My good friends Graham and Dave came up today to see if we could finally fix my Green Cortina. I still cant seem to cure the popping that I'm getting on the over run.
Graham is a proper qualified mechanic and has spent a good deal of his life working on cars, so I was grateful to have a bit of expert knowledge available. (No offence to Dave, but Dave's like me: self taught!)
The first thing we did was to blank off the remote brake servo as this takes its air feed from the same pipe as the breather box from the engine. This made no difference.
Then we removed the pipe from the breather to the inlet manifold and just left the breather pipe floating free. This did exactly what I said it would do and the test drive resulted in blowing oil out of the dipstick tube. (I'd tried this before and seen the result)
It states in the workshop manual that the pipe from the breather box needs to go to the inlet manifold and the inlet manifold will the suck the gasses from the breather box and distribute them evenly back into the cylinders to be then expelled via the exhaust ports.
While investigating this Graham noticed that the outlet in the centre of the inlet manifold had been welded closed. (See below)
With this being welded up, somebody had then drilled and tapped another hole in the inlet manifold and then added another fitting in the top of the inlet manifold. (See below)
The issue with this is that the hole had been drilled between inlet ports three and four, so therefore the gases aren't entering the inlet manifold centrally and so cannot be transferred equally into the four inlet ports.
This would also explain why, when I've taken my spark plugs out after a long run to see what colour they are, the front two have always been a sooty black and the back two have always been a lean white!
Because the front two are getting hardly any air, and the back two are getting too much.
Now, whether this will be the cause of the popping on the over run, I don't know, but it certainly isn't right and needs addressing. So, our work finished there and then and will have to resume once I've bought another inlet manifold that hasn't been bodged or butchered. (Four years I've had this car now and I'm still finding bodges on it!)
It was still a good day though as I hadn't seen Graham for a good few years now, so it was good to have a catch up. 😊
