[850CSi]

Hey all,

Back when I did my oil pan gasket I found a broken off bolt thread in the pan. I couldn't find any obvious source on the bottom side of the engine.

I bring it up now because I've got my valve cover off and I'm trying to see if I can find the source or anything else that's amiss.

For reference, it looks like the threads are the same diameter & pitch as the E8 hex screw that holds the valvetronic motor in place (see photo).


Anything else I should examine while I have the valve cover off? I'm going to be swapping my ESS and spark plugs/coils as well.

(I've got an Aug 2008 build so I've been worried about head bolts but thankfully all 4 of the ones up front look great)

[IllSic_Design]

BMW had a vanos bolt recall, the bolts would loosen/back out/snap off.

https://www.e90post.com/forums/showthread.php?t=1095480

[e91Owner]

That looks like many etorx bolts on the e90... if you have the approximate length and exact head size, it will help you track it down. The obvious place a similar length one (just shy of 2 inches-43mm) is used is on the lower right of the oil filter housing for you were looking at it from the left side of your car.

https://www.realoem.com/bmw/enUS/sho...67#11427525334

The bolt that you have photographed is not one of the bolts mentioned in the recall above. The TSB had good photos of them... they are big T45 bolts where the heads sheared off, not etorx.

[850CSi]

Originally Posted by IllSic_Design

BMW had a vanos bolt recall, the bolts would loosen/back out/snap off.

https://www.e90post.com/forums/showthread.php?t=1095480

Think that's on later years; camshaft bolts look good on my car.

[850CSi]

Originally Posted by e91Owner

That looks like many etorx bolts on the e90... if you have the approximate length and exact head size, it will help you track it down. The obvious place a similar length one (just shy of 2 inches-43mm) is used is on the lower right of the oil filter housing for you were looking at it from the left side of your car.

https://www.realoem.com/bmw/enUS/sho...67#11427525334

The bolt that you have photographed is not one of the bolts mentioned in the recall above. The TSB had good photos of them... they are big T45 bolts where the heads sheared off, not etorx.

Yeah, the problem is I never found the bolt's head anywhere, just the broken off thread that I photographed (puzzling...). And I don't even know how much of it broke off, so I don't know how long it is either!

As depicted, it looks very similar to the E8/M6 screws from the valvetronic motor 07129902813.

But most places I'm finding a screw of that size are on the outside of the engine and I don't see any obvious way a part of the thread could've wound up in my oil pan.

Anything I should be looking at with the timing guides, camshafts, etc?

[e91Owner]

Originally Posted by 850CSi

Yeah, the problem is I never found the bolt's head anywhere, just the broken off thread that I photographed (puzzling...). And I don't even know how much of it broke off, so I don't know how long it is either!

As depicted, it looks very similar to the E8/M6 screws from the valvetronic motor 07129902813.

But most places I'm finding a screw of that size are on the outside of the engine and I don't see any obvious way a part of the thread could've wound up in my oil pan.

Anything I should be looking at with the timing guides, camshafts, etc?

Ah... I see. I thought you were photographing the two halves of the bolt. The valvetronic motor bolts are M6. Some other M6 ones are the vanos solenoid bolts. It also helps to know if they are magnetic as aluminum bolts would be attached to the block.

It's really a needle in a haystack, though. There are tons of M6 bolts.

[850CSi]

Yeah, that's what I figured -- a lot of similar bolts in there. And more than likely something near the bottom that I missed.

Anything else I should look at before I close it back up? My valvetrain looks good to my untrained eye but I don't think I'd notice if anything was actually wrong!

[850CSi]

Photo

[e91Owner]

Originally Posted by 850CSi

Yeah, that's what I figured -- a lot of similar bolts in there. And more than likely something near the bottom that I missed.

Anything else I should look at before I close it back up? My valvetrain looks good to my untrained eye but I don't think I'd notice if anything was actually wrong!

Were you just changing the VCG or did you do anything else?

Not much preventative in there, although I'm sure someone could think of something. The chain guide looks good which has had some instances of failure and all of those bolts in the TSB that doesn't apply to your car are there. Can't really think of anything else I've done with that off other than replace failed stuff on my N52s, although you might just check the condition of your ESS, since it's right there and I'm sure you don't want to be pulling that cover off again any time soon.

[bluewater328]

Could be a head bolt - tho most of those are just the sheared off tops. Do a search for head bolts and you'll see the history. Lots of people find the external one by the OFH broken and you're supposed to go check the other three inside the valve cover. Two in the front and one in the rear. Pelican parts has a nice article on it and shows you where to check — replacement is a different story and prob requires a mechanic:

https://www.pelicanparts.com/BMW/tec...lt_Testing.htm

Vanos bolt possible too

[850CSi]

Originally Posted by e91Owner

Were you just changing the VCG or did you do anything else?

Not much preventative in there, although I'm sure someone could think of something. The chain guide looks good which has had some instances of failure and all of those bolts in the TSB that doesn't apply to your car are there. Can't really think of anything else I've done with that off other than replace failed stuff on my N52s, although you might just check the condition of your ESS, since it's right there and I'm sure you don't want to be pulling that cover off again any time soon.

Thanks.

Gasket, coils, spark plugs, and ESS (no faults, but I found some oil when I removed the connector from the old one) was the plan.

I've just swapped the new ESS in; as I was doing so I noticed some north/south play in the chain guide. Normal?

Video:

[850CSi]

One additional piece of information: the broken thread I had found in the oil pan DOES stick to a magnet.

Originally Posted by bluewater328

Could be a head bolt - tho most of those are just the sheared off tops. Do a search for head bolts and you'll see the history. Lots of people find the external one by the OFH broken and you're supposed to go check the other three inside the valve cover. Two in the front and one in the rear. Pelican parts has a nice article on it and shows you where to check — replacement is a different story and prob requires a mechanic:

https://www.pelicanparts.com/BMW/tec...lt_Testing.htm

Vanos bolt possible too

Yeah thankfully all four head bolts in that area look good. I poked at the heads with a pick and no movement.

[e91Owner]

Originally Posted by 850CSi

Thanks.

Gasket, coils, spark plugs, and ESS (no faults, but I found some oil when I removed the connector from the old one) was the plan.

I've just swapped the new ESS in; as I was doing so I noticed some north/south play in the chain guide. Normal?

Video:

Originally Posted by 850CSi

Thanks.

Gasket, coils, spark plugs, and ESS (no faults, but I found some oil when I removed the connector from the old one) was the plan.

I've just swapped the new ESS in; as I was doing so I noticed some north/south play in the chain guide. Normal?

Video:

Honestly, other than looking at it, I don't think I've ever wiggled it to see any play unless you see excessive wear on the track, it's probably GTG.

[850CSi]

Yeah I wasn’t intending to, I just discovered it sort of accidentally as I was getting the ESS out.