Control Valve/Heat Sensor - Haynes

[Ben]

Thanks for the update guys .......and the photos etc helped !

I actually made a mistake and should've said to ADD shims to the base of the air valve housing because as Joe says adding shims adds fuel throughout the range !

You might need to make up a thicker one, innitially I used some hard card from an old paper file, the emery paper mightn't be thick enough. I have since removed this and added a washer to the base of the 'stat housing as my problem was different to yours !

I am wondering if my car has the same air valve as Wills because I can see no washers but I can see a very small, maybe 5/6mm, dark coloured bolt with a slightly larger lock nut when I peer down into the air valve. It struck me that this might be for adjustment but I didn't fiddle in case something fell off inside!!

Anyone shed any more light here ??

Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[ja17]

Hello Ben,
Yes the earlier versions had an adjustable end.
Joe

Joe Alexander
Blacklick, Ohio

[knirk]

Hi Joe,
I removed both shims. And just to confirm; I have now leaned out the fuel mixture? The engine actually runs smoother now. Before it was somewhat misfiring during acceleration with partial throttle, not with full throttle. I had expected to add shims to richen the mixture to compensate for needing more throttle to accelerate after the CV/HS has warmed up.

I am going for a 120 mile trip right now to check it out – it seems promising.

Will: If you add/remove washers under the baro. compensator – is it the same as the CV/HS – remove washer to lean, and add washer to richen?

After 4 times this job became very quick (5 min) and easy - I took a picture for those of you who would like to experiment.

Download Attachment: cvhs.jpg
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Per G. Birkeland
69 280 sl aut 834
Norway

[W14]

Per: yes, the baro. shims work the same way as the thermo. shims: Thicker shim for richer mixture.

I don't think you want to use compressible material for the shims, as the adjustments are quite sensitive.  That's why the originals are metal, even the paper-thin ones.  I've used tin plate and aluminum.

Unless you are using all new parts, it's probably a good idea to get  some base-lines: I used a pan of water on the stove, and a thermometer, to check and measure the travel of the brass temp. bulb; Checked the total travel of the air-slide plunger; Measured the air-slide plunger extension required to shut-off the air; Measured the extension required to bottom the mechanism under the WRD in the IP.  Then I drew a diagram and did the math to make the adjustments.

Will W14
1965 230SL 4spd
Victoria,BC

[knirk]

Thanks Joe and Will.
After removing both shims the engine did not perform too well after all. I will put them back. I will try once more to add a shim before I move on.

Since the engine is running so well when it’s cold I haven’t thought about IP timing at all, but this may very well be the cause. When I mounted it I felt a little unsure about if the alignment marks was really aligned. And I guess it is also important to make sure there is no slack in the timing chain when setting the flywheel position for alignment.


Per G. Birkeland
69 280 sl aut 834
Norway

[Naj ✝︎]

Per,
Could your problem be ignition related rather than fuel?
What distributor have you got (Bosch 0 231 116 051)?
Also, have you still got points or changed to electronic ignition?
I have a similar mid-range (3000 to 3500 rpm) misfire that I can't trace.
On later 280sls they put extra valve/relay to cut off vacuum retard. My feeling is this may have something to do with it :evil: ??
Sorry, guys, warm-up issue has gone off track.
naj

65 230SL
68 280SL

[ja17]

Hello knirk,
Precise adjustment of the injection pump timing is not critical on this type of injection. You need only to get close. The most important thing is to make sure you don't install the pump 180 degrees off. 20 degrees after top dead center on the compression stroke is correct. 20 degrees after top dead center on the exhaust stroke is not correct. This will cause some running problems.

Joe Alexander
Blacklick, Ohio

[knirk]

Thanks again Joe.
Yes Naj I may have a wrong distributor. I have discussed it with my Norwegian mechanic. It will give me 30deg at 3000rpm, and about 17 at 1500rpm, but is way off at idle. When I decelerate passing 1500rpm the engine often backfires - wich I have related to the distributor. I didn't think that it had anything to do with the lack of throttle responce, but may be. I am away for work and will give you the distr. number when I get back (on a new string). It is a pointless system.

Per G. Birkeland
69 280 sl aut 834
Norway

[WillS]

A comparison between the old style thermostat and the new style that I got from Ray Paul (GREAT guy for parts) might be helpful.  If you install the new style thermostat without opening up the hole in the 'Guide Ring' (BBB, Fig. 07-14/33, #3), the operational length of the old style & new style thermostat shafts are very close (see attached picture).

