Plugs and durability

[230slhouston]

I am curious and need some comment from the engineers and people like Joe and DR Benz or anyone with plug issues/experiences.

Here is my experience, I installed new Bosch plugs (WRDC+) in my car (standing for 20 years). The car started but idled very rough. Starting was a milestone.

After a couple of starts it started missing and refused to start. After serious fiddling and troubleshooting and finally dipping the plugs in gasoline and igniting them (out of the car of cause)to dry and warm them up, the car started and  idled fine for a while. I took it for a 10 mile drive, it was not responsive but anything for a first drive.

Next, the car started one morning fine then sputtered and started misfiring. Finally it did not start at all. I changed the coil and fiddled with everthing possible (considered a pump recon), I put in NGK BP6ES plugs today cranked the engine and it stared.

It now starts and sounds like a dream, no miss idles great.

Could a new set of Bosch plugs cause this heartache or is their a gremlin i am missing? The plugs are not fouled in any way.

Any comments?

Thanks
MB

[Raymond]

If you search the forum for Spark plugs, you'll find that you should not use the Resistor plugs in the car.  That's what the R in WRDC stands for.  

I'm not sure but I think the NGKs that you installed are non-resistor.  For Bosch you want W7DC plugs, or as Dr. Benz recommends W8DCo (Which I think are copper plugs?)

The other problem I've found is Bosch Plus plugs are finicky.  My Acura hated them. I put a set of Platinum Plus in our Nissan Pick-up and it runs great.  I put a set in the BMW 325 and the sucker ran rough and got worse fuel economy, but runs great on the Bosch Copper plugs.

That said, a car that has been sitting for twenty years might have myriad other quirky things to work out.  Like maybe varnish in the fuel lines, junk in the tank, leaking plug wires, vacuum leaks, sticky distributor advance, etc. etc. etc.

Ray
'68 280SL 4-spd Coupe

[ja17]

Hello MB,

Your oil is most likely contaminated with fuel from a rich running condition. Fuel contamination will cause poor lubrication so you may want to change your oil again soon. Has the level on the engine oil dip stick risen?

It sounds like something was stuck from the long period of storage. My first guess would be that the Warm running Device (WRD) is stuck rich. Use a section of water hose as a stethescope. Place one end at the small injection pump air filter. You should hear air rushing into the air filter on the injection pump when the engine is cold. The rushing air should stop when the engine is fully warmed.If your are not familiar with these terms or parts locations let us know. You may wnat to look at the "injection pump tour" for some photos. Keep us up to date.

Joe Alexander
Blacklick, Ohio

[230slhouston]

Joe and Raymond, thanks for the reply.

Joe,
You are perfectly correct, the engine oil level has risen and it is thinned. I will change the oil this weekend and not start the engine prior.

The oil smells of gas when the oil cap is removed while the engine is running.

I am not familiar with the terminology as to where the small injection pump air filter is. A picture will help. I will also take the pump tour.

Most important thing today is my lady started. One day at a time.

Thanks
MB.

[rwmastel]

MB,

Hi.  So, you're getting an old car up and running?  Repeating the advice of those more experienced than I, I would recommend you do the following in this order.  I see you have 50+ posts on our forums, so perhaps you already have covered much of this?

1.  Compression.
- Ensure compression is fairly consistent across all cylinders.
2.  Fuel.
- Remove the fuel gauge sending unit from the fuel tank (via the trunk floor) and look in tank for sediment.  Remove tank and clean it out if necessary.
- Replace fuel filter screen in fuel tank.
- Replace main fuel filter in engine bay.
- Ensure good fuel pressure and flow rate by measuring at the fuel tank, where the fuel line returns from the injection pump.
- Ensure the linkages in the engine bay are set up properly.
- Check the "7th fuel injector", or the cold start aid, mounted on the intake manifold for leakage.
3.  Spark.
- Try non-resistor plugs (I guess the NGK ones are good).
- Check your spark plug wires and caps for excessive resistance.
- Make sure you have a properly matched coil, ballast resistor, etc.
- Make sure the spark is on time by checking the timing and dwell at the various RPM ranges.
4.  Air.
- Replace your main air filter with a new one.
- Check the air filter on the fuel injection pump to make sure it pulls air when the engine is cold, but not when it's warm.
- Make sure the venturi flap on the intake manifold will close all the way, but not bind.  This is related to the linkage comment above.

