Author Topic: Another Warm Start Thread (Read 12073 times)

Theclaw · « **on:** July 12, 2015, 23:11:19 »

I've got a hot start problem. So I removed the warm start device on top of the fuel pump. I can't find the reference but the internal thermo device is stuck solid. I've indicated it by pointing it with the pencil in the image below. Everything else seems to slide ok (yeah, there's some gunk in there but that's not stopping things from moving around). Can I get this piece by itself?

Other solutions, ideas?

Jeff

Theclaw · « **Reply #1 on:** July 13, 2015, 02:24:43 »

After some searching, and excuse my newbie approach, this is the injection pump thermostat, part number D205-019B at Buds Benz. Is this the usual culprit of a hot start problem?

Thank you,

philmas · « **Reply #2 on:** July 13, 2015, 08:38:53 »

Well, this might be the culprit…among some other things!
You may want to check the CSV as well.
Replacing the thermostat by itself is no big deal.

ctaylor738 · « **Reply #3 on:** July 13, 2015, 15:19:50 »

On a 250, the problem with a hot start is that the fuel in the metal lines evaporates, and it takes a lot of cranking to push fuel through to open the injectors and allow the car to start. You can try various hot start techniques.

- let the pump run for 5 seconds so some fuel circulates before cranking
- put the gas pedal to the floor to get as much fuel as possible to the injectors

Also, be sure that the "start" solenoid on the back of the pump is getting power and clicking when the starter is cranking. This solenoid moves the pump's rack to the full rich position, which helps fuel supply while cranking.

It also helps to have a strong fully charged battery and a starter that really spins the engine.

Theclaw · « **Reply #4 on:** July 13, 2015, 16:26:25 »

Quote from: philmas on July 13, 2015, 08:38:53

Well, this might be the culprit…among some other things!
You may want to check the CSV as well.
Replacing the thermostat by itself is no big deal.

The CSV looks to be recent, I can look it up when it was replaced. The car belonged to my Dad and he was pretty good in keeping records.

Chuck, I keep the car on a CTEK charger and it cranks pretty strong. I have not tried letting the fuel pump run for a bit before cranking. I did pump the pedal vigorously when I was stuck the last couple of times.

WRT the thermostat in the injector pump... is there a way to test it similar to testing a standard thermostat ie, set it in a pot of water and measure the temp when it opens?

Jeff

ctaylor738 · « **Reply #5 on:** July 13, 2015, 20:18:37 »

Your cold start valve won't help you on a hot start because it won't get activated. Pumping the pedal won't help. It's not like a carbureted car where you need to get a squirt from the accelerator pump! Some cars respond to the pedal to the metal while cranking.

You can test the thermostat by running some cold water on the bulb, and note how far the shaft sticks out. Then put it in some very hot water. The shaft should extend another 6-7 mm.

Theclaw · « **Reply #6 on:** July 13, 2015, 23:22:33 »

Well it did just that, extend 6mm, but when it cooled down, it did not retract. Only when I forced it did it go back to the original position.

ctaylor738 · « **Reply #7 on:** July 14, 2015, 01:21:30 »

It's all good. There is a powerful spring further down in the WRD that forces it back up as it cools.

Theclaw · « **Reply #8 on:** July 14, 2015, 01:33:07 »

So it's my starting technique?

Theclaw · « **Reply #9 on:** July 14, 2015, 02:21:36 »

Now I have an issue putting it all back together. It looks like the washer between the two halves may not be the right size. The OD of the thermostat is 13mm and ID of the washer is 12.2mm. You can see from the wear marks that it was last mounted in a non-concentric manner (Image 3). Also, I think I have the plunger in the right direction but there's a wire lock washer inside one side of the plunger (image 1). The shiney side looks to be the side that meets the thermostat (image 2). However, the side with the wire lock washer seems to meet the spring but it's not seating right.

Suggestions?

Image 1

IMG_4817 by theclaw900, on Flickr

Image 2

IMG_4816 by theclaw900, on Flickr

Image 3

IMG_4812 by theclaw900, on Flickr

Image 4

IMG_4819 by theclaw900, on Flickr

Image 5

IMG_4820 by theclaw900, on Flickr

scoot · « **Reply #10 on:** July 14, 2015, 02:35:08 »

Quote from: Theclaw on July 13, 2015, 16:26:25

I did pump the pedal vigorously when I was stuck the last couple of times.

Jeff, my recollection is that the hot start instructions in the owner's manual are to hold the pedal half way down and crank. At least that's what works for me.
Scott

Theclaw · « **Reply #11 on:** July 14, 2015, 02:44:57 »

After looking at this, http://www.sl113.org/wiki/Engine/WarmRunningDevice maybe I have the air valve upside down. Still there's the question of the washer. Not in the image in the link.

