Oil leak help
Thread Starter
Newbie
Joined: Feb 2016
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1986 420 SEL
Oil leak help
Hey everyone,
I'm new to the forums and hope I'm posting this in the right place.
I recently bought an '86 420 SEL and am largely a DIY'er/am in the process of restoring it.
I just noticed that I'm leaking a considerable amount of oil (a drip every few feet while driving up to temperature) from what appears to be a large threaded plug that has (2) 10mm bolts, (1) on either side. This is located above the oiler filter housing, to the right of the passenger side exhaust manifold, (see picture; plug in question in red circle). The oil is leaking from this plug onto the filter housing.
Can you guys please help me identify what this plug is called and possibly recommend what would need to be fixed/replaced to stop this leak? gasket, name, etc.
Thanks in advance!
-Patrick
I'm new to the forums and hope I'm posting this in the right place.
I recently bought an '86 420 SEL and am largely a DIY'er/am in the process of restoring it.
I just noticed that I'm leaking a considerable amount of oil (a drip every few feet while driving up to temperature) from what appears to be a large threaded plug that has (2) 10mm bolts, (1) on either side. This is located above the oiler filter housing, to the right of the passenger side exhaust manifold, (see picture; plug in question in red circle). The oil is leaking from this plug onto the filter housing.
Can you guys please help me identify what this plug is called and possibly recommend what would need to be fixed/replaced to stop this leak? gasket, name, etc.
Thanks in advance!
-Patrick
Junior Member
Joined: Jan 2012
Posts: 43
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From: Grand Junction, Colorado
1988 560SEL
your oil leak;
I'm almost POSITIVE that the item you circled is the cam chain tensioner ... it does have spring pressure pushing on it ... pull the valve cover to confirm; it's 3:19 am & 27 degrees outside, so I'm not gonna go outside to confirm my suspicion, but i am VERY sure it's the chain tensioner. Replace the seal/o-ring/gasket VERY carefully ...
Last edited by Tony Funches; Feb 22, 2016 at 05:23 AM. Reason: typo ...
Newbie
Joined: Apr 2016
Posts: 6
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From: San Jose, CA
w201,w124,w126
It is the timing chain tensioner. Its spring loaded but oil pressurised. If the car has 100k miles and you don't know if its been replaced yet or not, then go order a new one from the dealer. I don't recommend a cheaper aftermarket part here. This part is critical to your engine. If it fails, bye bye engine.
Replacing it is straight forward but be careful to ensure everything is lined up properly.
Open the passenger side cam cover and mark the chain and sprocket position. Loosen the tensioer bolts, both bolts at the same time, slowly. Might make a bit of a mess. To install the new tensioner, you will need longer versions of the bolts you just removed, thread both in and slowly tighten both bolts at the same time. Once its close enough, fit the original shorter bolts one at a time.
And for what its worth, when you open the cam cover, if your timing chain guides look reddish/brown in colour, change those too. They should be bright white.
Replacing it is straight forward but be careful to ensure everything is lined up properly.
Open the passenger side cam cover and mark the chain and sprocket position. Loosen the tensioer bolts, both bolts at the same time, slowly. Might make a bit of a mess. To install the new tensioner, you will need longer versions of the bolts you just removed, thread both in and slowly tighten both bolts at the same time. Once its close enough, fit the original shorter bolts one at a time.
And for what its worth, when you open the cam cover, if your timing chain guides look reddish/brown in colour, change those too. They should be bright white.
