Pulled the S52 back out, have some questions

[Varinn]

Looking for input on a few things with my stock S52B32.

Car is burning crazy amounts of oil, has a pretty hard misfire on cold starts, and a few other issues. I have some other jobs I wanted done before winter anyways so I just spent the morning yesterday and yarded the motor out. Head will go for a checkup and budget refresh, bottom end might get some work but only if needed. I am not planning any performance upgrades during this, just maintenance.

1: Oil burning on deceleration and when starting from an idle'd stop. I'm thinking valves stem seals and guides? If guides, I hear that the only fix is to buy new valves with larger stems, is this true?

2: Compression after 5 strokes was 170/170/165/170/165/170, peak reached at 8 strokes and it was 210 across the board. Test was done with all 6 plugs removed, no air filter, and throttle at 100% open. Are these acceptable? I'm finding mixed reports and the Bentley doesn't list optimal or standard range, only the minimum.

3: Car has an M50 manifold, with the TMS adapter kit. The "heatshrink" piece didn't stick and when I pulled the CCV tube out it just pulled apart. I suspect this was a massive vac leak causing a poor idle? I'm going to buy a new hose and use a clamped silicone tube instead to extend it. Also the drain line from the cyclone has a pretty harsh bend in it to reach the dipstick tube, anyone come up with a good solution to make sure it's nice and smooth? The plumbing under the intake is very convoluted and messy, is it worth deleting the TB heater and welding the metal pipe shut/plugging the head port? I live in a climate similar to Seattle, I don't care about any "performance gains" but wouldn't mind having less things to fail.

4: e28 green motor mounts, I should have trusted my instinct on install. The studs don't line up right and it forces the passenger side to twist a bit. It was ok for a year or so but recently I got vibrations in the wheel when going over bumps. The passenger mount is collapsing and the oil pan is now sitting on my e36 steering rack. What are the best alternative option? I'm thinking of going with AKG cause of the angle, but I hesitate on using Poly for the NVH.

[VanBimmerhead]

Greetings,
Sorry to hear your having some nasty issues there, hopefully I can help if only just a little.
I have done a few E30 swaps myself, including an s50 which is similar to yours.

1. If your oil consumption problems are related to your valve stems, you may have a couple options: get the oversize stemmed valves you mentioned, or purchase a new / reconditioned head. In the case of many cylinder heads it is possible to install new guides. But unfortunately the S5x heads have a tendency to crack as they cool and shrink around the new cooled guide. The heads for these engines are readily available, and fairly inexpensive. This assumes of course, that the guides are your issue. Have you explored any other possible sources, head gasket etc?

2. What is more important in your compression results, is that they are consistant. No individual cylinder is considerably lower in reading. The ultimate number is influenced by several factors which vary, and is somewhat less important unless there is a low individual cylinder. If you have access to a differential pressure tester, it may be usefull in determining if your valve guides are indeed worn, because you can manipulate the individual valves during, and see if sideplay is partially unseating a valve. You will also be able to detect other sources of leakage.

3. The hoses under there are pretty crowded. I have the throttle body heater on mine deleted and use the coolant circuit for my turbo coolant lines. I haven't noticed any adverse icing of the butterfly, but my intake is sort of heated by compression. I doubt that you would have issues, but I have had older m20s ice up in below 0 conditions.

4. I have had success with mounts that look like the ones you are currently using, but I have a 1/4" spacer plate on my subframe which acts as a doubler, it elevates the oil pan, and allows for some hole relocation. I also trimmed a 45deree angle cut of about 3/8 of an inch from the end of the rubber mount steel, so that it is allowed to spread out more. I know that there are also some plug and play mounts available, but I have not personally used them. The E24 M6 mounts I used have held up for over 10 years, but I have heard others like you say that they break. Sideloading differences maybe?

Hope some of that helps. I know how frustrating these problems can be.

[Varinn]

Greetings,
Sorry to hear your having some nasty issues there, hopefully I can help if only just a little.
I have done a few E30 swaps myself, including an s50 which is similar to yours.

1. If your oil consumption problems are related to your valve stems, you may have a couple options: get the oversize stemmed valves you mentioned, or purchase a new / reconditioned head. In the case of many cylinder heads it is possible to install new guides. But unfortunately the S5x heads have a tendency to crack as they cool and shrink around the new cooled guide. The heads for these engines are readily available, and fairly inexpensive. This assumes of course, that the guides are your issue. Have you explored any other possible sources, head gasket etc?
I will be looking at any possible sources. I've got another car to drive so I can take my time and look closely for any problems. I'll likely get the motor on a stand tonight after work and try to get the head off tomorrow. I'm still debating on whether to take the head to a machine shop for inspection and repairs, or checking it myself and telling them what needs to be done.

