Mercedes 2.5-16 Cosworth rolling restoration

[JOEPRO]

Some of you will have seen posts on this car I recently got home. This is starting a proper thread on it. The car will need weld repairs so that will feature in the coming months too.

Ill summarise this as best I can to date. The seller owned the car for 15 years but it was off the road as he was in Australia and left the car in a garage in Ireland. The car was also left outside at times and exposed to weather. He was reffered to me by local MB garages and I went to look at the car. As soon as I seen it was a manual 2.5-16 in 199 pearl black (the most desirable model and colour which matches my 1992 500E) I knew it was my car and it would be coming home with me!

The seller made the sale extremely difficult but I held in there and got the car home in the end.

As it was in his garage:



It has rust in the typical areas for these cars but honestly not too bad. The car is amazingly original and all complete. Very few Cosworths still have all their original parts and wheels etc.

It had 3x major concerns:

No V5 and not sorned for 15 years.

Engine had not ran in 15 years.

Engine had a leaking freeze plug behind rhe exhaust manifold so did not hold any coolant at all.

 

[JOEPRO]

I have since sent off a V62 form and to my pleasant surprise no questions asked, a new V5 arrived in my name and its now correctly sorned. My plan is to carry out a full restoration in long term but for the next few months I want to recommission the car and get it back on the road. A rolling restoration so to speak.

First job, get the engine gently recommissioned. I removed the spark plugs and added ATF / Diesel mixture to the cylinders and let that soak in for several days. Then I changed the engine oil and cranked it with no plugs until it made oil pressure. All good. New plugs fitted and fuel tank drained. (Old petrol stinks bad!) The fuel pumps sounded like they were running and it would fire off but ran poorly and hardly at all at first.

The KE injection rubber boot was torn / rotted. This and most all parts for these cars are NLA (No longer available) now. So I found that a 300E boot fitted just with slight opening up of one port. I also discovered one of the dual fuel pumps was dead so I fitted 2x new fuel pumps and new injectors. The fuel distributor was stiff and some debris visible inside. I ultrasonic cleaned it and that worked really well, freed up. The car now starts up and runs but I cannot run it for long until I sort the coolant issue.

 

[JOEPRO]

I forgot to mention I had also cleaned the fuse box and renewed all fuses with new old stock flosser copper ceramic fuses and cleaned all engine electrical plugs which were green inside.

So thats 2 of the concerns sorted. V5 and the engine starts and runs decent. That leaves the bad freeze plug:

To get at it I had to remove the lovely 4 branch exhaust manifold. But that job took many hours and the whole exhaust had to come off. I then could see the bad freeze plug:







Removed:



Rusty!



As with most parts, MB said the freeze plugs were NLA. 19mm plugs. The first one I tried above was too tight. So I got a set from another supplier and they fitted properly. Light smear of dirko sealant and drive them in with a socket.



Since there are 5x the same size behind this manifold and it was a session to remove as space is so tight I renewed and pressure tested all 5x plugs:




When pressure testing I discovered more leaks. The radiator was toast, leaking in several places. NLA , I found only one manual aftermarket radiator for sale new in Germany - ordered.

The thermostat housing was leaking and a bolt snapped. No stat installed! I had new bolts and stat on the shelf





Then the last leak is from inside the car. Somewhere in the heater matrix. Aparantly another common leak in these cars and could just be an O ring. I have assumed the worst and ordered a new heater core.

I also completely stripped and degreased the alternator and have left it in for a full rebuild. No obvious faults but its a good time to get it reconditioned when off the car.

The exhaust system is rough, walker back and mid boxes have rust. So I have a new stainless system on order and ill weld / repair / VHT repaint the original front exhaust section before refitting.

 

[JOEPRO]

And just this minute the exhaust manifold is bolted back on. I had copper manifold nuts on the shelf but when I checked them the spanner size was in between a 12 and 13mm. The original nuts were a decent 12mm fitment. So I spotted that in time and ordered more nuts this time Febi and they were a tight 12mm spanner fit.



I will start refitting the large heat shield and other parts until the rebuilt alternator, new radiator and other parts turn up.

