Kouks e34 complete rebuild

[kouks]

Just watched a video on removing valves and lapping them. Not too complicated but tedious and time consuming. The guy did it by hand. Nice professional video.

Has anyone else done this type of work in their home garage and want to chime in on difficulty and time plus any good results?

I was thinking of replacing just the valve seals, but after watching the videos I'm thinking might as well lap the valves too if I'm in that deep.

[Binjammin]

Lapping valves is really pretty easy. If you use the double d***o suction cup tool, be warned that it sucks and you'll just have to get used to it. Half the time or more it just won't stick and you'll have to clean the lapping compound off and try again, or it will slip off while you're using it etc...


but overall, the work is simple and it's all about just consuming time. Keep track of which valve goes where too.

[kouks]

^ Pretty much what I got from the video. They use that tool and before hand used a brass brush on table grinder to clean the valves.

[Binjammin]

^ Pretty much what I got from the video. They use that tool and before hand used a brass brush on table grinder to clean the valves.

I wouldn't even bother, just use the suction cup thing. The amount of time spent rigging up something will still be greater than the amount of extra time fiddling with the tool. It's inconvenient, but it does work. Just try to keep the lapping compound off the valve face, that makes it hard for the suction cup to stick.

[kouks]

I wouldn't even bother, just use the suction cup thing. The amount of time spent rigging up something will still be greater than the amount of extra time fiddling with the tool. It's inconvenient, but it does work. Just try to keep the lapping compound off the valve face, that makes it hard for the suction cup to stick.

Just for my education, before I spend a godly amount of time lapping the valves and changing the seals, the main question is: What will I gain? Is the possibility of a few psi of compression worth the time or is this just an exercise in OCD behavior, like all the time I'm spending cleaning the engine bay from years of grease which will not contribute anything to the drivability of the car, just make it pretty. I expect with my schedule that this will take me about a day per cylinder (man hours spent vs man hours available).

Or should I just throw the head back on and get on with it. Still need to raise the block and remove the oil pan before I start the rebuilding process.

I'd like this engine to last me another 60,000+ miles, for a total of about 300,000 on it. That would be about 5 years of daily use on the car. Anything more would be icing on the cake.

[Binjammin]

Lapping the valves will give better sealing for sure, but it's more than just that. I think you're overestimating the time required by like an order of magnitude. This is one of those jobs that I'd just sit down at the bench, put some music on, grab a nice cold iced tea, and enjoy doing. It's not the sort of thing I could do all day, every day, but as a job on one of my own projects? I'd be happy doing it. If you're going to put new valve seals in then everything is already going to be taken apart, so for another hour or two, you'll be setting the valves up to be sealing for a good amount of time down the road. It's just another step in future proofing for a while.

[Old525i]

According to my Bentley book (the bible to some), BMW doesn't sell valve guides as replacement parts. They suggest that a shop ream the guides and install oversize valve stems. That could be why the shop is charging $700+ for a valve job. I have read on the net that a worn valve guide may cause a few pounds of lost compression if the valve doesn't land consistently on a spot that will seal the cylinder properly.

However, there is an easy way to determine if a valve guide is worn out. Insert a new valve until the head is flush with the end of the guide (oil side of the engine). Rock the valve and measure the tilt clearance with a dial indicator. For all M5x engines, the maximum wear is 0.5 mm or 20 mils. The book says that valve seats should be resurfaced if new valves or guides are installed (here they are referring to after market guides).

It is all described in section 116-18 of the B book.

[Binjammin]

BMW doesn't sell a lot of the parts they put in their cars, but you can still source them. IIRC someone was trying to find m30 valve guides recently, not sure if they ended up being able to or not, but I would imagine finding m5x engine guides would be a lot easier.

[Old525i]

The first one listed by Google:

http://www.achillesmotorsports.com/H...hpvg-s52us.htm

[kouks]

Thanks for all the info guys, good discussion. I have not foraged this far into rebuilding a head before so I'm a bit spooked about it, but its all a big erector set anyway. I'll do the wiggle test suggested above and hopefully all are doing well. My assumption is that is all the valves are seating well and holding pressure just fine now, they should be in overall good shape and the guides are still doing their job. The seals are not metallic so that's why I'm thinking of changing those. I really don't want to get into resurfacing the valve seats, since that's the $700 job.

The car ran fine before it overheated, actually pretty smooth, so I'm hoping I don't find anything wrong with the valves.

Since you guys know what you are talking about, any opinions on the surface of the cylinder walls pictured on the previous page? Anything to worry about?

[Old525i]

It is difficult to say how much that corrosion will affect the compression on those two cylinders. It depends on how deep the pitting is. You have two compression rings and one oil control ring. I would take a close up picture of the pitted area and show it to a local machine shop to see what they have to say. Since this will be a 60000 mile engine and you are doing most of the work, I would leave it as is and hope for the best. BUT, that is my opinion.

However, don't use Victor Reinz gaskets. My M20 engine developed an oil leak from the head gasket.

[Binjammin]

It is difficult to say how much that corrosion will affect the compression on those two cylinders. It depends on how deep the pitting is. You have two compression rings and one oil control ring. I would take a close up picture of the pitted area and show it to a local machine shop to see what they have to say. Since this will be a 60000 mile engine and you are doing most of the work, I would leave it as is and hope for the best. BUT, that is my opinion.

However, don't use Victor Reinz gaskets. My M20 engine developed an oil leak from the head gasket.

