280SL warm up regulator - PeachParts Mercedes-Benz Forum

freshairfiend · #1 06-25-2015, 04:24 PM

Any information anyone may have re repair or replacement of a new, used or refurbished warm up regulator for a 1985 280SL(Euro) would be gratefully received. I am being informed by my mechanic that such a part cannot be repaired and a replacement is unavailable and I just don't understand how that can be when the 2.8 dohc engine was so widely used for so many years. I'm also being informed that an upgrade (that is apparently available) will cost around $1,500 which seems a bit steep. Comments, advice or information are welcome. Thanks

timm9 · #2 06-25-2015, 04:39 PM

When I was searching for one some years back they were getting very hard to find not to mention expensive. The last 'new' unit I saw on line was almost $1,400.00. Is there a part number on the existing WUR?

I may still have an old WUR that came off an 82 I owned previously. I suspect they won't be remotely close but it can't hurt to look. Have you checked with Programa? They may be able to help.

freshairfiend · #3 06-26-2015, 12:13 AM

Thanks TIMM9. I will check the part number and let you know, however the engine for the "82 and my '85 are pretty similar and I think the fuel delivery system is the same so perhaps your old WAR would fit. I'm not familiar with Programa. I would welcome a little expertise from anyone who is aware of any later models that used this engine as to whether this part would be interchangeable, or in fact whether any other models could be adapted.

rowdie · #4 06-26-2015, 07:34 AM

I don't know if this link will be allowed here. CIS Flowtech - Rebuilding Bosch Fuel Distributors & Warm-Up Regulators
If it doesn't work google CIS Flowtech. They rebuild fuel distributors and WURs. They supply many parts houses and have a good reputation.

The MB part number is 110 070 00 62

freshairfiend · #5 06-26-2015, 12:56 PM

Thanks. That's great information. I found the link but was unable to use any of the sub-links. I did email them for further information though and will hope to hear back from them in due course. Thanks also for the actual part number which may come in handy too as previously I have only been able to supply a VIN and being a grey market import that doesn't always help.I'm a bit surprised though that the number starts with 110 rather than 107

Frank Reiner · #6 06-26-2015, 02:17 PM

Quote:

Originally Posted by freshairfiend

Thanks. That's great information. I found the link but was unable to use any of the sub-links. I did email them for further information though and will hope to hear back from them in due course. Thanks also for the actual part number which may come in handy too as previously I have only been able to supply a VIN and being a grey market import that doesn't always help.I'm a bit surprised though that the number starts with 110 rather than 107.

The MB P/N starts with 110 because the WUR is a component of the engine rather than the chassis. The engine is a M110, whereas the chassis is a R107. The complete engine # (beginning 110.9xx) is stamped into the top surface of the engine block (the cast iron part) on the forward left side, aft of the distributor, and inboard of the air flow meter and throttle body. The engine # will be definitive in obtaining parts.

The WURs are more often identified by the Bosch P/Ns, which are stamped on the body of the WUR. The form of the P/N is:
0 438 140 xxx
The last three digits will be between 145 and 157.

The WURs are eminently rebuildable.

What, by the way, are the symptoms that led to a diagnosis of a faulty WUR?

rowdie · #7 06-26-2015, 03:27 PM

Quote:

Originally Posted by Frank Reiner

What, by the way, are the symptoms that led to a diagnosis of a faulty WUR?

Good question. The WUR on this engine is in a bad location. I know a member here that had a problem with the wires deteriorating. Repaired them and 2-3 years later they broke again. Chased the problem for over a year and never checked since it had been repaired.

freshairfiend · #8 06-26-2015, 07:44 PM

The symptoms of the WAR failure were similar to fuel starvation when the car was started from cold. The car always fires on the first shot but almost immediately the revs fall off and the engine barely keeps running. After about 15-20 seconds she evens out a little however any attempt to increase engine speed at this point will cause the engine to stall until about a minute later when the tach registers its usual idle speed. Once running normally the car acts as always. The last three numbers of the WAR are apparently 103 which doesn't fall between the parameters suggested by Frank. Just hope the mechanic read them correctly, they are evidently a bit obscure.

