Changing valve stem seals with heads in situ - Rv8

[Pupp]

Anyone done this...? tips?

[GreenV8S]

Rope, and a valve spring compressor like this one:

http://www.justoffbase.co.uk/Valve-Spring-Compress...

[Pupp]

GreenV8S said:

Rope, and a valve spring compressor like this one:

http://www.justoffbase.co.uk/Valve-Spring-Compress...

Rope??

You knew I'd ask...

[Pupp]

Pupp said:

GreenV8S said:

Rope, and a valve spring compressor like this one:

http://www.justoffbase.co.uk/Valve-Spring-Compress...

Rope??

You knew I'd ask...

Ahh, goddit... down the plug hole then up to TDC to hold the valves in place? Fab!

Presumably something non-fibrous

[eliot]

Or compressed air in the cylinder.

http://www.justoffbase.co.uk/Compressed-Air-Adapto...

[GreenV8S]

eliot said:

Or compressed air in the cylinder.

http://www.justoffbase.co.uk/Compressed-Air-Adapto...

I've got one of them but never tried it. The problem is that if you ever manage to bash the valve enough to dislodge it, or it simply leaks a bit too much, the seal will be broken and you lose the pressure and then the valves drop in. Stuffing some nylon ripe down the plug hole is quick and easy and pretty foolproof, which suits me fine.

[dern]

GreenV8S said:

Rope, and a valve spring compressor like this one:

http://www.justoffbase.co.uk/Valve-Spring-Compress...

That's exactly what I used and did.

[That Daddy]

GreenV8S said:

eliot said:

Or compressed air in the cylinder.

http://www.justoffbase.co.uk/Compressed-Air-Adapto...

I've got one of them but never tried it. The problem is that if you ever manage to bash the valve enough to dislodge it, or it simply leaks a bit too much, the seal will be broken and you lose the pressure and then the valves drop in. Stuffing some nylon ripe down the plug hole is quick and easy and pretty foolproof, which suits me fine.

They work just fine,i actually made my own many moons ago(Pupp if you want to borrow let me know)i also found the rope trick a bit hit and miss when you have plug holes in confined spaces,dont get much call for this kind of work anymore so my airline tool is collecting dust now

[Tanguero]

GreenV8S said:

eliot said:

Or compressed air in the cylinder.

http://www.justoffbase.co.uk/Compressed-Air-Adapto...

I've got one of them but never tried it. The problem is that if you ever manage to bash the valve enough to dislodge it, or it simply leaks a bit too much, the seal will be broken and you lose the pressure and then the valves drop in. Stuffing some nylon ripe down the plug hole is quick and easy and pretty foolproof, which suits me fine.

Unless it tangles and knots inside the cylinder... DAMHIKIJKOK

[GreenV8S]

That Daddy said:

i also found the rope trick a bit hit and miss when you have plug holes in confined spaces,dont get much call for this kind of work anymore so my airline tool is collecting dust now

I've only ever need to do it on the V8S and access is a doddle there. Surely if you have enough access to get the plugs out, you have enough to shove a bit of string in the 'ole?

[That Daddy]

GreenV8S said:

That Daddy said:

i also found the rope trick a bit hit and miss when you have plug holes in confined spaces,dont get much call for this kind of work anymore so my airline tool is collecting dust now

I've only ever need to do it on the V8S and access is a doddle there. Surely if you have enough access to get the plugs out, you have enough to shove a bit of string in the 'ole?

Tried it years ago with a cologne v6 Peter and it was a pain it the neck,thats when i made the tool(was not easily available back then,early ninties)only tried it the once mind.

[Pupp]

That Daddy said:

GreenV8S said:

eliot said:

Or compressed air in the cylinder.

http://www.justoffbase.co.uk/Compressed-Air-Adapto...

I've got one of them but never tried it. The problem is that if you ever manage to bash the valve enough to dislodge it, or it simply leaks a bit too much, the seal will be broken and you lose the pressure and then the valves drop in. Stuffing some nylon ripe down the plug hole is quick and easy and pretty foolproof, which suits me fine.

