First Time Engine Rebuild

[abdeweese]

Doing my first ever engine rebuild here in a month. Need all the help and wisdom I can get.

93'
525iT => e34 & M50
190,000

What special tools will I need?
Have:
-Eng & Metric sockets
-open & boxed wrenches up to 9/16's and 15mm
-a few torx
-and patience

Check vack soon

Thanks All,
Ab

[wingman]

Bentley?

[joshua43214]

You forgot 12pound sledge, assorted chisels and a cutting torch.

reassembly is simple, hammer to fit, file to flush, paint to hide.

If it brakes on disassembly, it needed replaced any way.And as always, its German, so it just neds a little force.

You also need a 1/2 torque wrench and a 3/8 torque wrench. If you have to chose between them, get a 3/8" that can go 20% above the head bolt torque, you will need the lower torque accuracy for the rod and main bearings. I recomend NOT using a click type, the double beam wrenchs are inheritlanly more accurate, and the cheap clickers have a narrow accuracy area and that is spotty. An 18" or longer breaker bar is nice also. A ring compressor for installing the pistons.


Get litle box's or cans. sort fasteners by system or location. IE, all PS fitting in one can, all intake in another. Don't feel like you have to be macho about it, take pictures, make drawings etc, anything to aid your memory putting things back together.

On reassembly, tighten fasteners as you put them in, that way you won't forget to tighten something, it would really suck to forget to tighten a rod bolt. Its OK to do silly things like tie a piece of yarn arround a bolt that you have to tighten later. There is alot to keep track of, and most professional mechanics have trouble remembering everything unless they spend alot of time doing heavy engine work.

Pay extra close attention to the orientation of things like rod and main bearings, which side of a gear faces forward, what direction the pistons face. Mark all parts as you remove them in a maner that can not be cleaned off, numbered stamps are good, but take care in where you stamp items to prevent distortion of parts. Don't count on the service manual to tell you how to put a part back on, make sure you see how it came off, like I said, a camera is your friend. Even after many many years or fixing cars for a living, I still make an occasional drawing for reference.


never ever ever set a piston on its top with the rod installed, lay it over on its side.

its a big job, be patient and good luck.

[yaofeng]

Full set of 3/8" drive and 1/2" drive metric socket wrenches up to 27 mm. 1/2" drive breaker bar, 3/8" drive and 1/2" drive torque wrenches. Beam type is better I agree. Open wrenches all the way up to 32 mm will help you a lot. !5mm is not enough.

Get an air compressor and impact tool when you have the urge and when budget allow. You'll ask yourself later, "Why didn't I get theis sooner?"

[Dave M]

Aside from your basic sockets etc covered above, Bentley will cite a number of BMW tools, most related to cylinder head timing. If you want to puchase a camshaft locking tool, the cheapest i found was from Catalyst Racing in Colorado. In hindsight, you don't need it, just use a straight edge across the squared ends of the cam.

For the secondary chain tensioner, I used two safety pins.

I don't recall needing a wrench or socket larger than 21 or 22 (for the crackshaft nut). I borrowed a 600ft/lb torque wrench from a machine shop to tighten the b!atch and a 4ft steel pipe i found to loosen it.

Keep asking questions along the way as many of us here have done this job,

Dave M

[genphreak]

You forgot 12pound sledge, assorted chisels and a cutting torch.

reassembly is simple, hammer to fit, file to flush, paint to hide.

If it brakes on disassembly, it needed replaced any way.And as always, its German, so it just needs a little force. Now I see why it takes me so much time... my method, process and planning are all wrong for the jobs at hand...

I can see how valid these points are, just wish I'd known them earlier too. Perhaps one can make up for deficiencies in these areas by drinking lots of beer, especially if jacking the car up, working underneath it or removing anything fragile and heavy with power tools. :D Thanks for the tips Joshua!

[DaCan23]

and dont forget, this applies to any work on our cars.... expect about a 50% breakage of any little plastic part you encounter... unless you do what I've done... send the GF to the stealer when you cant drive cause the car is in pieces...

Last example... when doing the complete front light rebuild... those stupid plastic cones on the headlights... somehow the stealer gave them to her for $1 each, retail was $2.20... she is a BMWCCA associate member as I send her to the stealer often, I think this is the largest discount I've had w/ them, thats 55% off woo hoo.

