Author Topic: testing baro compensator (Read 2805 times)

hands_aus · « **on:** July 18, 2019, 05:56:17 »

Long time since posting
Driving up the mountain to my friends place at Buderim the car struggles.
On flat ground the car goes great especially after i had the inj pump rebuilt with new seals etc in Sept.2014.
Car is serviced regularly with changes of fluids and rubber hoses etc.
September 2018 drove the car to Canberra and back (1652Miles, 2658 Kms) achieving 21.9 Imp mpg , certainly cleaned the engine and had no troubles.

How do I confirm my suspicions of the Baro Compensator?
I have never adjusted it.

thanks, any help appreciated

hands_aus (Bob Smith Brisbane Australia)
early 250sl best of the best

Cees Klumper · « **Reply #1 on:** July 18, 2019, 06:42:26 »

Hi Bob, good to 'see' you and that you still enjoy your SL.
On your question, it seems to me a test of the CO value at different altitudes would be the check, sine that is what the compensator is supposed to do: adjust the air/fuel mixture for the different air pressures at different altitudes. A quicker check might be to borrow one that is known to be in good condition and swapping it out with your current one, and seeing if that sorts out the problem. Best of luck

stickandrudderman · « **Reply #2 on:** July 18, 2019, 08:51:21 »

The Co should be the same at all altitudes so if yours IS changing then your barometric compensator should be suspected.

Pawel66 · « **Reply #3 on:** July 18, 2019, 16:47:26 »

Perhaps the quick test with the help of Technical Manual and food vacuum box would help in initial diagnosis?

hands_aus · « **Reply #4 on:** July 18, 2019, 20:11:30 »

Hey Cees, Colin, Pawel

Thanks for the replies,
still very enthusiastic here, i still have minor issues with the car so I look through the posts and tech manual
Weather permitting, the car gets driven every weekend.

Interestingly the car seems to work perfectly fine when on top of the hill/mountain
Next time I will stop half way up and do a split linkage test and then another test at the top of the mountain

I will definitely try to find the test in the tech manual and have a good read

cheers Bob Smith

Pawel66 · « **Reply #5 on:** July 18, 2019, 21:40:43 »

I think the basics are:
1. Is the pin stuck or moves? Usually it is stuck in down position, mine was stuck in up position.
2. Get a vacuum box for food. Put the BC in, close and pump out the air. The pin should stick out more.
3. Length of pin - here I do not remember...

ja17 · « **Reply #6 on:** July 19, 2019, 06:02:43 »

Seems like the injection mixture goes lean and the pin extends downward, when the barometric compensator fails. Altitude here in Blacklick Ohio is around 800 feet above sea level. At this altitude the barometric unit extends about 22 mm into the pump (from tip of pin to seating surface above threads).

wwheeler · « **Reply #7 on:** July 19, 2019, 14:59:54 »

I remember when I tested mine in Dallas (600 feet) it was about what Joe had. I also think that when it fails, the pin extends making it leaner. I was hoping to find a cross sectional view of the compensator and that would give you the info to say whether it would fail lean or rich. Just can't find anything.

mrfatboy · « **Reply #8 on:** July 19, 2019, 15:31:18 »

We have pictures and info in our wiki.

https://www.sl113.org/wiki/Engine/AltitudeCompensator

stickandrudderman · « **Reply #9 on:** July 19, 2019, 16:34:08 »

And don't forget hands_aus, I'll be in Brisbane in November!

hands_aus · « **Reply #10 on:** July 23, 2019, 04:19:41 »

Thanks again for the replies and the link to the Manual.

I tried removing the Baro Comp and boy it's on tight. I don't know if it was removed when I had the Inj pump rebuilt but it sure looks like the one that was on the car when I bought it in 2002.

Last Saturday I took the car on a drive up to the local hill/ mountain with the TV towers.
The car ate the uphill part of the trip and wasn't sluggish at all.

It could be just me expecting more and forgetting the car is 52 yo.

The next morning I started the car and it was as rough as could be and blowing lots of black smoke.
I sat around thinking about it and decided that as nothing had been changed I would check out the plugs.
They all were sooty black so I cleaned them and started the car again.
Same result as before running rough, missing etc
I turned the ignition off after 60 seconds and as they were as sooty as the previous check, I decided to exchange the plugs for new ones.

Started the car and everything was back to normal.

Took the car on a short run up the hill/ mountain again and it flew up the hill.
I did a split linkage test at the top of the hill and all was as it should be.

so happy here.

The local car club has a run to the coast on Sunday so I will head off and give the car a burn out
Cheers

stickandrudderman · « **Reply #11 on:** July 23, 2019, 15:48:14 »

I've been meaning to set up a youtube channel for years and this has given me the impetus I needed!
https://youtu.be/WjFQSocAGt4

Cees Klumper · « **Reply #12 on:** July 23, 2019, 17:11:47 »

And you have your first like, first comment and first subscriber!
Everybody, get over there and sign up!

hands_aus · « **Reply #13 on:** July 23, 2019, 20:44:03 »

Great video

Pawel66 · « **Reply #14 on:** July 23, 2019, 20:48:48 »

Like and subscription from me!

You may need some entry banner or something...

stickandrudderman · « **Reply #15 on:** July 24, 2019, 09:16:03 »

Quote

You may need some entry banner or something...

If I knew what you were talking about I might agree!

perhaps everyone could tell me what they'd like to see and I'll see if I can make it happen.

I will only post a new video once per month (probably).

Pawel66 · « **Reply #16 on:** July 24, 2019, 11:32:50 »

From your patio you have Top Gear and Wheeler Dealers - you just need 2 seconds one.

Kent has a nice one.

You just need to know:

What your channel is going to be about? (technical tips on mechanical aspects, overall restoration aspects, DIY only, etc.)
Who will watch your channel? (experts, amateurs)
What would be the mood/character - you want to be: trendy, funny, serious, technical/dry, etc.)?

And the most important one: what is the one single, one short sentence message you want viewers to receive with this banner?

stickandrudderman · « **Reply #17 on:** July 24, 2019, 14:00:08 »

Quote

You just need to know:

What your channel is going to be about? (technical tips on mechanical aspects, overall restoration aspects, DIY only, etc.)
Who will watch your channel? (experts, amateurs)
What would be the mood/character - you want to be: trendy, funny, serious, technical/dry, etc.)?

And the most important one: what is the one single, one short sentence message you want viewers to receive with this banner?

Does anyone else glass over when reading this or is it just me?

(Sorry Pawel, I know you're trying to be helpful but I just find this stuff so far beyond my comfort zone......)

Pawel66 · « **Reply #18 on:** July 24, 2019, 18:05:23 »

This was a very, very simplified brief....

FresnoBob · « **Reply #19 on:** July 25, 2019, 22:15:19 »

Great job Stick! Very clear and easy to understand.

I regularly drive my 230 SL to 7,000 ft and it runs the same as it does at sea level. Must mean mine is working, though I've never been able to remove it from the IP due to really frozen threads.

News:

Author Topic: testing baro compensator (Read 2805 times)