Unofficial BMW

Google Search

What's New

Search (Google!!)









Used Cars




In Association with

Home E12 E24 E28 E30 E34 E36 Z3 E39 E46 X5/E53 ALL
Ron Stygar Carl Buckland Dale Beuning Forums Help

Unofficial BMW Nav Map

From: "Pete Read" <>
To: "bdigest" <>
Cc: "Dave Nelson" <>, "Mformation" <>
Subject: Re: <E34><E28> Thrust Arm Bushings
Date: Tue, 2 Mar 1999 11:49:50 -0800

Dave Nelson asks about thrust arm bushings for his E34 M5:

>I can't seem to pin down the digest that may have had info on
>the replaceability of an E34 M5 thrust bushing, with that of a
>750IL? Is it a perfect fit, if not is there a heavier duty one
>that is? I've seen some chat about "cutting" down the 750IL for
>fit, but is this necessary for my car (E34)?


I wrote a couple of notes last year about thrust arm bushings for the E28 and E34 five series. The first was a warning about correctly modifying 750i bushings for E28s. Dinan 650.962-9401 and Steve D'Gerolamo 201.262-0412 both do it correctly (see references below to the first note which includes the correct dimensions). I've also included the second note with all the part numbers (see below).

The bottom line is that any E34 can use the 750i bushing (31 12 1 136 607)
without modification -- E28s need to have the width machined down. I also guessed that the 750i bushing would be a suitable, and much less expensive, replacement for the E34 M5. Since that time, I've talked
with James Leong at Dinan and he confirmed that they have successfully used 750i bushings with E34 M5s (James is always extremely helpful as is everyone I've talked with at Dinan).

...old post on thrust arm bushings....

Subject: <E24><E28><E31><E32><E34> Thrust Arm Bushings, Additional Info

Several people have contacted me about my "<E28><E24> 750i Bushing Warning (Dinan Bushings are fine)" post in bmw-digest v07.n1375 and Mformation #194, so let me add a little more detail.

Bill Shook (owner of Kraftwagen here in Northern Virginia) has told me more than once that he appreciates BMW's effort to keep improving parts when they find a problem area. A good example is the, twice updated, shift detent cover plate Bill told me about when I was looking for oil leaks at the back of my transmission. The old part was a pain to keep sealed properly, but the new improved part has a built in seal that doesn't leak (cover plate 23 31 1 228 470 for E28 M5/535i, E24 M6/635i, E34 M5 and many others).

Looking at the updates to thrust arm bushings, it seems that BMW has gone through a similar improvement process. However, the process has created quite a few superceded part numbers which adds to the confusion. I've tried to sort out the latest part numbers and update history (see below -- all prices from 1/97 book).

1.) E31, E32, E34 Thrust Arm Bushings (56 mm wide)

E32 750i, 740i E31 850i, 840i
31 12 1 136 607 $ 45.75

E34 M5
31 12 2 226 528 $104.75

E34 535i, 540i, 530i
31 12 1 139 456 $ 46.50
31 12 1 136 606 expired 03/91
31 12 1 133 488 expired 12/90
31 12 1 130 587 expired 03/89

E34 525i
31 12 1 136 605 $ 49.83

2.) E24, E28 Thrust Arm Bushings (50 mm wide)

E28 M5, 535i (after 9/85), E24 M6, 633i, 635i 31 12 9 058 819 $ 36.43
31 12 1 126 394 expired 11/90

E28 533i, 535i (til 9/85)
31 12 9 058 818 $ 30.98
31 12 1 125 428 expired 01/89
31 12 1 126 302 expired 09/86

E28 528e, 524 TD
31 12 9 058 817 $ 47.28
31 10 1 129 078 expired 11/88

If you look closely, you can usually find the last seven digits of the part number on the part itself. For example, the 750i/850i bushings will have "1 136 607" stamped in the green plastic insert which surrounds the center aluminum piece.

Each of the bushings above should be physically interchangeable within their group. That is, any of the group #1 bushings will fit on the E31, E32, and E34 cars, while any group #2 bushing will fit the E24 and E28 cars without modification.

