BMW e30 Cylinder Head rebuild

[86911TLCAB]

So I am taking the plunge and attempting to rebuild a cylinder head. have a couple of questions:

1. Valves--I have 5 bent exhaust valves and 1 bent intake valve. the valves are obviously bent at the head of the valve, but the stems seem ok. when I put a good valve into the same cylinder there is little to no play (equal to the valves that are not bent). i am presuming there isn't an absolute need to change out the valve guides as long as there is no play. True...or false?

2. Some of the videos i have watched show each valves spring/keepers/etc being kept together. Does this make any difference?

3. I have some very slight scoring on one of the camshaft journals (proper terminology). can this be removed with light polishing with 220 or higher sandpaper?

4. The head i was given (thank you Jeff/Hoophead) is really clean and looks great. I will likely take it to a machine shop just to verify it isn't warped and press on to put it back together. Is there a benefit to having it chemically cleaned?

am sure there will be other questions and any assistance is always appreciated.

[cmartin]

I would have the machine shop clean it up do a valve job and then bolt it in and go.

[86911TLCAB]

got that...but the fun part for me is learning how to take it apart, have it checked and put it back together..might mess it up, but then thats all about learning how to do it...i am not up for throwing 300 bucks at this only to bolt it back in...

So I have the head completely disassembled and will take it to a machine shop to verify it is not warped...and then need to buy some valves...and put it all back together...

still interested in any thoughts on the valve guides and the light scoring...the journal that is scored, has matching scoring on the race...i have read that some light scoring is not going to hurt anything...suppose the machine shop can help answer that also??

Is this what is referred to as doing the "top end"?

thanks...

[Trak Ratt]

Chemical cleaning prolly not necessary
got that...but the fun part for me is learning how to take it apart, have it checked and put it back together..might mess it up, but then thats all about learning how to do it...i am not up for throwing 300 bucks at this only to bolt it back in...

So I have the head completely disassembled and will take it to a machine shop to verify it is not warped...and then need to buy some valves...and put it all back together...

still interested in any thoughts on the valve guides and the light scoring...the journal that is scored, has matching scoring on the race...i have read that some light scoring is not going to hurt anything...suppose the machine shop can help answer that also??

Is this what is referred to as doing the "top end"?

thanks...Light scoring is normal (cold start ups) but bent valves could also be culprit. I suggest having it checked for cracks (don't recall name but 3 cocktails to thee wind). I bent some valves on a 3.2 motor and they hairline cracked 2 of the heads. Lots of good books and interweb articles on do'n the "top end"

[HughA44s]

Had a timing belt break on a 944 years ago and went through this process. I was told that anytime you replace a valve they need to grind the valve seat to match the new valve which needs to be done to a bear head. On one of the heads I had done the play was acceptable on the intake and only needed to replace the exhaust side guides which were out of spec. It is really a case of having it looked at. Also, I have had issues getting an Al head (and head-gasket) to seal with the block without having it fly-cut even though the head was not warped. At issue is the ability of the head-gasket to compensate for the ripple or waviness of the head surface. I had to pull the head back off and pull the motor, have the block and head surfaced before I could get a good seal. I did a 944 head gasket replacement for a friend of mine's 944 and we had the head fly cut and had good results on the re-install. So I am with CMartin - Take the head to a machine shop and bring home a bolt on ready head. Good luck with this rebuild.

[Trak Ratt]

Had a timing belt break on a 944 years ago and went through this process. I was told that anytime you replace a valve they need to grind the valve seat to match the new valve which needs to be done to a bear head...Disagree! on reasonably low mileage engines you don't need to recut the valve seats. Unless doing a 3 angle or performance rebuild.

BUT you do need/should lap your valves so they mate up to the seats anytime you have the head off. And don't forget the have the valve spring tension checked along with 10 dozen other things. More $$$ but my own experience w/Porsche AC engines is the rockers should be replaced so bet BMW has similar weak links ;) Did you get Dempsey's BMW book?

[HughA44s]

Dave,

Point taken - If I replace the word grind with lap I think we are in agreement. Also, I did a 3-angle on the head each time I had heads rebuilt. Also agree with the valve spring tension check.

[Trak Ratt]

Cool, and as you obviously know the valve seats are replaceable on most engines. Re cutting every time just means more work in fitting valves and eventually requires them to be replaced ($$$). Overall valve lengths should be check anyway as part of any rebuild and cutting the seat just means more may have to be taken off stem to keep everything in spec.