If the plastic pieces are cheap, dont waste time, just F'em and have all new ones ready...

[Anton CH.]

I am actually going to do the same thign this summer but without the vanos. I don't recall seeign all the specifciations in the Benteley for engine rebuilds. Where would I find all the tolerances and tighting torques for varous components inisde the engine.

[Dave M]

I am actually going to do the same thign this summer but without the vanos. I don't recall seeign all the specifciations in the Benteley for engine rebuilds. Where would I find all the tolerances and tighting torques for varous components inisde the engine.

Bentley does not go beyond cylinder head removal / dis-assembly. If you want instruction on dismantling the bottom end, Chiltons and Haynes cover this, with the Chiltons being the better manual (although Haynes does have nicer pictures of the 'perm guy' ;) ). For tightening torques, there is a downloadable (pdf?) file around which has been a big help to me. I believe Bill R. posted it a while back. I printed it all and bound it.

Dave M

[abdeweese]

Thanks to all for the helpful responses.

-Bentley. Check.

-I was eyeing a torque wrench at Pep Boys the other day. But it can wait until the trip to Harbor Freight. Are both the 1/2" & 3/8" really needed? Would one wrench and an adaptor do both jobs? If so which? What is "beam type"?

-Plan to change: timing chain [and associated gears], water pump, anything else while I'm in there? Any sensors? Thermostat?

-An engine lift? [Have a floor jack]

-Anyone have access to that PDF that Dave M mentioned?

-Surely there aren't any plastic parts in the engine. But as for gaskets I just assumed I could buy a rebuild kit with all new gaskets etc.

Ab

m50, e34, 190,000 miles

[yaofeng]

Are you taking the head off? You can't remove the main chain guide (BMW calls it the tensioner on the ETK) without removing the head because your M50 has an aluminum chain guide. I'd advise you not to separate the head from the block unless you have a bad haed gasket. If that's the case you cannot replace the main chain guide and there is no reason to.

http://i21.photobucket.com/albums/b274/yaofengchen/DSC_1649.jpg

Mark my words. You'll find your chain and gears to be pristine. You probable need to replace the secondary chain guide which is plastic. Of course all gasket once you open the engine up.

http://i21.photobucket.com/albums/b274/yaofengchen/DSC_1735.jpg

Do not get the cheap torque wrenches. Craftsman is good.

[Dave M]

Thanks to all for the helpful responses.

-Bentley. Check.

-I was eyeing a torque wrench at Pep Boys the other day. But it can wait until the trip to Harbor Freight. Are both the 1/2" & 3/8" really needed? Would one wrench and an adaptor do both jobs? If so which? What is "beam type"?

-Plan to change: timing chain [and associated gears], water pump, anything else while I'm in there? Any sensors? Thermostat?

-An engine lift? [Have a floor jack]

-Anyone have access to that PDF that Dave M mentioned?

-Surely there aren't any plastic parts in the engine. But as for gaskets I just assumed I could buy a rebuild kit with all new gaskets etc.

Ab

m50, e34, 190,000 miles


You likely needtwo torque wrenches as most reliable ones go from @5-30 and then from 30+ to 100+. I bought a good quality low torque and a beam type high torque. Nothings come loose yet :)

Oh, I should add that you may need to grind down the external torx required for the fron of the cylinder head to timin case cover. The bolts are deep and Bentley cites a BMW tool. Just take the torx to the grinder until it fits down the hole.

I purposely installed a wooden bbeem in the garage i built to accomodate a block and tackle for plling engines etc. If you have a sturdy beam available, borrow or buy a block and tackle. Otherwise you can rent a lift that rolls on the floor.

Buy an engine stand. It was the best $80 I spent.

BMW Torque Values (http://www.mwrench.com/Whitepapers/torqspec.pdf) found here.

Replace your front and rear crankshaft seals and gasket, timing chain gasket if you get in there. Otherwise, just standard head gasket, oil pan gasket etc...

Good Luck,

Keep in touch, wecan't think ofeverything at once ;)

Dave M

[yaofeng]

Oh, I should add that you may need to grind down the external torx required for the fron of the cylinder head to timin case cover. The bolts are deep and Bentley cites a BMW tool. Just take the torx to the grinder until it fits down the hole.

