Oil leak from mystery bolt
Moderators: GRNSHRK, ron, bfons
Oil leak from mystery bolt
Hi folks
Apologies if this has already been posted....
I have an oil leak from a mystery bolt, which appears to be on the lower timing case (red arrowed in two attached pics). I reckon it's probably a simple gasket change but I don't want to crack the bolt without knowing what its for, especially if someone's done this one before. Any tips?
Apologies if this has already been posted....
I have an oil leak from a mystery bolt, which appears to be on the lower timing case (red arrowed in two attached pics). I reckon it's probably a simple gasket change but I don't want to crack the bolt without knowing what its for, especially if someone's done this one before. Any tips?
- Attachments
-
- Clipboard04.jpg (196.63 KiB) Viewed 1260 times
-
- Clipboard03.jpg (177.09 KiB) Viewed 1260 times
1986 Zinnober 635 CSi
-
- Platinum Member
- Posts: 3710
- Joined: Thu Apr 08, 2004 3:24 pm
- Location: Gilroy (SF Bay Area) CA
Re: Oil leak from mystery bolt
Well, it's not that simple
It probably is the lower timing cover gasket that's leaking, but in order to remove the cover, you have to remove the big honkin' 36 mm nut on the end of the crank shaft
You might want to just keep it clean for now, until you are ready to do some other service, like the belts as well
It probably is the lower timing cover gasket that's leaking, but in order to remove the cover, you have to remove the big honkin' 36 mm nut on the end of the crank shaft
You might want to just keep it clean for now, until you are ready to do some other service, like the belts as well
Bobbo
1980 633 CSi Cypress Green/Pearl Beige
2017 X5 M Sport Xdrive 35i Carbon Black/Ivory White
2005 330 Ci ZHP Cabrio Imola Red/Bone/Black
- Ralph in Socal
- Platinum Member
- Posts: 2745
- Joined: Tue Apr 14, 2009 3:32 am
- Location: High Desert of SoCal
Re: Oil leak from mystery bolt
That mystery bolt is actually the cover for the timing chain tensioner spring
It's holding a spring and piston that pushes against the tensioner rail. Remove the bolt (nut?, cover??) and the spring will fly if you're not careful and ready to catch it
There is an Aluminum crush washer in place to reduce leaks. Simply replacing the washer may help fix your leak. In extreme cases the sealing surface needs to be restored (sanded flat) to effectively seal again.
The piston may need to be re-primed after taking it apart. Bently has the easy to follow procedure
Ralph
It's holding a spring and piston that pushes against the tensioner rail. Remove the bolt (nut?, cover??) and the spring will fly if you're not careful and ready to catch it
There is an Aluminum crush washer in place to reduce leaks. Simply replacing the washer may help fix your leak. In extreme cases the sealing surface needs to be restored (sanded flat) to effectively seal again.
The piston may need to be re-primed after taking it apart. Bently has the easy to follow procedure
Ralph
Last edited by Ralph in Socal on Mon Aug 15, 2022 8:11 pm, edited 1 time in total.
There is a very fine line between "Hobby" and Mental Illness.
85 635csi Zinno Auto
84 528i Euro
83 635 Euro Arktik
81 528i Kastanien 5-speed
88 528e Bronzit (Granpa Car)
86 535i Auto (For Sale)
81 633 csi (retired)
85 635csi Zinno Auto
84 528i Euro
83 635 Euro Arktik
81 528i Kastanien 5-speed
88 528e Bronzit (Granpa Car)
86 535i Auto (For Sale)
81 633 csi (retired)
-
- Platinum Member
- Posts: 3710
- Joined: Thu Apr 08, 2004 3:24 pm
- Location: Gilroy (SF Bay Area) CA
Re: Oil leak from mystery bolt
Doh
I didn't look at the arrow in the second screen capture
Yes, plus one, timing chain tensioner
I didn't look at the arrow in the second screen capture
Yes, plus one, timing chain tensioner
Bobbo
1980 633 CSi Cypress Green/Pearl Beige
2017 X5 M Sport Xdrive 35i Carbon Black/Ivory White
2005 330 Ci ZHP Cabrio Imola Red/Bone/Black
Re: Oil leak from mystery bolt
Like said above, it’s probably not actually leaking from there.
You might get lucky and it is . . . but highly unlikely.
You might get lucky and it is . . . but highly unlikely.
-
- Posts: 56
- Joined: Tue Feb 11, 2020 12:31 am
- Location: pensacola
Re: Oil leak from mystery bolt
I've had the same leak before. It may be the valve cover gasket, or upper timing cover. The motor lays over at an angle, and often the leaks shows up on the timing tensioner, but is actually from above somewhere.
- 86_6series
- Platinum Member
- Posts: 1069
- Joined: Mon Apr 02, 2007 10:08 pm
- Location: West Nyack, NY
Re: Oil leak from mystery bolt
+1 on the oil leak. I also thought it was the crush washer on the tensioner bolt.
Wound up being a loose bolt on the timing cover. The fan blowing caused the oil to accumulate
on the tip of the tensioner housing. After installing 3 washers, I finally checked and found the loose bolt.
Bob V
Wound up being a loose bolt on the timing cover. The fan blowing caused the oil to accumulate
on the tip of the tensioner housing. After installing 3 washers, I finally checked and found the loose bolt.
Bob V
86-635CSi
96-MB C220 SOLD
98-740i
71-Continental MK3
96-MB C220 SOLD
98-740i
71-Continental MK3
Re: Oil leak from mystery bolt
Many thanks folks, won't be touching that any time soon!!!
1986 Zinnober 635 CSi
-
- Posts: 6
- Joined: Fri Nov 11, 2022 7:51 pm
- Location: York, PA
Re: Oil leak from mystery bolt
Just read this thread.
I have the same drop of oil on the same tensioner/spring/piston retainer bolt. Will look at the timing chain cover bolts first, then maybe the valve cover bolts for good measure. General wipe up all around. Keep an eye on things.
Thanks guys, many thanks -
I have the same drop of oil on the same tensioner/spring/piston retainer bolt. Will look at the timing chain cover bolts first, then maybe the valve cover bolts for good measure. General wipe up all around. Keep an eye on things.
Thanks guys, many thanks -