M110 thermal reactor- still available? - PeachParts Mercedes-Benz Forum

Nate Stanley · #1 08-13-2002, 12:23 AM

Over a year ago, I inquired on this forum about what to do about my Mother-in-Law's '74 280 with the M110 six and the Solex 4bbl.

Specail thanks to all who responded, but I need to revisit that issue again, and maybe get some more information, which hopefully may have become more plentiful with the passing of another year.

Bottom line is that the thermal reactors are leaking and need replacement. Does any have a proven source for them, and if they are now no longer available, is there a smog-legal way to repair this car?

After struggling with this machine for the past 3 years, it's been a shame to see an otherwise fine engine spoiled with the '74 Calif emission controls. Specs are 6 degrees ATDC, and this poor car is choking on its own spent exhaust gases--

and when you advance it to 16 BTDC, it goes like it should, only it's not smog legal. Not living down there, I can't stay on top of this situation-- but the thermal reactors need to go and I'm wondering what to do next.

Has anyone gone thru this issue with this particular car, and how was the problem solved to the satisfaction of the Smog Police?

TIA,

ctaylor738 · #2 08-13-2002, 10:21 AM

Nate -

I read the original posts. When you say that you "heard" that the TR's are no longer available, does that mean that you checked with a dealer who actually did the MB-wide search? There is a big difference in how thoroughly the parts guys at different dealerships look for obscure parts.

I also believe that these things were used on '70's BMW's so you might see if any of the BMW sites have any information.

There is also a site www.suncityrecycling.com or something like it in southern California that might have some used ones that would work.

All I can think of ... good luck

Nate Stanley · #3 08-13-2002, 03:51 PM

Ok,
Here's the latest on the Thermal Reactor. I called Claridge's in Fremont this sfternoon. Their parts guy said they are not available in the United States. When they were, they retailed at $3200 per set--

Another source recommended to me a place called Miller's in Hayward as a source to rebuild them, but the guy I spoke to there didn't have a clue about the last time they did such a rebuild on this car.

It's against state law to put a used Cat on a car, so I may be up against the state referees form year year until 2004 or so-

Any other suggestions are welcome.

Mark DiSilvestro · #4 08-13-2002, 08:51 PM

A thermal reactor is not the same as a catalytic converter (although they both perform a similar function). Perhaps the prohibition against used converters would not apply unless the law specificly prohibits used thermal reactors.

Happy Motoring, Mark

cth350 · #5 08-13-2002, 11:17 PM

Here's a New Yorker question.... What's a thermal reactor ?

Catalytic converters I know about, but, a TR ?

Also, if you remove them, how does somebody (namely the inspector) know ? Like wise, if you put one in, how does somebody know ?

-CTH

Mark DiSilvestro · #6 08-14-2002, 01:27 AM

As best as I understand it, thermal reactors use air injected into a chamber, which is installed in place of the exhaust manifold, to oxidise the CO and HC in the exhaust stream. They can work with leaded gas, Disadvantages are - they rely on a rich fuel mixture to function properly causing lousy gas mileage. They generate a lot of heat next to the cylinder head eventually causing damage, warping, cracking etc (So I've been told)

Catalyctic converters can be mounted down the exhaust pipe, away from the engine. They use a platinum core (or other elements in the case of the more modern '3 way' converters) which react with the exhaust stream. They work better with lean fuel mixtures. Lead in fuel will coat/contaminate the platinum so unleaded fuel is required. This is why there are prohibitions on used catalyctic converters as the platinum can be contaminated or, after high mileage, lose its effectiveness.

For about the last 30 years, cars sold in the US have had an underhood emissions decal, stating what emmissions equipment it had. Here in Virginia, if the decals are missing, emissions inspectors are also issued a manual, listing what equipment the various cars are supposed to have. They are supposed to check for missing or damaged smog pump systems, converters, pcv components, vapor recovery components and fuel filler caps/ restrictors. Missing catalyctic converters are usually easy to spot. I think by now in Virginia (and maybe elsewhere), they are also checking for aftermarket air cleaners, so all those K&N air filters and chrome Hollywood air cleaners might become history!

Happy Motoring, Mark

cth350 · #7 08-14-2002, 07:40 AM

Ah, so the correct repair here is to get the federalized emission sticker and use it in place of the California one. Then get a pair of normal exhaust manifolds. Or are the other problems bringing a car "from NY" to California ?

-CTH

Mark DiSilvestro · #8 08-14-2002, 09:06 AM

Starting in 1974, Mercedes used the thermal reactors on M110 engines sold in all 50 states. As far as I know, cars sold in California, 1974 and newer, must be California emmissions legal. Re-decalling won't help.

