M62TU camshaft bearing cap problem.

[hrach1]

Hi guys
Few days ago I smelled burning oil and noticed some smoke coming from the engine area. I popped the hood and discovered that oil is leaking from the valve cover gasket and dripping on the exhaust. I checked the valve cover nuts and sure enough they weren’t tight and couldn’t be tightened because they were stripped by some incompetent mechanic.

I looked around the web and couldn’t find new or used cam shaft bearings to purchase so I decided to fix the threads with HeliCoils. I know that HeliCoils could potentially block the lubrication holes built into the camshaft bearing caps but I was using short HeliCoils and I thought I could fix the threads.

I fixed two of the caps properly without blocking the lubrication holes but I messed up the 3rd bearing cap. I used an electrical tape to mark the drill bit so I don’t drill too deep but somehow the tape had moved up and I ended up drilling little too deep and put a little hole on the bearing surface.

So my questions is that can I still use the same bearing cap? The hole edges are very smooth and it doesn’t look to me to scratch the camshaft. I have HeliColied the hole and installed the stud using red thread locker but O don’t want to install it until I’m sure it won’t cause problems.


See the pics.





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[jicaino]

Chamfer it and you'll be fine

[hrach1]

Chamfer it and you'll be fine

Thanks. It’s already chamfered. There are no sharp edges. I am just not sure if the red Loctite will be enough to hold the stud in place now that there is a hole under the stud.


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[jicaino]

Thanks. It’s already chamfered. There are no sharp edges. I am just not sure if the red Loctite will be enough to hold the stud in place now that there is a hole under the stud.


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It will suffice. Ask me how I know

Those are really hard to do by hand, the alloy is utter crap. I did this on one too.

[Jaaap]

Can you put threadlocker between the helicoil and the cap too?
That would eliminate another path for the oil(pressure) to escape.

[jicaino]

the oiler rails for the camshafs feed from that "leak" of oil pressure

there's 2 flat oil distribution rails bolted ontop of those caps before you button up the valve covers

[H3adBussa]

Hi guys
Few days ago I smelled burning oil and noticed some smoke coming from the engine area. I popped the hood and discovered that oil is leaking from the valve cover gasket and dripping on the exhaust. I checked the valve cover nuts and sure enough they weren’t tight and couldn’t be tightened because they were stripped by some incompetent mechanic.

I looked around the web and couldn’t find new or used cam shaft bearings to purchase so I decided to fix the threads with HeliCoils. I know that HeliCoils could potentially block the lubrication holes built into the camshaft bearing caps but I was using short HeliCoils and I thought I could fix the threads.

I fixed two of the caps properly without blocking the lubrication holes but I messed up the 3rd bearing cap. I used an electrical tape to mark the drill bit so I don’t drill too deep but somehow the tape had moved up and I ended up drilling little too deep and put a little hole on the bearing surface.

So my questions is that can I still use the same bearing cap? The hole edges are very smooth and it doesn’t look to me to scratch the camshaft. I have HeliColied the hole and installed the stud using red thread locker but O don’t want to install it until I’m sure it won’t cause problems.


See the pics.





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Why not get replacements from a junk yard? I've had to do it a couple times. Have a bag of them and two heads with them still on. You just have to make sure you get them from the same location that you need for your engine and install them in the same. Like, bank 1 intake 4 to bank 1 intake 4.

But the way you're doing it should work as well. I personally just see it as more of a risk.

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[TiagE39]

The bore that the threaded valvecover stud goes into has a grooved oil passage to lubricate the camshaft at that point. Threadlocker or helicoil will assuredly block it.

These studs are very delicate and are overtorqued very easily.

An alternate strategy is to pull extra intact cam bearing caps from a donor car. The line boring of the cam-way is to tight enough tolerances that caps may be shared between different cylinder heads. I know, technically this is breaking the rules, but there are many documented success stories of using this method and not damaging engine health. I ran into this same issue on my M60-530i-E34 and fixed it using this method. Make sure intake caps are swapped for intake caps and exhaust for exhaust. The exact placement number of the caps needn't match, but if it makes you feel better, go for it. M60 and M62 caps are exactly the same but M62TU caps should only come from an M62TU.

I can attest that in the entire time I had my 530i (I had to swap cam caps right after getting it due to oil leaks) it ran happily and did not glitter the oil.

I use the following torques on these engines. These are about the lowest you can go while still getting a good seal on the valve cover gasket (assuming a quality gasket in good condition):

11mm cam cap to cyl head - 15NM
10mm cap stud to oil rail - 12.5NM
10mm valve cover acorn nut to cap stud - 11NM

It goes without saying - use a quality, well calibrated 1/4" drive torque wrench.

[jicaino]

The bore that the threaded valvecover stud goes into has a grooved oil passage to lubricate the camshaft at that point. Threadlocker or helicoil will assuredly block it.

These studs are very delicate and are overtorqued very easily.

An alternate strategy is to pull extra intact cam bearing caps from a donor car. The line boring of the cam-way is to tight enough tolerances that caps may be shared between different cylinder heads. I know, technically this is breaking the rules, but there are many documented success stories of using this method and not damaging engine health. I ran into this same issue on my M60-530i-E34 and fixed it using this method. Make sure intake caps are swapped for intake caps and exhaust for exhaust. The exact placement number of the caps needn't match, but if it makes you feel better, go for it. M60 and M62 caps are exactly the same but M62TU caps should only come from an M62TU.