[onboost]

So I am taking the plunge and attempting to rebuild a cylinder head. have a couple of questions:

4. The head i was given (thank you Jeff/Hoophead) is really clean and looks great. I will likely take it to a machine shop just to verify it isn't warped and press on to put it back together. Is there a benefit to having it chemically cleaned?

am sure there will be other questions and any assistance is always appreciated.

Tito,

You should have the head both pressure & checked for warpage..

You may want to talk/take it to Pete @ J & F Motors.. 703-671-7757
4064 S. Four Mile Run Drive, Arlington, VA

I have used him for all my BMW machine work as well as some Porsche head work, case cleaning etc.. Just finishing-up 3.5 engine re-furb for and old Racing Dynamics car.. Pete did all the machine work, including the head except the port work.

Paul-

[86911TLCAB]

All information appreciated....my plan is to take the head to the machine shop and verify it is not warped and the clean up job is sufficient to mate to the engine block.

then will bring it home and lap the valves and put it all back together. Would appreciate anyone who might be willing to look at the final product and make sure i didnt do anything wrong.

I suppose the machine ship can check spring tension, but is there a tool for doing that which is easily available or best to just ask the shop to verify.

getting this far has been quite interesting...after this still have to do the timing belt...so much work ahead.

Just bought a 94 E36 single owner car with 130k on it...something new to play with after this gets done...

[onboost]

Tito,

On the M20 engine you should not only do the timing belt but both the tensioner and the water pump as well.
Extra parts but you save labor. If your water pump fails in 6 months, you have to pull all of the front engine stuff, including timing belt to replace. Oh, and buy a factory pump.. the after market stuff has been junk lately.

[86911TLCAB]

Paul, thanks. Do you have a recommended brand for the head gasket? Other than the bmw one?

[Drscope]

I’m ALL for learning how to do things yourself, but the head may not be the place to start.

On the one hand, almost anything will work and run. On the other hand there are a few very important things that can lead to quick failure.

Unfortunately most home mechanics don’t have the tools necessary to do a correct job on a head.

Depending on condition, some seats may need to be cut. You want them all at the same depth, so often this means either cutting them all, or replacing a few seats. And every time a seat is cut, the valve moves farther up inside the head. This leads to shrouding of the valve and a drop in compression which are both bad for power output.

Then you also want all the stems at the same height. So you need some way to measure this and also to grind the stems so you have the correct finish when they are done. This is normally one of the functions of a valve grinding machine. If you don’t have a valve grinding machine, you aren’t going to get an adequate job.

The valve grinding machine is also what cuts (grinds) the angles on the valve as part of the valve job.

Spring tension needs to be set for each spring. Too light tension and you get valve float. Too heavy and it takes way more power to simply push the valve open. Both situations are extremely bad for the valve train components and lead to early failure.

There are special fixtures to test valve spring tension, and then you need a selection of shims to be able to adjust it. Don’t have the tool or the shims and it’s not getting set.

If you have the machine shop do it and then you put it all together, you have to make sure that you don’t get anything mixed up and each piece goes in the correct location.

While the pistons may go up and down and make the car move, the head is really where all the power comes from and where most of the important work is done.

So the head really isn’t a place where you want to be learning on your own. Especially if it’s your stuff!

You would be much better off just having a competent shop do the head for you and then you simply reinstall it on the engine. Unless you enjoy working on this stuff over and over more then you enjoy driving it.

[Trak Ratt]

I totally agree w/everything above except not doing it yourself. for one thing unless you specify the machine shop blue prints your head (and provide details of what that means) you will likely not get that detail. Testing spring tension, stem length etc. etc. is crucial for high performance heads but most shops don't specialize in that kind of work. Remember 98%+ of productions cars aren't driven on the track no mater what the marque. Get yourself a good blue printing book or at least do some research on line. All can/will be reveled w/a little research. Report back w/reference so others may learn from your experiences! Keep posting, everyone learns when one learns and shares!!!

[86911TLCAB]

Ok. Sitting in the lounge in Frankfurt airport searching for some valve spring info.
Bmw e30 m20b25 engine valve spring specifics:

Installed height 1.495 inches. 68 lb
Compressed height 1.04 inches 164 lb

Anyone have a valve spring tester I can borrow or come over and use? Maybe ft belvoir hobby shop has one.

[onboost]

Paul, thanks. Do you have a recommended brand for the head gasket? Other than the bmw one?

I would recommend OE, Goetze, Cometic, or MLS. The last two are more performance oriented and thus are a few bucks more. The factory head gasket or the Goetze should be sufficient.