2. What is more important in your compression results, is that they are consistant. No individual cylinder is considerably lower in reading. The ultimate number is influenced by several factors which vary, and is somewhat less important unless there is a low individual cylinder. If you have access to a differential pressure tester, it may be usefull in determining if your valve guides are indeed worn, because you can manipulate the individual valves during, and see if sideplay is partially unseating a valve. You will also be able to detect other sources of leakage.
What you're suggesting is to remove the cams to give access to the valve stems, and with the cylinder pressurized using a leakdown tester to wiggle the stems and see if I can get any change in leakage through valves? I guess compression numbers aside this would be the better test of ring condition than my other numbers? I'm happy to see that the even numbers are promising, but I still can't help but feel that they are on the low side overall.

3. The hoses under there are pretty crowded. I have the throttle body heater on mine deleted and use the coolant circuit for my turbo coolant lines. I haven't noticed any adverse icing of the butterfly, but my intake is sort of heated by compression. I doubt that you would have issues, but I have had older m20s ice up in below 0 conditions.
In the end I will probably opt to leave it in place, once everything is back together it isn't such a big issue that it's cluttered. I do live in the PNW and we never reach temperatures as cold as yours in Alaska, but that's not to say I won't hit up a few mountains in the winter. It is my winter daily after all.

4. I have had success with mounts that look like the ones you are currently using, but I have a 1/4" spacer plate on my subframe which acts as a doubler, it elevates the oil pan, and allows for some hole relocation. I also trimmed a 45deree angle cut of about 3/8 of an inch from the end of the rubber mount steel, so that it is allowed to spread out more. I know that there are also some plug and play mounts available, but I have not personally used them. The E24 M6 mounts I used have held up for over 10 years, but I have heard others like you say that they break. Sideloading differences maybe?
I never heard of the e24 M6 mounts and did consider the spacer plate myself on my current mount setup. I think I'm still going to do some more research into dedicated swap mounts to avoid any future problems.

Hope some of that helps. I know how frustrating these problems can be.

Thanks for the tips

[2mAn]

I love my AKG mounts....

[exhaust]

I love my AKG mounts....

Which mounts? I'm concerned that something solid or super stiff would mess up my ride quality

[M3PO]

I have AKG mounts also. They didn't seem to line up perfectly either but I was told to "just tighten them down" and so far so good. They "line up" once you crank them down.

I have lots of noise and vibration but my car has no firewall insulation and a LW flywheel with no idle compensation.

[E30335i]

rode in a s52 daily track car w/ akg mounts. not even harsh.

[mpowerful]

I have e34 525i (m50) mounts. After you grind the alignment nub off they line up perfectly and they are nice and cushy. Been running em 1 1/2 years with no problems. Oh and they cost like 10-15 bucks each haha.

[ZekeTheSneak]

Your subframe mounts will bend over time from the new engine. The stock subframe on mine bent just from driving it. One thing to look at. I bought the shittt blue ones that are from one of r3vs sponsors and they suck horribly. Spent the extra money on akgs and they fit great.

My engine smokes horribly as well, hence why i never drive it anymore :( let me know if you find the cause of the oil burning. I believe mines from the oil control rings...

[Varinn]

More questions and a few updates.

Ordered AKG motor mounts and trans enforcer cups with new e21 mounts. Also ordered new main and rod bearings, conn rod bolts, bottom gasket set, timing guides, vanos oil lines and CCV breather line, spark plugs, coil boots, exhaust manifold studs (some came out) and a bunch of other random assorted crush washers, gaskets, etc.

I have not decided if i want to replace the chains yet, as the sprockets are expensive and I always prefer to replace as a set.

Head is off and has been cleaned. It goes to the machine shop for a skim, valve grind, and further cleaning. They will check and replace guides and install seals, but they're 90% sure guides will be ok, and are positive they can be replaced as they've done it a couple times for my friend's BMW shop before.

Block is my next focus, I borrowed an inside mic set from a friend and measured between 3.400" and 3.403" on all cylinders, measurements taken at top, middle, and bottom of the stroke length and both on the front/rear direction, and left/right (in relation to the crankshaft).


I've never used this tool before, so it's possible there's a margin of error on my measuring. I'm thinking to dismantle the block and send it to the shop for a hone and I'll have them install new rings. What is the maximum bore I can use and still keep the stock pistons? I want as little material removed in the hone process as possible which is about 0.001" on average. Does this seem ok? If it is, I'll take the block to them for a hot-tank, hone, and (when the parts arrive) the ring install.

