Lotus Elan and Lotus Elan Plus 2 Forums

I've just lifted the head of and it seems to me that it hasn't been touched in years.

This cannot have been overhauled 500 miles ago surely! It doesn't coke up that fast.



What is the approved method for cleaning the soft alloy, (the exhaust ports are black and sooty as well). Are there products available that will disolved the carbon and leave the ali untouched?

That looks pretty normal to me. In fact it looks healthy! Easily possible after 500 miles or so.

Really? I'll take your word for it until I get the valves out. That should be interesting.

The depth of deposits, especially on the exhaust valve head will tell you. You get a thin black coating very quickly and it does not build up much on the alloy head itself or the inlet valve head overtime. But you get the hard brown deposits on the exhaust valve that continues to build overtime. From the photo I can see the brown deposits on the exhaust valve head. If that is thicker than around 0.05 mm then it is not a recent rebuild IMHO ( or they did not bother to clean up the valve)

cheers
Rohan

Thanks for the replies chaps.

Are there any modern techniques to remove the carbon other than the usual physical scrapers / wire brushes etc?

I use gasket stripper spray to clean the head face itself including the carbon in the combustion chambers. its designed to remove deposits left by gaskets and sealants but works well to also remove carbon.

cheers
Rohan

Vince

Did you clean the head face for the photo as it looks quite clean. when ever I have removed my head the face is stained around the outside of the fire ring area especial in the middle two cylinders indicating a long time of use.

Hope this examination is not a problem

Remember heads can coke up faster when running rich, or where slight play in valve guides allows a bit of oil through.

Rohan,

Like this stuff - http://www.ebay.co.uk/itm/291276456685

This alternative is a bit strange - http://www.ebay.co.uk/itm/281942466559
as it states it will remove any gasket and also "Can be used as a gasket maker or dressing" No idea what that means! "Dressing"- like on a salad? I almost tempted to buy a can to see what it does.

John ,

Hopefully no additional major problems.
I just decided that, considering the rest, it would be silly not to strip the whole engine to check it. It would appear that the head was removed and replaced a short while ago. Whether anything in the way of "lead free" mods were done is another matter. At the least I would expect new valve seats.
Patently the valves themselves were not decarbonised so I have not a lot of hope.

The engine did not smoke or show outward signs of distress. Considering the state of it, it actually ran quite well!

Vince

promotor wrote:Remember heads can coke up faster when running rich, or where slight play in valve guides allows a bit of oil through.

It is certainly a bit rich, even when hot it has that characteristic rhythmic "hunting" sound.

Hello all
Look the pictures.
It's a very, very cheap methode to clean.The rest you can give to the pigs.
Sorry it's not a TC in your sense, it's a Audi 5 cylinder TC 20 Valves
with only 100kmiles.
Since this operation I've done 10kmiles with him. The emissions
are perfect. State-controlled last week.







Cheers Urs

That is certainly a novel method. Air blast with Corn Semolina ?? I have to admit that is not something that would have occurred to me.

Thanks for the enlightenment!

Vince

Argh! Semolina...school dinners flashback

this is what I use
http://www.crcind.com.au/products/clean ... t-stripper

cheers
Rohan

But you probably love cous-cous