Frank Reiner · #9 06-26-2015, 09:02 PM

Quote:

Originally Posted by freshairfiend

The symptoms of the WAR failure were similar to fuel starvation when the car was started from cold. The car always fires on the first shot but almost immediately the revs fall off and the engine barely keeps running. After about 15-20 seconds she evens out a little however any attempt to increase engine speed at this point will cause the engine to stall until about a minute later when the tach registers its usual idle speed. Once running normally the car acts as always. The last three numbers of the WAR are apparently 103 which doesn't fall between the parameters suggested by Frank. Just hope the mechanic read them correctly, they are evidently a bit obscure.

I am remiss in providing incorrect end codes; the numbers that I quoted are for USA vehicles. 103 is correct for a Euro car.

The symptoms suggest that the fuel flow control valve in the WUR is partially stuck in the closed position, possibly due to a small piece of dirt. As a consequence, the control pressure is too high when the engine is cold.
The WUR can be opened and cleaned.

This edit is to change the statements of control pressure valve blockage, and control pressure response. [FR]

freshairfiend · #10 06-27-2015, 01:33 PM

Thanks Frank, you really are a fountain of knowledge. I'm afraid my own experience dropped off along with carburetors and I'm a bit past doing most of my own stuff now anyway. It certainly seems worthwhile to check out your suspicions regarding the results that may be obtained by cleaning the existing WAR. If you're correct it would be a hell of a lot less expensive too. Thanks again for your input.

freshairfiend · #11 06-28-2015, 12:55 PM

Just an afterthought but how do the symptoms of an actual WUR failure differ from what I have described?

Frank Reiner · #12 06-28-2015, 03:02 PM

Quote:

Originally Posted by freshairfiend

Just an afterthought but how do the symptoms of an actual WUR failure differ from what I have described?

The Control Pressure Regulator, known to all as the WUR, is, at its heart, a valve in the Control Pressure bleed line. When there is greater bleed, the pressure is lower, and the fuel/air mixture is richer. When there is less bleed, the pressure is higher, and the mixture is leaner.

WUR failure can occur in two modes: Valve open (greater bleed = rich mixture). OR, Valve closed (little bleed = lean mixture). The described symptoms correlate with Valve closed (or dirty). Post start, a cold engine requires a richer mixture; if lean, it will not readily accept throttle opening.

freshairfiend · #13 06-30-2015, 02:46 PM

Once again, thanks for all the information. The WUR was opened up and as you had suggested it was somewhat dirty and even rust was present, however cleaning things up had no beneficial effect. Performance was not improved and the car is still responding as previously when first started. I guess the extra labor was worth a try but this time it didn't work out.
Thanks to Rowdie though I have been in touch with Flowtech who offer a pretty good deal on building a new part from scratch so will have to go that route. At least thanks to the forum I can get a new part - the shop people had told me there were none available anywhere through their sources.

nobby · #14 07-02-2015, 01:04 AM

Quote:

Originally Posted by freshairfiend

Once again, thanks for all the information. The WUR was opened up and as you had suggested it was somewhat dirty and even rust was present, however cleaning things up had no beneficial effect. Performance was not improved and the car is still responding as previously when first started. I guess the extra labor was worth a try but this time it didn't work out.
Thanks to Rowdie though I have been in touch with Flowtech who offer a pretty good deal on building a new part from scratch so will have to go that route. At least thanks to the forum I can get a new part - the shop people had told me there were none available anywhere through their sources.

Do yourself a favour and check that you have 12V at the WUR harness. Check the connector for corrosion, as well. It's in a bad spot and gets the brunt of bad weather.

CIS Flowtech has rebuilt 2 WURs for me over the years, 1st at $225 and the last one at $250.....and Larry is a fountain of CIS knowledge and loves to chat.

nobby · #15 07-02-2015, 01:07 AM

Quote:

Originally Posted by rowdie

Good question. The WUR on this engine is in a bad location. I know a member here that had a problem with the wires deteriorating. Repaired them and 2-3 years later they broke again. Chased the problem for over a year and never checked since it had been repaired.

Aaaaannndddd.......that would be me.

I was so frustrated that I almost sold the car!

But I got pretty good at changing AAVs....now that's in a b*tch of a spot.