Another HG replacement thread, questions as I find them...

**aeronaut** · 03-25-2018, 08:31 AM

Hey folks, hoping to do a 'quick' head gasket replacment. 95 S50. Hope this thread can leverage the knowledge on this forum. So, questions as I come across them.

My vanos timing tools (cam lock, TDC pin, vanos rotote) got delayed in delivery, but I'd REALLY like to get started today and even get the head off if I can. So, question 1.
It's not clear to me why I need to have any of the above tools to remove the head. Is it because the Vanos itself must be in a particular timing to remove the vanos?

**pbonsalb** · 03-25-2018, 09:46 AM

You don’t need cam timing tools for removal.

**aeronaut** · 03-25-2018, 09:51 AM

Thanks, that makes sense. Yaaa...can get started today!

**spyderg0d** · 03-25-2018, 09:54 AM

It depends on if you plan on removing the cams out of the head or pulling the head with the camshaft off.
the lock tool helps keep the cams from turning themselves from the valve springs force and causing a open valve from contacting either a tdc piston, or any other object while head removal or setting it down. I usually pop the camshaft off before I remove the timing chain, this prevents the cams from rotating to make valve contact. then increasing the primary timing gears releases the camshaft without any worry of activating a valve.

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*then involving the primary timing gears

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*then unbolting..... I hate autocorrect

**aeronaut** · 03-25-2018, 10:03 AM

Originally Posted by spyderg0d

It depends on if you plan on removing the cams out of the head or pulling the head with the camshaft off.
the lock tool helps keep the cams from turning themselves from the valve springs force and causing a open valve from contacting either a tdc piston, or any other object while head removal or setting it down. I usually pop the camshaft off before I remove the timing chain, this prevents the cams from rotating to make valve contact. then increasing the primary timing gears releases the camshaft without any worry of activating a valve.

- - - Updated - - -

*then involving the primary timing gears

- - - Updated - - -

*then unbolting..... I hate autocorrect

Good tip, makes sense. I've done this many times on (non vanos) OHV motorcycles, and use the same technique.

**pbonsalb** · 03-25-2018, 11:17 AM

I always pull the cams, but there is a method for leaving them in. If I recall correctly, you pull the vanos and exhaust sprocket to disconnect the bottom end from the top end then you rotate the bottom end about 45 degrees off TDC so no 2 pistons are all the way up and contact is not possible.

The special tool sprocket rotator is useful when removing (or installing) vanos but you can do the job without it using a screwdriver blade to move the exhaust sprocket. Just be careful it to slip and break the old brittle plastic upper tensioner assembly.

**spyderg0d** · 03-25-2018, 06:36 PM

eh.. they say that bob. what that doesn't account for is someone trying to lug up the 75lb head with cams on, then realising it's too heavy and then dropping it back down while holding it onto the block.. effectively crambing the valve sideways. lol. or it gets caught on a hose that wasn't undone, or a still plugged in sensor. I agree. I Always remove the camshaft before head removal too.

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and as far as the timing sprocket removal, I loosen the exhaust timing gear with a 10mm wrench before removing the timing chain. I rotate the crank to gain access to the other camshaft gear bolts. Then I set at tdc.

**XnWarden** · 03-25-2018, 06:43 PM

Originally Posted by spyderg0d

75lb head... too heavy

Get your weight up then little man

Sent from my VS987 using Tapatalk

**aeronaut** · 03-26-2018, 08:00 AM

Great info folks, thanks.

Next question....95 S50, VIN shows build date of 09/95.

IIRC, these engines had a failure prone "valve retainer". Including my build date? And, specifically, which part(s); 6, 8, and/or 9?
(Haven't decided if I'll replace, but knowledge is good

)

Screenshot from 2018-03-26 07-40-20.png

**pbonsalb** · 03-26-2018, 08:04 AM

The S50 has retainers known to crack — now is the easiest time to replace. Also the vanos intake gear stack lacks a spring shim that reduces rattle but requires longer studs to fit the shim should you decide to add it. You could instead put a beisan anti rattle washer into the vanos unit itself.

**aeronaut** · 03-26-2018, 08:10 AM

Besian vanos repair/rattle kit ordered yesterday.

So both upper and lower "spring plates", 6 & 8, as BMW calls them?

**pbonsalb** · 03-26-2018, 09:51 AM

I don’t know. It’s the retainers that seem to be the issue not the seat locators.