The bigger engine, heavier cars have the stiffer bushings. So the stiffest E31, E32, E34 bushing is the 31 12 1 136 607 used on the 750i/850i, while the stiffest standard E28 bushing is the 31 12 9 058 819 used on the M5/M6/535i/635i.

As I described in my earlier post, the 31 12 1 136 607 for the 750i/850i is the high performance bushing of choice for E24/E28 cars, but it must be properly machined to prevent interference. You won't find the part number on modified 750i/850i bushings because the plastic insert with the part number is also machined.

One last note -- if I had an E34 M5 I'd be very tempted to try the 750i/850i parts when it came time to replace my bushings (less than half the price of the M-parts).

Pete Read
'88 M5
Arlington, VA

From: "Pete Read" <>
To: "Mformation" <> Cc: <>
Subject: Re: <E28> M5 Chasing Coolant Leak
Date: Tue, 2 Mar 1999 16:33:07 -0800

John Weese asks about E28 M5 coolant system leaks: >I read the excellent articles in the past two ///M Power Newsletters
>by Pete Read (Thanks Pete!), and I have a question relating to coolant
>loss. My stock '88 M5 is losing coolant when the car sits for awhile
>(is cool not hot). That seems like a loose hose connection to me, but
>I'm at a loss as to where to look. These M-Engines are really "packed"
>in there and it's very difficult to see all the hose connections!


Sorry this response is so late, probably too late to help you, but maybe it will help someone else. Thanks also for the compliment on the M-Register newsletter articles. By the way, for those of you who subscribe, the March newsletter should be arriving in a few days. As I said in my editor's note, the delay is all my fault this time -- unfortunately I've been letting real life interfere with my automotive interests.

Your coolant loss while the car cools down sounds just like the problem that I described in the August 1998 newsletter. I was looking for the source of a slow loss of coolant. Bill Shook suggested that I pressure test the system with the engine cold. I couldn't believe how much coolant leaked out around the lower thermostat housing hose when pressurized cold -- it didn't seem to leak at all when warm. That short hose is very difficult to align and tighten properly, so it's a likely candidate, but any of the hoses can cause a problem.

Cold pressure testing is effective because the most common cooling system leaks result from slightly loose hose clamps. These small leaks are hard to find because the parts expand as the engine warms, before the system pressure increases enough to cause noticeable leakage. However, after the car is shut down and cools, the system is still pressurized. As the parts cool and contract, leakage occurs.

Pete Read
'88 M5
Arlington, VA

From: "Pete Read" <>
To: "Mformation" <>
Subject: E28 M5, E24 M6 Cooling System: hoses/clamps, thermostat, radiator,
water pump
Date: Tue, 2 Mar 1999 16:37:55 -0800

While I'm thinking about cooling systems, I've included some information that I put together for the M-Register newsletter last year (see below).

Since my write-up, my thermostat failed and I got to take some of my own advice. I ordered the $25 "OEM factory replacement" from Bekkers, but it wasn't the correct Wahler 4231.80. It looked like it would fit, but didn't seem to be nearly the same quality as a typical BMW Wahler or Behr thermostat. By that time, a driving school was fast approaching, so to reduce risk, I just ordered the standard M5 parts from a local dealer.

I knew the older big six thermostat would fit, but there was still some question in my mind about the square cross-section o-ring versus the round cross-section o-ring from the M5. The o-ring groove turned out to be square, so there's no reason why the cheap square-section o-ring won't work fine ($1 versus $14).

So to recap my cheap thermostat advice, just buy the old big six thermostat and o-ring (like Paul Hahn did), plus the tiny o-ring that only fits the M5/M6.

Quan Part Number      Description                    Price
---- ---------------  ---------------               -------
 1   11 53 1 254 065  Thermostat 80 C               $14.31
 1   11 53 1 250 399  Thermostat o-ring               1.03
 1   07 11 9 906 328  Thermostat small o-ring         0.30

...Cooling System write-up, M-Register Newsletter January 1998...

