Exhaust manifold heat riser shaft bushings

1965 - 1972: 250S, 250SE, 300SEb, 280S, 280SE, 280SEL, 280SE 3.5, 280SEL 3.5, 280SE 4.5, 280SEL 4.5, 300SEL, 300SEL 6.3, 300SEL 3.5, 300SEL 4.5
Post Reply
W108-1967 250S
500 K
Posts: 516
Joined: Mon 11 Oct, 2010 9:28 pm
Model you own: w210
Location: Tamworth NSW

Exhaust manifold heat riser shaft bushings

Post by W108-1967 250S » Tue 07 May, 2013 12:16 pm

Has anyone done the job of pressing in these bushings? I had a trial run and put the bushings in the freezer for a few days, then put a relatively newly painted exhaust manifold in the oven at 180 degrees...luckily the wife did not see the clouds of smoke, on opening the oven! :nono: :error:

They did not quite fit, but I feel a few taps with a copper mallet might have done it? I plan to clean up the holes in the manifolds, with a metal file, before trying again. I suspect I will need dry (nitrogen) ice. Where can you get that in Canberra? I would have thought leaving them outside in Canberra over winter would do it!! :jokercolor:

enginah
C Class
Posts: 35
Joined: Sun 10 Mar, 2013 9:07 pm
Model you own: w108
Location: Auckland, New Zealand

Re: Exhaust manifold heat riser shaft bushings

Post by enginah » Fri 10 May, 2013 9:13 am

The problem is that you dont have enough of a heat differential, i would be dubious about heating it too much and yes having a look at dry ice is the way forward,
unless you have damaged the sleeve, dont file it down, as when everything settles it risks having too much clearance and greatly reducing the running life of the bushing.

the oven should suffice for heating, you just need to have every thing there and ready to go, because as soon as you pull it out of the oven / ice, they will start cooling/ heating rapidly... you usually only have a few seconds and yes a soft mallet would be pretty key... or even a hydraulic press would be the key.

or better yet, take em to the local workshop and get them to press em for you, $20 for peace of mind!

good luck
1972 280 SEL 3.5 - Betty

W108-1967 250S
500 K
Posts: 516
Joined: Mon 11 Oct, 2010 9:28 pm
Model you own: w210
Location: Tamworth NSW

Re: Exhaust manifold heat riser shaft bushings

Post by W108-1967 250S » Fri 10 May, 2013 7:59 pm

Thanks Enginah, good advice. Yes, I'm not filling them as such, just going to use a file to clean out the holes in the manifold as they are a bit rusty/cruddy from the old bushings. Might take them to the MB Spares and see if they will press them in for me. I need to order the carb mounting gaskets and other bits for the heat riser valves, before they get scarce! :happy3:

User avatar
cuisses
300 SLR
Posts: 1825
Joined: Thu 19 Nov, 2009 9:18 pm
Model you own: w108
Location: Canberra

Re: Exhaust manifold heat riser shaft bushings

Post by cuisses » Fri 10 May, 2013 9:18 pm

I suspect I will need dry (nitrogen) ice.
Correction: dry ice = solid carbon dioxide :book:

I can get liquid nitrogen from work, but I can't imagine Mercedes calling for this to assemble an engine part.

Your suggestion of taking it to JG to bash in is very sound.
David Williams

W108 280SE 4.5 (Papyrus White and Palomino)

W108-1967 250S
500 K
Posts: 516
Joined: Mon 11 Oct, 2010 9:28 pm
Model you own: w210
Location: Tamworth NSW

Re: Exhaust manifold heat riser shaft bushings

Post by W108-1967 250S » Sat 11 May, 2013 4:24 pm

Well I spent a pleasant Saturday afternoon cleraning out a bit of rust and muck in the exhaust manifold holes for the bushes. I cleaned it gently with a rat tail file, till all signs of rust was gone, without eating into the casting itself. Decided to have another look at the bushes now the holes were cleaned up. Got the bushed out the deep freeze. The bushes do have outside bevelled edges, so sort of self guide the very innitial bit. So I thought "Give it a go!" So good news! :king: After a few firm but gentle taps with my trusty copper mallet, the bushes went in, nice and firm! :love10: Who says never trust a mechanic with a hammer!

So, now need to order those springs and the valve plates, to get it all together. I have the rods or shafts, by far the most expensive part. The butterfly valve plates need to be welded to the shaft, so a visit to MB is now a must! Then it will be getting the new exhaust/intake manifold gaskets which are part of the carb's mounting, and I can put the whole carb/inlet/exhaust assembly back on the engine. That will be good! :rr: Yet another job on my Benz which has left me smiling.