Maybe the washer doesn't belong there?

franjo_66 · « **Reply #12 on:** July 14, 2015, 06:02:43 »

Hi Jeff

Just chiming in that you may want to check & test the CSV
I had the same hot start problems with my 230SL

I had the CSV reconditioned along with the injector pump, injectors, plus new 123 distributor, coil, wires, etc
Turned out that the CSV was the culprit

Disconnected the CSV and now hot starts are perfect (I live in Australia so no issue with cold starts either)

Regards
Franjo

Theclaw · « **Reply #13 on:** July 15, 2015, 00:17:33 »

It looks like at one point the thermostat seal ring was replaced by a washer that did not have the correct ID. For good measure, I've ordered a new thermostat and new seal ring from BudBenz.

ja17 · « **Reply #14 on:** July 17, 2015, 14:04:47 »

Exactly what are your starting issues. Cold, hot etc?

Theclaw · « **Reply #15 on:** July 17, 2015, 14:08:38 »

It would not start after driving for for a while. Last time it occured I had taken maybe a twenty minute drive, let it sit for 30, then it would not start. I'm new to this car and may not have been following the right procedures, such as holding open the throttle instead of pumping it. It would crank hard but would not catch.

I've got a new filter, thermo and proper spacer coming for the WRD. Once those arrive I'll see how it goes and report. Thank you all for the advice so far.

Theclaw · « **Reply #16 on:** July 29, 2015, 14:55:22 »

I finally got a new thermo, spacer and filter. My old filter was probably 90% clogged. You could really tell the difference when I blew threw the new one. The spacer from Bud's didn't fit and I had to enlarge the hole a little in order for the thermostat to fit. I put some sealer on there too.

I took it for a ride the other day. It wasn't that hot but I got the temp up a bit, not crazy high but certainly warmed up. Let it sit for a while, then tried to fire it up. It turned over a little more than average but it fired up. I'll have to try it again on the next hot day we have.

ja17 · « **Reply #17 on:** July 31, 2015, 14:48:38 »

Your image #4820 has the washer ring upside down. Check the fuel return line to the tank to make sure it is not clogged.

Theclaw · « **Reply #18 on:** July 31, 2015, 14:52:46 »

That washer was a plain old flat washer not the proper spacer. You can tell that the thermostat was just sitting on top of it off center. I replaced it with the proper part.

I'll have to investigate the fuel return line.

Thanks,
Jeff

Theclaw · « **Reply #19 on:** August 12, 2015, 01:51:47 »

I've put together everything but the spacer from Bud's Benz needed to be modified a bit. I've driven it around some and still have an issue.

Cold Start Valve?

franjo_66 · « **Reply #20 on:** August 12, 2015, 04:04:29 »

Jeff - try disconnecting the CSV and then see how you go?

Hope you sort it out soon !

Rgds
Franjo

Theclaw · « **Reply #21 on:** August 13, 2015, 23:18:20 »

Quote from: franjo_66 on August 12, 2015, 04:04:29

Jeff - try disconnecting the CSV and then see how you go?

Hope you sort it out soon !

Rgds
Franjo

I'll be darned! It's like 85 Fahrenheit outside. I took it for a spin, and got the temp gauge way above 180. The CSV was disconnected from the beginning. After my drive, it started after 5 minutes, then after 15 minutes, then after 40 minutes. I'm going to have to do some homework on the CSV. I never drive the car in "cold weather". Can I just leave it disconnected?

Jeff

franjo_66 · « **Reply #22 on:** August 14, 2015, 09:38:04 »

Hi Jeff

Glad to hear some positive progress on this !!

FYI - even though Sydney has a fairly mild climate, we have had a pretty cold winter and some mornings the temperature is around 4C
I have no cold start issues whatsoever (with CSV disconnected)

But given your location in USA your winters are colder
I'll defer to the other more experienced members, but sounds like you have pinpointed the problem area

Good luck
Franjo

Theclaw · « **Reply #23 on:** August 14, 2015, 14:30:59 »

Thanks Franjo,

This is a summer car so even though the winters here in Chicago are pretty nasty, this is a fair weather car.

Jeff

VincentR · « **Reply #24 on:** August 25, 2015, 12:41:35 »

Hello,

Warm start problems potential reasons can be :
1) Your csv continue to inject gazoline even with warm engine : to be sure of that disconnect it. You will then check if you have one better warm start. One indication can be the color of your ignition plugs (too rich mixture);
1.1) If your csv inject in warm engine that can be the component which drives it : I mean the cold start device/thermostat (fitted on the engine head) : it give the green light to csv to inject. MB P/N is A001 545 92 24 but not always available in MB;
1.2.) If your csv inject in warm engine that can be the csv itself which stays open (magnet failure in open position).

2) The other reason is : gazoline pressure decrease in the metal lines between IP and injectors.
2.1) Reasons : either leak of one or more injectors either failure of "no return" valves (one or more. they are based on IP top at each output to injector). No return valves bosch P/N is 1 417 412 001 and MB P/N A000 074 1715 but very hard to find now and around 150usd each.
Leaks of injectors or leak of no return valves makes the metal fuel lines between IP and injector without the correct pressure and you have start problem on one or more lines. It finally starts but after some cranking seconds and the engine turns on only on partial number of cylinder instead of full 6 cylinders.

I hope this will help.

Best regards.
Vincent R
France 280 sl 1970

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Author Topic: Another Warm Start Thread (Read 12073 times)

Theclaw

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VincentR