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Made some progress today, picked up another head for $150, hopefully this one is good. I resorted to a framing square as a staight edge and the cams were still in place so the valves were in the way but I wanted to check as best I could before buying it. I also pulled the m52b25 pistons and crank out of the engine. The bearings all looked great. I mangled the first m54 vanos gear when I was cutting it down but I found a couple more cheap so I have two more chances to get it right. Here are the 2.5 liter parts:
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I got the craigslist head to the machine shop and it is within tolerances. Still a bit bummed about the first one because it looked so clean, this one isn't as pretty, the thermostat housing surface needs to be dressed up but it will do. The warped head was thoroughly cleaned before the final measurement that ruled it out, so it looks beautiful, it is just a crying shame to look at.
I did a much better job cutting down the helix (what I've been calling the vanox gear) gear on my second attempt. Both times I chucked it up in drill press and used a cutting wheel in my grinder to cut it down but on the first attempt I did not have it true enough in the chuck so it wobbled and raked the side face of the gears with the wheel. The head of the bolt will need to be trimmed as well, but not quite as much, I'm going to trial assemble it with the vanos first to see where it bottoms out. It is an internal torx and is torqued over 50 ft lbs so I don't want to reduce that tool interface any more that necessary. Another option I'm considering is cutting the backside of the bolt's head down in a lathe and if this causes the bolt to bottom out, I can just shorten the threaded end. When I disassembled the gear, it was very tight, from what I've read, 50 ft lbs is adequate but I will be using red locktight and going a little tighter. After I cut the gear down, I cleaned it up with a file and finally some 600 grit sandpaper to the very ends of the splines so it engages smoothly. A cell phone pic won't do it justice but it is very smooth.
Last edited by gdavid; 09-22-2017 at 12:36 PM.
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Here is the trimmed helix gear and a couple shots of the block in primer
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Now it looks like a 9N tractor engine
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nice lookin car. cheers!
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I'm continuing to make slow but steady progress with the engine rebuild. I honed 2 cylinders so far, had to take a quit for the night and when I went to resume I found that my engine hone stones were falling apart. I had put some new medium grit stones on my ancient cylinder hone before I did the first two and apparently the vibration or WD-40 I was using as a lubricant weakened the glue that held the stones to their metal backing. Nothing is made worth a damn these days.
I am currently debating whether to replace my intake lifters or not. The exhaust cam, ledge, and lifters are original to that head, so it is a no brainer to leave them together but my intake cam is from a different engine, it would probably be a good idea to use new lifters on that side. Unfortunately the ledges and lifters from the warped block look better than the ones from good head that I will be using but my machinist is telling me not to swap ledges between different heads.
I finished cleaning the pistons and installed half of the rings but realized I should back up and check the ring gap on all of them before assembling everything. I am using a frankenstein set of rings that fits the m54b30 pistons without using that style of oil ring. Many claim the oil ring design of the m54 is to blame for a tendency to coke up and start burning oil, I'm convinced enough to be going with a conventional 3 piece style of oil ring like found in the m52 engines. The m54b30 (not sure about 2.5 liter engine) uses a 1.2 mm top ring rather than the 1.5 mm top ring found in m52 engines so I couldn't just order a set for one of those engines. I asked an ebay seller to put together a set with the right sizes and style I wanted and ended up paying $145 or so. I also bought my main bearings, connecting rod bearings, upper and lower gasket sets from him as well.
If I can get new stones for my hone today I should be able to start assembling the bottom end tonight.
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Man!! You have incredible energy and enthusiasm!!!
Be aware there are differences between OBDI and OBDII engines, though they look exactly the same.
The crank position sensor was moved from the front cover (both engines use same crank trigger harmonic balancer) to the block just above the starter for OBDII - mounting boss and hole in block not present in OBDI hardware. The OBDII cranks have the trigger wheel for the new pick-up location forged into crank.
The engine cylinder head temperature sensor set up is different. Both of these differences in the OBII wire loom are going to be hurdles.
Look closely at the cam ledges, there are differences in the various M50/S50/M52/S52 and M52TU and may or may nor be compatible with you cam choices.
The OBDI 325 front cover has a different return coolant hose interface.
OBDI valve cover has different EGR interface and does not accept the OBDII coils which have a different wire loom.
Going from OBDI engine to OBDII car in going to be a new challenge as I believe you are pioneering relatively new ground.
OBDI engine wire loom only has one pre-cat O2 sensor/pot-cat O2 sensor. OBDII ECU will be looking for two, not sure OBDI engine harness plugs into OBDII ECU.