You should probably buy a gasket set as it will include everything need to put the top end together like valve seals, intake and exhaust gaskets, and the front timing cover gaskets. Try Bavarian Autosport or Turner Motorsport for these items.. also the dealer pricing may be pretty good too with your BMW Club discount

[BlackTalon]

Ok. Sitting in the lounge in Frankfurt airport searching for some valve spring info...See, everyone always estimates Tito's capabilities and amazing drive when it comes to this stuff. All this namby-pamby BS about needin' this, and gettin' someone to do that... But Tito steps up to the plate and actually flies to Germany to get all the knowledge he needs to knock out this project directly from the horse's mouth! :cool:

[86911TLCAB]

Paul thanks will do so.

Dave, thanks for the vote of confidence. It can't be that hard to do this. Plus as long as it runs after I put it together I will consider it a success.

[86911TLCAB]

Paul, Bavarian has a gasket kit, but doesn't detail who manufactures the head gasket. Do you know if it is Goethe or the victor Renze one which I keep reading many are having issues with early failure?

[onboost]

Paul, Bavarian has a gasket kit, but doesn't detail who manufactures the head gasket. Do you know if it is Goethe or the victor Renze one which I keep reading many are having issues with early failure?

Not sure who they're using these days but Bavarian usually does they're homework and sells decent stuff. They've been around a while.. you can also check BMP in Texas.

[cmartin]

you will likely not get that detail. Testing spring tension, stem length etc. etc. is crucial for high performance heads but most shops don't specialize in that kind of wor

That sounds great for a race engine.

Nothing wrong with doing it all yourself, we all have our limits. I'm the guy that rips out the plumbing in the house but doesnt think twice about dropping a head off at the machine shop. :)

[86911TLCAB]

here are a few pictures. note the scoring on the camshaft. is it safe to lightly polish or should I even worry about it?

[Trak Ratt]

If you can catch your finger nail on it, get it worked over or replace. "Save" it will prolly be but will eats lots of other parts before self-destructing down the road.

Chris and engine will benefit from careful assembly! There 'free HP" in doing things right. Lots of engine builders guard there engine building processes closer than their daughters!!!

[smdubovsky]

dissenting opinion: leave it as it doesn't hurt anything. Not really any different than a groove deliberately cut for oil (see some grooved journal bearings for examples.) Its not going across the face so not a problem IMO.

Just make sure the large particle of crap that originally made it isn't still embedded in either the cam or head. Feel for it and use magnification if needed. IF its still in there, I suspect its stuck in the softer aluminum head or bearing cap.

[Trak Ratt]

dissenting opinion: leave it as it doesn't hurt anything. Not really any different than a groove deliberately cut for oil (see some grooved journal bearings for examples.) Its not going across the face so not a problem IMO.

Just make sure the large particle of crap that originally made it isn't still embedded in either the cam or head. Feel for it and use magnification if needed. IF its still in there, I suspect its stuck in the softer aluminum head or bearing cap.Not really desenting as much as pointing out that the grove part isn't a problem, just the ridge if any. I did forget to mention finding the culprit :oops:

[86911TLCAB]

Thanks. Am getting a good idea of what this requires. Looking forward to getting back home and get this started.

Have read through many how to examples of cleaning the block. Is there a preferred cleaning method?

[86911TLCAB]

Thanks. Am getting a good idea of what this requires. Looking forward to getting back home and get this started.

Have read through many how to examples of cleaning the block. Is there a preferred cleaning method?


Ok..so set a goal of pulling the head and removing all that was needed to do the timing belt by Sunday...succeeded. Spend a lot of time cleaning as well as the car has been leaking oil for a while.

Head came off pretty easily. Couple of obvious needs include a few valves bent and one rocker. But I have two full heads to make one good.

Head gasket came off pretty clean from the block. A couple of the piston heads have a slight indent where they hit the valve. Is this something to worry about. I don't intend to go any deeper into this engine so if it is this car is heading to the donation yard.

Otherwise, tomorrow plan to disassemble the head, and ensure I have one good and get needed parts to a machinist to look at.

Picture below of the block. Cleaned it up some but other than checking for it being flat, don't plan to resurface with any abrasive material unless it doesn't appear flat. Any recommendations appreciated.

[86911TLCAB]

Little update. Stripped the head from the car and now have 11 good valves and a camshaft without the scoring. Will try to get the head, camshaft, springs to a machine shop tomorrow. I tried to check if it is flat, seems to be, but will let them verify.

Spent some time on the block this evening. It also appears flat and so hopefully will begin installing late this week, though I will keep cleaning the block till I am comfortable I have it clean enough.

Been quite a new experience for me. Let's see if I can get it all back together.

