https://www.r3vlimited.com/board/ en Thu, 06 Aug 2026 21:33:03 GMT vBulletin 60 https://www.r3vlimited.com/board/images/misc/R3V.jpg https://www.r3vlimited.com/board/ https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m20/10165041-vibes-the-bad-kind-and-dual-culprits Wed, 05 Aug 2026 22:42:08 GMT alarmed but enough it annoys me. I know balancing a quarter on an M20 is maybe too high an expectation but I'd struggle to imagine it balancing much of anything that was taller than it was wide right now. When not in 4th/not highway speeds it seems to be mostly engine, when in 4th at highway speeds in particular it feels more like a gearbox source thing.

What's been done recently or recently-ish: New motor mounts this spring, fresh transmission mounts (~year old or so), both are rubber. Ignition system is fairly fresh (5yish, cap and leads were replaced), front suspension done this spring, rear is to-do. Transmission was swapped, resealed and given Redline fluid (AT->5spd), new driveshaft, bushings, guibos CSB etc etc. Diff function tested fine. Got recommendation from driveshaft shop to do the motor mounts as that often solves it and it's a new driveshaft that was allegedly tested before shipping. Motor mounts improved it somewhat but in 4th gear I still get notable vibration but 1, 2, 3, 5 all are fine. ICV was given some cleaning out, no difference. Valves were adjusted about 3000 miles ago so I strongly doubt they're the culprit. Sparkplugs are similar age. ECU stomp test returned no error codes (1444 clear). CPS was replaced when I bought the car 5y ago, intake boots were within the past few years as well. Injectors are a bit tired but not so much I think this'd be the cause. I ran some MMO through with a tank of fuel, no change. I've put about 10k on it in the past 5 years, usually 2-ish a year (I don't commute every day but it's my daily), to give you an idea of wear. Mostly in-town but some highway stuff and last spirited autocross was June '24. Blue coolant was flushed like two years ago as well, and is still lookin' fine. I'm slightly overdue on oil timewise but it's only been about 3000mi and I used a full synthetic.

Granted have an exhaust leak at the downpipe to headers flange that I'm going to tackle after some medical hiatus from car working (probably in a couple months) but this vibratory issue predates that having made itself known, it mostly just causes more engine grime and a slightly extended cold start. I intend to resolve that obviously, but when I do, any pointers as to what else to look at? I'm also likely doing my timing belt and water pump and coolant hoses at the same time, later this year ideally, so while I'm monkeying around with the engine... Rebuilt greentops will happen when I get a SSSquid chip. No smoke at tailpipe, no backfiring, oil looked fine when last changed.

Wheels and tires were balanced last year, so it ain't those.]]> M20 Maybe Magpie https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m20/10165041-vibes-the-bad-kind-and-dual-culprits https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m10/10164899-low-mpg-on-idle Wed, 05 Aug 2026 00:48:49 GMT is it a bad gauge, or if it is a real issue, how to troubleshoot it?
for reference, i'm getting about 230 miles on a full tank of 91, mostly city.]]> M10 ronle https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m10/10164899-low-mpg-on-idle https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/transmission-driveline/10164892-differential-output-flange-in-and-out-play Tue, 04 Aug 2026 19:27:15 GMT
I can't seem to find specs on the differential, particulary how much in and out play to expect on the output flange.

Appreciate the insight... ]]> tomstin https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/transmission-driveline/10164892-differential-output-flange-in-and-out-play https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m20/10164847-intermittent-split-second-fuel-cutoff-after-replacing-timing-belt Mon, 03 Aug 2026 16:36:28 GMT Thanks!]]> M20 Ian 87 325ic https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m20/10164847-intermittent-split-second-fuel-cutoff-after-replacing-timing-belt https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m20/10164789-timing-belt-noise-repost Sat, 01 Aug 2026 14:52:21 GMT

this is my first post on the forums so I'm hoping somebody might be able to lend a hand , I recently did a timing belt and water pump change on my 320i (we also replaced the spring and guide pin on the tensioner) , now as far as I can tell ever since I had the belt done it has had a whine which appears whenever I rev the engine
at first I thought it was my fan clutch but after removing the accessory belt the noise remained , it sounds like when a viscous fan is on full lock I will link a video of the noise so you can hear it for yourselves , now as far as I know we did the procedure correctly for tensioning the belt ,
we fully compressed the spring on the tensioner , set TDC and fitted the new belt , released the two 13mms and the spring set itself against the tensioner , locked the tensioner down then spun the engine two full rotations then slacked off the tensioner nuts to see if there was any additional movement which there was not , then locked it down again , I did some digging online and some say that the noise will eventually go away , im not sure how true this is but I don't really drive the car much so I don't see that happening on its own]]> M20 Blau320i https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m20/10164789-timing-belt-noise-repost https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m20/10164638-euro-m20b25-piston-compression-height-spec Wed, 29 Jul 2026 19:41:53 GMT
Does anyone know compression height spec for euro 9.7:1 b25 pistons, or how to identify them? I'm trying to discern if a set of replacement pistons overseas are 8.8 or 9.7:1 before I order.