Dave M

I found no problem with the two external torx bolt using my E8 socket. My problem is I miscounted the number of bolts fastening the lower timing cover to the bolck. Darned Bentley, I used figure 13 and counted 14 bolts. So after all 14 bolts and the two locating pins are removed I started prying with a big flat blade screw driver to loosen and remove the cover. Not realizing there are at least two more, maybe three bolts on the valve train still holding the timing cover in place, I cracked the cover prying it with the bolts still on. I think it cost me 70 bucks to get one new.

http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/Bentley_BMW_5-Series_Service_Manual.jpg

[Dave M]

That blows. The smaller head bolts for the timing cover are harder to see as the holes are filled with oil.

You must have had a skinny @ss torx to get in there. As long as it gets done :)

Dave M

[joshua43214]

The beam type wrench has a large rod for a body and a smaller rod with a pointer that sweeps accross a scale near the handle. They are the old fasioned type wrench. The click type, will have a fat body and the handle can be rotated to set the torque, when you reqch the torque, it will make a click sound. click type tend to be inaccurate at the extremes of their useful scale, and at low torque, the click is often almost impossible to feel. Also, click type need to have their setting turned down imediately after each use, or they will become even more inaccurate. The type that don't need to be set down are very expensive. The design of the beam style wrench makes it more accurate accross a greater span and far more reliable in the long run.

You can get by with just the 3/8 wrench porvided its max torque is about 20% higher than the head bolt torque. The double beam type are more accurate and remain accurate for a much longer time. If you do end up buying a click type,make sure its in a sealed box, people play with them and leave the setting turned up, which ruins the wrench. You can probably rent a 1/2" torque wrench, but this ( http://www.sears.com/sr/javasr/product.do?BV_SessionID=@@@@0047714595.1146145065@ @@@&BV_EngineID=ccjeaddhimgiejhcegecegjdghldghf.0&vertical=TOOL&pid=00944642000&tab=spe#tab ) is only 30 bucks, ive had one for over 20years and its still going fine. I would trust that for your rod bolts before I would trust a cheap click type. This is a nice 3/8" wrench but mroe expensive http://www.amazon.com/gp/product/B00004SQ3C/ref=nosim/104-9244425-7030351?n=228013 , and goes to 600 in/lbs (50ft/lbs). If you are not experienced with torquing parts by feel, you will not regret haveing a good low torque wrench, use it on every thing until you get the proper touch. Rod bolts are probably the single most abused part in an engine, very important they recieve the proper torque.

You can rent an engine hoist, or use a come along tossed over a beam,then push the car back. I actualy swaped an engine for a guy in an abandoned lot with a come along tossed over a tree branch once. an engine stabalizer is very nice(the beam with a hook at each end used for tiping the engine). a 4' lentgh of 3/8" chain for lifting. Harbor freight sells engine stands cheap, they are a very nice conveienance. An old blanket to go under the engine while you work and a large dish pan to catch drips. Lots and lots of rags.

If you don't use a stabalizer, bolt both ends of the chain to the engine, hook the chain with the crane and find the balance point, then put a 2' long 1/4 bolt/washers through the chain to make a loop arround the hook. keep the chain as short as possible. always lower the engine to 1" from the ground before you roll it arround, they do fall of the chains when you hit bumps.

I have had countless engines out of countless cars. The first time is always intimidating, but it's really a matter of scale. Think of the R&I like an extra complex water pump replacement, it really just nuts and bolts. The rebuild though requires special attention to parts, but its still a matter of scale. make drawings, take notes, don't try to remember every thing on your first time.

BTW, how far do you plan to go with this. Do you plan to check bearing clearance? are you replacing pistons? What led to this over haul in the first place? If you had a rod knock, its a very good idea to make sure the rods did not become ovalized. These jobs can very quicly get out of hand with machine shop fee's. If you had an internal mechanical failure like a rod or main bearing failure, I recomend you send the block striped with only the pistons and crank installed to a machine shop and let them guide you as to how far to go. They will know what you should "technicaly" replace, but can still save and can advise you better than posting pics here on worn parts. You would be amazed the number of totaly raged out parts I have pulled from engines that "ran fine", and how far out of spec things like cylinder roundness a car can tolerate. Always double check the torque on parts when you get it back, many machine shops just zip the engine back together since they expect you to properly torque every thing.

