Radiator cap upgrade???

[E38740iMD]

http://www.ebay.com/itm/BMW-Billet-C...7cd28c&vxp=mtr

This question is for the experts. Does this really make sense and worth the purchase?

I think it all sounds good just to make a sale. But maybe some truth behind it?

[m735is]

I've read about using this cap on the e39 page due to higher pressures and cooling system failures, but I also think there's a genuine BMW cap from a later model that works the same for less money.

You can read through this and decide:
http://www.bimmerfest.com/forums/sho...d.php?t=680512

[bolloc]

I had no idea the pressure was that high in these systems, in fact now I have to look that up. As a rule though I usually figure if that is the spec there is usually a good reason for it. As parts get old they will degrade so I guess for those that don't want to replace old hoses or brittle parts in their 20+ year old car this might give them a grace period. Actually if the system pressure is really that high, and if it will work as efficiently at a lower pressure I would have installed something like this years ago. Now though I am not that concerned, the only parts that haven't been changed in my cooling system are that cap and the reservoir.

As far as that sale description is concerned, scare the hell out of a customer to justify the need and the price, good marketing

[demetk]

Hey thanks for finding this. Last time my headgasket blew and pressurized the cooling system the damage extended beyond just the headgasket. One of these caps would have prevented this.

[ross1]

A 2.0 bar relief pressure doesn't mean the system is always operating at 2 bar. This is the maximum pressure allowed before it will allow coolant or steam to vent. You'd be very hot when at 2.0 bar or have issues as in the above post.
BMW does offer a 1.4 bar cap (the part # is not on the one I have perhaps someone else has the PN), I believe as part of a campaign regarding bursting heater cores.
You'd be better served by keeping your cooling system parts fresh than babying dodgy ones.
This conversation reminds me to get in the garage and change out the cracked coolant tank on the wife's E39.

[dragracer440wed]

E-30's and E-34's with the M20 engine had the 1.4 bar cap part# 17111742232

[shogun]

-quote-Most BMW vehicles manufactured between 1982 and 2006 run a cooling system vent pressure of 2.0 bar (29 psi). The problem is that the cooling system components are barely rated to handle that pressure when brand new. As the plastic parts heat cycle hundreds of times while exposed to the degrading effects of heat and coolant, they lose some of their strength. The result can be a ruptured part somewhere in the cooling system-unquote-

The 2 bar relief pressure is fine with me. Their statement is to scare the people when saying "The problem is that the cooling system components are barely rated to handle that pressure when brand new".
How can they make such a statement without any reference to testing etc?
I had not any problems with 2 bar, but a coolant cap should be replaced from time to time, many radiator companies insist to replace the cap too when selling a new radiator, otherwise no warranty. And that is good, because a cap looks quite easy but when you open up one you see that it is a piece of engineering.
BMW had a recall on 2 bar caps, also my car made in 11/88 got a new cap free of charge.
Subject: Rad Cap Recall TSB 170198 TSB 170198 was issued in October 1998. SUBJECT: Radiator Cap Recall - No. 98V-178

