Hard Cold Start

[toneypenna]

I thought I posted this question a few days ago, but I can't find it anywhere on the site. Probably the fact that I'm a bit computer challenged. and did something wrong, so I will try again. Also thanks to all that answered my post about conversion to Electronic Ignition. I have orders a distributor and coil from 123 ignition.

My new problem, 1964 230 SL.  Very hard starting when cold, the only way I can describe it is starting a carbureted car with the choke not working. When it starts getting to operating temperature, runs and idles fine.
I checked the technical Manual and came up with a possible bad  Cold Start Valve, am I headed in the right direction ? Any thoughts or advice from previous experiences will be greatly appreciated.

Jim

[Pawel66]

Here is your lost thread: https://www.sl113.org/forums/index.php?topic=34381.msg251430#msg251430

[ja17]

First of all, take a 12 volt test light or voltmeter and check to see if your cold start valve on your intake is activating when the engine is cold. Let us know.

[Pawel66]

First of all, take a 12 volt test light or voltmeter and check to see if your cold start valve on your intake is activating when the engine is cold. Let us know.

This is the lamp test from the previous thread.

[toneypenna]

Sorry for the delay in getting back to you but lately Saturday is the only day I have time to get involved with this project.
As suggested I checked and have power during cranking at the C/S valve. Also checked and have gas to valve, screen is also clear .
Removed assembly from intake and could see fuel coming through.
Everything appears to be working correctly, any thoughts where I should go next?

Thanks,

Jim

[MarkCan]

Hi Jim,
Since I just rebuilt the CSV, it’s all fresh in my head. When you say;

Removed assembly from intake and could see fuel coming through.

Is the fuel actually coming from the jets at the end? In my case it was not.
It should be a nice mist.

[ja17]

Next  use the test light or meter to see if you are getting power to the top solenoid on the back of the injection pump when you activate the starter when the engine is cold.

[toneypenna]

Will do, let you know how I make out.

Thanks again

Jim

[toneypenna]

Just saw fuel, don't remember if it was a mist . I will double check.

Thanks,

Jim

[toneypenna]

I hope I'm replying to the right persons here, still having a problem navigating this site. I always have a problem finding the posts to reply to.

I checked power to the top terminal on the injector pump and yes i have power. Also double checked the fuel at the CSV and yes a fine mist, appears to be plenty of fuel. Checked the air pipe that goes to the CSV and didn't have any, I believe this air is supposed to push the fuel. Went back to the injector pump and  i believe is a cold start thermostat sitting on top of a small air pump. took the pump out and it was plugged with debris which looks like it's debris   anti freeze that leaked in from the cold start thermostat. I'm looking at replacing both these pieces. Is there agreement on this or should I approach this from a different angle.
I will attempt to  attach pictures.

[Pawel66]

This may be the cause of difficult cold start - engine is not getting more air when it is cold, so it is getting more fuel (CSV and solenoid work), but not more air as the air passage is clogged - too rich to run.

You got to WRD device. Some of these parts are hard to get. You may want to attempt cleaning. Just do not clean the air valve piston and its bore with sand paper, they need to be a tight fit to be able to cut off air.

Please look through the Technical Manual and posts on WRD: https://www.sl113.org/wiki/Engine/WarmRunningDevice

It is not an air pump. In essence, when engine is cold, the air valve inside is open and allows lots of air to be sucked to the engine. The air goes through a filter that is inside this "gold" tin. There is a paper insert there - you may want to buy this filter and replace it as well. As engine warms up, thermostat expands, air valve piston moves and blocks the air passage - when engine does not need so much air any more. That is why the piston need to fit its bore - if it does not, air goes through even when engine is warm, causing the lean condition. It is easy to check if air is coming through or not - unscrew the filter and feel with your finger if there is suction there.

But judging from your picture the air passage is completely clogged. I would clean it, not destroying the bore walls surface nor the piston surface - they need to be a tight fit.

When putting it back together, it is good to put some sealant between the thermostat and its housing to prevent coolant from leaking down - as might have happened in your case.

If you manage to clean it, replace the filter, check and replace the thermostat if need be (check: should be expanding ca 5mm when you put it in a kettle with hot water), put it back together with some sealant as I wrote - you should be ok.

[ja17]

Yes, I think your onto your problem now. Remove the round air filter and try soaking the whole mechanism in some different solvents and penetrants. Some carburetor cleaner may even work well. A heated ultra-sonic cleaner set-up with the correct solution also works well.

[toneypenna]

Thank you for that information, it make sense after your explanation. I'm staring to understand the system with an emphasis on starting.
Probably won't get back to this until Saturday, I will keep you posted on my progress. I'm sure I will be in need your future guidance.

Thanks Again

Jim

[toneypenna]

Started soaking it today, I'll let you know how I make out. Probably won't be until Saturday before I really get into it.