I'd agree with almost everything here, especially on the pitting. It all depends on how bad it is, and that's hard to gauge in pictures. I'd argue with the Reinz gaskets though, I've used them for over 20 years and never had an issue with them. I've seen other guys online say the same thing, but I've never heard another pro talk crap about them. I wouldn't use a part if it were risking comebacks, and I use them by default.

[locknload]

Honing the cylinder might be a solution for you to clean up some of the pitting, but I've only done it on bare blocks. I would think you could do it without removing the piston if you are careful and can protect the top of the piston to keep any foreign material from getting between the piston & cylinder wall, but I defer to the professionals on whether it's recommended or not.

A few helpful hints on the lapping. Make sure you get the silver/grey ring all the way around the valve seat and face. If it has any breaks in it (meaning not a complete circle), it indicates a bent stem or possible cracked seat. Also, when reassembling the valve/spring/etc, it helps to put a spot of bearing grease on the top of the valve stem to hold the keepers in place as the spring and cup come up. A magnetic tipped screwdriver is a big help in getting the keepers in & out.

[Binjammin]

Honing the cylinder might be a solution for you to clean up some of the pitting, but I've only done it on bare blocks. I would think you could do it without removing the piston if you are careful and can protect the top of the piston to keep any foreign material from getting between the piston & cylinder wall, but I defer to the professionals on whether it's recommended or not.

A few helpful hints on the lapping. Make sure you get the silver/grey ring all the way around the valve seat and face. If it has any breaks in it (meaning not a complete circle), it indicates a bent stem or possible cracked seat. Also, when reassembling the valve/spring/etc, it helps to put a spot of bearing grease on the top of the valve stem to hold the keepers in place as the spring and cup come up. A magnetic tipped screwdriver is a big help in getting the keepers in & out.

Oh hell yeah, grease on keepers is mandatory.

[kouks]

Thanks for all the great info gents. I'm picking up the valve and spring compression tool from Old525i tomorrow. He basically works down the hill from me. I'll get this started next week.

As far as the imperfection on the cylinder wall, my finger nail does not grab on any edge in any direction I come at it. It is definitely not as smooth as the rest of the cylinder. It is more of a discoloration at this point. I'm sure at the microscopic level there are imperfections though.

If I do hone the top of the cylinder wall, it will be wider than the bottom end by a thousandth of an inch or so. Not much but the rings will have to expand and contract slightly as they move up and down. That worries me more than just leaving it alone and continuing the build.

[kouks]

Started removing the valves and lapped my first valve tonight just to try it out before I really get into it tomorrow. Not a problem, but tedious. The exhaust valves are crusted over and the lapping tool won't hold unless I clean them completely, so I'm using a drill with a 180 fine grit paint scraper (made of aluminum oxide and fabric) along with brake cleaner to clean them. Worked good on the first valve. Tried to find a copper brush as a drill bit but couldn't, not even at harbor freight.

The spring compressor tool I got from Old525i will only work on the first two cylinders due to the depth of the springs in the head. Ordered another one from Amazon that should be here tomorrow to continue.



Although in real life the valve looks and feels completely smooth, this photo shows that there are scratches on the surface. Probably should not use the drill and scraper again. I'll use 600 emory cloth to smooth out the scratches. Guess I'll do it manually with a brass brush...talk about time invested.

[Binjammin]

Easiest way to use the c-clamp style compressor (which is also the best, unless you've got one of those elaborate lever dealios) is to cut up a cheap socket to go between the retainer on the top of the valve and the spring compressor. You'll basically want to cut a little less than a quarter of the socket away, to give you a window to get a small pick in to pull the keepers out when you've got the spring compressed.

Oddly enough I just rediscovered this little bit of know-how myself, I'm breaking down a broken m52tu head to get the valvetrain out, and doh, could only get like 4 valves out. Damnit.

[kouks]

Go to Amazon and search valve spring compressor M50. It's like $45 and is a perfect C clamp type, has the openings already done to remove the keepers. The tool has great reviews.

[Binjammin]

$45? I'll make one for $3

[Frchdragon]

Asked about a complete valve job, $729. Don't really want to pay that much.

Looks like a lot of money, I never paid more than $500 Cdn to rebuild my BMW cylinder heads (cheaper on the 4 cyl).
It is for the complete job, from cleaning to 3 angles valve grinding, new seals and all.

[kouks]

Completed lapping cylinder 1 and the front valves in cylinder 2. Compression tool won't reach any others. New one should be in later today. Working at a pace of about an hour per cylinder. As Old525i told me.."it's therapy". Most of the time is spent cleaning and smoothing the surface of the valves so the suction cup will work.

So far no significant wiggle in the first 6 valves I've completed. Looks like the guides are in good shape.

[Binjammin]

I made my own tool tonight. I used a bolt, two washers, a nut, and a chinese socket I cut up. Works awesome and cost virtually nothing. If I had to do it without these supplies it would have cost right around $3. Works great.

[kouks]

I made my own tool tonight. I used a bolt, two washers, a nut, and a chinese socket I cut up. Works awesome and cost virtually nothing. If I had to do it without these supplies it would have cost right around $3. Works great.

Pic?

[biasvoltage]

Tried to find a copper brush as a drill bit but couldn't, not even at harbor freight

would a brass gun barrel cleaning brush work? I've got some, seems like it should chuck up in a drill OK. Try your local Big 5 or Turner's Outdoorsman.

[Binjammin]

Pic?

Went to bed while I sent them to myself. lol.