Many thanks. So I decided to do the plugs and injectors on my “new” 1980 450 slc. Plugs were easy, injectors after 40 years were another story. Not sure why I decided to change them as they worked well enough to pass the dreaded California smog test, but I did them. I now have a new found comprehension for leaving sleeping dogs asleep. On the plugs, Bosch ones, it still had “ Made in West Germany” stamped on them! New ones are now from India….., still Bosch.
Thanks for your comment. I am contemplating testing and changing the injectors on the 280SL - what sort of issues did you face....and has the running of your car improved noticeably. As a matter of interest, what was the number on your spark plugs? Mike
Greetings. Re issues the biggest pain was getting the fuel injector nozzles out. I am fairly sure they were the original ones from 1980 so well caked in, brittle and the O ring was as hard as nuts. As such, it took quite a bit of pulling and brute force. One nozzle refused to budge, I could turn it a full 360 but out was another matter, so I had to split it with a screw driver and get it out. On the V8 you’ll need to disconnect the fuel lines, even a couple to the distributor to undo the nut on the fuel injector. Clearly air filter etc has to come out. Watch out for old vacuum lines which will shatter. The injectors came out super easy. It’s the nozzle that is the pain. And on the drivers (lhd) first cylinder closest to the firewall you’ll need to disconnect the linkage to access the screw to remove the small pressure plate which hold the injector in place. Nozzle was the worst but by a long way. Plug numbers are WR8DC. Bosch made in W Germany. All the best and many thanks for all your great vids. Power steering pump is the next job, then engine mounts, steering coupler, shocks, bushing, brakes, all fluids and then the rust hole in the spare wheel well. @@MikesMercsandothercars
Thanks for the detailed reply.......I'll prepare myself for the worst! I'm really surprised that your 1980 450SLC would use resistor spark plugs....are you 100% sure this is correct? If you have the VIN number I can double check with the Mercedes Parts department here in Bristol. Mike@@MJR67
Thanks for your comment...and I do appreciate your sentiments. I suppose I could have just given the facts, but I thought a small quiz might be a more fun way to convey this info. .... After all, if you can answer the questions correctly, you know you don't have to watch any more of the video. Mike
No/ 1 incorrect. The MAIN purpose of a spark plug is to provide a spark to ignite the air/fuel mixture in the combustion chamber. Answer C is technically correct, but it is a secondary benefit and not a primary one. Similarly you could ask what is the main purpose of fuel passing through the induction system? The Main purpose here would be to provide an air/fuel mix into the combustion chamber for the purposes of ignition, yet the secondary benefit would be to provide an element of cooling.
Thx for your comment - Question 1 is phrased as follows: "The primary function of a spark plug is to ignite the air fuel mixture in the combustion chamber.......what is the OTHER main purpose?" KInd regards. Mike
Number one is incorrect. The spark plug does not remove heat from the combustion chamber. Spark plugs have an optimal operating temperature, too low and they foul with carbon build up and stop producing a spark, too hot and they cause detonation. The heat rating required in an engine can vary over a large span (generally the higher performing an engine is, the more heat the plug has to withstand without becoming a hot spot that cause detonation).
Thank you for your comment. Here is a quote from NGK: "The spark plug is heated during combustion and must dissipate that heat to the cylinder head at a certain rate to avoid overheating the ceramic firing end" Here is a quote from Bosch: "The term heat range refers to the speed with which a plug can transfer heat from the combustion chamber to the engine head." Kind regards, Mike
I'm not sure that your assertion "The spark plug does not remove heat from the combustion chamber" is validated by either of those quotes - I would say they both directly contradict this. The picture at 4.34 in the video clearly shows that the spark plug is dissipating heat from the combustion chamber. Let me know if you think I am misinterpreting this picture. Many subscribers know more than I ever will about these matters and I am always keen to learn, and obviously set the record straight if I have made incorrect statements. I maintain that the combustion chamber would be hotter, were it not for the fact that the spark plugs dissipate some of the heat. Do you disagree with that sentence? Mike
@@MikesMercsandothercars You've misunderstood that diagram. it show's that ~20% of the heat buildup in the spark plug is dissapated by the cold air from the intake, the rest of the heat in the spark plug (not the combustion chamber) is dispersed into the cylinder head, and externals of the plug. Again, the spark plug has no function of cooling the combustion chamber, it's only meant to stay within an optimal heat range in accordance to the engine which it's fitted to as to produce optimal spark. That is all.
Thanks for taking the time to comment I really appreciate your input. I made a mistake at 4.30 in the video inferring that the '100% figure' related to the total heat in the combustion chamber - as you rightly point out, it relates to the heat generated in the electrode of the spark plug as part of the combustion process. I have added a correction in the text under the video. I have also written to the leading spark plug manufacturers to see if they can tell me what percentage of the heat generated in the combustion chamber is actually accounted for by the spark plugs. Whether anybody has ever worked that out is of course another question...Once again thanks for taking the time to correct me. Mike