They work just fine,i actually made my own many moons ago(Pupp if you want to borrow let me know)i also found the rope trick a bit hit and miss when you have plug holes in confined spaces,dont get much call for this kind of work anymore so my airline tool is collecting dust now

Cheers TD, appreciate that and may take you up on it... on the risk of the vaves 'dropping in', presumably if the engine is at something like TDC on the pot in Q, the valves cannot fall so far they're irretrievable?

[rev-erend]

Correct - at TDC most valves can only fall a max on about 1 cm - most are more like 3~4 mm.

[That Daddy]

rev-erend said:

Correct - at TDC most valves can only fall a max on about 1 cm - most are more like 3~4 mm.

[dern]

That Daddy said:

rev-erend said:

Correct - at TDC most valves can only fall a max on about 1 cm - most are more like 3~4 mm.

Unless you can lock the engine there's a risk that if the cylinder at TDC is the one you're pressuring (assuming that's what you're talking about doing) that it'll turn the engine over losing the pressure and the safety net for your valve.

[That Daddy]

dern said:

That Daddy said:

rev-erend said:

Correct - at TDC most valves can only fall a max on about 1 cm - most are more like 3~4 mm.

Unless you can lock the engine there's a risk that if the cylinder at TDC is the one you're pressuring (assuming that's what you're talking about doing) that it'll turn the engine over losing the pressure and the safety net for your valve.

Yes,should have mentioned this you do have to get the engine at true TDC when working on that cylinders stem seals(including cylinder leakdown tests,for same reason)or you will have an engine turn over rapidly all by itself good heads up Dern 4th gear with the handbrake on is also a good idea and remember how crap the handbrake is so wedging the brake pedal down may be a better method

Edited by That Daddy on Saturday 19th July 10:40

[Pupp]

That Daddy said:

dern said:

That Daddy said:

rev-erend said:

Correct - at TDC most valves can only fall a max on about 1 cm - most are more like 3~4 mm.

Unless you can lock the engine there's a risk that if the cylinder at TDC is the one you're pressuring (assuming that's what you're talking about doing) that it'll turn the engine over losing the pressure and the safety net for your valve.

Yes,should have mentioned this you do have to get the engine at true TDC when working on that cylinders stem seals(including cylinder leakdown tests,for same reason)or you will have an engine turn over rapidly all by itself good heads up Dern 4th gear with the handbrake on is also a good idea and remember how crap the handbrake is so wedging the brake pedal down may be a better method

Edited by That Daddy on Saturday 19th July 10:40

Surely if all the other plugs are in tight and the thing is in gear, it's not going anywhere?

[Pupp]

Next obvious Q, is which are the most effective seals to go for on a serp engine... have seen a variety of types offered? The neoprene ones for RPI any cop?

[GreenV8S]

Pupp said:

Surely if all the other plugs are in tight and the thing is in gear, it's not going anywhere?

Once that cylinder is pressurised the engine becomes unstable and will very quickly drop that piston unless it remains perfectly balanced at TDC. If you want to see how effective the transmission is at preventing this, try handbrake and into 4th gear and then engage the starter for a moment. The engine moves quite a long way before all the backlash is taken out of the transmission and all the bushes wound up to stop it.

[That Daddy]

GreenV8S said:

Pupp said:

Surely if all the other plugs are in tight and the thing is in gear, it's not going anywhere?

Once that cylinder is pressurised the engine becomes unstable and will very quickly drop that piston unless it remains perfectly balanced at TDC. If you want to see how effective the transmission is at preventing this, try handbrake and into 4th gear and then engage the starter for a moment. The engine moves quite a long way before all the backlash is taken out of the transmission and all the bushes wound up to stop it.

this can be quite alarming,also keep fingers well clear of pulleys too when you pressurize the cylinder for the 1st time,you will soon find out if you have true TDC or not,also make sure you have no one standing in front or back of the car when you do this(pets included)only a warning.

Edited by That Daddy on Saturday 19th July 13:14