gunson gas tester feedback

[merrill]

so, been trying to fine tune the 66 230 sl.  

used the gas tester at home and; at idle; got a reading of 10% co.

then drove the car to the inspection station where the very kind attendant agreed to test the co for free.

at  904 rpm the reading was 8.66
at 2609 rpm the reading was 9.99

so, this is more feedback on the accuracy of the gas tester.  It appears that the unit does a decent job at measuring the co.

what is strange on this car is the mb mechanic has taken the vent line from the valve cover and vented it under the car instead of having it hooked up to the intake.  I remember my dad saying this was to help try to get the car tuned since the motor was worn.

when I pulled the #1 spark plug today it was dirty with carbon that wiped off with ease.  the plug was new 2 days ago and I put about 200 km on the plugs. At least the plugs are not wet with oil, that would be worse.

matt

Matt
66 230 sl - "white"
78 300 D - Blue
98 C230

[rwmastel]

My valve cover breather was vented below the car when I bought it.  It is to keep the (oil) blow-by from recirculating back into the intake manifold.  My engine is worn, compression is low at 120 - 130 PSI.  What's your compression?

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

[merrill]

Rodd,
I plan to check my compression soon.  here are the values I have from previous receipts

5/86 125,499           2/87  135,110
1   140                 105
2   145                 105
3   150                 120
4   150                 120
5   135                 115
6   150                 120

The only real change between the tests is a rebuild injection pump was installed 8/86  127,784

I am suspicious of the change in values, especially when less than a year passed.  and the only real change was the inj pump.  
I wonder if pacific fuel injection screwed up the pump rebuild or the mechanic screwed up the mixture setting on the pump?
Thus causing the rings to burn up?

On a post today I noted the current co % is high at idle and at 2500 rpm.  I think the values were 8.66 and 9.99. I am going to call hans at H and R on monday see what he thinks.
when I pulled the plugs all had carbon which easily wiped off.

the car runs great after I installed all new ignition components and set up the timing etc.  
I sure would like to get the car running right so I can get that vent hose hooked back up properly.

matt



Matt
66 230 sl - "white"
78 300 D - Blue
98 C230

[ctaylor738]

Fine tuning?

I'm no tree-hugger, but running around at 10% CO and venting your crankcase directly into the atmosphere is pretty bad for the air we all need to breathe.  It's also potent ammunition for those who want old cars off the road entirely.

Chuck Taylor
1970 280SL #14076
Falls Church VA

[merrill]

chuck,
I agree, but at least i know where I am starting from.

torqued the head and adjusted the valves today.  all but one was tight.

I will double check the timing, etc and then re test the co%.
the inspection station attendant suggested using a decarbonizing agent called seafoam in the oil and fuel to get rid of some of the carbon.
he told me that they have success using this stuff when other cars fail emissions.  

I will also call hans tomorrow and see what he thinks.  I may pull the inj pump and injectors and send to him for rebuild.  depends on what he says.

Also, I will re do the compression test and see what the values are.
I am suspicious that the second test was bogus.  If I do get more reasonable values I will be more prone to re connect the vent tube to the intake.

matt

Matt
66 230 sl - "white"
78 300 D - Blue
98 C230

[hands_aus]

If I had my car in the condition your is in now I would re-instate it to original specs....timing, linkages, hoses, oil level, spark plugs, leads, CSV, WRD, Injection pump etc.

What do you have to lose?

My understanding of the CO level on the 113 is that the reading is only taken at HOT IDLE because the CO level can be way out at higher RPM.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[merrill]

Bob,
so, that is exactly what I have done.  everything should be origional in terms of function etc.  (hans inspected wrd and csv)

When I did the valves yesterday they were all tight. I had a hard time getting the feeler guage in the gap or in some cases not at all.

I wonder if tight valves contributed to the problem?

In response to Chucks comment,  the car measured at 8.66 at idle but the min level for texas is 8.5 so it barely failed the test.

matt

Matt
66 230 sl - "white"
78 300 D - Blue
98 C230

[rwmastel]

quote:Originally posted by merrill

I am suspicious of the change in values, especially when less than a year passed.

Matt,
I recall those varied compression numbers, I suspect the testing procedures (or tester's skills!).  You sound skilled enough, it will be interesting to see what your numbers are after the head bolts and valve adjustment.  These alone may have a big effect.

quote:Originally posted by merrill

when I pulled the plugs all had carbon which easily wiped off.

Sure it was carbon?  Maybe just too much fuel (running rich) or oil (blow-by or something else)?

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

[merrill]

Rodd,
so, I too am interested in the retest numbers post valve job etc.

As far as the spark plugs, the plugs had a dry powder like coal dust that easily wiped off.  the plugs were dry when removed.  

according to the haynes manual spark plug analysis page, the plugs looked like ones that were diagnosed with the fuel mixture too rich.

Talked to hans at H&R today, he said to do the following
1. raise the idle from 700 to 850 rpn via the intake idle adjustment screw.   this alone will change the co.

2. check the venturi linkage adjustment

3.  the oil level in the inj pump has nothing to do with the co.