[hberwald]

Great job! I like to see someone dive in and explore...it sounds like you are on the right track and will have a successful outcome.

[86911TLCAB]

Thanks...an exploration it has been...

If there is anyone local who has experience with block preparation and would be willing to come by and take a quick look at the block sometime this week...I have plenty of beer in the fridge..

[Dr K]

Tito,
Which cylinder are you going to run with only one valve?

[86911TLCAB]

Head is ready for pick up....clean and skimmed (it had some slight warping)...

block is clean from my perspective...Jeff coming by tonight to have a beer and give me his opinion.

remaining few parts ordered today and should be here by the weekend...

Engine bay cleaning largely complete...swapping power steering hoses and a few other parts as I go. The cap off the fuel injector came off last night while cleaning...for reference Advance auto part 274081 is a generic o-ring/cap kit.

tonight will clean all valves, pull the two power steering hoses and then start lapping valves and reassemble the head tomorrow.

next update and picture will be a reassembled head.

[86911TLCAB]

Thanks to all who helped out. A big thanks to hoophead for his assistance and the books and the cylinder head. The job is finished. Rebuilt head, new timing belt, loads of gaskets etc. was well worth the effort. Car fired up on the first go..now let's if the head gaskets lasts...

[BlackTalon]

Congrats, Tito! Pretty good that you went from "I need to find another car" to "Yep, I fuching knocked another one out" in less than 3 weeks.

[VaSteve]

Yeah...way to go.

[Jase007]

Nice. Post some rebuild pics. :)

[roundel]

Glad it fired up! That's great.

[86911TLCAB]

Sadly I am not that good with a camera. Lots of blue tape with writing and some notes reminding me where things go.

In the end it was pretty straight forward. Amazing how simple some of these are put together. Didn't really track what I spent but was something about 700 bucks but it included a new radiator and a other things that have needed replacement. Car runs much better.

Next project is to replace the rear suspension components after doing lexus 400h timing belt next weekend.

I must admit a great deal of satisfaction. I do have a goal of rebuilding an engine someday. At this point I wouldn't hesitate to take a rebuild on. Thanks for the kind words..

[vascott99]

Congrats!!!! CHEERS!!

[Trak Ratt]

You just rebuilt your BMW head and got that lump running again!!! Next project: "learn to use my frack'n camera" ;)

[VaSteve]

The proud owner and his running car.

[N0tt0N]

Well done!

[Dr K]

What a great thread!

[Low Oil Pressure]

Greetings:

I have been studying this thread with interest. With considerable trepidation I will be pulling the head from a 87 IS as there's bubbling gas in the expansion tank, and thus a steady stream of water out the overflow.

I saw one mention of a recommended machine shop in VA, but given the thread dates from 2014, I wonder it's still relevant. Ditto parts sources.

I'm also wondering about special tools needed such as ?VANOS adjuster? -- (Can I rent one somewhere?)

Any input appreciated.

[86911TLCAB]

The machine shop is still there. Didn't realize any of the e30 engines had a vanos? Don't you have a timing belt? Is so then there is no vanos on the car. Only tool I borrowed was the valve spring compressor to remove the valves. If you don't want to do all of that yourself, you can give the shop a complete head and they will return a clean one back to you all ready to install. Cost a little more but I do lots of these things just to learn how and I have a basic rule that if I can do it myself I will..let me know if I can help answer any questions.

[Low Oil Pressure]

Since I don't yet know what a VANOS is, I don't know if I have one or not. (I saw it mentioned in writeups on the job.)

[This is the biggest car job I've ever tackled alone; last head gasket job was on a Datsun 210 with pushrods.]

Yes, I'd take the intact head to a recommended shop.

[86911TLCAB]

Vanos is a timing system installed on e36 engines starting about 94. Doubt you have one on yours unless you have a different engine. Plenty of procedures online for the head gasket replacement. Really wasn't that difficult. Take lots of pictures, label things clearly, and don't be in a rush.

[86911TLCAB]

Just went back through the thread. On the machine shop...I used a shop in the manassas area. They are still there and have used them since. On boost also listed another shop which may be closer to you. One thing I would recommend is to have a second person to help pull the head off and put it back on when ready. It isn't that heavy but given the angle can be a bit difficult. Also make sure the crank shaft is correctly positioned prior to torquing head bolts. Was the one mistake I made.

[cmartin]

Since I don't yet know what a VANOS is, I don't know if I have one or not. (I saw it mentioned in writeups on the job.)

[This is the biggest car job I've ever tackled alone; last head gasket job was on a Datsun 210 with pushrods.]