User avatar
Bartman4800
300 SLR
Posts: 2116
Joined: Fri 10 Oct, 2008 12:10 am
Model you own: w111
Location: Perth WA

Re: Exhaust manifold heat riser shaft bushings

Post by Bartman4800 » Wed 15 May, 2013 8:19 pm

Can you post some pictures?
1963 220 Sb Sedan "Kermit" (Australian Assembly)
1960 220 Sb Sedan "Zum Schlachten" (Early German Assembly, with a torsion bar spring for the bonnet) - Stored in Country WA
1981 Subaru Brumby 1.8 with Weber and 5-speed box "little utie" - Sold to another enthusiast!
2006 Ford Focus "daily driver"
2002 VW Passat V6 30V Station Wagon (SOLD - This car into a money pit)
2011 Kia Sportage "Missus commuter Bus"
2002 Mitsubishi Rosa Bus (converting it to a motor home)

W108-1967 250S
500 K
Posts: 516
Joined: Mon 11 Oct, 2010 9:28 pm
Model you own: w210
Location: Tamworth NSW

Re: Exhaust manifold heat riser shaft bushings

Post by W108-1967 250S » Fri 17 May, 2013 10:42 pm

Yes, as soon as I can get some new "flatteries" for the camera! :Doh: I plan to picture the rebuild of the shafts once I get all the parts I need from MB Spares, but will post pics of what I have so far.

W108-1967 250S
500 K
Posts: 516
Joined: Mon 11 Oct, 2010 9:28 pm
Model you own: w210
Location: Tamworth NSW

Re: Exhaust manifold heat riser shaft bushings

Post by W108-1967 250S » Sat 18 May, 2013 5:11 pm

As promised some pics of the new shafts, the re conditioned counter weights and the newly installed shaft bushes.
You do not have the required permissions to view the files attached to this post.

Coralpolyp
B Class
Posts: 17
Joined: Tue 01 Oct, 2013 8:35 pm
Model you own: w108
Location: Collinsvale, Tasmania

Re: Exhaust manifold heat riser shaft bushings

Post by Coralpolyp » Sun 11 May, 2014 9:04 pm

Hi
I've just dismantled my manifold setup, sandblasted the exhausts today and decided to research the heat risers. My car has nothing visible externally, but I discovered inside that shafts are there and the butterflies are set/seized in the 'warm' position, but the shafts are completely ground off outside, and no pins, weights or springs exist.
I suppose I could just carry on with this setup effectively made redundant, but if viable I may try to restore the manifolds and make the valves operational. I only have a thousand more jobs to do on my car so what the Hell.
Can you give me an idea of the cost of the parts you needed for this job? Is it just a bimetallic spring coil working on the pin and shaft? What are the black parts in the photos - steel cases for the mechanisms? Did you order the stuff ok through your Mercedes dealer?
Thanks
Matt

User avatar
Mercmad
Mercedes Demigod
Posts: 8103
Joined: Sun 11 Sep, 2005 8:01 pm
Model you own: w109
Location: Brissy
Contact:

Re: Exhaust manifold heat riser shaft bushings

Post by Mercmad » Mon 12 May, 2014 7:55 am

The black parts are counter weights .It is most important that these things are fitted and working because 1/ it warms the intake to get the intake air up into the temperature range where the engine is running at 80C and combustion works properly 2/ once warm,these close the flow of hot exhaust gas away from the base of the intake preventing vapour lock . These do not block the exhaust flow as a lot of folks think. Also,the carbs are damaged if the baffles are stuck or have been removed becuase of the heat radiating up through the bottom.
note: on older USA engines the baffles on the V8 engines do block the flow slightly on one bank to force the exhaust up through the intake manifold to warm it up and these did get stuck resulting in power loss. This doesn't happen with the Mercedes design.

User avatar
Stuart
C Class
Posts: 31
Joined: Fri 24 Jun, 2005 8:43 pm
Model you own: w108
Location: Strathalbyn, South Australia

Re: Exhaust manifold heat riser shaft bushings

Post by Stuart » Wed 22 Oct, 2014 9:14 pm

I realise this is an older post, but... I have just separated my manifolds after realising that they were out of alignment. I also had wondered what the two 'black things' which appear in parts/workshop manuals were, because my 250S doesn't have any. Now I know why, the heat riser flaps have been replaced by some PO with bolts :angryfire:

Because my car is only used on "Nice days" (i.e. not too cold), I am seriously considering making up a couple of blanking plates to protect the carbs (especially as they are new Webers!!).

Before I go ahead, any words of wisdom, please? :dontknow:

User avatar
ansteadeh
C 111
Posts: 835
Joined: Thu 11 Aug, 2005 3:55 pm
Model you own: w114
Region: Queensland
Location: Brisbane

Re: Exhaust manifold heat riser shaft bushings

Post by ansteadeh » Thu 23 Oct, 2014 2:22 pm

Mine are set permanently in the closed position. In QLD the weather never gets cold enough that they need to open and warm the carbies up. Anyway, I only run my car when the weather is mild/warm. It doesn't take long before the engine gets to operating temp and I'd rather they were closed anyway to protect the carbies from over heating leading to warpage

Post Reply

Return to “W108/109”