I changed my radiator and hoses several years ago, so some of the details are forgotten. Hopefully the basics I remember plus a list of parts and prices from the fiche, and some tips from Paul Hahn, John Hartge and Carl Nelson will be enough to get you through the job.

Thanks especially to Carl Nelson for all his advice including researching the older big six thermostat compatibility with the E28 M5. Keith Wollenberg highly recommended Carl for technical advice and parts and I've certainly been impressed. Carl is in San Diego, CA at CNPR/La Jolla Independent, 800.466-8184.

Draining Coolant

The only coolant drain found on every M5 is the engine block plug. It is located under the exhaust manifold near the number six cylinder, just like the standard 535i.

The parts fiche shows a radiator drain bolt, but most M5 radiators do not have one. Carl Nelson says the drain bolts on early radiators often froze in place and could not be removed, so they were omitted on later radiators. The lower radiator hose is not very low, so the only way to drain the radiator is by removal or siphoning.

Paul Hahn found that a good partial drain can be done with a 1/4 inch siphon hose inserted down through the radiator hose opening. He also was able to siphon much of the block by inserting the same size small hose through the hose attached to the underside of the overflow tank.

Siphoning saves time, but the most thorough drain is with the block plug and radiator removal. It is a messier job, but the block plug (19mm wrench) and radiator aren't very hard to remove. Radiator removal also makes it easier to change some hoses.

Only the seal ring for the block drain plug needs replacement when draining the system. A tip from Steve Morey is that the drain plugs are perfect for plugging the rear load leveling accumulators when eliminating the load leveling system.

Quan Part Number      Description                    Price
---- ---------------  ---------------               -------
 1   07 11 9 963 200  Plug seal ring A14x18          $ 0.30
 1   07 11 9 919 228  Block drain plug AM14x1.5        0.75

To remove the radiator:

  1. Remove plastic fan clutch shroud (two phillips screws)
  2. Remove fan clutch (32mm wrench)

    My $20 32mm Craftsman combination wrench just barely fits. Width of the wrench is 0.48 inch. A 1 1/4 inch SAE wrench will also fit if it is thin enough. Remember that the fan clutch has left hand threads -- turn wrench clockwise when facing the engine while standing in front of the car.

  3. Disconnect wires from the two temperature sensors on the driver's

    side of the radiator.

  4. Remove radiator hoses (hose clamps). Take special care with

    the small bleed hose. Too much force can easily break the small plastic nipple.

  5. Remove two bolts (10mm wrench) and lift radiator straight up.

Cooling System Hoses and Clamps

Heater hose access requires intake plenum removal (see instructions above). John Hartge suggests attaching the short water pump hose to the thermostat housing first as it makes alignment easier. My "-827 bypass pipe inlet elbow hose" failed first. It's just in front of the #1 exhaust pipe, so I imagine the extra heat helped its demise.

Note that M5 and M6 hoses are the same except for the hose from the plastic tee to the expansion tank. The five series parts fiche incorrectly shows the part number from the M6. You can make it work by twisting it a little -- that's what I did. Stan Simm noted this problem in the July '94 MPower. Both the M6 and the correct M5 part number are included below.

Quan Part Number      Description                    Price
---- ---------------  ---------------               -------
 1   11 53 1 306 828  Water pump to t'stat hose     $10.13
 1   11 53 1 306 829  Bypass pipe to t'stat hose     11.57
 1   11 53 1 306 832  Radiator to t'stat hose        32.77
 1   11 53 1 306 850  Heater return to t'stat        21.67
 1   11 53 1 306 851  Expansion tank to T hose       30.80 (M6 only)
 1   11 53 1 284 598  Expansion tank to T hose        8.53 (M5 only)
 1   11 53 1 310 625  Radiator hose, pass side       44.53
 1   11 53 1 306 827  Bypass pipe inlet elbow hose   22.72
 1   64 21 1 374 635  Heater outlet hose             14.25
 1   64 21 1 374 636  Heater inlet 1 hose            15.33
 1   64 21 1 374 637  Heater inlet 2 hose            11.85
 1   17 12 1 712 736  8x13mm vent hose (per meter)   12.03
 8   16 12 1 180 237  L10-16mm hose clamp             0.35
 4   07 12 9 952 111  L23-29mm hose clamp             0.40
 6   07 12 9 952 113  L26-33mm hose clamp             0.45
 3   07 12 9 952 115  L32-38mm hose clamp             2.00
 7   07 12 9 952 121  L47-54mm hose clamp             2.00

Thermostat Operation

The thermostat housing has four main hoses plus a small bleed hose which makes the system self-bleeding. Three hoses return coolant to the housing, while the short lower hose pulls coolant from the housing back into the water pump. The water pump then forces coolant back into the block.

