Vavle Job

Luke · Post by **Luke** » Wed Feb 04, 2004 9:36 am

One of the many tasks I have in the next few weeks is to adjust my valves.

While I've got the covers off is there anyway I can de-coke the combustion chambers? Any solvents I can spray in there to reduce the build up, that sort of thing, or is it not worth the hassle?

Dimitri · Post by **Dimitri** » Wed Feb 04, 2004 12:28 pm

Hiya, a few years ago, I came across a system that apparently the old-timers used to de-coke without removing the head etc.

I used this method on an old Mark1 Transit (ex-BT van in light yellow) and it seemed to work very well I must say.

1) put a small amount (enough to circulate around the piston rings) of something like REDEX into the spark plug holes if possible for each cylinder and leave overnight to soak (turn crank a little to allow penetration)
2) remove the filters from the carbs and turn over engine (keeping the spark plugs out) to remove any excess REDEX and put the plugs back in
3) Now get a litre bottle with cap and put a few small holes in the cap - fill with water and screw cap back on
4) with engine running (on high idle - use one hand to keep high) squirt the water into each carbs top (filter removed) while reving the engine slightly to keep the engine running and watch that carbon come out with the redex and water.
5) I have not heard of this damaging the engine in any way, but maybee someone could correct me on this

It works because if anyone has had a leaking head gasket can tell you - the cylinder and piston that has the leak ends up being cleaned by the water combusting with the fuel.

Good luck and watch the valve adjustment - I frequently have to adjust them 2 or 3 times each to make sure I get the gap just right as tightening tends to open the gap slightly as the threads pull tight on the nut

stay gold Dimitri

Luke · Post by **Luke** » Wed Feb 04, 2004 12:44 pm

water!

in a combustion chamber!

I'd rather like to avoid that if you don't mind, isn't it likely to blow the engine apart?!?!?

69Olive · Post by **69Olive** » Wed Feb 04, 2004 1:12 pm

I did the Redex thing on an old BMW I used to own (minus the water part!

). It seemed to have some effect - watch the smoke billowing out the back when you first drive it after the treatment.

Not sure I'd try it on my beloved Porsche though.

Dimitri · Post by **Dimitri** » Wed Feb 04, 2004 5:55 pm

Lol - yes it sounds scary. but isnt really as long as you keep that engine reving while squirting .... ha ha - I haven't heard of anything blowing up, I guess the worst that could happen is that the engine cuts out while squirting, so you just stop squirting any more, turn her over a few times and she should start - the difference is that any water entering into the combustion chamber sits there and gets expelled with the cycle - compared to a coolant leak (head gasket blowing) there is plenty of available water to suck into the chamber on every cycle so of course with large leaks the cylinder gets flooded and locks.

The method I gave is pretty safe and realy does a great job of cleaning (softens the carbon deposits on the crown and chamber) the loose carbon out - Ask the older chaps in the know - they should confirm this method, but it is one of those little known secrets in a sense.

I shall follow the replies avidly waiting for the shock effect lol - PS I have tried it on my 912 as well with amazing results (very easy really) - visualy checked condition of chamber and I could see the aly crown for the first time

(Some might worry about ring wear - my answer is don't. the small time it is getting the water (which quickly turns to steam in there) it will 'water down' the oil residue on the rings to such a small degree that it could not cause any damage)

Remember - on highly aspirated cars with turbos / superchargers one of the next upgrades is to install water injection for cooling and combustion stability with the added bonus of keeping your combustion chamber clean for longer

Luke · Post by **Luke** » Thu Feb 05, 2004 9:40 am

Thanks Dimitri, call me a coward but I think I'll avoid the water splash!

I think once I have the valve covers off I'll spray a bit of carb cleaner into the chambers and leave it a while, it should soften up most of the residue, and hopefully clean it out a bit. I can't afford a engine rebuild if I put too much water in

Dimitri · Post by **Dimitri** » Thu Feb 05, 2004 12:05 pm

That's cool Luke - no worries and I understand - better to be carefull than pay the price later - the REDEX thingy works well though and no fear of causing problems with that - good luck with it anyway