Yes, I'd take the intact head to a recommended shop.

Really not a big difference in the job, I think simpler since just a timing belt and no pushrods to inspect. TDC before disconnecting and its simpler to get done. Are you planning a valve job? If not, why a machine shop?

[86911TLCAB]

Headgasket

[Low Oil Pressure]

Really not a big difference in the job, I think simpler since just a timing belt and no pushrods to inspect. TDC before disconnecting and its simpler to get done. Are you planning a valve job? If not, why a machine shop?

Given the 200K+ mileage, I think it prudent. Don't know until it is off, if then. A shop closer than Manassas would be nice; I don't have a visa to go that deep into Virginia.

TDC on which cylinder, and why?

And any recommendations on where to buy the needed parts kit? I'm assuming water pump, tensioner as well as gasket kit.

[Was about to go to Horror Freight for E-Torx sockets but don't see a set of same...]

[86911TLCAB]

You want to put it at tdc for cylinder 1 after you get it all cleaned up. You will cycle the Pistons while you are getting everything cleaned up. Then right before you place your new shiny and clean head back on the block (which the shop should set the cams at tdc for cyl 1) make sure you put the crank back to tdc for cyl 1. I didn't do that and after torquing all the head bolts down went to put on the belt and the crank wouldn't cycle. Had to undo the bolts. Lift the head a bit, cycle the crank then retorted the bolts. Not a major thing, but the gasket could have been damaged and the head bolts are supposed to be one torque bolts. So better to do it correctly. Not sure where I purchased the kit. Admit I bought aftermarket and it all seemed to be fine. Still running (though I sold it to someone so he is driving it) after 3 years. I think based on the thread I bought the kit at bravarian. Pretty sure I got torx set from harbor freight. Once you start taking it apart you will see how easy this is. My car had lots of built up oil so while the head was being skimmed I cleaned the engine really good. Also may need some head bolts, and exhaust studs. Not sure if your exhaust has been off so that can always be a problem.

[Low Oil Pressure]

The header<->pipe bolts were off several years ago when the transmission was ...upgraded... from a then 3-speed [1,2,5] to a five speed again. I recall that was really ugly but hopefully it will be easier this time.

[86911TLCAB]

I think it is prudent to have the head checked. Frankly your symptoms are likely caused by a gasket and one might be able to get away with just replacing the gasket without skimming the head and verifying it has no cracks. If you want to save a few bucks strip the head yourself and then plan to rebuilt it after the shop checks it and skims it. I think I paid about 110. It is a little more work but if I can do it, anyone can. There are a few good videos online for doing that.

[86911TLCAB]

I also spent a lot of time cleaning the block. I did my best to verify it was flat, but didn't do anything special other than clean the heck out of it. A also used an old head bolt which I dremeled grooves across the threads to allow junk to collect so the bolt holes were as clean as possible. This helps to get correct torque on the bolts.

[cmartin]

Like I said, why a machine shop? Is there a crack? Are you doing a valve job?

Clean, inspect, install parts in reverse order.

[86911TLCAB]

If you know what to look for I suppose you can do your own clean and inspect. In my case I preferred to have someone else tell me that knew what to look for that the head and the valve guides were all ok. I also had them look at the camshafts and the valves. Having never done this before and not having any experience it made sense to me to have it looked over by someone who deals with these all the time. You have a problem. What’s to say the problem could be from a cracked head vice a head gasket. If you can’t rule that out yourself then get help ruling it out. In the end you get to decide how you want to proceed. We are here just to provide options and ideas.

[smdubovsky]

Since you are in MoCo, Burtonsville machine shop is closer and has done several of our BMW heads.

[cmartin]

x2 very happy with Burtonsville machine, but its a been a few years

[Low Oil Pressure]

So I'm into this adventure with the help of a friend.

We have managed to get the fan off, radiator out, and distributor apart.
But.... there's the rpm sensor on a plug wire. Bentley shows a connector for it under the big diagnostic connector. We don't see such & thus we can't get it out of the way. Where is the plug/jack hiding?

https://photos.app.goo.gl/IgTs5mfIWnSC6V2D2
https://photos.app.goo.gl/fcMUox0zycJyUVv33
[/URL]https://photos.app.goo.gl/LjivNq8ZOjj4XKZu2
([/URL]https://photos.app.goo.gl/LjivNq8ZOjj4XKZu2)

[86911TLCAB]

If I recall that works its way around front of engine near the distributor and plugs in some place on the right side of the engine. Once you remove the coolant y connection and the distributor you should see it.