Happy Motoring, Mark

ctaylor738 · #9 08-14-2002, 09:10 AM

Is the requirement to get to a specific level of tailpipe emissions, plus reduce evaporative leakage? Or is it a requirement to have the original smog stuff in place and working?

If the former is acceptable, I would think that a non-California carburetor, standard exhaust, and a catalytic converter would do the job. There is a lot of room under the car, and I would bet that Timevalve or somebody would build a standard 280 exhaust with a converter added. In fact, Timevalve might be a good place to call for advice on this.

cth350 · #10 08-14-2002, 09:57 AM

but with the right set of decals, it becomes a NY car that was driven to California and then registered.

So my 1974 280C has the same reactors ? And we're not talking about the little silver pipes that deliver air from the air pump, right ?

-CTH

Mark DiSilvestro · #11 08-14-2002, 10:02 AM

I worked in a Virginia auto repair shop for many years, that also did state safety and emmissions inspections. I used to do most of the emmissions repairs for vehicles that had failed inspection. I can only state what the procedure was in Virginia and assume that California would be similar.

Here in Virginia, emmissions testing is not state-wide yet, but is only done in certain 'poor air quality' regions such as the Washinton DC area. They do however check for catalyctic converters as part of the Va state safety inspection
The requirement in Virginia was that the Vehicles had to pass CO and HC standards on a graduated scale, depending on the age of the vehicle. At one time the requirement was to test all vehicles 1968 and newer but that was relaxed to vehicles newer that 25 years old, recently. The older vehicles were permitted pretty high levels so they had to be in pretty bad shape to fail. The other requirement was that they had to have all of the correct emissions equipment and that it be connected. They didn't test to see if it was all functioning, just that it was hooked up and not tampered with. With the introduction of the 'treadmill' test, 1981 and newer vehicles are also being checked for NOX readings. There can be no 'visible smoke' during the test.

3 years ago, I had to make a 1980 Triumph TR8 emmisions legal for a friend. It had been converted to a Holley 4V carb in Georgia by the previous owner who had disconnected most of the emmissions hardware. I had to install a new smog pump and belt, then adapt / fabricate new plumbing to connect the vapor recovery, PCV and EGR systems to the aftermarket carb and manifold.
It passed the emmissions test easily but it was noted that it had a 'Hollywood Accessories' chrome air cleaner and would fail on future inspections, as this was being phased in to the Va emmissions program.
I was able to find a legal air cleaner with the fresh air snorkel, and hot air flap/tube in a salvage yard from a 1984 3.8 TBI V6 Cougar/T-Bird that fit almost perfectly.

Happy Motoring, Mark

Nate Stanley · #12 08-14-2002, 10:11 AM

CTH 350,
The thermal reactors are grapefruit-sized bulbous objects that are bolted right to the exhaust side of the cylinder head. They are made of thin stainless steel and there is a front and rear unit, each covering the exhaust ports of three cylinders.

What complicates this is:
1) Ca emission laws require all equipment to be in place.

2) This car has a conventional smog pump that puts air into these reactors, one pipe per cylinder port. It also has all the other usual gulp valves and plumbing that goes with this setup.

3) As I understand it, any replacement of this obsolete reactor would require that the smog pump output be replumbed into a conventional exhaust manifold that has been drilled and tapped for these smog pump pipes, then a downstream cat be added.

What this does is open my mother-in-law up to any number of possibilities to dump big bucks into a solution that may exceed the value of the car, and not pass the smog referee's inspection anyway.

Is there anyone out there who has done this in California and gotten it past the referees?

Mark DiSilvestro · #13 08-14-2002, 10:20 AM

CTH,
Your 280C should still have a thermal reactor if it wasn't modified previously. On 280 M110 engines, it looks like a 5 inch diameter cylinder that runs the length of the cylinder head and is bolted to where an exhaust manifold would be. If you don't have the reactor, you're better off without it as long as you don't require emmisions testing where you are. California requires 1974 and newer vehicles to be tested. If the vehicle wasn't California certified, California might not allow it to be registered.

Happy Motoring, Mark

cth350 · #14 08-14-2002, 10:30 AM

Well, I don't have such a gizmo on either of my M110s, so I guess I'm safe.

Thanks all for the early AM education.

-CTH

Mark DiSilvestro · #15 08-14-2002, 10:50 AM

Nate,
The manager where I used to work had a 1976 280 (114 body) and it had the reactor.
We also had a customer with a 1975 280S.
I don't remember if there were 2 mounted end to end, just that they looked like one long cylinder. Is it possible to take your reactors off and have them welded?

CTH,
It's possible that your 280C was built before Jan 1974 and no reactor was installed or I could be mistaken and reactors were on 1974 California cars but weren't required on 49 state 280/280S until 1975.
I know that BMW didn't install reactors on some of its cars until 1975.

Happy Motoring, Mark