The rocker cover is in a sorry state and one front stud is broken. Someone had RTVd the nut back in place it was just sitting there

New Elring gasket set coming from Germany in a couple of weeks time. So I will wait a few more days then pull the rocker cover and shot blast the old paint off. I will spray it with gloss black high temperature enamel and paint in the letters like it was originally. I will be using new black stainless nylon dome nuts as that will look alot better than the current setup. I have all the original cover plastics, the plastic screws were stripped out so new trim screws are on their way.

 

[Mark 5]

This is great stuff, photos are great.

Not really a clue on the mechanics but enjoying the progress and the process.

 

[roofman]

I forgot to mention I had also cleaned the fuse box and renewed all fuses with new old stock flosser copper ceramic fuses and cleaned all engine electrical plugs which were green inside.

So thats 2 of the concerns sorted. V5 and the engine starts and runs decent. That leaves the bad freeze plug:

To get at it I had to remove the lovely 4 branch exhaust manifold. But that job took many hours and the whole exhaust had to come off. I then could see the bad freeze plug:

View attachment 514242

View attachment 514243

View attachment 514245

Removed:

View attachment 514251

Rusty!

View attachment 514244

As with most parts, MB said the freeze plugs were NLA. 19mm plugs. The first one I tried above was too tight. So I got a set from another supplier and they fitted properly. Light smear of dirko sealant and drive them in with a socket.

View attachment 514246

Since there are 5x the same size behind this manifold and it was a session to remove as space is so tight I renewed and pressure tested all 5x plugs:

View attachment 514249
View attachment 514250

When pressure testing I discovered more leaks. The radiator was toast, leaking in several places. NLA , I found only one manual aftermarket radiator for sale new in Germany - ordered.

The thermostat housing was leaking and a bolt snapped. No stat installed! I had new bolts and stat on the shelf

View attachment 514247

View attachment 514248

Then the last leak is from inside the car. Somewhere in the heater matrix. Aparantly another common leak in these cars and could just be an O ring. I have assumed the worst and ordered a new heater core.

I also completely stripped and degreased the alternator and have left it in for a full rebuild. No obvious faults but its a good time to get it reconditioned when off the car.

The exhaust system is rough, walker back and mid boxes have rust. So I have a new stainless system on order and ill weld / repair / VHT repaint the original front exhaust section before refitting.

my Vivaro van had a bad alternator and they wanted nearly 200 notes for a new one, new reg/rec unit and new slip rings and brushes come to £50..took me an hour to recon mine and now perfect..something to consider on your Cossie.

 

[JOEPRO]

my Vivaro van had a bad alternator and they wanted nearly 200 notes for a new one, new reg/rec unit and new slip rings and brushes come to £50..took me an hour to recon mine and now perfect..something to consider on your Cossie.

Thanks, yes I have a local alternator / starter rebuilder a 1/2 mile from my house who is one of the best in the business. I get him to proactively rebuild all my starters and alternators. He does them for around £50. New bearings, slip ring and brush / reg set + bench test + warranty. Never had a bad one from him, they always work great. I believe its better to have your original units rebuilt than buy any aftermarket or unknown reman units.

 

[Farside]

Is that a wee bit of piston slap when cold?

 

[JOEPRO]

Is that a wee bit of piston slap when cold?

You have some hearing bud

No piston slap. Its running good. First startup means it has to build oil pressure first few seconds and the valve train makes some noise. Perfectly normal. Video was recorded on my phone in my carport with several rust holes in the exhaust that may be throwing it off audio wise.

 

[roofman]

To be fair the last cossie merc i heard running seemed clackety top end...are they hydro lifters or straight from under the cams

 

[JOEPRO]

To be fair the last cossie merc i heard running seemed clackety top end...are they hydro lifters or straight from under the cams

Yes that's correct. Most MBs of this era had hydraulic lifters. But these 16V "Cossie" engines have buckets and shims so would be noisier than most

 

[JOEPRO]

I got a couple of other small jobs done today. Replaced the dud automatic antenna for a new one along with proper seal. Bedded in black sika and excess wiped off to ensure water can't get in there





Tested and working. Very 80's!

