Just entered the E38 world with a 750iL needing a lot of care. Drivetrain help sought

[atakordie]

I recently purchased a 2001 750iL in steel blue metallic with 138k miles after searching for one in my price range for quite a while. Purchased with knowledge of a check engine light, among other problems. However, PO did not divulge (or did not know about) other major issues, but I am plowing ahead and revitalizing this car with some TLC, the way it should have been all along. If I can, I plan to chronicle the work I do to it in this thread. It is a 4 owner car, the 4th owner - the one I purchased from - only had it for 9 months and managed to trash up the exhaust with some loud aftermarket drone producer. So first thing first, I need an exhaust assembly for a 750. No one seems to have one, especially not near me. The third owner died and the fourth owner bought it from his estate. I have all or most of the records from the 3rd owner. He spend at least $20k on it, but looking under the hood and chassis as well as the interior, you couldn't tell. At any rate, here are a couple of quick shots of the car, followed by questions and info:

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Don't worry, I've taken off the "V12" front license plate, but still need to debadge the V12 chrome decal from the trunk lid (can't see that in the above pic).

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If you are still reading, I could use some help with diagnosing the engine and transmission. I have had off-and-on difficulty connecting INPA and DIS (even though it works fine on my E39), so I used a Peake reader and found that there are misfire codes for cylinders 7-12 as well as #5. I cleared the codes and they didn't come back for a little bit, but the check engine light comes on eventually (yet sometimes turns off for a short time). At one point, I managed to get DIS to give me a P1270 code (engine torque imbalance I think?). I replaced both MAF sensors with new Bosch units as well as a right side cracking intake boot, but the check engine light keeps coming back. I then foresaw more sinister issues at hand. I have put the 750 on jack stands in the carport (no garage ) and have removed the front suspension (since that needs replacing). The engine at idle speed has a bit of a vibration to it, even though the motor mounts look new. After reading the records and finding that owner #3 drove the car 5 miles with the temp gauge in the red (and me having a mild heart attack), I performed a compression test on the M73 (with the engine warm, fuel disabled, all plugs out) last week with the following results:

Cyl 1: 220 psi
Cyl 2: 209
Cyl 3: 209
Cyl 4: 206
Cyl 5: 220
Cyl 6: 223
Cyl 7: 218
Cyl 8: 233
Cyl 9: 224
Cyl 10: 226
Cyl 11: 219
Cyl 12: 211

Cylinders 2-4 were lower than the others, so I retested only #4 (time constraint) and got 215 psi. These numbers seem somewhat high to me, and my hunch is that oil is getting by the oil control rings or perhaps the valve guides, but I don't have enough experience to tell if that is accurate. I did notice a bit of oil on most or all of the spark plug electrode tips and threads. I have removed the heat shields from under the exhaust headers and can see oil coming from what looks like the bottom of the exhaust ports/studs on the passenger head as well as at the head gasket. The driver side head is mostly blocked from view by the steering box, but it appears one or two ports have the same problem. Pic of this leak below. The starter cover is drenched in oil, but is apparently not dripping. I have not noticed visible smoke coming from the tailpipe, even when following this car from behind. However, there is a muted raw fuel smell from the exhaust and the fuel purge valves start clicking within a short time after starting the engine (at least, this is different behavior than my 540). I am contemplating running a Liqui-moly engine flush treatment before draining the oil to alleviate any sludge before removing intakes, etc, but this would obfuscate any oil coloring diagnosis, oil analysis, or checking for coolant in the oil. What are your thoughts on this leak? Cylinder 2 is just as bad as number 4 (on the left) below.


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Moving on to the transmission situation.... There is a distinct constant whine under load only after the tranny warms up. Perhaps this is a low fluid situation (output seal is leaking a bit, as well as either the rear main seal or input seal), but there is also a distinct rubbing/whining noise when the transmission upshifts under acceleration. I've posted a video of that below, the sound is hard to hear over the loud exhaust, but happens around 2000 rpm shift there at the end of the clip, so turn up the volume. What does this noise say to you?



I have also noticed an occasional slight jolt when it downshifts from 2nd to 1st. I have ordered the parts for rebuilding the valve body (as this transmission was installed from another car, with unknown mileage and origin before my ownership) and I have all the seals but still need the output seal nut special tool. I wonder if the torque converter needs replacing? Also, a separate issue I think, but the shifter is a bit loose and nebulous when selecting gears. I think I can fix this by adjusting the bowden cable tension, as I understand it.

