Hi all, I find myself in the un-enviable position of having a 2.0 Tfsi motor with significant carbon build up on the back of the inlet valves and probably within the inlet manifold itself, I have an internal flap stuck!

I know what my choices are. Unfortunately there are no workshops in the town that I live that offer a walnut blasting service, so unless my other plan is workable, I'm looking at purchasing equipment to do the job myslef, at considerable cost.

My "other" plan is to set each cylinder in turn to tdc, closing the inlet valves, then filling the cavity behind the valves with an aggressive carbon disolving fluid and then slowly washing the carbon build up with a series of long paintbrushes slowly desolving the stuff, which I would then pump out with a small pump.

My question is this; has anyone tried it this way before or can anyone see a problem with this method that I have not seen. I have not had the inlet manifold off the engine yet so have not seen in person the kind of access I will have to do this, but a couple of videos I have seen suggest to me there is space to achieve this.

Comments on this appreciated.

Thanking you in advance.

I can only speak from a couple of decades of regularly decoking engines as we once had to do before detergent fuels, often there was oily carbon build up on the back of the inlet valves sometimes almost blocking the inlet tract, and whilst it was easier to remove than the grey coked on deposits on the piston crowns, combustion chambers, valve heads and the tulip of the exhaust valve I don't think any solvent would touch it other than a 48 hour trichloroethylene heated vapour bath.

 

I used to spin the valves in my lathe or pillar drill and use a carbide scraper, walnut blasting unquestionably works and Mr Muscle oven cleaner works OK on turbo vanes but I dont think a brush and solvent is going to do it for you without mechanical scraping with curved spoon like tools with a cutting edge & then removal of the debris by vacuum.

 

If you were able to get access to work on the back of the valve head you would most certainly need to rotate it to get to all of it, I'm not sure how you would achieve that.

Even standard engine diff & Haldex oils swell the seals and make the plastic pump bores oval on both my vacuum and syringe type oil suckeruppers, the latter does not even come into contact with the liquid, they would not last 10 minutes with any cleaning solvent, I have yet to find a pump spray that can resist brake cleaner and carbon on an inlet valve would just laugh at that stuff.

Thanks JR, appreciate the reply. You raise some interesting points. I did think some initial scraping would be needed to get the big stuff out, and am happy to do this.

What you say about the other side of the valve that is out of sight, I'm guessing L shaped scrapers might help.

I hear what you say about solvents not being great at dissolving carbon, but I was thinking more a fluid of the like that is used to clean EGR valves, which I have used to great effect.

I do have a few large syringes that don't have rubber bungs but solid plastic ones, which I use for vacating brake fluid from reservoirs, so I think I could draw the cleaning fluid out with them.

I appreciate your input, thank you.