406 Coupe with ES9J4S with oil leaks

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Martijn Bouwman
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Joined: 14 Nov 2020, 08:35

406 Coupe with ES9J4S with oil leaks

Post by Martijn Bouwman »

Hi, i recently bought myself an reasonably well maintained 406. Reasonably well meaning it went to the dealer for most off it's life and had some bushings replaced but it's still a oil leaking mess under the bonnet. I know the valve covers are leaking and that it's an common problem. I think the majority off the oil on the engine is dripping down from up top. What i'd like to find out is if theres more possible points off oil leakage thats likely so i can solve as much as i can before cleaning up the mess and check whether i've been succesfull.

What im also curious about is if the engine blocks has a tendancy to leak between the cilinderhead and the cast aluminium piece that is retaining the cams. From what it looked like to me theres just some putty between those parts

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xantia_v6
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Re: 406 Coupe with ES9J4S with oil leaks

Post by xantia_v6 »

Welcome to the forum, The ES9 engines are prone to top-end engine leaks, but if re-sealed carefully they should last at least 10 years, maybe 20 before they need doing again.

Usually it is the top cover seals that go first, but the joint between the heads and the blocks that carry the cams do sometimes leak, and this requires removal of the camshafts to fix. All of the joints are sealed with Loctite 5910 (which is apparently the product that the factory used).

I have never seen a camshaft oil seal leak.

Here is a short description I wrote a few years ago when I first did one (I have done 3 or 4 others since then). viewtopic.php?t=37551

Martijn Bouwman
Posts: 2
Joined: 14 Nov 2020, 08:35

Re: 406 Coupe with ES9J4S with oil leaks

Post by Martijn Bouwman »

thanks this helps a lot! ill clean up the stuff i can reach without taking anything apart to see if i can tell whats leaking on the first bank to help me decide whether it's worthwhile to just do the top covers or to prepare for further digging down.