406 V6 rocker cover gasket replacement
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  1. #1
    Tadpole
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    Default 406 V6 rocker cover gasket replacement

    My 1998 406v6 has a slight oil leak from the rocker cover and there are fumes from what I assume is oil dripping onto the exhaust. Slight smoke is visible from the front of the engine bay, and can be smelled inside the car. Is gasket replacement time-consuming? Whatís involved for the mechanic? The motor is otherwise in very good condition.

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  2. #2
    1000+ Posts N5GTi6's Avatar
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    Is the problem with these motors that they don't have gaskets there ?

    Cheers

    Justin
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  3. #3
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    Need to replace the rocker covers as there is no gasket. You can reseal with a gasket glue but its not going to work for long if at all.
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  4. #4
    Fellow Frogger! Roland's Avatar
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    Sorry to disagree with HITO but:

    if you remove the covers, give them a good clean and dry the mating surfaces.

    Then use a reputable sealant and reseat and bolt the covers back on then all will be well again.

    cheers
    Roland

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    Quote Originally Posted by Roland View Post
    Sorry to disagree with HITO but:

    if you remove the covers, give them a good clean and dry the mating surfaces.

    Then use a reputable sealant and reseat and bolt the covers back on then all will be well again.

    cheers
    Roland

    100% resealable what would replacing metal covers do itís a d8

  6. #6
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    Ah my apologies i thought you were talking about the plastic v6 covers. If they are metal yes reseal with a quality sealant and you should be fine
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  7. #7
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    I'm doing this at the moment on the same motor in an Xm... I've tried a couple of things on these motors in the past.. at one stage I made rocker cover gaskets from ruberised cork, it didn't last all that long. Found the best is to just use very good quality sealant, be careful to put enough on the rocker covers as there's about 1mm gap to take up, and let it set a little before you tighten. You'll need to remove the cam boxes as there's likely to be leakage where they meet the heads, and in the 406 that's much easier with motor out. Also a good time to replace plugs, leads, timing belt, tensioners, water pump, and give it a bit of a birthday. Also, have a m6 helicoil kit on hand. I'd recommend helicoils on 16 of the threads, even if they feel good at the time you do them, they have a habit of pulling out as you tighten them... those 16 are the ones ones that take the longest bolts that hold down rocker covers and go through cam boxes.. they're the ones closest to the spark plugs on inlet and outlet cam boxes of both back and front banks. Good luck. Just be clean and get your surfaces completely dry before you put sealant on.

  8. #8
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    Quote Originally Posted by angru View Post
    I'm doing this at the moment on the same motor in an Xm... I've tried a couple of things on these motors in the past.. at one stage I made rocker cover gaskets from ruberised cork, it didn't last all that long. Found the best is to just use very good quality sealant, be careful to put enough on the rocker covers as there's about 1mm gap to take up, and let it set a little before you tighten. You'll need to remove the cam boxes as there's likely to be leakage where they meet the heads, and in the 406 that's much easier with motor out. Also a good time to replace plugs, leads, timing belt, tensioners, water pump, and give it a bit of a birthday. Also, have a m6 helicoil kit on hand. I'd recommend helicoils on 16 of the threads, even if they feel good at the time you do them, they have a habit of pulling out as you tighten them... those 16 are the ones ones that take the longest bolts that hold down rocker covers and go through cam boxes.. they're the ones closest to the spark plugs on inlet and outlet cam boxes of both back and front banks. Good luck. Just be clean and get your surfaces completely dry before you put sealant on.
    Almost exactly what's just been done to my D9, which is coming up to 300,000km. I paid a mechanic I trust, as I needed to get the job done (would have taken a long time if I'd tried!).

    Didn't take engine out, did do cam boxes as well as covers. Only one helicoil was needed. Changed plugs but not coil packs (did them myself not too long ago). In addition to timing belt, water pump, idlers and tensioner, the camshaft & crankshaft oil seals were replaced. Also replaced crank pulley, accessory belt and all it's idlers and tensioners.

    I was pushed into doing the whole job because a) it was 6 years since the timing belt was changed (although only 90,000km) b) I was hearing alarming noises when the air-con compressor cut in c) very uninviting smells from the cam boxes leaking onto the exhaust manifolds. Was not cheap, but the ES9J4S is such a great motor that I really did not want mine to be killed by lack of maintenance. At almost 18 years old and over 290,000 km, it still uses virtually no oil or coolant.

    Cheers

    Alec

  9. #9
    Tadpole
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    Thanks so much everyone. Thatís been very helpful. Itís interesting that the autoshop that Ďidentifiedí the leak spoke of a gasket when there isnít one. I would not tackle the job myself and frankly, as the car is 20 years old, weíre going to make a tough decision if the cost makes it uneconomical. Nevertheless I appreciate the detailed replies.

  10. #10
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    Quote Originally Posted by IainB View Post
    Thanks so much everyone. That’s been very helpful. It’s interesting that the autoshop that ‘identified’ the leak spoke of a gasket when there isn’t one. I would not tackle the job myself and frankly, as the car is 20 years old, we’re going to make a tough decision if the cost makes it uneconomical. Nevertheless I appreciate the detailed replies.
    My 406 is 18 years old (and has travelled almost 300,000km) and is of course worth very little. However, not only does it seem to me to have a lot of useful life left, but the question I ask myself is "What would I replace it with?" A newer car would cost more, and so depreciation becomes a factor (not an issue with a 406!). A newer car would not necessarily be trouble-free - for example a friend of mine has recently spent $3,000 having the clutch replaced on his recent-model Subaru Outback (diesel). Also look at the problems people are having with modern direct-injection petrol engines. I find my 406 to be comfortable, reasonable on fuel (not great compared to a newer diesel, but OK), good handling - all in all a good long-distance tourer, and in a different class to the modern Jap or Korean things that we hire occasionally. After all, a 406 SV was a $50k+ car when new, and mine in general strikes me as a quality piece of engineering that was built to last.

    With your D8, in addition to the oil leaks issue, does the engine use any significant oil or coolant? How is the compression? How soon are the cambelt & water pump due for replacement (and don't forget accessory belt + crank pulley)".

    If you've got reasonable/good compression on all 6 cylinders, and the engine is not using much oil or coolant, and the timing belt etc. are OK for a couple of years yet, (and of course assuming the rest of the car is still in reasonable condition) then it could well be worth spending the money - it'll probably be less than the cost of 12 month's depreciation on a newer car.

    Cheers

    Alec

  11. #11
    Tadpole
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    Hi Alec thanks for your comments. The car has done 180k and runs/drives very well indeed. Little or no oil is used. Equally coolant. Sadly the paintwork has suffered badly from the uv light and the clear coat has flaked in places - The car is not kept in a garage. Iíve looked under the car at the fitted covershield that protects the engine from road debris. It has a moulded section at the back edge where the exhaust pipe turns along under the car. There is evidence of oil having landed on the upper side of the cover and then bled round to the outside. There appears to be an oil stain on the first few inches of the exhaust pipe where itís horizontal under the car. That would explain the fumes. Iíve spoken to the Peugeot service people and they confirm no rocker cover gasket. They did say it could also be the Ďcamshaft solenoid valve seal which is a common source of oil leaks. I had the thermostat replaced elsewhere and Peugeot tell me the solenoid seal/valve is right in the same area. Not sure if the thermostat replacement and the leak can be related.... If itís the rocker cover they estimate 8 hrs labour. If itís the solenoid valve, around NZ$500 plus 2 hrs labour to replace the valve. Of course youíre right - depreciation on a new car, or outlay on another car is far higher. Decision time looms.

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