US Spec 8.8:1 as far as I can tell is 34.2mm. 206.7-(75/2)-135=34.2mm.

This measurement also doesn't take into account the dome of the piston above deck, so perhaps CH isn't helpful?

I found measurements of 34.090 on Yenmax 3104600050 b25 pistons.

Yenmax specs:

https://pdfs.yenmak.com.tr/31-04600_BMW.pdf

Help?
]]> M20 AWDBOB https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m20/10164638-euro-m20b25-piston-compression-height-spec https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m20/10164385-re-pinning-a-motronic-1-3-dme-connector Thu, 23 Jul 2026 14:47:54 GMT
The only recent-looking product I could find is this:
https://technicaracewire.com/product...46026648191253

I believe they are JPT terminals, which can only be removed with a tool like this:


This tool is $75 for some awful reason.

Is there a cheaper tool to use, if this is even the right tool at all? What sort of crimper would I need? Does anyone have a video guide, or even a how-to with pictures?]]> M20 rogerscgreg https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m20/10164385-re-pinning-a-motronic-1-3-dme-connector https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/transmission-driveline/10164183-serviceable-u-joint-replacement Sat, 18 Jul 2026 14:38:21 GMT
Beyond a hammer/sockets and a balljoint tool don't have any pressing tools. My other option is to order a u joint and bring it to a shop to install.

I wasn't able to find documentation of any e30 guys doing this.]]> 88Sedan https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/transmission-driveline/10164183-serviceable-u-joint-replacement https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/transmission-driveline/10164154-help-replacing-center-support-bearing Fri, 17 Jul 2026 16:15:13 GMT
I am confused with what realoem is showing in its diagram.

https://www.realoem.com/bmw/enUS/sho...oogle_vignette

So mine was missing the dust cover #14 entirely. Can someone familiar with assembly tell me how the dust cover is retained? There isn't room to press the bearing in anymore so I am 99% sure the dustcover would go on after the c clip. Do the 2 shafts being pressed together retain it?

Also confusing me is that diagram shows 2 of the large retaining collars #16 & #18...?

My car also doesn't have the #17 toothed washer. It is shown between the two retaining collars...do I need this and where does it go?

I need someone to make sense of this for me please. Since my car is an '88 I double checked that in regards to driveshaft there should be no difference early to late '88.

1) I need dust cover correct?
2) Where is it installed exactly?
3) Same 2 questions about the toothed washer.]]> 88Sedan https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/transmission-driveline/10164154-help-replacing-center-support-bearing https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m20/10164069-warped-valve-cover-what-s-next Thu, 16 Jul 2026 05:13:45 GMT
What do people usually do in this case? Get the valve cover machined or get a replacement?

I've heard from someone that you could use RTV instead of a gasket in the meantime with the warped valve cover, would that work?

Thank you!]]> M20 eight-0-eight https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m20/10164069-warped-valve-cover-what-s-next https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/alternative-tuning-w-a-r-megasquirt-etc/10164003-i-pre-ordered-a-mafsync-module Tue, 14 Jul 2026 20:58:17 GMT
It interested me because it's plug n play and should greatly improve throttle response. If I get around to building a b27 or b28 stroker the afm won't be a restriction anymore and I can still use a chip to tune.

I know sssquid was working on a similar adapter before going belly up.

https://reviveurride.ca/mafsync.html]]> Alternative Tuning / W.A.R / Megasquirt / etc 88Sedan https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/alternative-tuning-w-a-r-megasquirt-etc/10164003-i-pre-ordered-a-mafsync-module https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m20/10163832-valve-cover-off-center-after-gasket-install Thu, 09 Jul 2026 19:03:27 GMT Replaced valve cover gasket, on install unfortunately stripped a stud. Had to drive it back home 30 miles and take the cover off again a day later to remove the stud. I believe in both cases after putting the cover back on, the cover seemed to be off center. Did I botch the gasket install? No oil leaks after driving 50+ miles after second removal. Replaced valve cover gasket, on install unfortunately stripped a stud. Had to drive it back home 30 miles and take the cover off again a day later to remove the stud. I believe in both cases after putting the cover back on, the cover seemed to be off center. Did I botch the gasket install? No oil leaks after driving 50+ miles after second removal. M20 bhp793 https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m20/10163832-valve-cover-off-center-after-gasket-install