MODEL: E31, E32, E34 and E36

Situation: BMW of North America, Inc. has voluntarily initiated a safety recall campaign that involves the coolant system of the affected vehicles. The coolant system is composed of a number of components that are exposed to continuous thermal and mechanical loading. The malfunction or failure of a coolant system component, such as a thermostat, water pump or fan belt, can result in significantly increased coolant temperature and system pressure.
If the indications (e.g., movement of coolant temperature gauge needle into red zone) of such a critical overheating condition are not heeded by the driver, and if, in addition, the vehicle is operated under high-load conditions such that the elevated pressure cannot be adequately relieved, it is possible that damage to, or failure of, a coolant system component could occur. If a crack were to form or a seam were to separate in the heater core end piece, hot coolant could suddenly be expelled. In some cases, the coolant could contact an occupant and cause skin injury. Also, coolant expelled from the heater core as vapor could cause fogging of the interior surfaces of the windows, reducing visibility and the driver's ability to control the vehicle.
To minimize the likelihood that any coolant system malfunction could lead to damage to the heater core end piece, a new design radiator cap will help control pressure and provide greater coolant overflow in the event of overheating.
Affected Vehicles: The procedure given in this bulletin must be performed on all affected vehicles identified on DCS. (A copy of the letter which will be sent to all affected customers is attached to this S.I.)In order to determine if a specific vehicle is affected by this recall, it will be necessary to utilize the "Service Menu" of the DCS (Dealer Communication System). Based on the response of the system, either proceed with the corrective action or take no further action.
The Chassis Number Ranges listed on the attached chart are only for informational purposes and are not to be considered as the only deciding factor. The affected vehicles are limited to vehicles within these ranges but not all of these vehicles are affected by the recall. The final decision is the DCS inquiry.
Correction: The radiator cap must be replaced with the redesigned cap on all affected vehicles.
Procedure: The redesigned radiator cap should be installed on all affected vehicles in the customer drive area by a qualified service adviser or technician.
Caution: The radiator cap must be opened slowly when the engine is at operating temperature to avoid possible scalding. On vehicles with a hot engine, check the coolant temperature gauge reading before removing the radiator cap. This can be done while retrieving the vehicles mileage with the ignition switched on. DO NOT REMOVE THE RADIATOR CAP ON OVERHEATING VEHICLES. (If the coolant temperature gauge indicator is past the center line of the scale allow the engine to cool down before removing the radiator cap.)
Parts Information: Due to limited availability of parts for this Recall Campaign, BMW center parts order quantities will be restricted. The campaign control system will be used to screen BMW center orders for excessive quantities. A DCS message will be sent out indicating how many pieces per week a BMW center will be allowed to draw from BMW NA. Please place orders using only the logical part numbers. Ordering of the individual part numbers or any quantities ordered above the maximum weekly allotment will automatically be backordered and canceled. Should there be any questions, please contact the Parts Consultant Group at 1-800-272-0202. An initial quantity will be shipped to each BMW center starting on October 30, 1998. Below is a listing of the logical part numbers which should be ordered to support the Recall Campaign. Description Part Number
Radiator Cap (all engines except M20) 50 50 5 022 222 Logical part number 17 11 1 742 231
Radiator Cap (M20 engine only) 50 50 5 033 333 Logical part number 17 11 1 742 232
Radiator cap identification:
Part Number 17 11 1 742 231 All except M20 - 2.0 bar "200" designation on cap.
Note: Cap insert (arrow) with "200" and part number designation is black in color.