4.  the co actually goes up as rpm's increase then drop about 4000 rpm.

so, back to fine tuning.
matt

Matt
66 230 sl - "white"
78 300 D - Blue
98 C230

[hands_aus]

quote:Originally posted by merrill

Rodd,

3.  the oil level in the inj pump has nothing to do with the co.

Matt
66 230 sl - "white"
78 300 D - Blue
98 C230

Hey Matt,
Your oil level seems to be right.

If the injection pump oil level is too high, this causes the govenor weights to spin in the oil. This makes it almost impossible to lean out the air/ fuel mixture. So indirectly the mixture is affected and obviously the CO level too.

Ask how I know.
I removed about 500ml of oily sludge from my injection pump. After replacing the oil with about 200ml of oil, I was able to 'fine tune' the car with a huge economy difference, 9mpg > 19 mpg around town.
And that makes me  

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[glennard]

What is the compression after adjusting to .003 and .007?

Adjusting idle speed with idle air?   Sounds like too much idle fuel.

Do the richness test.  i. e.   1. Disconnect the vertical link between the FI pump and rod across the valve cover. 2. Rotate the rod across the valve cover slowly to open the butterfly.  This will increase the air flow at constant (idle)fuel flow.  The rpm should increase 50 rpm max (or so) and then stall out as the mix become too lean to run as the butterfly is opened more.

If the idle speed goes up to say 950 or 1200, it is rich.  Turn off and click the injection knob CCW a click and try again.  Repeat to 800 rpm

The BBB recommendation, as I remember, is engine should run about 50 rpm on the rich side.

All being in sync, should purr like a kitten - a Jefferson nickel will balance on the valve cover!

[enochbell]

glennard,

What a great tip on setting the IP, I never heard of that technique but it makes a lot of sense.  I assume that if opening the air causes immediate drop in rpm then you need to adjust IP a click or two CW until adding air causes an increase in rpm?

Thanks,
g

'64 230sl, fully sorted out...ooops, spoke too soon

[hands_aus]

quote:Originally posted by enochbell

glennard,

What a great tip on setting the IP, I never heard of that technique but it makes a lot of sense.  I assume that if opening the air causes immediate drop in rpm then you need to adjust IP a click or two CW until adding air causes an increase in rpm?

Thanks,
g

'64 230sl, fully sorted out...ooops, spoke too soon

g,

yes correct.
It is commonly called the 'Alexander technique'  

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[enochbell]

thanks for the clarification, I think I get your joek?

g

'64 230sl, fully sorted out...ooops, spoke too soon

[merrill]

Glennard,
well, tried the richness test, 3 times on my 66 230 sl today.
1. just disconnected the linkage, the rpm's went to almost 2000
2. motor off, turned screw ccw on the inj pump, tried again, 1400 rpm
3. motor off, turned screw cc4 on the inj pump tried again, 1100 then a stumble.

I noticed that if I rotated the linkage arm slowly I could maximize the rpms.

from the last test, checked the co% with my gas tester.  at 875 rpm it was 5 - 5.8%.  

then the trouble started, the car would not start, I think the inj pump was too lean,  before the adjustments the car ran great.  

so I wonder if the motor is just worn and needs to be rich OR does this indicate another issue??  

I am embarrassed to say the mixture screw on the inj pump was probably turned 8x ccw.

I turned the screw cw x4 but the car would not idle, so back to the drawing board.  I should have made note of exactly how many times I turned the screw ccw.

matt

Matt
66 230 sl - "white"
78 300 D - Blue
98 C230

[merrill]

glennard,
well, now I know why the car ran rough when I leaned it out.
did a compression test today, below are my results.

cylinder   1 2 3 4 5 6
11/07 dry 45 40 60 66 60 60
11/07 w oil 75 70 70 66 60 60
2/87 105 105 120 120 115 120
5/86 140 145 150 150 135 150

all tests are in lbs per sq inch
all tests done per the procedure in the bbb.  guage accuracy verified.

looks like it is time to look into a motor rebuild.
matt

Matt
66 230 sl - "white"
78 300 D - Blue
98 C230

[rwmastel]

quote:Originally posted by merrill

glennard,
well, now I know why the car ran rough when I leaned it out.
did a compression test today, below are my results.

cylinder    1  2  3  4  5  6
11/07 dry   45 40 60 66 60 60
11/07 w oil 75 70 70 66 60 60

Matt,
I'm suprised your car would run at all with less than 80 psi in each cylinder, but who knows?  Do you think the rings/cylinders are shot, or are the valves not closing?

- Never mind, I just read your other posts dealing with this issue.

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

[merrill]

Rodd,
spoke with mile elias at metric motors today. he was stumped as to why the car does not burn oil at idle or running, the exhaust clear.

He also did not no at what compression pressure the motor would not run.  

Since the vent line from the rocker cover is disconnected and venting over the motor, I wonder if there is exhaust blow by escaping thru the exhaust valve seal when it is open?

I wonder if there is a way to attach my compression guage to the rocker arm cover and measure the pressure?

matt

Matt
66 230 sl - "white"
78 300 D - Blue
98 C230