Unless your state or county does not have some sort of emissions inspection, might be tough getting inspection with OBDI electronics in an OBDII designated chassis/VIN.
I believe you are going to want to read through this thread and then work backwards as much as possible attempting to retain OBDII engine management -
https://www.bimmerforums.com/forum/s...what-I-learned
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Last edited by bluptgm3; 10-06-2017 at 09:05 AM.
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Thank you for the heads up, I'm working exclusively with OBDII parts. The parts engine from a 323 so the crank position sensor is in the block. The head I will be using is still at the shop, it is from a OBDII engine as well and I am either using the sensor from the 323 in it or replacing with new. I am also going to add an analog sensor for a separate temp gauge to give me a better sense of the engine's actual temperature versus the stock "gauge".Originally Posted by bluptgm3
Last edited by gdavid; 10-06-2017 at 08:42 AM.
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You can see the block's hole for there crank position sensor here. Due to the confusing naming of the 323, the lowly m52b25 is easily forgotten.
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Ya, sorry missed that. You are on it, sorry for the miss-direction.
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I appreciate any and all tips. I picked the second head up from the machine shop with a clean bill of health today and should be able to get it back together soon.
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Also, and perhaps you are aware, the "400" casting "S" variant heads use different valve springs than the "non-S" heads.
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Last edited by bluptgm3; 10-07-2017 at 10:41 AM.
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Question for anyone who may be reading this. Is it safe to swap cam trays / ledges between heads? The ledge and lifters from my head that is straight and valves that seal are heavily varnished and the lifters are collapsed. The ledges and lifter from the bad head look great but my machinist has warned me against transferring ledges. Were the cam trays line bored while connected to the head at the factory? I can see how this would cause the cam journals to be out of line when put on a new head but I have no idea how they were machined. I have where forum members have the transfer of trays but I would like to know the longevity of such repairs. I respect the machinist a great deal but he does not specialize in BMW. If it is a really bad idea to transfer them, I will buy new lifters and clean the varnished trays as much as possible which isn't the cheapest option and not ideal but I know I shouldn't transfer lifters between trays. Either way my intake cam won't be original to the intake tray. This is a very modest HP build that I plan to put a lot of miles on. Thanks for any advice.
As far as a progress update, the M54b30 crank and pistons are in the block. I need to order new main cap bolts and connecting rod bolts which I was wavering on reusing but I would be a silly risk for a small savings. It is assembled with the old bolts but I'll be replacing them with factory new rather than ARP. Everything feels very good, my main bearings plastigaged to 0.0015" and the crankshaft would spin freely (coast) about 3/4 a turn before I installed the pistons and rods. I need to pull my valves, polish the faces and reinstall with new valve stem seal. The machine should would have done this if the valves needed lapping but the sealed up fine. I have some build up on the face of most of them which probably wouldn't hurt a thing but could wreck a ring if anything broke free and I want to replace the valve stem seals anyway. Slow but steady progress. Once cool byproduct of this effort is my 5 and 7 year olds are getting to see the guts of an engine. Between diagrams, your tube videos and seeing the parts in person it seems to have sunk in with my 7 year old. She can identify the parts of an engine and thinks the "explosion" that occurs in the cylinder is pretty cool.
Last edited by gdavid; 10-10-2017 at 08:04 AM.
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Bump my thread back up, hoping for an answer about swapping trays in my previous post.
The engine build is at a crawl at this point. The head is apart, waiting for me to clean up the valves and exhaust ports before putting it back together. The longer this build drags on, the larger my list of upgrade "wants" becomes. If I can't/shouldn't transfer the cleaner trays and lifter from the warped head, I need new lifters and now I am (foolishly) considering valve spring upgrades. It would be great to find a deal on a unused performance set from a rebuild that stalled out but there is no way I can justify $600 for new. Stiffer springs with hydraulic lifters is probably not worthwhile and I definitely don't need solid lifters. The Bentley manual prescribes just lining them up on a flat surface and checking with a straight edge, between the two heads I should have plenty of good ones. Both heads are 400 casting units, thanks for the reminder bluptgm3.