I am almost tempted to pull the engine and rebuild it if I can, since the transmission will be out anyway and I just found a leak at the radiator yesterday, but I don't own an engine hoist or stand yet and don't have a nice clean work area, other than a small shed. Obviously, I'd rather not do it unless necessary.

I'll need to replace the downpipe for cyl #1-3 (seen at left below) as well, since it has a broken flange.

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Other issues abound and I will speak to those later if I can't figure them out from searching here.

Thanks for your help. I'll post more pictures when I can.

[Mayorchuck]

Welcome here. Beautiful car. I'm not a 750 guy but there are some good ones here who will help.

[blackknight530i]

I thought the "V12" badge was OE. Why remove it?

[chrisn7]

Although its annoying, you are not alone with INPA/DIS issues - when trying to read the DMEs, though the other modules read ok. I've yet to find anyone with this issue who has found a solution.

The oil may be from the cam cover gaskets, so that might not be as serious as you assume. On changing my plugs recently, I too noticed that there was some oil on the threads, but I don't have any engine issues AFAIK.

Gearbox - well non OEM filter have been known to collapse internally whech seems to lead to whining, though I have not personally experienced this. Hard shifts may be dirty fluid, so perhaps a filter/fluid change would be a good start..

[M I C H A E L]

Sounds like it needs some good lovin. Don't worry we got you covered here. I'm not very knowledgeable on the 750s but others will Chime in on this....

Beautiful car by the way.. Thought I saw one similar on craigslist and eBay. Wonder if its the same one.

[xboss]

I thought the "V12" badge was OE. Why remove it?

It's not OE

[blackknight530i]

Ah, ok

[Timm]

The compression values are reasonably even, and as you report, a second test saw a different reading - not an indication of gasket failure. As already suggested, the valve covers are much more likely to be the source of the oil leak. As you have good compression, having single-cylinder misfires will be due to HT problems, HT leads, distributor caps and rotor arms.

[atakordie]

Although its annoying, you are not alone with INPA/DIS issues - when trying to read the DMEs, though the other modules read ok. I've yet to find anyone with this issue who has found a solution.

The oil may be from the cam cover gaskets, so that might not be as serious as you assume. On changing my plugs recently, I too noticed that there was some oil on the threads, but I don't have any engine issues AFAIK.

Gearbox - well non OEM filter have been known to collapse internally whech seems to lead to whining, though I have not personally experienced this. Hard shifts may be dirty fluid, so perhaps a filter/fluid change would be a good start..

Ah, ok. I still can't read the ABS module for some reason. I need to change the 6 rubber brake hoses, so I need to cycle the ABS valves after that. Hopefully I can figure out what I'm doing wrong here.

I'll inspect the cam cover gaskets and report back when I do.

I thought the transmission whine happened before the fluid heated up, not after. But I do already have new fluid ready to go with the proper filter and all.

The compression values are reasonably even, and as you report, a second test saw a different reading - not an indication of gasket failure. As already suggested, the valve covers are much more likely to be the source of the oil leak. As you have good compression, having single-cylinder misfires will be due to HT problems, HT leads, distributor caps and rotor arms.

Thanks, hearing that is encouraging. I have new coil wires. I'll inspect the caps and rotors, though PO said they had been done recently. The entire left bank giving misfires seems like it may be a coil or cap/rotor issue (though after clearing the codes twice, I can't seem to get them back and now I'm having trouble reading the DMEs again). I'll inspect next time I work on her and report back. Not sure exactly what to look for, but if it looks old, I'll probably buy new. I have a new set of BMW coil wires already waiting.

Vis-à-vis the compression, TIS says the M73 should be 10-12 bar (145-174 psi). That's why I thought my measurements seem high. I also can't figure out why there would be oil on the plugs...not fouled...just there. I'll try to check the compression chamber visually if I can.

[atakordie]

Ok, so today I removed the intakes and valve covers and found that the intake manifold gaskets have a myriad of cracks in them and about half of the ports appear to be leaking to some extent. I had dismissed this as a misfire possibility earlier because the PO claimed he had changed them recently. On a side note, the interior of the intakes are coated with oil, so perhaps this is why I have oil on the spark plugs? I assume it is the oil separation system, though the CCVs look pretty new.

