I was able to pull off the seal and remove the spring seat and push it back into place temporarily.....

....and complete the job.

Once all put back together the engine ran smother than ever (two new valve shims in place) with all the hydraulic lifters now within specification.

I will sort out the valve guide next time I take the heads off. Over-sized guides are supposed to be installed with liquid Nitrogen to shrink then just drop in.

Anyone know where you can buy liquid Nitrogen?

 

[8ob]

I did the other bank of cylinders today however on cylinder 1 I got more than I bargained for. The entire valve guide came out with the seal.

I would just knurl the outside of the guide and press it back in with loctite.

Bob

 

[wookie]

I would just knurl the outside of the guide and press it back in with loctite.

Where's the fun in that ? playing with liquid Nitrogen would be much better.

Being serious for a minute, your suggestion is how I would do it as well.

Anyone know where you can buy liquid Nitrogen?

Do you not know anyone in your local uni physics dept ? or any industry that uses it that would "lend" you a bit ?

I used to know someone in a physics dept that let us play with a bit, it's fun/weird stuff.

 

[RaceDiagnostics]

I used to work in CERN and Edi Uni Physics depth, so that's a possibility although a H&S will be a pita.

 

[wookie]

I used to work in CERN and Edi Uni Physics depth, so that's a possibility although a H&S will be a pita.

That's a good point, I last played with it decades ago when H & S was just "wear these gloves and be careful"

 

[rtbcomp]

It may be "sucking eggs" and all that, but you can stop the valve dropping in by breaking an old spark plug China bit off & welding a air line fitting to it, turn the engine to tdc on that cylinder & connect the compressor to pressurise the cylinder. I've also heard of it being done by feeding cord down through the plug hole & then turning to tdc.

I'll bet there has been someone somewhere that has not done it on tdc & dropped a valve down in & had to take the head off

Bottom dead centre on the cylinder you're working on, of you have it at tdc and nudge the engine it could turn 180 deg. and you loose the valve. As @wristpin says, the pressure holds the valve in place.

 

[RaceDiagnostics]

I can confirm that 8 bar will easily spin the engine in either direction if its at TDC.

Having done this job now for 8 cylinders, I would now definitely say if you are working on an old engine with questionable compression/leaks. rope is the way to go. Using air then coming across unexpected problems is just way too stressful. Using rope will cost you a couple of minutes per cylinder but is stress free.