Top View Part Number 17 11 1 742 232 M20 only - 1.4 bar "140" designation on cap.
Note: Cap insert (arrow) with "140" and part number designation is yellow or black in color.
NOTE: Vehicles produced after 11/94 which are not affected by this recall may have radiator caps installed without the "140" or "200" designation on top of the cap. These caps are the redesigned style and should not be replaced due to the "missing" designation number. DCS inquiry is the final decision if a vehicle is affected by this recall. Recall Campaign
Label Instructions:
This Recall Campaign has been assigned code number 228. After the vehicle has been checked, and corrected if necessary, obtain a label (SD 92-090) and:
a) emboss your BMW dealer warranty number in the middle of the label (1);
b) punch out code number 228 printed on the label and,
c) affix the label to the B pillar as shown:
If the vehicle already has a label from a previous Service Action/Recall Campaign, affix the new label next to the old one. Do not affix one label on top of another one because a number from an underlying label could appear in the punched-out hole of the new label.
Warranty Information: Reimbursement for this Recall Campaign will be provided through Campaign Entry.
Special Defect Code: 00 17 05 01 00
Work Package #1 Replace radiator cap.
Labor Operation: 00 51 398
Labor Allowance: 1 FRU
Parts Allowance:
(Reference to Logical Part Numbers)
All except M20 M20 only
50 50 5 022 222 50 50 5 033 333
17 11 1 742 231 17 11 1 742 232
Quantity 1 1
Model Type Engine Chassis Number Range Model Prod. Range
525i E34 M20 1518003 - 1519170 4/88 - 1/89
525i E34 M20 BC89002 - BC93621 1/89 - 8/90
525iA E34 M20 2081003 - 2086548 5/88 - 1/89
525iA E34 M20 BE19000 - BE31999 1/89 - 3/90
525iA E34 M20 GB21000 - GB25580 3/90 - 8/90
535i E34 M30 2173003 - 2174313 4/88 - 1/89
535i E34 M30 BF08002 - BF13162 1/89 - 12/92
535iA E34 M30 2090001 - 2094985 1/88 - 1/89
535iA E34 M30 BF61000 - BF75064 1/89 - 1/93
735i E32 M30 1630001 - 1630922 9/86 - 1/89
735i E32 M30 DB28001 - DB28146 2/89 - 8/90
735iA E32 M30 1640001 - 1644999 9/86 - 5/87
735iA E32 M30 3200001 - 3214128 5/87 - 1/89
735iA E32 M30 DB61000 - DB72069 1/89 - 6/92
735iL A E32 M30 3315001 - 3319335 1/88 - 12/88
735iL A E32 M30 DC23006 - DC31766 1/89 - 7/92
318i/2 E36 M42 JA00000 - JA11269 11/91 - 11/94
318i/2 A E36 M42 JC10013 - JC17629 12/92 - 11/94
318i/4 E36 M42 FG00000 - FG13601 11/91 - 11/94
318i/4 E36 M42 LA00000 - LA00237 11/94
318i/4 A E36 M42 FK58003 - FK69861 10/92 - 11/94
318i/4 A E36 M42 LA07000 - LA07267 7/94 - 11/94
318iC E36 M42 EC82005 - EC84142 1/94 - 11/94
318iC A E36 M42 ED15001 - ED17065 11/93 - 11/94
318ti E36 M42 AM50002 - AM50004 11/94
318ti A E36 M42 AM70005 - AM70012 11/94
325i/2 E36 M50 EF35004 - EF49592 7/91 - 11/94
325i/2 A E36 M50 EK00008 - EK16184 10/91 - 11/94
325i/4 E36 M50 FE00004 - FE20379 1/91 - 11/94
325i/4 E36 M50 FE40000 - FE40359 5/94 - 7/94
325i/4 A E36 M50 FF75006 - FF94999 3/91 - 8/92
325i/4 A E36 M50 FL00000 - FL19999 8/92 - 2/94
325i/4 A E36 M50 FM00000 - FM06927 2/94 - 11/94
325i/4 A E36 M50 FM10000 - FM10706 5/94 - 7/94
325iC E36 M50 JC78006 - JC82537 5/93 - 11/94
325iC A E36 M50 JD30006 - JD40098 4/93 - 11/94
525i E34 M50 BF94002 - BF98999 8/90 - 4/92
525i E34 M50 GB34000 - GB38249 4/92 - 11/94
525iA E34 M50 BJ57004 - BJ96999 8/90 - 10/93
525iA E34 M50 GK40000 - GK53855 10/93 - 11/94
525iA Tour E34 M50 GD20001 - GD25321 10/91 - 11/94
530i E34 M60 GE53002 - GE55183 12/92 - 11/94
530iA E34 M60 GE83001 - GE92453 11/92 - 11/94
530iA Tour E34 M60 GF80000 - GF81118 11/92 - 11/94
540i E34 M60 GA64002 - GA64388 7/94 - 11/94
540iA E34 M60 GF25000 - GF32726 11/92 - 11/94
740iA E32 M60 DE60000 - DE69144 6/92 - 4/94
740iL A E32 M60 DE83002 - DE93104 8/92 - 3/94
840Ci A E31 M60 CC89001 - CC90040 9/93 - 11/94
750iL A E32 M70 2765007 - 2770000 7/87 - 11/88
750iL A E32 M70 3056001 - 3056836 11/88 - 1/89
750iL A E32 M70 DC74000 - DC81782 1/89 - 3/94
850Ci E31 M70 CB42005 - CB42855 11/90 - 7/93
850Ci A E31 M70 CB72010 - CB75364 9/90 - 6/94
850Ci A E31 M73 CD05000 - CD05001 11/94
M5 E34 S38 BK05004 - BK06690 11/89 - 3/93
M3 E36 S50 EH00000 - EH03703 11/93 - 11/94
M3 A E36 S50 EN90009 - EN90012 10/94
850CSi E31 S70 CD00001 - CD00148 6/93 - 11/94