**spyderg0d** · 03-26-2018, 01:43 PM

Not me good sir. I was referencing the modern 18yo first car diy'er.

**aeronaut** · 03-28-2018, 07:33 AM

Originally Posted by pbonsalb

I don’t know. It’s the retainers that seem to be the issue not the seat locators.

My confusion is around what is commonly called retainers, and what BMW calls a "lower spring plate" and an "upper spring plate", one each per valve. My assumption (there's that word) is that the crack prone 'retainers' everyone talks about is the "upper spring plate" (I don't believe the lower spring plates have much tension on them). But, I haven't found anything to confirm that.

EDIT: And, wonderful youtubes...I've heard it's the keepers that crack. UG.

**pbonsalb** · 03-28-2018, 07:52 AM

Yes, the uppers are the retainers.

**aeronaut** · 03-28-2018, 02:25 PM

Looks like classic #6 HG failure.

oGg7hgy.jpg

XQhbZRN.jpg

Almost ready to go to the machine shop

6W7PRH0.jpg

Completely ignoring my orginal intent of 'minimal' headgasket replacement, I emailed Riot Racing to see if they had S50 regrinds in stock. Thankfully, they do not.

**aeronaut** · 03-28-2018, 02:39 PM

Ok, I've only talked to one machine shop (one recommended by a good local BMW independant). But I feel like I didn't ask enough or the right questions.
They offered to clean, pressure test, and measure flatness. Sounded good to me.

What's the short list of questions to ask? Any specific machining process I should be asking for?

FYI, my very recent leakdown showed 96-99% across all cylinders. So I haven't even considered a valve job.

I'm just kinda rethinking what else to do while in here after investing 6 hours to get to this point.

**jc43089** · 03-28-2018, 04:25 PM

Pressure test is important. Look carefully for cracks from the exhaust valve seats to the coolant ports.

**pbonsalb** · 03-28-2018, 05:11 PM

Ask shop what it charges for multiangle valve job. Usually it’s the best bang for the buck in head work.

I always ask the shop to check the head - are guides good? And clean, pressure test and deck. Some cracks are hard to see, which is why the pressure test is worthwhile. But inspect yourself if you want to do some cleaning yourself. You can pay shop to disassemble and hot tank but don’t have to.

**aeronaut** · 03-28-2018, 05:53 PM

Thanks folks. I'll have shop clean, pressure test, and inspect. I'll add a Q about cost of multiangle valve job, makes sense at this point.

Is it standard procedure after a HG failure to just get the head resurfaced, or will they measure flatness / inspect, then make a decision?

**pbonsalb** · 03-28-2018, 08:41 PM

Always gets resurfaced. Just a question whether it’s .002 or .005 or .008. Hopefully .002.

**aeronaut** · 03-29-2018, 02:55 PM

Called three machine shops, visited two, and easy pic of one. It's amazing what difference it makes when the person behind the counter actually feels excited about their work, and it's the owner.
Clean, pressure test, inspect, deck, and valve job.

**aeronaut** · 04-04-2018, 03:04 PM

Waiting for machine shop, so doing odds and ends. Block/piston clean up. I'm trying to balance removing all the gunk against being too abrasive:

dbAueZx.jpg

6ctneuR.jpg

VOd72lm.jpg

Any guess as to what caused this? Maybe an electrode off of a spark plug at some point in its life? 2 pistons have similar dings.

EqSMVuE.jpg

**spidertri** · 03-29-2019, 10:59 AM

Sorry to bump a year old thread, I'm going through this now. What did you do to get the block surface to that point? I've got mine smooth but I have areas that are stained/carbon build-up and they're being stubborn coming off. I've been using brake cleaner and fresh razor blades but it's slow going. Trying to keep abrasion down and keep stuff from going into the ports.

**aeronaut** · 03-29-2019, 03:24 PM

Originally Posted by spidertri

Sorry to bump a year old thread, I'm going through this now. What did you do to get the block surface to that point? I've got mine smooth but I have areas that are stained/carbon build-up and they're being stubborn coming off. I've been using brake cleaner and fresh razor blades but it's slow going. Trying to keep abrasion down and keep stuff from going into the ports.

I don't quite remember. I bought some special (expensive) stuff, but it was no better or worse than WD40 and/or brake cleaner. The GOOD stuff is no longer available..too DANGEROUS. lol.