The radio wiring is all a mess so ill basically be rewiring the lot. The Blaupunkt head unit in the car I thought was original but im not so sure anymore. Its very basic and maybe too new.



There are also Blaupunkt speakers and a CD changer in the boot which would have been dealer fitted when the car was new. But since this is not the original dealer fitted radio I may go for a modern unit with Bluetooth etc that still looks period. Like a Continental brand head unit.



Im sure FM broadcast will also be turned off at some point in years to come. So DAB would make sense. I am not sure if a regular power antenna works with DAB though? Or would that require a separate antenna hidden in the car and leave an auto antenna there for aesthetics.

 

[roofman]

Cool build this, and a bit of a rare car thats still servicable..

 

[JOEPRO]

There is a centre console part on the dashboard which is cracked and falling apart. Common to go bad so there are no good used ones available. However there are .stl files for sale so I purchased one tonight. It doesnt fit my printer so ill have to print it in 2 parts



(Ps I wouldn't print it vertical like that I was just testing that the file worked)

I will print it in black PETG, glue together and fill / sand / spray it in the coming weeks ahead of the heater core replacement. I plan to have the whole dashboard and heater box removed in the next week or so. I see it as a great opportunity to sort the mess of radio wiring with full access, clean all the vents thoroughly and fix any niggles In the dashboard.

 

[Farside]

I got a couple of other small jobs done today. Replaced the dud automatic antenna for a new one along with proper seal. Bedded in black sika and excess wiped off to ensure water can't get in there

View attachment 514313

View attachment 514314

Tested and working. Very 80's!

The radio wiring is all a mess so ill basically be rewiring the lot. The Blaupunkt head unit in the car I thought was original but im not so sure anymore. Its very basic and maybe too new.

View attachment 514315

There are also Blaupunkt speakers and a CD changer in the boot which would have been dealer fitted when the car was new. But since this is not the original dealer fitted radio I may go for a modern unit with Bluetooth etc that still looks period. Like a Continental brand head unit.

View attachment 514317

Im sure FM broadcast will also be turned off at some point in years to come. So DAB would make sense. I am not sure if a regular power antenna works with DAB though? Or would that require a separate antenna hidden in the car and leave an auto antenna there for aesthetics.

I'd not be surprised if an ordinary antenna will pick up DAB ok. Radios are much less sensitive in receive to aerial lengths.

 

[Turbo]

That's another car I'll have to see when I'm up your way again!

Regarding the dab, you can get a combined fm/dab roof aerial but I'm not sure about a wing mount.

To be honest I wouldn't bother because DAB reception is rubbish nearly everywhere in NI.
My dads golf has dab and on a trip to Magherafelt I tried using the dab and it was useless. You would get very patchy reception but it kept cutting out.

I use internet radio most of the time. I have the audials app on my phone and I send it via bluetooth to the headunit in the car or van.
It has a buffer on it so if your phone signal drops for a few seconds the radio will keep going.

 

[jo1010]

Great to see that you stayed the course with the 'difficult' seller....he presumably convinced that the car was worth far more in that horrible condition of disuse than it really was?
I must admit I'd have thought twice before buying...chasing down every single o ring and sealing rubber throughout the vehicle is a labour of love for sure....and also moisture getting into ECUs as well wrecking them....all part of the fun ......

 

[AVI_8]

Interesting car, look forward to reading your thread, I’m sure there will be some challenges along the way, definitely an appreciating car these days

 

[JOEPRO]

Great to see that you stayed the course with the 'difficult' seller....he presumably convinced that the car was worth far more in that horrible condition of disuse than it really was?
I must admit I'd have thought twice before buying...chasing down every single o ring and sealing rubber throughout the vehicle is a labour of love for sure....and also moisture getting into ECUs as well wrecking them....all part of the fun ......

The Crazy Cossie story of buying this car is an interesting one for sure - I fully documented it here: Post in thread 'Looking at a 190E Cosworth 2.5 Manual tomorrow' https://www.500eboard.co/forums/thr...osworth-2-5-manual-tomorrow.21576/post-311775

 

[Morris]

Wow! That's quite the story. Well done for sticking with it.