BMW Recall
Item Affected: ENGINE AND ENGINE COOLING:COOLING SYSTEM
Date Announced: 8/14/1998

Description of Recall:
VEHICLE DESCRIPTION: PASSENGER VEHICLES. A MALFUNCTION OR FAILURE OF A COOLANT SYSTEM COMPONENT, SUCH AS A THERMOSTAT, WATER PUMP, OR FAN BELT, CAN RESULT IN SIGNIFICANTLY INCREASED COOLANT TEMPERATURE AND SYSTEM PRESSURE. IF THE INDICATIONS OF A CRITICAL OVERHEATING CONDITION IS NOT NOTICED BY THE DRIVER, IT IS POSSIBLE THAT DAMAGE TO, OR FAILURE OF, A COOLANT SYSTEM COMPONENT COULD OCCUR.

Action Needed To Fix It: DEALERS WILL INSTALL A NEW DESIGN RADIATOR CAP TO CONTROL PRESSURE AND PROVIDE GREATER COOLANT OVERFLOW IN THE EVENT OF OVERHEATING. once copied from http://www.dealerrater.com/recalls/
---------------------------
So check if yours are already replaced, otherwise replace against new ones.
Ross says it all:"You'd be better served by keeping your cooling system parts fresh than babying dodgy ones."

[E38740iMD]

Hey thanks for finding this. Last time my headgasket blew and pressurized the cooling system the damage extended beyond just the headgasket. One of these caps would have prevented this.

. never seen a radiator do that before

- - - Updated - - -

lets just switch cars

[demetk]

Yeah, me neither. After the rad could warp no more, the rad hose finally blew off the water pump and released the pressure. The poor neglected radiator cap performed amazing well. It was going to hold pressure no matter what. It's now lying under a few metric tons of garbage at the local dump.

What you want to switch cars for? Yours looks to be my car's twin.

[E38740iMD]

update I now have this coolant cap. feels good and easy to apply opening force when you tightened the cap. it takes precise leveling to get it to tightened. but its a nice piece. pair this with a 71c behr thermostat and new waterpump with a new bleeder screw. car runs comfortably cool .

[Mainfold]

Just a little tidbit of information to consider and add to this old thread:
Your worst-case scenario & most common place you'll encounter the pressure buildup, will be after a medium drive (where you get up to operating temp and a bit above), and then you have load on the engine with reduced cooling efficiency. This, being a scenario like if you're going to reverse up a relatively steep driveway.
You then reduce cooling efficiency and add load at the same time, as well as moving more coolant to the front of the system increasing the pressure peak zone being the radiator and your pipes/hoses where they connect to the radiator.
If you for instance have something like the E39 or E46 with the M54 or M52 with the radiator hoses that have the engineered "weakest link"-channel/groove in the fitting where it slides onto the radiator intended to prevent the system over-pressurization via leaking the coolant intentionally out of the channel in the fitting on the hose, you'll be likely to see a little run-off there from such, and a lot of folks when backing up will turn off their AC to reduce noise to hear as they reverse, meaning you have even less heat removed from the system (when the AC isn't blasting that heat into the cockpit and reducing system heat, because it's turned off). In such a given case, a lower bar cap is beneficial (lower like, from 2.0 to 1.4/1.2) as you'll then be letting the air-pressure vent off through the cap rather than coolant through the channel.
Very much a specific scenario, but one that's likely to affect those engines with those same cooling system designs. Though interestingly enough the E60 system with the M54 doesn't get this problem (not sure if the hose fitting has the engineered-in channel like the E39 & E46 hoses, if any E60 owner has a clue about it, feel free to correct/add it) but they seemingly operate better with the same 2.0 bars for the caps.

A tip to those struggling with it on the E39 & E46 pressurizing the system until it comes out the channel in the hose-fitting, and you want a OEM solution over an aftermarket one.. then the E30 325ix cap is the same type of design but 1.4 bar, so it's a possible solution (assuming you don't have a head-gasket problem, which you should be able to tell by smelling if there is any exhaust smells in the cooling system). The reason I would favor it, is to prevent the late-life damage that they tend to get on the systems after x amount on the odo, as there's so much plastic used in areas that have no business being plastic on the M54 for instance (as the god-awful idiocy that is the CCV system attests to).

I'm going to be testing it on a 310k km E39 soon, to see if its coolant leak from the upper radiator hose fitting is solved by swapping to a 1.4 (as it has had the hose itself swapped previously and still having leaks, and radiator is not cracked/punctured), as the second the cap is unscrewed the leak stops.

[moroza]

This is equivalent to installing a lower-amp fuse to prevent circuit overheating. Passes my BS filter, seems a good idea, BMW apparently made the same change, I'd just get an OE cap instead of a pretty but expensive aftermarket one.