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Valve cleaning with Tunap's 933 system

We were recommended to take on this job by our friendly auto electrician Parry's Auto Electrics in Gaerwen after he'd diagnosed a misfire on a Citroen C4 (Sebastian Loeb special edition) with the 1.6 16v THP engine, was due to high carbon build up on the valve train.

With the Tunap 933 kit, the principle of the equipment is that it gives a fast, effective solution to remove the carbon build up without having to dismantle the top end of the engine and therefore replace more expensive bits like the headgasket and timing belt and the associated bits and pieces that come with those jobs.

I think I could have chosen an easier car for the first attempt with this kit but needs must and so we started to attack the problem.

The issue with the C4 with the THP in and probably similarly with most THP powered engines like the Minis the inlet is on the back of the engine. The extra gift the C4 adds is the windscreen extends unnecessarily into the area you are working in and adds extra difficulty and risk whilst you're manoeuvring the Tunaps metal trigger system about the place.

So we removed the inlet manifold completely, including the studs so that we could cover the inlet ports we weren't working on, as you do it individually and turn the engine to TDC (top dead centre as the valves are then completely closed) before staring the blasting process. This stops any granules being blown back then finding their way into the engine.

Putting together the tool was relatively straightforward and the instructions clear to give you the correct psi settings for the air system.

I found that given the access being on the back of the engine and under the windscreen meant that using the hoover attachment and the tool was problematic and so resigned myself to doing a cleaning job at the end to facilitate a better job of the valves.

Here are some photos of the process I took with a small pinhole inspection camera from Werkzeug tools.

This picture shows one of the 8 valves we did prior to using anything on it at all.

This next picture shows a mid point in the process, we found that sometimes we required a small pick tool to get to the tougher build-up and the back of the valve to help the granules have the desired effect.

One more stage picture before the last one shows a point at which we used a decarbonising spray to assist with the back of the valve build up where the valve stem was effectively in the way.

Lastly after blowing out the remaining decarbonisation fluid,then blasting it again, then using the 933 system 'neutralising solution' (which effectively dissolves any remaining grabulate in the intake tract) this was the result.

The result was better than I expected given the difficulty and the car now runs well with no limp mode when given full load.

So in summary, a successful attempt at the job. In this case it took me too long and I would rather have tried it firstly on a transverse engine with forward facing or a longitudinal engine lent over like a BMW straight 6, but lessons are learned in difficulties!

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