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Unknown oil leak

8K views 3 replies 2 participants last post by  300cvirgin 
#1 · (Edited)
My recently built 300c 5.7 has been on the road for about a week now. It turns over and runs ok. But it seems to have a multiple cylinder misfire half the time. And a tapping noise only when misfiring.

I'm using mds plugs and deleted the Mds loom. I have all non Mds tappets. So no Mds just a cel. It should still run fine, right? The car turns on/off Mds by solenoid activation not stopping injector or spark but.... I have a or some misfires and idles a little rough. It seems to come and go. If I put my foot into it for a while the misfire tends to go away but as it is misfiring when I stop I can see smoke coming from beneath the bonnet from the right head and that's when it is really leaking oil.

It is leaking a lot of oil and I can smell it burning inside the car. I thought it may be the valve cover gasket and oil is leaking into the spark plugs causing the misfire but the gaskets are good and not leaking and this wouldn't cause the oil leak on the floor.

My exhaust is fine, with the smallest amount of water dripping out and no smoke. But it does smell rich.

I did notice one day trying to get rid of the misfire by doing a 0 to 70mph as fast as possible, that a brief cloud of smoke came out the back. It was grey white in colour. When the engine runs without the misfire there is no smoke.

I read it could be the PCv but I have inspected it and all is good now as the pipe connecting it to the intake collapsed especially when it is misfiring. I have since replaced the pipe with an un collapable one.

I occasionally get an error code for o2 and knock sensor again only when it's misfiring.

Does anyone know what this could be?
 
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#2 ·
The MDS modification has me thinking that might have something to do with things not being right, but I don't know enough about the entire MDS system to help troubleshoot (other than, put all back to stock and see if problem persists).

But I wonder about that tube for the PCV collapsing. The fact that it would collapse, is it because one end is sucking and the tube was so old and weak it would do that? Or that the other end would stop providing so that the only other space to suck from was that in the tube? The later tells me that changing the tube isn't going to fix the problem.

If you spray the engine and bay down with cleaner really well, induce the oil leak, and quickly shut it down, can you then determine where the oil is coming from? That should help in diagnosing.
 
#3 ·
Hey Jim. I'm totally stumped by the PCv. I was hoping there would be a specific fault someone could pinpoint. I have no idea how I can even clear or clean inside the intake manifold.

The oil leak is coming from the bottom of the engine or at least the middle. Nothing at all can be seen from the engine bay from any angle. All looks fine but defiantly leaking onto the cross member and onto a part of the exhaust from the smoke rising from underneath the head.
 
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