w123 230e 4 star to unleaded

[Richie]

I got in touch with the local mers dealer today to ask what i have to do to change my 1984-5 w123 230e from leaded fuel to unleaded fuel and they said that i can just change over no problem then the man on the phone said that he personally would put some leaded fuel in every 3-4 tank fulls if he said this i might damage the valve cushions i am a bit stuck can anyone help or what do you do in your w123 cheers.

 

[pluggers]

Im not too up on this as i've never been down this route but I would have thought that octane boosters would be just as effective as putting in leaded fuel.As I seem to think that leaded fuel (4 star ) will be fazed out eventually?

 

[andy_k]

the 230 engine should run fine on superplus unleaded (our W123 230E used to) theoretically it needs 98ron fuel and superplus is 97ron - near enough for me

the 230 engine is just about bulletproof but i would strongly advise getting the timing chain changed on yours - i read in another post the engine has done 230k with no history - on the W123 engines the simplex timing chain should be replaced every 100k maximum.

Andy

 

[Richie]

Thanks for the info everyone i wondered if any one has any idea how much it would cost to get the timing chain changed it sounds like a MAJOR job specialist only?????

 

[andy_k]

Thanks for the info everyone i wondered if any one has any idea how much it would cost to get the timing chain changed it sounds like a MAJOR job specialist only?????

not a big job and one that any reasonably competant home mechanic can do.

If you change the chain and tensioner/guide the whole job should be less than £200 even if you pay somebody to do it for you.

Andy

 

[Stratman]

There is more to running on unleaded than just the octane rating. I'll repeat here what I wrote in an earlier post.

Lead (as tetraethyl lead) was added to petrol to indeed boost the octane rating. This allowed higher compression ratios leading to increased power and efficiency. This lead then coated the combustion train, as can be seen in the white deposit on the inside of the tailpipe of a 'leaded' car. This was found to have a cushioning effect on the valves as they repeatedly impacted against their seats. In black and white days, this wasn't too important because engines were low-revving and had little valve lift, so the impacts were not too severe. As power outputs increased, due in part to higher revs and greater valve lift, these impacts became harder and more frequent. Then Shell tried introducing unleaded fuel without telling anyone. Vauxhalls in particular were badly affected by this. The cast iron valve seats quickly became 'pocketed' and the hydraulic tappets ran out of adjustment. Because this cushioning layer of lead was no longer present, the constant impacts between valve (particularly the exhaust valve) and seat wore the seat away. Shell eventually owned up.

When time was called on leaded fuel, many engineering shops had a nice sideline going in replacing cast iron valve seats with more modern ones made from (I think) austenitic steel (or is it iron?).

So, as well as the ignition timing, check the valve seat material. It could save you an expensive rebuild.

 

[Richie]

There is more to running on unleaded than just the octane rating. I'll repeat here what I wrote in an earlier post.

Lead (as tetraethyl lead) was added to petrol to indeed boost the octane rating. This allowed higher compression ratios leading to increased power and efficiency. This lead then coated the combustion train, as can be seen in the white deposit on the inside of the tailpipe of a 'leaded' car. This was found to have a cushioning effect on the valves as they repeatedly impacted against their seats. In black and white days, this wasn't too important because engines were low-revving and had little valve lift, so the impacts were not too severe. As power outputs increased, due in part to higher revs and greater valve lift, these impacts became harder and more frequent. Then Shell tried introducing unleaded fuel without telling anyone. Vauxhalls in particular were badly affected by this. The cast iron valve seats quickly became 'pocketed' and the hydraulic tappets ran out of adjustment. Because this cushioning layer of lead was no longer present, the constant impacts between valve (particularly the exhaust valve) and seat wore the seat away. Shell eventually owned up.

When time was called on leaded fuel, many engineering shops had a nice sideline going in replacing cast iron valve seats with more modern ones made from (I think) austenitic steel (or is it iron?).

So, as well as the ignition timing, check the valve seat material. It could save you an expensive rebuild.

Cheers mate i will at the same time as i get a quote from the local merc dealership.