I can attest that in the entire time I had my 530i (I had to swap cam caps right after getting it due to oil leaks) it ran happily and did not glitter the oil.

I use the following torques on these engines. These are about the lowest you can go while still getting a good seal on the valve cover gasket (assuming a quality gasket in good condition):

11mm cam cap to cyl head - 15NM
10mm cap stud to oil rail - 12.5NM
10mm valve cover acorn nut to cap stud - 11NM

It goes without saying - use a quality, well calibrated 1/4" drive torque wrench.

Very good advice.
If you do helicoil, you need to insert a short helicoil down the bore past the oiling passage, and then relieve the threaded portion uptop with a metric counterbore, to assure no interference

[hrach1]

It will suffice. Ask me how I know

Those are really hard to do by hand, the alloy is utter crap. I did this on one too.

Thanks! I knew it should be ok but I haven’t done this before so I thought I ask. I’m going to remove the rest of the studs and put a red Loctite on them so this doesn’t happen in the future. Of course I’ll apply the Loctite in a way that wouldn’t block the oil passage. Maybe I’ll discover some more caps with stripped threads that needs to be fixed. Thanks again


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[hrach1]

Why not get replacements from a junk yard? I've had to do it a couple times. Have a bag of them and two heads with them still on. You just have to make sure you get them from the same location that you need for your engine and install them in the same. Like, bank 1 intake 4 to bank 1 intake 4.

But the way you're doing it should work as well. I personally just see it as more of a risk.

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Thanks. I will look some more around and see if I can find a car with M62TU in a junkyard near me.


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[hrach1]

Very good advice.
If you do helicoil, you need to insert a short helicoil down the bore past the oiling passage, and then relieve the threaded portion uptop with a metric counterbore, to assure no interference

Yes, that’s what I’ve exactly done. I used short HeliCoils but what I didn’t do is to get rid of the threaded portion on the top. That sounds like a good idea. Thanks.

Another problem I faced is to tap the hole straight. I used drill press to drill the hole straight but the material is soft and make it hard to tap straight, specially that the top portion of the threads includes the oil passage hole which makes the tap to wobble a little bit until it reaches the hole wall bellow the oil passage.

I didn’t notice that the threads weren’t straight until I screwed down the stud. What I ended up doing is to bend the stud a little so the portion sticking out of the cap was straight. For the rest of the caps I used a long 1/4 socket and inserted one end on the top of button that releases the socket from the wrench and then I lowered the drill press bit into the other end of the socket which helped me to keep the tap and the wrench straight. Like so (see the pic)



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[hrach1]

It will suffice. Ask me how I know

Those are really hard to do by hand, the alloy is utter crap. I did this on one too.

I know what you mean!
But im getting a hang of it.


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[hrach1]

The bore that the threaded valvecover stud goes into has a grooved oil passage to lubricate the camshaft at that point. Threadlocker or helicoil will assuredly block it.

These studs are very delicate and are overtorqued very easily.

An alternate strategy is to pull extra intact cam bearing caps from a donor car. The line boring of the cam-way is to tight enough tolerances that caps may be shared between different cylinder heads. I know, technically this is breaking the rules, but there are many documented success stories of using this method and not damaging engine health. I ran into this same issue on my M60-530i-E34 and fixed it using this method. Make sure intake caps are swapped for intake caps and exhaust for exhaust. The exact placement number of the caps needn't match, but if it makes you feel better, go for it. M60 and M62 caps are exactly the same but M62TU caps should only come from an M62TU.

I can attest that in the entire time I had my 530i (I had to swap cam caps right after getting it due to oil leaks) it ran happily and did not glitter the oil.

I use the following torques on these engines. These are about the lowest you can go while still getting a good seal on the valve cover gasket (assuming a quality gasket in good condition):

11mm cam cap to cyl head - 15NM
10mm cap stud to oil rail - 12.5NM
10mm valve cover acorn nut to cap stud - 11NM

It goes without saying - use a quality, well calibrated 1/4" drive torque wrench.

Thanks
You’re absolutely correct but I have used short HeliCoils that wouldn’t block the oil passage hole. I also made sure that the thread locker was applied at the tip of the stud and was very careful not to touch the oil passage hole. I also made sure that I applied just enough Loctite that it wouldn’t ooze up into the oil passage. And finally I used high pressure air to blow the oil passage hole from the other side of the hole to to blow out any Loctite that possibly got into in the oil passage.

I’m still going to look for cam caps from a M62TU donor engine. One of this forum members was very nice and offered to send me cam caps from a M62 engine. I was going to get it but changed my mind after reading your post about cam caps for M62TU must come from a M62TU donor.
Thanks again for all the info


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[djhagen]

Just stripped one of my intake cam caps, closest to the firewall. Any donors out there?

[djhagen]

I'm an expert on this now ... repaired three of them and have it down to about 30 min.

[Keith Nguyen]

Would you mind sharing your fix? I’m working on a 4.6 (m62tub46) and I’m not sure if a donor cap will work in my case. Looks like the last person in here stripped the stud. I found a grommet misting oil which led me to this mess.

[ex1988shark]

Anyone know how much stud should be left stuck out of the cap? I need to replace almost all of them.

[jicaino]

Anyone know how much stud should be left stuck out of the cap? I need to replace almost all of them.

Last time I repaired all.of the exhaust cam caps u left exactly 19mm of stud protruding from the cap.