BMW N62 valve guide replacement

[flashcoder]

Hello, I am new here.

Have this notorious BMW Valvetronic V8 engine (N62) burning oil (typical problem with these) that I am rebuilding (sort of rebuilding, not planning to touch the bottom). Rebuilding just the heads because most valves had very noticeable side-play. Certainly over the spec which is like .25mm. Originally was planning just to replace the valve guide seals but obviously the problem is much deeper and changing just the seals will not fix the real reason why it burns oil.

Ok so I bough new valve guides OD=10.03mm ID=6mm (CANYON) these engines have bronze alloy guides. Bough a set of new exhaust valves (they look much worse than intakes) because they were not too expensive. Next I have a set of correct Neway cutters 15 45 60 and two solid pilots 5.98mm and 6mm. I also have ordered (still waiting to come in) the valve guide removal and installation tool from Amazon, sold by TOKAR tools (here is the link https://www.amazon.com/dp/B08Q4FZSBB), this might be an overkill tool but it looks like a proper tool and I just have no idea how difficult the removal and installation will be (never done it before) and if I will not need it then I might just return it. It might be sufficient to use the traditional head heating and dry ice method to get the valve guides back. But we will see.

Now the question that I dont understand completely is the reaming part of the guides. I would not want to go past 6mm ID, that is the factory spec. I would rather aim for 5.99mm undercut and then hone is that is necessary at all. The new exhaust valves measured with caliper: 5.96mm - 5.97mm tops, the intakes (which I am reusing) are 5.97mm - 5.98mm max.
What would be your recommendation how handle the reaming part? What size reamer to pick in order to not overshoot? From what I understand while reading about reaming bronze guides is that they usually come out a little undercut like 1/2 thou. So my choice was K-Line KL1110NB .2362 (6.0mm) bronze valve guide reamer (also will use their bronze reaming oil).

Do I need anything else? The hone procedure? How to choose the hone and which one should I buy?

Any advice regarding this project is much appreciated.

[68corvette]

If you are going to ream any more 6.0mm guides in future, you might want to look for Carbide instead of HSS.
https://goodson.com/collections/reamers ... de-reamers

Carbide cutters will produce straighter holes, cut better and will last longer.

6.00mm will cut a slightly smaller hole, depending of the material hardness.
Simple Flex Hone will clean it with few passes to 6.00mm size.
Or if you want to invest to future, you can check Sunnen valve guide hone set.

[flashcoder]

Thanks for reply! Yes I already looked ar Goodson, they are on the expensive side.. $200 for a reamer is a bit steep given that I am not planning to make this a business. Ok I have 2 BMWs with this N62 V8 engine and the other probably has the same issue or will have it sometime in the future. The HSS type reamer for Bronze should last to get 64 valve guides (2x 32 per engine) done?
Sure I would like to get carbide reamer if it lasts 10x longer, it is always better to have reliable tools. So I found these guys -KPMI (Kibblewhite Precision Machining - "manufacuring high performance valvetrain for 80 years") and this is their catalogue:
http://media.kpmi.us/PRO_00110_ValveGuideTools.pdf

As you can see the carbide reamer and hone tool together is well under $200. Yes those are not the spiral type reamers but straight 6 flute type and designed for bronze allow guides. The spiral type probably is somewhat better but if the hone will be used anyway then it should be fine?

Yeah about the cutting oil, I could order one from K-LINE or use the famous Tap Magic or just go with ATF, btw the one Goodson sells is as red as ATF (maybe they just sell ATF ). Does it make a big difference what cutting oil is used?

[dannobee]

Yup, use a flex hone (aka ball hone). Sneak up on the size, and very carefully, as it's easy to remove too much material. Chuck the hone up in your drill and hone for a couple of seconds, then clean and recheck the size. Total hone time will likely be under 10 seconds for each guide. Possibly well under. Like I said, go slow and measure often with your snap gauge or mark the depth on your tapered pilot with a sharpie.

One thing that you need to be careful with when using the Neway cutters is that the motion of turning the cutter with your hand will flex the pilot, especially on a small pilot like 6mm. Use your concentricity gauge early and often to ensure that you're cutting the seat straight.

[sbcharlie]

Good luck.

[HDBD]

You can get the guides in without that tool. The heat plus chill method is prefered. Heat the head before pounding the old guides out. Sizing of the OD will depend on what comes out and how they fit, measured with precision tools. The HSS reamer will work for a set or two of heads. Ball hone if needed and use a split ball and mike to measure. A mike should be used to measure valve stems not calipers. And Neways, in my opinion, have no place around a high performance european V8. I would replace all the valves with OEM or better.

[MotionMachine]

Neway, ball hone, hss reamer? On a 32V BMW??

[HDBD]

I see your point, really if you need to have the seats done by a professional shop the rest all becomes irrelevant, they should do the whole job.
Otherwise sounds like a bit of a cluster with less than a good result.

