valve cleaning

[Davezj]

Here are some befor and after pics. admitidly they are not that bad to start with but the carbon on the exhaust valves was rock hard and would not budge with any other method of cleaning.

before cleaning:-

IMG_20171101_171640.jpg



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after cleaning:


-IMG_20171101_175004.jpgIMG_20171101_174914.jpgIMG_20171101_174910.jpgIMG_20171101_174857.jpgIMG_20171101_174917.jpgIMG_20171101_174920.jpgIMG_20171101_174924.jpgIMG_20171101_175000.jpgIMG_20171101_174956.jpgIMG_20171101_174950.jpgIMG_20171101_174946.jpgIMG_20171101_174941.jpgIMG_20171101_174940.jpgIMG_20171101_174938.jpgIMG_20171101_174933.jpgIMG_20171101_174929.jpgIMG_20171101_174928.jpg

[Davezj]

remainer of the pics.

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[Davezj]

by the way i found out that the inlet valves are made of steel but the exhaust valves are made of 2 different metals welded together. the head is stainless steel i think (non ferous) and the valve stem is steel.
you can just about see on the exhaust valves where the head is welded to the stem, there is a little bobble in the thickness.

[Davezj]

this what i used to do the cleaning.

A wire brush wheel on a mini bench grinder and the valve goes in a drill to rotate it while cleaning with wire wheel.

IMG_20171102_212614.jpg

[Bobby~d]

Lots of pics there Dave. Great work as usual. They look like new.

[Amonlym]

I believe the exhaust valves are sodium filled (a warning about it in the engine manual!)

[Davezj]

I just tested them with a magnet.
So it could have been anything really.
I did a bit of looking on line and there are some really exotic materials for the exhaust valves.

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[Nick Mann]

Ferrous means contains iron Dave. Stainless steel is ferrous.

[Davezj]

ah yes,
stainless steel is steel and contains iron at the end of the day.


i had it in my head that all ferrous metals were magnetic. but not so.

oh well rever mind, i will have a look at the manual with the reference mentioned above.

[Davezj]

I believe the exhaust valves are sodium filled (a warning about it in the engine manual!)

what manual and what section was it that had the reffernce to the valves. it will save me going throught the multiple manuals i have.

jap language manual
uk spec manual
the jap translated manual
or supliment sheet from the manuals.

[Davezj]

do you mean the handling and disposal warning of the exhaust valves in the PWEE9622 supliment which covers the 6A12 MIVEC engine and the 6A13 SOHC engines not the 6A13TT DOHC engine.

it does seem to imply the exhaust valve are sodium filled valves.

however the valves i removed from my head have 2 distinctive metal types one magnetic one not magnetic.

i would have thought that if the valves i have were sodium filled the entire valve would be made of the same metal type.
i have done a bit of reading up and sodium filled valve are exactly as the name says a hollow stemed valve which hs soduim metal inside it and when hot the sodium is liquified and moves about inside the valve stem transfering heat better than solid valve to the valve guide and on to the head.

i would have thought this type of soduim filled valve would be made in one piece.

so i am not sure the exhaust valves in the 6A13TT engine are sodium filled, unless the manufacturing of the sodium vale is a t two piece process for the body of the valve.

more reading required.


i found this quote about the SR20DET engine.

SR20DET heads are nearly identical to their non-turbo counterparts except for one thing. The turbo heads have sodium filled exhaust valves. Sodium filled valves have a hollow head and stem filled about 60% with Sodium. Sodium has an extremely low melting point (about 100 degrees C) and boiling point (880 C). In a hard-running engine, the valves are hot enough that the sodium in the head of the valve vaporizes and travels up to the cooler stem where it condenses back to a liquid again. The phase transition from liquid to gas absorbs a lot of heat, and the condensation dumps the heat in stem where the lage metal-to-metal contact between the valve stem and guide transfers that heat to the cooling system. Without this heat pipe effect, vastly more heat would have to be transferred through the valve seat. Too much heat through the valve seat, and you get a burned valve.

Sodium filled valves, then, are a really good idea on engines like mine that run 900C exhaust temps for half an hour at a time.

[Amonlym]

Ill have to check myself Dave, but that probably that same supplement, as it went on to discuss how to make broken valves safe for disposal

[Davezj]

I have just been looking at a video about sodium filled valves and they do seem to be two part items that are friction welded together.

So it would be logical to assume the 6a13tt engine has the same sort of valves.
I am not saying sodium filled valves are bad it is just a video that explains the way they are made.



https://youtu.be/t4Xz4eyKWO0

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