The valve cover gaskets look and feel quite new as well. PO said he had those done recently, and it looks like he was telling the truth about that. There may be a small leak there at cylinder #6, but I think it is residual mess from before the gasket change. The valve covers really don't seem to be leaking. However, a huge leak seems to be emanating from the timing cover area and is running down the front of the engine and the forward area of the heads at cylinders 1 and 7. Still not sure of the source of the exhaust manifold leak. I couldn't figure out right away how to remove the heat shielding just below the spark plug holes (for a better inspection of the exhaust manifold leak area), so I'll tackle that another day.

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This shows what I assume is a timing housing gasket leak at bank 2.

The real news is that the head bolts at cylinders 2 and 4 on the exhaust side of bank 1 are finger loose, so I assume those two bolts have snapped somewhere and I need to remove the head and inspect. No bank 2 bolts were loose. There is some heavy varnishing inside both heads. I ran some engine flush at idle for 10 minutes before draining the oil, so it may have been worse before. There is some sludge buildup in the timing chain area, as you might be able to see in some of the pics below. Not sure what to think or do about that.

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The distributors look rather new to me, so I don't think that is a source of worry.

Since bank 1 has 2 broken head bolts, I'll need to investigate that, but should I go the full mile and take off the other side as well? I've never removed a head before, but it looks pretty straightforward. I guess I can take it to a machine shop and have them check for warps and cracks as well as clean it up. I'm still contemplating pulling the motor and working on it out of the car. Comments or suggestions?

[board57796]

Watch out for the coolant passage connecting the back of the heads. I missed it and while trying to get one head off, snapped it right in half. (This was on my previous 750).

[M I C H A E L]

honestly, youre in this far, I would just pull it out and do everything it needs addressed, then be worry free from here on out.

[atakordie]

Thanks guys.

[M I C H A E L]

Thanks guys.

No problem. Plus it will be a lot easier to work on. I'm glad this rare bird is in the hands of an experienced person.

[bruinbro]

FYI the e31 forum may be of some help.

[mboor]

If it were me, id pull the motor, take both heads off, and do it right. Like Michael said, your already in this far.... might as well go all the way. Glad to see your saving a facelift 750. you will grow to love this car once its running and driving properly. It will far out weigh the expense and the pita of fixing it.

[Sansouci]

Great job of uncovering all the mis-deeds and non-deeds of the POs. I would figure out the need for a trans OH (I don't recall seeing the mileage on the post) but certainly a fluid change should be part of the job as well as exhaust studs, motor mounts, exhaust hangers etc. That's before you get to the suspension. That appears to be OK as your to-do's focus on engine/trans.
Related to this, I'm trying to see if any one recommends European Transmission & Parts in Cumming Georgia. Let me know!

Good luck with your restoration. The body looks fine
--Ken

- - - Updated - - -

Duh Oh! 138k. Trans fluid but check what comes out, pieces, color etc. to gauge your situation.
--Ken

[xboss]

What miss deeds and non deeds? A recent PO put 20k into it!

The broken head bolts are a common 750 problem.

[mboor]

i have read that broken head bolts are common as well. luckily mine were not broke when i did my intake / valve cover gaskets. i had a similar amound of sludge build up around my timing chains. I think this is common on high mile engines, not necessarily something to worry about. if you pull the engine and do the head gaskets you can cleam most of it out then

[M I C H A E L]

i have read that broken head bolts are common as well. luckily mine were not broke when i did my intake / valve cover gaskets. i had a similar amound of sludge build up around my timing chains. I think this is common on high mile engines, not necessarily something to worry about. if you pull the engine and do the head gaskets you can cleam most of it out then

The banjo bolts huh? I heard that too.

[xboss]

These M73 engines make an incredible amount of heat. If you open the hood after a 3 mile drive it feels just like opening an oven.

[dburt86]

sweet car. Sweet color.

Im not sure i would pull the motor just to do the heads. I mean, you already have the intake mani off, now its just the exhaust mani's and head bolts. Unless theres issues you want to take care of down below.