Thanks Again,

Jim

[Jordan]

Jim, mine took about 4 days of soaking to get it moving.  once you have even a minute amount of movement keep at it and it will free itself up.

[toneypenna]

I made some assumptions I would like to run by you guys. I have the  WRD soaking in Carb Cleaner. The piston I am trying to free up comes out on the coolant housing side of the valve? The small 7mm screw with lock nut that screws into the piston  is some sort of adjustment? The plunger that protrudes on the injector side of this valve currently moves about an 1/8" with spring resistance, is this correct? Can't figure out what the small screw that goes in the side with a roll pin does except maybe a stop for the piston when it frees up. Head broke off without using  excess force.
 Attached Pictures show valve with plunger (adjustment ) screw in place and  out and other pictures of broken screw with roll pin.
This valve looks different than the one pictured in the technical manual under WRD. That one has 3 mounting points, the one I have shows 2.

Thanks again for sharing your knowledge.

Jim

[toneypenna]

Marcus
I'm making progress.
You were right, took about 5 days in carb / parts cleaner to get the piston moving freely.
One problem I have  with it is the the piston, it won't come out of the bore due to what appears to be a stop in the sidewall of the valve.
See pictures I posted in previous post. Looks like a screw with a spring under the head and a roll pin, head broke off with hardly any force on it. Does this screw in or is it pressed in??

I could probably leave it as is but if anyone else has some thoughts on it, I would appreciate any guidance.

Also I have not yet checked the operation of the thermostat.

As always I appreciate everyone sharing their knowledge with me.

Jim

[toneypenna]

To everyone that helped with my cold start problem:

Success, I put everything back together Saturday and everything appears to be operating as it should. Started right up with no problem, sucking air through the filter port on the WRD on top of the injection pump and shutting down when warmed up.
Idle is to fast but that is probably due to my changing the distributor to a 123 electronic just before I tackled the cold start problem. Anyone know the accepted RPM for a stick car and what the timing should be with the electronic distributor??? Is there an idle adjustment some where? I searched the Tech Manual and couldn't find anything, but that's  probably on me not doing the search properly.

Again as before any help is greatly appreciated.
Jim

[Melburnian]

Hi Jim,
Ive been having similar problems to you and in researching it I discovered a brilliant you tube video you must watch. It walks you through the entire process of  servicing and setting the mechanical fuel injection pump. Minute changes to the settings will effect your idle speed. Search "problem solver garage "on you tube for the video. Its very helpful.
good luck,
Simon.

[toneypenna]

Simon

Thank you for the you tube tip, very enlightening especially the fuel injection adjustment part,  a great help to me.

Thanks again for your help.

Jim

[roymil]

Hello, saw the question about the idle speed and adjustment and wanted to save you some time. Correct idle is about ~750RPM on most models when fully warmed up.  It's not a single screw adjustment if done properly, although there certainly are multiple screws you can turn to impact the idle speed, most of them would be wrong things to do.  It's worth a read through  the starting aids and tune up tour in the technical manual section before you tackle the idle speed.  There is a specific iterative process that involves adjusting the fuel pump (engine off!)  and then idle air screw while running.   Also the linkage tour is well worth a read.   Thanks again to the veterans of this site for putting all that together!

https://www.sl113.org/wiki/TuneupOverview/Start

[ja17]

Good advice Mark!

[Benz Dr.]

This may be the cause of difficult cold start - engine is not getting more air when it is cold, so it is getting more fuel (CSV and solenoid work), but not more air as the air passage is clogged - too rich to run.

You got to WRD device. Some of these parts are hard to get. You may want to attempt cleaning. Just do not clean the air valve piston and its bore with sand paper, they need to be a tight fit to be able to cut off air.

Please look through the Technical Manual and posts on WRD: https://www.sl113.org/wiki/Engine/WarmRunningDevice

It is not an air pump. In essence, when engine is cold, the air valve inside is open and allows lots of air to be sucked to the engine. The air goes through a filter that is inside this "gold" tin. There is a paper insert there - you may want to buy this filter and replace it as well. As engine warms up, thermostat expands, air valve piston moves and blocks the air passage - when engine does not need so much air any more. That is why the piston need to fit its bore - if it does not, air goes through even when engine is warm, causing the lean condition. It is easy to check if air is coming through or not - unscrew the filter and feel with your finger if there is suction there.

But judging from your picture the air passage is completely clogged. I would clean it, not destroying the bore walls surface nor the piston surface - they need to be a tight fit.

When putting it back together, it is good to put some sealant between the thermostat and its housing to prevent coolant from leaking down - as might have happened in your case.

If you manage to clean it, replace the filter, check and replace the thermostat if need be (check: should be expanding ca 5mm when you put it in a kettle with hot water), put it back together with some sealant as I wrote - you should be ok.

230SL cold start thermostat only moves about 1.5mm to shut off. Later 280SL is 5 -7 mm. I believe this difference is due to the much smaller cross section on the 280 slide valve housing.