1998 Mercedes C230 Kompressor Sport Manual.

Just about completed the list of bits & pieces to have the car ready for the road on 1st May.

I got the second pair of new rear tyres fitted, when back to Yokohama Advan Sport 105's. I'll advertise the new Kumho's as their no good to me, even if I get a few bucks back it will be better than a kick in the ass.


I also finished cleaning up the rear suspension on both sides and subframe. Yeah, it's an old Merc and worth darn all but it's just nicer having everything clean and fresh.


The last item to do is fit a self sealing hose adapter to the inlet hose for the I.A.T gauge. The adapter is due to be delivered tomorrow.

I got tried of the noise from the ported & overdriven S/C even with the sealed air box & ITG cone filter. I had lined the box with insulation foam sheets, all sides including the lid but it was still too loud.

Here on the left.


What to do? The stock air filter housing is well designed and keeps the stock S/C noise levels very well suppressed, but it becomes a restriction and flow is maxed out when hitting above 250 bhp. In actual fact if the engine is tuned for 270 bhp or more the filter housing will cost 15-18 bhp at max rev's. Now, I'm at approx 250 bhp refitting the stock housing shouldn't cause a lost in max power but may not give the best throttle response, but I'm unsure about that.
Since I was using 75mm diameter hoses for the inlet & outlet of the homebrew sealed air box I decided to use the same on the stock air filter housing rather than stick with the original 63mm.
A few mod's later to the filter housing including removing the interior baffling at the inlet and outlets  and job done. What a different from a noise perspective, along with no noticeable lost in throttle response or outright power and LTFT's and AFR's haven't changed.

Inlet, basically the same as I used with the sealed air box but larger that the original stock inlet.




Outlet, removed the 63mm built in flange and fitted a 75mm aftermarket flange, sealed with epoxy glue - messy but great stuff.


Inlet connected into air filter housing. Nice and smooth alloy pipe right into the housing.

So, what's happened in the last three weeks? A few things...

As I mentioned I had a three month old Bosch MAF fail, ordered another and fitted it. That lasted all of c.10 miles after I when wide open throttle! Almost all engine power lost, the usual fault codes and misfires on several cylinders.
Refitted an old Bosch MAF I had, it worked but there was engine flat spots @ 3 & 5000 rpm. Fitted my spare Pierburg MAF but disconnected the MAF voltage clamp and left the IAT resistor in place. All good, the car pulled like a champ. I've since covered 250 miles and still good. Doing a 340 mile round trip next week, the car will get a proper workout then.

My main concern was why two new genuine Bosch MAF's failed, both failed after I fitted the third version of a S/C but this could be coincidence. There's five possibilities I can think of:

1. Some engine coolant/debris found it's way into the inlet hose of I.C when changing over the S/C's, possible but doubtful.
2. Some left over alloy flakes were still lodged in the S.C intake pipe after I ported it, again possible but doubtful, I really did make sure I had cleaned out the pipe after grinding and polishing it.
3. Some excess grease from the S/C rear bearings got to the MAF's. I did make sure there was enough grease but nothing excessive.
4. The Bosch MAF's didn't like the voltage clamp, thus they failed rather quickly. Again, doubtful as nobody has reported MAF clamps causing MAF failure. Now, Bosch has redesigned their MAF's and just maybe this has something to do with it. Photo below.
5. I use oiled air filters, had a cone fitted and then changed over to a modified stock air filter box with an oiled panel filter, excess oil could damage the MAF but I've never had an issue on that front, ran the oiled cone for 8,000 miles+ and have used them previously in other cars without any problems. Now, people have had issues but every time it was caused by over oiling the filter.

Best course of action was to remove the I.C., boost hoses & pipes and remove the outlet cover from the S/C and inspect. Everything was as clean as whistle, including the S/C rotors. I found no debris, alloy flakes/dust or dirt etc. Cleaned everything anyway, washed out the I.C twice and both the water and brake cleaner came out clean.
Having said that, debris could have been there and by the time I checked everything it had been digested by the engine and there was no evidence left? I wish there was, at least then I know I screwed up and what caused two MAF's to fail.
On a positive note, I made a warranty claim against one of the MAF's which was accepted and I received a full refund.

New Bosch design MAF in the foreground.




Checked the spark plugs, nice color on all but managed to crack the insulator on one because while taking it out I was not paying attention. They'd covered 10,000 miles so fitted a new set.

The engine idle was rough on cold start up and was progressively getting worse. The usual suspects are a vacuum leak, MAF, engine temp switch etc. I had, as good preventive maintenance replaced the temp switch about 40,000 miles ago with a Beru switch. Reckoned, it was no harm to refit the original switch and bingo cold start idle back to normal. I'll order a new switch soon.

I ordered a new Pierburg MAF to replace the old one I have currently fitted and I bought a Pipercross oiled panel air filter to replace the old stock paper filter. The Pipercross may not flow a whole lot better but I reckoned it better to have than not. It has defiantly changed the induction sound but not made the sound more intrusive.




I removed the standalone IAT gauge, it worked but didn't react quick enough to my liking. I may refit at some stage. And last but not least I've had a slight vibration in the steering wheel, suspecting front wheels need balancing I decided to just check and adjust the wheel bearings and then had the wheels balanced, that sorted the issue.

So, there you have it, a busy three weeks and annoying at the same time too.

Oh, I rarely post photos of the old machine, don't look too close. Still it would look o.k. to a blind man on a galloping horse!

A small update.

New Pierburg MAF fitted, fuel trims and timing look spot on and the car is pulling like train. It's definitely got the 200bhp @ wheels that I always wanted, possibly more according to people that know about these engines. Being candid, I don't really care as it's driving great and feels like it's producing c.250BHP, not that I'll ever be happy with max power, could always do with a bit more! 

Fitted a spare used engine temp switch, cold start idle is now back to normal  and carried out an engine oil and filter change, usually done between 4-5000 miles. Also replaced a h/lamp bulb and dash illumination bulb.  

Booked an N.C.T. (MOT) and it passed with no advisories.

I've ordered a new engine temp switch, a Bosch MAF it's scaled differently to the new Pierburg currently fitted, it will be interesting to see if there's much between them. Also coming is a spare Bosch crank position sensor, rear brake pads and a spare oil filter.

So, in a nutshell not much to report, thankfully. 




   

A few photos. Not bad for 157k running double stock boost.

The inlet valves and seats looking not too bad, the exhaust is a different matter but I suppose to be expected at the mileage. Plenty of valve lapping required which is something I haven't done it in twenty years and still hate it.

Demag, appricate the info but I'm just not a fan of drill method even if I've use it in the past. Also, I've the luxury of not being under pressure time wise. I'll stick with the stick!🙂

I started doing it by hand, it's the proper way, the way everyone who knows what they're doing does it. After 5 minutes, sod this, I'm using the drill.

Good to see you're still at this yoke. A bit of a sleeper, especially with the MO plate