Guys, did I forget anything?

This is a lot of stuff, but it will fix the vast majority of the problems most people face.  If you are still having difficulty after this work, please let us know about it and we'll help.

You can look through the technical manual and see what's been written about fuel (and other topics).
http://www.sl113.org/wiki/pmwiki.php?n=Fuel.Start

Here's some good forum links with detailed info and pictures, but you can use the Search feature yourself to find many more.

http://index.php?topic=5003
http://index.php?topic=1712
http://index.php?topic=6277
http://index.php?topic=5486
http://index.php?topic=3659
http://index.php?topic=790


Rodd
Pagoda Technical Manual
please contibute: http://www.sl113.org/wiki/pmwiki.php
1966 230SL
2006 C230 Sport Sedan

[230slhouston]

Rodd,
Thanks for the list, I had the tank cleaned and coated (re nu it process), new air filter, CSV does not leak (at least from the little bolt screw removed to see if it leaks when running)

Joe,
I took your advice about the WRD. Here is what I did:
1. Removed it, cleaned it out, although the plunger inside did move freely.
2. Removed the copper thermostat device, and put into hot water, the pin did move about 3mm.
3. Assembled it and submersed the coolant end in hot water and then try to blow or suck a vacuum through the filter hole, it was sealed.

I installed it and started the car, it sound beautiful. I tried to use a hose as stethoscope but got to much external noises. So I took of the filter, started the car when cold, I sued my finger on the filter inlet, there was vacuum, my finger got sucked in. After the car warmed up, vacuum decreased considerably. There is still a slight (very slight) vacuum though, is this normal?

I did change my oil; it was very thin for only 15 miles and some starting in my garage. I replaced it with 20W30 is this oil OK?

BTW, when looking at the back of the IP, enrichment screw turned CW enriches or should it turn CCW to enrich?

Thanks everyone for your help.

MB

[230slhouston]

One more question, on the WRD, there is 14mm "bolt" on the device that is spring loaded and when rotated has a offset pin to adjust the travel of the plunger. It has an "O" on one side which sets the travel to max, two lines on the opposite side to set the travel to zero.
I turned this without first making sure the exact position, my fat fingers Where should it be set? I set it midway for now.

Thanks MB

[psmith]

It sounds like the resistor plugs were part of the problem.   Something else to check, based on your name, I am guessing you have a 230 SL.  The pump on a 230 has it's own oil supply and dipstick.  The way I understand it, the oil is what forms a seal around the little pistons that pump the gas.  No oil, no seal.  

Also, the gas tank has what is known as a "flower pot" at the outlet of the tank with small openings around the perimeter to let gas in.  Hopefully when they recoated your tank they didn't block those holes.  Make sure the filters are clean and check the flow to the pump.

Pete S.

[ja17]

Hello MB,

Your oil weight should be OK. Most owners will use a 10-40W or similar. Turning the idle enrichment screw clockwise (as looking forward from the driver's seat), richens the mixture. This adjustment can be carried out only when the engine is not running. These injection systems tend to "wear" rich (become richer} as they miles accumulate. Remember also, these cars like to move once started. Starting and stopping and letting them idle over and over again, can cause problems fouling spark plugs.

As far as I know the 14mm screw on the early WRDs, is used for testing or set-up and is not actually used as an adjustment. It should be left to allow the slide valve full travel.

Joe

Joe Alexander
Blacklick, Ohio