So my 03 g35 coupe with 175000kms started leaking oil from the valve cover I think just on the driver's side I think 10-15000kms ago. I got a shop to replace the gaskets and now after they did it they're saying valve covers need to be replaced as well. Specifically they said "it needs new valve covers when the valve cover gaskets have failed. It's how they designed the engine". I understand this has to be done sometimes but they didn't say the original covers are damaged. I suppose it just depends on if they're damaged or not? If it's just one that's damaged could I just replace the one? They quoted $610 each for new covers. Canadian dollars that is.

Thanks everyone would really appreciate some input!

 

Reason is the spark plug well tube seals are built into the valve cover, if they're not leaking right now they will be SOON (probably as soon as you reinstall the valve covers) and the shop wants to save you some money by not having to have the job done twice.

There are plenty of aftermarket options for the valve covers to help bring the cost down. OEM Nissan covers are like $250 apiece. It's quite a bit of labor to replace them which is probably where the bulk of your cost is coming from though.

Ask for an itemized breakdown of the estimate.

 

Question, probably dumb, is there a seal/o-ring where the spark plug well tubes push into the heads or is it just up top at the valve cover? I'm at the point
where I've let the leak annoy me enough. Also what A/M valve covers have given the best results, I've never seen it mentioned and the prices are all over
the map.

 

No, I just did both of mine and re-used the valve covers. The only time to replace them, so I have come to learn, is when the spark plug tube gaskets go, you'll know as you will have oil in your spark plug recess.

 

I have always reused my covers with the old tube seals. The seals shrink over time (heal / cool cycles) and start to weep. Cleaning up the covers and spark plug tubes and applying Ultra grey RTV. Add new gaskets and reassemble. It's not a fun job but 2-3 hours of work and about $25 beats $600+ Never had one leak after a reseal job. A shop will only replace the covers and gaskets because they don't want to be liable if it leaks again. I think I wrote it up somewhere on a thread here.... I can look it up if you need a step by step DIY.

 

Next time I drill out the seals on one I plan on making a DIY, it's not that hard really. I used a hole saw through a 4x4 to make a wooden alignment dowel that fit INSIDE the hole in the valve cover, then stuck that wooden dowel on the drill bit of the larger holesaw which keeps it centered while drilling.

 

The OEM valve covers have "non-serviceable" spark plug tube seals. But with a little bit of time, a dremel, some RTV and a few Honda spark plug tube seals you can have a set of valve covers that are serviceable. If this sounds like something you might be interested in doing you can take a look at this guys video. He's got a bunch of G35 specific content.