Also, if you don't want to learn how easy it is to break rings on expensive BMW parts, let a machine shop install them as well. Don't think that passing part of the work onto a machine shop is betraying the DIY community, they have all the special tools and experience that you lack, it may be about the same cost or even cheaper than buying the specialty tools.

[abdeweese]

Motivation: Engine leaks slowly in many places and a mechanic said that my compression is low. I plan on verifying that last part before dismantling the whole thing. I'm also doing it because - and my girl friend looks at me like I have two heads when I say this but - It's fun. :) Plus it has 190,000 miles on it and needs a new fan and water pump, could probably use a thermostat too.

Whats the fun in owning it if you can't take it apart and learn how it works.

It's a great excuse to buy a tourque wrench(s). And an engine stand. And larger wrenches. And ... ... ... says the kid in the candy shop

Is the head the same as the valve cover?

What causes the power [thrust] to lag slighty behind engine RPMs, low ATF?

What do yall mean about "grinding down the torx." I know them as small start shaped bits. It seems foolish to grind away at these. Or do you mean the OD of a sock et on the torque wrench? ???

Thanks gotta go.
Ab

[abdeweese]

I get it.. Grind the OD of the torz shaft. => Skinny and able to fit in tight holes.

[abdeweese]

Dave,

What units are you in?

"~5-30 ??" and "~30-100 ??" ft-Lbs or Nm?

I'm looking at the 3/8" craftsman on sears for $23. But it has 0-70 ft-Lbs => poorer resolution than 5-30 ft-Lbs.

And a second for $27 - 1/2" drive up to 150 ft-Lbs.

Sale ends tihs saturday, 4/29/6.

Cheers,
Ab

[Bill R.]

consider buying a beam type torque wrench in this day and age. I think its safe to say that i have had the most experience in building engines of anybody who posts on this board. I had a beam type 35 years ago for my very first torque wrench, of course micrometer type click torque wrenches were much more expensive then and not very common. The accuracy of most micrometer type wrenches is now typically better than any beam torque wrench and the click type when used properly doesn't allow nearly as much margin for error as a beam type.Let me clarify that statement. The micrometer click type you adjust to the correct torque and pull the handle until you feel it click and go on to the next bolt. The beam type you have to watch the graduations and make sure you don't pull too little or too far and on alot of them the graduations aren't nearly sharp enough and parallex errors do creep in. Especially alot of the older beam type where the needle sat up off the gauge portion. Click micrometer type are much easier for the casual user to use correctly.
Rather than waste my money on a beam type torque wrench i would go for the micrometer type that sears currently has on sale for 48 in 1/2 and 3/8. In fact since my proto has broken the ratchet mechanism once more i'll probably go get one of the sears ones before they go off sale. Also if you do a search on the internet you'll find a number of torque wrench only sites that will give you some more info on current torque wrench types and inaccuracies among them.
For what its worth , testing on the cheapo harbor freight and other really cheap click type has indicated that they are as accurate as many that cost a lot more. I think i will go get this wrench tomorrow in fact.
(http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00944595000)






Dave,

What units are you in?

"~5-30 ??" and "~30-100 ??" ft-Lbs or Nm?

I'm looking at the 3/8" craftsman on sears for $23. But it has 0-70 ft-Lbs => poorer resolution than 5-30 ft-Lbs.

And a second for $27 - 1/2" drive up to 150 ft-Lbs.

Sale ends tihs saturday, 4/29/6.

Cheers,
Ab

[Anton CH.]

Bill: Any chance you could post the pdf with all the tolerances and torque specifications again? I have a paperback Benteley and it doesn't say anything as far as rebuild is concerned.

[Bill R.]

scroll further down you'll see that Dave posted the torques spec sheet.
The tolerances and torques spec is a book/cd all of its own.



Bill: Any chance you could post the pdf with all the tolerances and torque specifications again? I have a paperback Benteley and it doesn't say anything as far as rebuild is concerned.

[jjw]

Check out the snap-on techwrench torque wrenches, electronic torque wrenches. It will show the end torque value, and also show the instanious torque that's been applied, very good to aviod breaking fasteners. http://buy1.snapon.com/catalog/item.asp?P65=&tool=all&item_ID=66659&group_ID=17226&store=snapon-store&dir=catalog