On the passenger side of the thermostat housing is a bypass tube which crosses the front of the engine. Coolant bypasses the radiator this way, traveling from the passenger side towards the driver side, when the thermostat is closed. Entering from the back is the heater/expansion tank return. Finally, on the driver side is a large radiator hose.

As the thermostat opens, the "button" on the end closes off the bypass tube. Coolant then travels through the radiator, hot fluid entering on the passenger side and relatively cool fluid returning to the thermostat housing from the driver's side where it's pulled back into the pump again.

Looking at the M5 thermostat and o-rings listed below (don't forget the small $0.30 o-ring), you'll notice that they are priced like real M-parts -- $50 for the thermostat alone.

Paul Hahn replaced his M6 thermostat with an older big six thermostat p/n 11 53 1 254 065, list price $14.31. This interested me so I borrowed John Hartge's old broken M5 thermostat and compared it with a new -065 thermostat at the local BMW dealer (they don't stock the M5 thermostat). The only obvious difference is the "button" size with the M5 being a smaller 30mm versus 35mm.

Next I checked with Carl Nelson. At first he was concerned about thermal shock at warm-up from the different sized buttons. Then he measured an M5 housing and convinced himself that the larger button on the -065 thermostat will work fine.

I also checked with long time M-Register member Mark Luttrell at Bekkers Import in Albany, GA 800.624-5410 x11. Bekkers has a direct OEM source for M5 thermostats as they are able to sell both the thermostat and o-rings together for less than $25 (versus $65 list price).

Quan Part Number      Description                    Price
---- ---------------  ---------------               -------
 1   11 53 1 307 737  Thermostat 80 C               $49.34
 1   11 53 1 304 202  Thermostat o-ring              13.88
 1   07 11 9 906 328  Thermostat small o-ring         0.30

Radiator, Water Pump

Like the rest of the cooling system, the radiator and water pump are specific to the M5/M6. The cap is also higher pressure, 1.4 bar versus the 1.0 bar of the normal big six engine. After checking the radiator price, be sure to read David Hutton's radiator repair article (see below).
Quan Part Number      Description                    Price
---- ---------------  ---------------               -------
 1   17 11 2 226 018  Radiator                     $850.45
 1   17 11 2 227 683  Radiator cap, 1.4 bar           9.69
 1   11 51 1 312 539  Water pump                    131.95
 1   11 51 1 265 654  Gasket, water pump              0.73

Pete Read
'88 M5
Arlington, VA

From: "Pete Read" <>
To: "Mformation" <>
Subject: E28 M5 versus E34 M5 Self-leveling System
Date: Wed, 3 Mar 1999 12:19:48 -0800

In case anyone is still confused about whether the self-leveling system is connected to the power steering pump -- well it all depends on whether it's an E28 (E24 M6 is the same) or an E34 M5.

The E28 M5 has a completely separate system with the pump located under the spare tire in the trunk. I just disconnected the power connector to the pump, removed the old shocks, and left the rest of the system in place (plugged the accumulators with block drain plugs, p/n 07 11 9 919 228). For more details, look back at my post in Mformation #88 "E28 M5 Suspension Installation Procedure".

The E34 M5 is different in that there is no dedicated pump for load-leveling. The power steering pump is used instead, so the '88 735iL removal procedure described in the October Roundel should work fine.

Pete Read
'88 M5
Arlington, VA

Unofficial Homepages: [Home] [E12] [E24] [E28] [E30] [E34] [E36] [Z3] [E39] [E46] [X5/E53] [ALL] [ Help ]