While the pace of this engine build is a snails pace, I really don't have any urgency because the m52 in my car is running well. I have put over 11k miles on it since June and oil consumption has dropped from when I first bought it. The low miles on the car suggest it sat for a long period of time at some point and I suspect the oil rings were sticking. The varnish under the valve cover suggest it missed some oil changes as well. Regular use and frequent oil changes have helped. I was adding about 1/2 quart every 600 miles (~two fill ups), and now I'm around 1/2 quart every 1200-1500 miles. Some of the initial loss was a leaking vanos line (fixed) and my oil, valve and timing cover gaskets are sure to be seeping some. I get P0420 and P0430 codes periodically and they seem to be more frequent during warm weather, which makes me suspect an air/fuel mixture issue rather than burning oil. I passed Maryland emissions inspection back in the summer (when I was getting and clearing the codes more frequently). I have a pair of spark plug no-foul extensions riding around in my trunk waiting to go on but I would prefer to sort it out without resorting to a short cut, it would be very frustrating to keep getting codes with the overhauled engine. Another factor in my engine swap planning is the transmission, my wife doesn't drive manual and I want a second car she can drive, so for the time being I need to stay with an automatic in my car but I plan to replace her car at some point. If I hold of on my engine swap till then, I can put in an manual.
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Wire wheeled the valves last night, the back side of the exhausts where pretty nasty as well as the valve seat (on the valve, not the head) surface. One valve had a chipped edge right on the face of the valve, very small and did not reach the seat but it needs to be replaced. I cleaned them up using a wire wheel and a cordless drill to hold the valves. I slipped the end of each valve stem in a 1" section of fuel hose and then put that in my 1/2" drill's chuck. Worked great and made short work of 24 valves. I also checked the valve spring height with a straight edge per the Bentley manual and they are good.
I think I had a bit of miscommunication with the machine shop I used, I asked to check the head surface, inspect for cracks, test valves for sealing and grind if necessary. If grinding was necessary, they would go ahead and put valve stem seals in it. When the first head was unusable and I brought back the second head which looked filthy, I assumed some cleaning would be required and expected to be charged accordingly. When the second head checked healthy in terms of not being warped and the valves passed pressure testing, they did exactly as I had asked and stopped there and charged me very little for it ($70 to inspect both heads and the first head was well cleaned). Great guys and very fair but I should have been clear when I brought the second head in (looked worse) to go ahead, break it down and clean it up. Maybe I look like I have a very limited budget (maybe they called and spoke to my wife). I think they just confirmed the second head was not warped and said it was good to go, I will have to go over it carefully for cracks when I finish getting the carbon off. I'm not going to bother with a 3 angle grind, but I will lap the valves and do a water test for leaks.
Any advice on transferring cam trays between heads?, I've never seen warnings against doing it on here but the mechanist discouraged it. Then again he isn't a BMW specialist.
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Holy... !!! That is my exact same color!!! Stock as hell =) You, sir, have a darn good taste.
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Yes cam trays can be swapped between heads with matching cams.
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Continued progress on my engine build. Like all builds I am constantly debating needs versus wants. I am going throught the head now and I can see how $4k could be spent on parts and machine work. That is no where near the type of project I am undertaking, but there are upgrade temptations at every turn (new guides, custom valves, stiffer springs, solid lifters, ect). While I don't have a luxurious budget, I am fortunate to have the time to avoid rushing. I did a poor man's valve job with lapping compound and a drill. In the picture below you can see the exhaust valve to the left before lapping and the one to the right after.
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I put some oil in the valve guides, chucked a length of fuel hose in my drill and slid the hose over the end of the valve stem. The hose was a little too big so I used hose clamps to get it to grip, I used a fine lapping compound and kept the speed low.
The mating surface for the thermostat housing was pitted heavily between the two holes so I build it up with some JB weld, I will sand it flat when it cures.
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Still moving ahead slowly, actually last night I moved backward. I got a late start but started installing the valves. It has been a long time since I assembled valves and by the fourth one, I was feeling more proficient at getting the keepers into place. I was tempted to continue but it was way late and I was afraid of getting sloppy and damaging something.
Went to bed, laid there thinking until I realized I left the valve stem seals out. One step ahead, two steps back.
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Valves in with stem seals this time. No upgrades to the head, springs or valves but cleaned out a lot of carbon and checked the springs.
Last edited by gdavid; 12-29-2017 at 07:23 AM.
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Good luck with getting it back in action.
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Thanks, the car is in action racking up at least 80 miles/day. This is a spare engine.
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I gotcha, all of the recent posts were about head work, I thought it was your only motor.
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Anyone have a timing cover to sell?
I started to clean it up today and realized it was all cracked up, it is intact but has hairline cracks running through it. They don't seem to be concentrated at any particular point but are worst around the front main seal. The donor car was crashed but I don't see what could have hit the cover behind the harmonic damper, the damper was still on the engine when I got it so I doubt it was damaged in transport. The crank's thrust bearing was fine so I don't see how the crank could have caused the damage. I am probably forgetting something obvious. I could always wait and swap the one in the car on to the spare motor when I am ready to repower the car but I would very much prefer to have it ready to go for a quick swap.
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