[Varinn]

Cylinder head is done, valves got a 3 angle and new guides/seals. Nothing fancy.

Parts arrived yesterday and I dropped the new rings, bearings, and bolts atthe machine shop this morning. The powdercoated timing covers, accessory brackets etc are all ready for pickup. Hoping to start assembly next weekend

[ZekeTheSneak]

Did this resolve everything? You got me thinking my guides are bad. I had my valve stem seals redone but that didnt fix the issue

[Varinn]

Did this resolve everything? You got me thinking my guides are bad. I had my valve stem seals redone but that didnt fix the issue

Yes and no...

The engine has been fully assembled and installed back in the car but I have some new (and much more annoying issues) to deal with. As far as I can tell the thing is no longer burning oil on deceleration. I have put approximately 30km on the motor since the rebuild.

Problems since the rebuild are:
Rough cold idle
Unable to maintain idle when hot (stalls out at lights or any stops but restarts easily)
Throttle often erratic in terms of feel. Sometimes very sluggish, sometimes very responsive to input.
Drives well once above idle rpm's
TPS shows 99.6% at WOT, but never below 16% when fully closed (readings from torque app). Readings taken while closed-throttle stop is not touching the actuator and the cable was disconnected. Measured 1.4k closed to 4.5k ohms at WOT. The butterfly is as far closed as it can be.
New clutch setup is barely functional, pedal engagement is in the last inch at the top of the pedal. It is so close to the top I do not believe it fully engages when not touching the pedal.

Trouble codes (no CEL)
P1519 - Valve timing (ie: Vanos mechanically stuck)
P0155 - 02 sensor heater circuit (Bank 2 sensor 1)
P1423 - Secondary air injection bank 1 flow too low
P1421 - Secondary air injection valve short to ground
P0500 - Vehicle speed sensor

Work done
- All new seals for complete engine and transmission
- Cylinders re-honed
- OEM S52B32 rings
- OEM main and rod bearings
- Valve stems
- Valve guides
- Valve grind
- Replaced all vacuum hoses and caps
- New 3.5bar FPR, fuel filter, professionally rebuild injectors
- New Plugs, cleaned and improved all engine connections
- All timing chain guides and tensioners
- New belt, tensioner, and both pulley bearings
- New AKG motor mounts, trans mounts, shift bushings, and a modified shift platform
- Custom power steering lines
- SPEC stage 1 clutch kit for 325i on oem m20 flywheel, modified to clear S52 pan

My first finding after the rough starts was a smoke test, I found and fixed one split vacuum cap on the bottom of the intake manifold. I have not had a chance to re-test since as I had to return the smoke tester and the 20-pin to OBD adapter to my friend's shop before I could try again.

Intake temporarily rigged up for testing, I plan to re-install my modified oem airbox when I solve these issues.

I will be replacing the o2 sensors, and likely the TPS. All wiring has been checked closely and it is hooked up correctly. No obvious issues with poor connections or damaged wires. I have to look at that vehicle speed sensor fault as I never had any issues with it before the rebuild (that I was aware of). I did not have a code reader at the time but the fault never showed up on any services at my friends shop with ISID/GT-1.

I am not sure what I could be doing wrong with the valve timing. I am following this process to a T but after rotating the engine twice the timing is never in the same position. Exhaust camshaft is at perfect TDC, intake came goes out of alignment by a few degrees. Bentley manual says on second check to just loosen the exhaust cam bolts and adjust the intake then re-lock the cams. This seems to me like it is limiting my vanos sweep.

The clutch is another issue, dimensionally it seemed to be the same as my original 323i flywheel with stock Sachs clutch and throwout bearing. The SPEC supplied TOB is approximately 1mm longer from the ears to the bearing surface. The original clutch engagement was mid pedal stroke and the clutch stop easily perfect the throw. The new clutch pedal feels like it binds at the bottom of the throw and the slave never fully releases at the top. Hydraulics have no air in them. I suspect a portion of the system is longer than the original causing the throwout to always have some pressure on the pressure plate springs.

[Varinn]

On my first attempt, this is how the cams looked after installing the vanos, locking the bolts on the exhaust sprocket, removing the timing blocks, and rotating the motor twice. After doing it again, but making sure to have the teeth engage with zero excess movement on the vanos I ended up with the cam being out by the same degree except in the opposite direction

[FredK]

I still think the helical gear is off by one tooth even though you've said you've tried it two times, in one case resulting in the above, and in the other, the cam with the same rotational error but in the opposite direction.

Maybe take a look starting at Step 18 here:

http://drvanos.com/docs/stage1.pdf

just to see if it is any different from the procedure you have been following.