Download Attachment: IP_Therm_Arrows.jpg
45.54 KB

[lurtch]

Hello to all - - and a SPECIAL THANKS  to those of you who have posted photos of the guts of the troublesome FI pump thermostat. Not all of them look as good as the ones appearing here on the website. I am still struggling with mine. After you  take a look at what I had to start with, you will see why I am happy to say that  " - at least I've finally got it running" .
The screw holes look freshly tapped because they are,  - - the screw heads sheared off because of devastating corrosion everywhere in the unit. As you can also see the seal ring was also a goner.  Digging my way out of this - - Larry in CA

Download Attachment: temp-bulb-housing.jpg
33.34 KB

[JPMOSE]

First of all...thanks for some Sunday morning reading.  Having just received my late 250SL on Tuesday, I have spent much of the weekend performing maintenance tasks.  One on the list is the replacement of the air filter on the injection pump.  So I just read through this thread to get an education.  But I have some questions now:

1)  What is the reason for wanting to extend the warm up period?  Is the orginal specification not sufficent?  I live in Atlanta and the car will always be garaged (lowest temp. is around 55 F even when it gets down to 10 F outside.  Would I even need to be concerned about this?

2)  Although I hate throwing money away, would it just make sense to install a new thermostat for $55 on a 40 year old car if it has never been replaced (or is this a part that rarely goes bad)?

3)  If I do replace the thermostat, does the replacement part with a different seat (looking a Ricardo's photos) not require any modification afterall?  I see in one of the later posts that a measurement of both shafts reveals about the same length w/o any modification.

4)  I have sprayed WD40 on the seat of the air filter I am trying to replace.  With a thin wrench I am trying to remove the ^%$%$# thing and it will not give!  I am afraid of applying too much force because there seems to be a lot of stress applied to the thermostat housing when I do so!  Any advice is appreciated!



Best Regards,

J. P. Mose
1968 250SL

[Ricardo]

Hi JP
In my case my old thermo bulb was the same style as my new one except with a larger base ring, unlike Wills old type with the locking nuts. If I didn't enlarge the hole in the seating washer the thermostat would not sit straight as the difference was quite small and the thermostat kept tipping one way or the other. Without enlarging the hole mine would not have given the correct length either, so I guess it depends on the set up you have. As for the need to change the thermo, I suspect that they work or they don't and it states somewhere in the BBB, that one should never pull the plunger part out of the thermo, so I suspect that if air or coolant get down the shaft of the thermo that the length may alter and this would affect warm up. I don't think it's just a matter of how cold the outside temps are. The engine needs an enriched fuel supply until it has reached near operating temp and would probably run quite poorly without this thermostat operating.
Ricardo

[George Davis]

JP,

WD40 isn't all that great for breaking threads loose.  You might try Break Free or some other "real" penetrant/thread loosener product, they really do work better, or at least I think they do.

If that didn't do it, I would probably put the wrench on it, put a fair amount of pressure on it, and then give the end of the wrench a rap with a hammer to shock it loose.  Light rap at first, increasing force if necessary, and stopping when I get nervous. Getting the wrench as close as possible to a 90 degree angle to the WRD body will help to reduce the bending force on the base flange/securing screws.  Use your own judgement on this, I have broken things before...

George Davis
'69 280 SL Euro manual

[rwmastel]

quote:Originally posted by George Davis

WD40 isn't all that great for breaking threads loose.  You might try Break Free or some other "real" penetrant/thread loosener product, they really do work better, or at least I think they do.

Yes, WD40 is not a penatrant or a lubricant.  It's a water displacer.  Use a penatrant.  I've not heard of Break Free, but it sounds impressive!  I use PB Blaster.  http://www.pbblaster.com/

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[JPMOSE]

Thanks for the advise on the penetrant.  It turns out the wrench was binding against something else (which I didn't notice at first).  I then put needle nose vise grips on it and it came right off.  Man those injector air filters are expensive!

Best Regards,

J. P. Mose
1968 250SL

[JPMOSE]

Rodd...I bought some PB Blaster upon you advice.  Great stuff!  I used it the free the bolts on my repair calipers, which I had no luck the day before.  I was ready to apply heat and then I tried PB.  After 1 hour and a few taps with the hammer, all four bolts came loose.  I am hooked on the it.  JP

Best Regards,

J. P. Mose
1968 250SL

[rwmastel]

quote:Originally posted by JPMOSE

Rodd...I bought some PB Blaster upon you advise.  Great stuff!

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[JPMOSE]

OK so I misspelled advice!  :oops:   It's stressful today at Lockheed Martin!!!

Best Regards,

J. P. Mose
1968 250SL

[rwmastel]

I didn't even notice that, I was just happy that you were happy with the product.  I'm glad I could help.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420