[lambo1]

Hi Maybe this will help, I have a 1988 e32 750 and a 1996 e38 750 the 1988 was bought in a bad condition and smokes a lot and fouls plugs, and runs very very rich, and only on 6 cyl, I have spoken to a very old BMW mechanic and he said the reason for the oil on the plugs is a leaky sump that allows pressure to end up in the pcv system, and so gets sucked through the engine, I was somewhat doubtful about his telephone diagnosis, until I parked the car on a slight hill, only to find the sump oil poring out at the rear, I guess he was right about the sump leak, unfortunately he says you have to drop the exhaust and the trans to get to two rear sump bolts, can anyone confirm.

[atakordie]

Update:

I've been steadily working on this car when I have time. Seems like most of my time is spent cleaning...very dirty drivetrain at all points. The subframe and engine bay had about a centimeter deep amount of grime/sludge from power steering hoses and various engine gasket leaks. It's a shame a PO spent $20k on this car (work not done by him), since I've gone through and inspected nearly everything on the car and there is barely a sign of repair work that has been done, and a lot of work was supposedly done within the last 10k miles. Reading reviews of the shops that did the "work," I wonder if they did anything at all for some of the work orders. I'm more upset that the mechanics that did the various jobs managed to lose so many fasteners and create problems in the process. I'll be spending about as much as that PO did to get it right, except I'm doing it all myself. For now, I'm tackling the engine, transmission, differential and full suspension & steering. This means big bucks for 4 OEM struts, all links, bolts, gaskets, hoses, cooling system parts, etc. I've decided to hold off on most of the interior work for now until the car is running again. It's just too much to think about and store parts while doing the engine and working outdoors with no garage. Still need a good spare M-par for the trunk at some point.

I'd like some feedback about some of the issues I've found, shown below in the pictures.

I got the engine and transmission out in June, but had to wait until last week for disassembly after the timing tools finally arrived. I wanted to check the timing before disassembly to determine if there was an issue there first.

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Decided to go ahead and change all 4 seals on the transmission, as well as rebuild the valve body. thectsc.com really helped me out when I had a ZF spring out of tolerance. The whine I was getting may very well have been a combination of problems. First, the filter was not Filtran made. Second, the ATF fluid was red in color (yet fairly clean), which is NOT the same as the approved fluid for the transmission as far as I know. The ATF1 I have for replacement looks a lot like engine oil...not red like the typical ATF I've used before. Who knows if that caused damage or not. But putting the right stuff will be a good thing to do. I also had the tired-looking torque converter rebuilt. They needed my core (pictured), since there were none available for this car apparently.

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Working outside really bites, especially in the summer here. Very humid and rainy. Thank goodness we're moving next year.







So I went ahead with checking the disassembly and timing (a little off; nothing major), then removed the heads. Unfortunately, I moved the crank by hand a little when working over the engine. This caused some valve-to-piston contact on two cylinders, enough to notice after removing the heads. I haven't cleaned off the carbon buildup yet, but there appears to be a small indentation or mark on these two pistons. Not sure if this is a problem or not. Also, noticed some vertical scoring of many of the cylinders, but I'm not sure of the cause... must have happened some time in the past (I've put about 350 miles on the car since purchase). The marks are deep enough to catch a fingernail. There are dark burned-oil looking ring marks at the top of each cylinder bore. Not sure if this is a sign of something or not either. The car was overheated at some point, so maybe it has to do with that. Lots of varnishing and sludge around the timing chain area... something akin to mud poured out of the chain tensioner region when taking off the top timing cover and smelled like tar/burning oil. One last note was a wear pattern that looks to be present in each cylinder closer to the bottom of the bores. Piston skirt rubbing evidence? I don't know, and I don't own the necessary micrometers to get dimensions. Please let me know if these images below are a sign of something gone wrong. If a rebuild is required, I am hesitant but willing to forge ahead. Worst case scenario would be to purchase a new block with pistons included (and crank??) from BMW. A machine shop might charge a lot to correctly rebore or hone the bores, and new oversize pistons/rings are pricey. The head bolts that were loose (mentioned above) were not broken. All bolts came out wholly intact. Not sure why 2 were loose on bank 1. Any advice on the above?

[psjr]

I don't know much about the scoring, timing, etc. but if the motor has all these possible issues why not just buy a known good used one? Should be under $1000 I'd think due to low demand.