[BillK]

Neway, ball hone, hss reamer? On a 32V BMW??

Was just thinking the same thing

[flashcoder]

Neway, ball hone, hss reamer? On a 32V BMW??

Aand? What is your point? HSS reamer will not last all the 32 valves? Ok will get the carbide reamer. That is why I am asking here because I have no experience with these type of repairs.

About the ball hone, as far as I understand it is used only just enough to even out the tolerance (if any) and clear up the schuffs from reaming. Alot of rebuilders dont even use a hone just slap it all together and never had issues (given the clearances are good).

I dont think these engines are much different or require higher precision. This aint space technology, just a regular V8 with 4 valves per cylinder and crappy designed rockers trying to wobble them all around the place.. And then someone had a bright idea to smash Valvetronic on top of this mess. Well that is probably the only thing that requires a bit of attention when cutting valve seats, it is probably important to watch the the valve height. But then again if the seat ends up too deep then just trim the valve. Obvioulsy I am simplifying things, not trying to say that this is a piece of cake job but in principle there is nothing much different from any other engine. Or am I wrong?

Lets not forget, the engine was running FINE (except the oil burning part) with tolerances way out and crooked worn valve seats with valves bouncing all over the place. So just doing a careful job with the regular tools should not make it worse than that

[flashcoder]

I see your point, really if you need to have the seats done by a professional shop the rest all becomes irrelevant, they should do the whole job.
Otherwise sounds like a bit of a cluster with less than a good result.

Exactly, no good machine shop will agree to do a valve job on worn guides because it makes no sense. And if machine shop does the whole job including the guides then it gets $$$$, imho the car is not worth it. Here in LA shops like to ramp the prices up as soon as its a BMW or anything European. Most of them dont even want to touch that.

[HDBD]

Find a shop in Bakersfield, or Acton , jk.

[sbcharlie]

I have worked on these heads. The problem always was the valve guides wearing out. These heads are quite a challenge. Use Fred Flinstone Neway cutters are a joke. Remember when you destroy the head there a bit pricy.

[BILL-C]

Badly worn guides usually result in seats worn off center. It takes a lot of finess to fix that with neway seat cutters. Good luck!Those tiny ball hones usually wear out in a hurry and are not intended for significant material removal. Do you have a valve grinder to tip the valves? Valve spring tester and shims? How are you going to clean the heads properly? Do you have access to a head resurfacer? It would be crazy to not resurface the heads while they are off. You picked one heck of an engine to do your first valve job on!

[flashcoder]

Badly worn guides usually result in seats worn off center. It takes a lot of finess to fix that with neway seat cutters. Good luck!Those tiny ball hones usually wear out in a hurry and are not intended for significant material removal. Do you have a valve grinder to tip the valves? Valve spring tester and shims? How are you going to clean the heads properly? Do you have access to a head resurfacer? It would be crazy to not resurface the heads while they are off. You picked one heck of an engine to do your first valve job on!

Youre correct, I have noticed exactly that, I tried to make photos but it is hard to see that in photos. I will give another try and post here. I do understand that Neways are oldschool tools and need alot of finess, will try to do it very carefully, that is why I got solid pilots, not going to use power tools just manual careful approach. Dykem and check often that cutter touches full circle when turned with just two fingers, sort of that is the plan.

I dont have the valve tip grinder. I am goin to use new exhaust valves (made in Germany by CRP). Intake valves will go to machine shop for resurfacing. Why are the valve tips important? Is that specifically for this engine because of Valvetronic? I was thinking that valve height could be an issue because of that Valvetronic but then again the hydraulic lifters should even things out if the valve height is within the spec.

Valve spring tester, no I dont have that neither. But why? Is that because springs can go crooked over time?? I have had several BMWs with older inline 6 engines where the hydraulic followers are pushing on valves precisely on the same axis and valve wear is never an issue, so I can conclude that springs themselves can not create forces that are causing premature valve guide wear.

The heads they are already pretty clean just a few spots of carbon in exhaust ports. I am using Berrymans Chem Dip for to get the carbon out. Not dipping entire head in it just a brush and patience. I know sounds insane. I just got the parts washer but not sure which solvent to use, some of them can damage aluminum. Thinking about getting PSC-1000 from Tractorsupply, I have one store about 1 hour away from where I live..

Sure the heads will be resurfaced by machine shop as soon as the valve job will be done. Before the assembly of the heads.

I know this engine isnt the best candidate to start with but hey older BMW inline 6 engines that I was dealing with before never had such issues with worn guides. I have taken apart 200K+ miles engines and got away with just a refresh like a basic valve job which any machine shop can do. This engine is way more expensive to do. And I am willing to try. Worst case scenario - I will go to Pick n Pull and get replacement heads, junkyards are full with BMWs with these V8s exactly because of these oil burning problems which then later lead to catalytic converter efficiency issues and once it hits that problem no-one is going to put that money in such an old car and they all end up in junkyards. Kind of sad. I like the car and want to try to save it.