In a fit of Corona-virus-self-isolation-crawling-up-the-walls-with-boredom I ordered in some bits from a local motor factors the other day, which duly arrived this morning

I R XCITE

An air filter each for both cars, and new spark plugs x8 of two different flavours. Lets move the cars up onto the drive so i can legitimately say I'm on my own property doing this and get stuck in

Not exactly 5-spanner stuff here. 4x 8mm captive screws hold the lid of the air filter housing on, then pull the old filter out. I think this might have been last changed in 2013?

Its not gone far since then, but its still a bit manky. And in with a nice* new one. Hengst wasn't the cheapest one that GSF sold, but it was the second cheapest, cos thats how I roll.

Lid on, bolts done up and TICK. next, the plugs. The engine is covered with a big protector as they all are these days, so that was removed. The front 2 bolts are easy, but the back ones are horrible things and you seem to be unwinding them for eternity before they finally let you extract the cover. Underneath there is no rail, just the push-fit pencil coils. I pulled one out, put the spark plug socket and 3/8 extension down the hole and oh... ummm we'll need another extension then won't we?

I rummaged in the garage for another extension and found a weenie one which gave just enough room to get the ratchet on the end and undo the plug. It came out fairly easily and while old and clearly heat-worn it was the right colour, a sort of rusty brown indicating (I think?) clean combustion

New one in. Bosch R6's which again were the 2nd cheapest ones GSF sold that would fit the Daewoo.

Gapped correctly out of the box as well. I repeated this with the other plugs, 2 and 3 were a bit oily and manky

So I'm not sure whats going on there? Maybe oil slopped down the bore at some stage? or maybe a leaking rocker gasket? I don't know.

I used the genius idea of putting the new plugs on a bit of old hose to lower them in and get them to bite the thread. The advantage of this is that you're not dropping them electrode-first down the hole, and if you start to cross thread the plug, it'll just spin on the hose rather than chewing up a new thread in the cylinder head.

All in all a successful mission. The car started and ran fine afterwards so I'm calling that a success. I kept the two least manky old plugs just in case and they'll go in the boot as emergency spares. After the Saab debacle this seems like a good idea. I reckon this work should give me about another 30bhp - ten for the air filter and 5 each for the plugs? Taking it up to about 35hp TOTAL.

Then onto the Mercedes. For some reason air filters for this thing are weirdly expensive. I finally got round to buying one at GSF the other day and it turned up earlier. I swapped the dusty current one over and then had a serious look at the spark plugs.

Apparently M111 engines are hardy things but like to eat plugs, so I bought some Denso K20TT plugs at GSF at the same time as the air filter.

I took off the plate that sits between the cam bulges in the cylinderhead and was presented with a disappointing sight

Hmmm, male torx? I don't have the right bits for removing those. Lets try with an 8mm hex socket instead shall we? I managed to remove one coil pack without totally b0rking the bolts, then had a go at taking the plug out. This had been previously done up by Thor and was SERIOUSLY tight, so much so I repeatedly checked and double checked I wasn't turning the ratchet the wrong way. Eventually it released its grip on the cylinderhead threads and came out. Looking at it, its in surprisingly good condition, and is also a fancy-pants NKG Iridium jobbie which are like £20 a go, so I chickened out and gently put it back after putting a tiny bit of penetrating oil on the thread and lowering it back in on the end of a bit of syphon hose. Do we think old (20k miles?) iridium plugs are better than brand new Denso non-iridium plugs? The Denso one can go in the glovebox for now

and I'll have a think. The colour is right on the plug tips and they don't seem excessively burnt on the insulation ceramic stuff so probably alright?