Check around the bolts for small cracks especially the one in the corner on the timing belt side/IM side. Unfortunately, the valve covers on these cars are not the best material. Sometimes if a bolt is overtightened or not the correct length it can cause cracks. It happened to mine.

Also remember that these are not your average aluminum. So if you go to weld it, it will be more challenging then just welding aluminum.

tschuhly said:

Check around the bolts for small cracks especially the one in the corner on the timing belt side/IM side. Unfortunately, the valve covers on these cars are not the best material. Sometimes if a bolt is overtightened or not the correct length it can cause cracks. It happened to mine.

Also remember that these are not your average aluminum. So if you go to weld it, it will be more challenging then just welding

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tschuhly said:

Check around the bolts for small cracks especially the one in the corner on the timing belt side/IM side. Unfortunately, the valve covers on these cars are not the best material. Sometimes if a bolt is overtightened or not the correct length it can cause cracks. It happened to mine.

Also remember that these are not your average aluminum. So if you go to weld it, it will be more challenging then just welding aluminum.

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I will check them, what do you mean by not your average aluminum, just really thin and crappy? would I be better off trying to find a business that might do it or should I just replace it entirely with one made of a stronger material, if those exist.

I was told by someone that they are a mix of aluminum and magnesium or something. Basically, it is dirty aluminum, and it makes for a very sloppy, dirty weld. Not that I have personally experienced it but only what I have heard.

The oil cap seal could be another source.

dwb said:

The oil cap seal could be another source.

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That's where mine used to leak. Changed the gasket to a new soft one and still did but not as much. Retensioned the spring clip on the bottom of the cap and the combination fixed it.

Oil cap seal. Mine is doing the same thing. FYI EVO-8 cap is a perfect replacement and much better quality, or you can "double up" on the seal.

I am going to order a new evo 8 oil cap and seal and see if it makes a difference I read that the oil can be a common problem but the only thing that makes me doubt it is that I havent seen oil residue around the oil cap. I know the pic I took wasn't great but you can see that there isn't residue around the cap.

OwenRonn said:

I am going to order a new evo 8 oil cap and seal and see if it makes a difference I read that the oil can be a common problem but the only thing that makes me doubt it is that I havent seen oil residue around the oil cap. I know the pic I took wasn't great but you can see that there isn't residue around the cap.

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This may be a bad idea but If it were me, I'd just clean everything really good, put some paper towel around the oil cap, and then let it run for a little to see if the paper towel seems to be picking up any oil from the cap. It may also show the general area that it's leaking from if not the cap.

Obviously the biggest thing to be careful of here is fire...paper, oil, heat, not the best combo

I had this oil in the valley problem for years and never could find out exactly where it was coming from.
It turned out to be a small crack somewhere in the valve cover. I never saw it.
Even English Racing didn't see it until they put the car on the dyno to start tuning it, and then they discovered the oil coming out.
They didn't try to repair the valve cover. I don't know why. Maybe it's like tschuhly is saying about the difficulty of welding it. Anyway they just emailed me and said the valve cover is cracked, we'll have to find a good used one somewhere. Which they did.
A few people in here have bought fancy expensive new ones from, forget now who, I'd have to look it up.