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MG TD TF 1500 - Running rich and Cadmium found in the oil

Had a problem over the past year where the Carb jets do not move up fully to the normal driving position. After pulled the choke out and the engine then runs too rich. It first showed by the engine dieseling when I turned it off. It ran fine - but it did not want to stop. So something needs to be done.

I have replaced some of the carb hardware - leavers etc. and fitted two new return springs. The carbs have never leaked and I don't want to pull the jet seals out as they are working OK - even if tight.

Would it be better to replace the Bowden cable in the choke pull Assy. with a suitable solid piano wire?
This would push the jets back up completely and assist the return springs to do their job.
I presume I would have to silver solder the wire into the pull knob end and try not to melt the plastic knob.

According to the Oil Analyses I just had done it confirmed the engine is running very rich - showing oil dilution but also an elevated Cadmium level?

Not sure where that comes from or what would cause that.

Any ideas?

Rod
R. D. Jones

This was the Oil Report


R. D. Jones

Kinda looks like my monthly lab reports.
L E D LaVerne

I heard rumors L E D you have 20/50 in your veins :)
R. D. Jones

What brand of oil are you using? I would try a different oil and test again. My understanding it is an additive some companies put in.

Frank
Frank Cronin

I have been using Castrol GTX 20/50

With ZDDT additive for only the past year.

Having come from England I did not know of the removal of the Zink by the oil police here and started a little late with the ZDDP.

Don't think there is any Cadmium in it?

Rod
R. D. Jones

MG TC. I have just replaced my metering needles and jets without upsetting the sealing of the jet. I did it without removing the carburettors from the car.It has improved carburetion substantially. I also tinkered with the linkage because at one point my jets were not returning fully. You must have a little 'slack' in the choke cable so you push the jets fully home after releasing the choke. There was a lot of trial and error with the linkage and I spent a lot of time on my knees with the air filter off but with the standard chock cable my jets return properly.
Make sure you lube the new jets before inserting them and then make sure you centre them properly.
Ian Buckley

Rod,

Cadmium is a very infrequent metal trace in oil analysis. In any case, it is classified as a result of wearing metal, and so it should come from the engine (not oil, fuel, cooling water, etc.). The same report you showed states that sources of cadmium can be some electroplated coating or solder. Cadmium could be pulled off by the attack of the oil, not necessarily by mechanical wearing.

13 ppm is a very small concentration (as is 15 ppm of copper), so I would not be upset by this result. Of course this all depends on how long the engine has been running with this oil.

Jesus
J Benajes

Thanks Jesus for the info.
The oil had been in the car for a year and had only done 700 miles.

Ian, I too have been there on me knees tinkering for several hours to try and get the jets to return up to the fully choke closed position. :)
The balance on the carbs seems right (When listening to the hiss) and it ticks over with just a slight burble now and again - I put down to being too rich. If I push the jets up by hand it all looks good a lot better.

Trouble is up here in Maine you need the choke on all starts till he high summer comes around.
Jumping out of the car to push the jets up once it is warm is a pain.

I was thinking piano wire would allow me to just push them up when returning the choke to off. The return springs just don't seem to have enough heft to do it on their own. Even new ones.

Putting on stronger springs would just add more effort to he choke pull. That for me, is not a good solution.

Rod

R. D. Jones

Rod - where in Maine are you?

Tom
t lange

Tom

I'm in Backfield - just north of Lewiston of route 4 on 117.
R. D. Jones

I believe the cad in the oil is from the lead/tin/antimony/indium bearing shells rods and mains. Nothing to worry about at those levels though.
Brian Warmuth
ZBMan

The new unleaded fuels are very dry. It takes a strong spring to return the jets as less lubrication is available. It may also be beneficial to drop the jets and oil the jets from the top and bottom, and exercising them between oil applications. Don't worry about getting it down the jet, the oil won't hurt any thing.

Also, make absolutely certain your jets are centered.

Hope this helps.

Dave
Dave Braun

Thanks guys
appreciate the thoughts.

Will definitely try some oil on the jets and check they are centered.

I don't think there is a problem with the level of fuel in the float chambers - but will check that.

I guess the float needles should also be looked at - Could be flooding from there. I have the Gross balls valve type - been in the car for ever.
Though I must admit, just sitting with the ignition on and the engine not running I would expect to see fuel or at least hear the pump running more that it does if they were bad?

Rod


R. D. Jones

Rod, I have had the same problem with the jet not returning all the way up. I sat and used Aerokroil penetrating oil and dropped the jet (pulled mixture control) and then pushed them back up . Exercised them about 10x each and now they return by themselves. I did not have to remove the jet in my case. I think they were not lubed at the rebuild or if they were maybe not enough. Solved the problem tho!
C.R. Tyrell

This thread was discussed between 20/05/2013 and 23/05/2013

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