1985 300D-T (CA) Trap Cat removal DIY - PeachParts Mercedes-Benz Forum

Jeremy5848 · #1 05-06-2008, 07:26 PM

I finally got around to removing the trap catalyst from my '85 300D-T (California version) W123 car. The next step is to visit my welder and have a test pipe made up so I can perform some experiments to measure the before and after effects of the procedure.

I didn't have to remove the intake and exhaust manifolds although I was prepared to do so and have the gaskets necessary to do so. Are there any reasons why I should R&R the manifolds just because I'm already in there?

By removing the components -- turbo, trap cat, manifolds -- one at a time, there is less weight to lift out of the engine bay.

The following procedure does not necessarily apply to the '85 Federal version since there are some differences. I didn't get any photos as my wife had the camera away from home. I used PB-Blaster penetrating oil to loosen the threaded connections.

1. Remove breather hose from valve cover to air intake.
2. Remove the air cleaner assembly with flex hose to turbocharger; plug or cover the turbo inlet to keep dirt out.
3. Chock rear wheels, jack up front of car, place on jack stands. Disconnect battery.
4. Remove heat shield next to battery ( 2-8mm bolts below, 1-8mm and 1-11mm bolt, at monovalve, above).
5. Remove 2-13mm bolts holding turbo oil drain tube to turbo.
6. Remove 2-13mm bolts holding turbo oil feed tube to turbo. Remove 1-10mm bolt holding a support clamp for the oil line. Note that the feed pipe bolts are longer than the drain tube bolts.
7. Remove 4-17mm nuts and washers that attach the trap cat to the turbo. A crowfoot wrench helps with the rear two bolts.
8. Remove the two clamps on the short flex pipe between the turbo and the exhaust pipe (13mm bolts).
9. Remove the 4-13mm bolts holding the brackets from the exhaust (at either end of the short flex pipe) to the intake manifold. I found that the bolts that are threaded into the intake manifold were far easier to get to and remove than the ones that attach to the exhaust flanges.
10. The turbo will now come off. The aluminum neck with two o-rings will come loose -- the small end goes into the turbo, the large end into the intake manifold. The short flex exhaust pipe will also come loose.

The trap cat is now exposed so you can get it off. It is held in three places: the single stud and nut on the front (4-bolt) flange that attaches to a support bracket, two 13mm bolts and nuts on a support bracket under the trap cat, and three 13mm bolts on the flange connecting the exhaust manifold to the trap cat.

11. Pull the upper turbo oil drain pipe out of the lower pipe. Cover or plug the lower pipe so dirt won't get into the oil pan.
12. Loosen the nut on the stud at the front of the trap cat but don't take it off just yet.
13. Remove the two 13mm bolts and nuts that attach the bracket on the underside of the trap cat to the block. It helps to have two people (or skinny arms) for this one -- one under the car and one above.
14. Remove the three 13mm bolts attaching the exhaust manifold to the trap cat. Two of the bolts can be accessed from above, one must be accessed from below. Note that there is a support bracket on the "below" bolt that is attached to one of the starter motor bolts. This can be left in place once the bolt is removed from the exhaust manifold.

Once all of that is done, you can remove the nut on the front stud, pull the support bracket off of the stud, and lift the trap cat out of the engine bay.

If you are replacing the entire assembly with Federal plumbing, you will also need to remove the exhaust downpipe, replacing it with the Federal version. You will also need to remove the manifolds and replace them with the federal versions.

If you are installing a test pipe in place of the trap cat, there should be more room to work without the bulk of the trap cat to get in the way.

Remember to replace all of the gaskets, seals, o-rings, etc., including the rubber seal where the lower turbo oil drain pipe goes into the oil pan.

Jeremy

jt20 · #2 05-06-2008, 07:30 PM

eagerly anticipating..
thank you

bgkast · #3 05-06-2008, 07:56 PM

Now is the time to swap in a different turbo, you can just have a different turbo flange welded onto the test pipe.

Jeremy5848 · #4 05-08-2008, 08:59 PM

When putting the lower turbo oil drain pipe back, do you put the rubber grommet in the oil pan and then stick the pipe into the grommet, or do you put the grommet on the pipe and then stick both into the oil pan?

I was lucky and had no problems removing the lower drain pipe. The old grommet was hardened with age but not yet solid plastic. I was worried about getting pieces in the oil pan but it came out clean. I put a rubber stopper in the oil pan hole while I finished cleaning up. Everything is now ready to go back together and I pick up the last grommet tomorrow.

I asked my mechanic about removing the manifolds and he said not to bother if there was nothing wrong with them. He did suggest checking the torque of the manifold nuts as they tend to loosen over time. This turned out to be good advice as I found them at only 10-20 ft-lbs. I couldn't find a torque spec in either the FSM or Haynes so I tightened them to 40-50 ft-lbs which felt right to me.

The welder is working on my test pipe and should have it ready next week. I'll update this thread at that time.

Jeremy

bgkast · #5 05-09-2008, 11:07 AM

Slip the grommet on the tube, put the O-ring on the bottom of the tube, insert it and push down on the grommet to seat it. It helps to lube everything with motor-oil. You got lucky with the old one. I had a heck of a time getting my less than 1-year old one out when I installed my VGT last weekend.

dirtcurt · #6 05-18-2008, 02:06 PM

Will the dealer still do the Trap Oxidizer removal for recall? Anybody try lately? I've got one and need to find out which way to go. Can you just knock the guts out of the oxidizer and re-install?

#7 05-18-2008, 02:54 PM

Quote:

Originally Posted by dirtcurt

Will the dealer still do the Trap Oxidizer removal for recall? Anybody try lately?

Yes, it is an open recall.

rickhou · #8 05-18-2008, 05:14 PM

Yes it is a open recall. But they will only do it two times. That's what I was told when I took my 85 Cali to the Dealer.

#9 05-18-2008, 05:17 PM

Quote:

Originally Posted by rickhou

But they will only do it two times.

That is because the replacement OxCat is designed to last much longer than the old TrapOx.

Jeremy5848 · #10 05-18-2008, 06:08 PM

The replacement trap catalyst is supposed to be good "forever" (like "lifetime lubricated" transmission fluid?).

Some folks have simply drilled a path through the guts of the trap and put it back on. However I would be concerned about getting all of the bits and pieces cleaned out so that they don't get blown into the turbo.

Jeremy

vwbuge · #11 05-18-2008, 07:57 PM

http://www.peachparts.com/Wikka/OM617CalToFed

Jeremy5848 · #12 05-31-2008, 11:07 PM

If I ignore losing the turbo oil feed gasket

then the car is back together. It was a windy day and I guess it blew somewhere while I was putting the drain back on. If I were desperate I could cobble something together but the car has been apart for over three weeks now so another couple of days won't hurt me while I wait for the dealer to get one.

Having a test pipe instead of a trap cat makes the reassembly so much easier. You can actually bolt the test pipe to the exhaust manifold from above instead of having to crawl under the car and fight the bolts into place.

If I didn't already have one of DieselGiant's radiator hose heaters, I could now do a factory block heater, assuming the plug would come loose. With the trap cat in place you can't even see the plug.

The pictures show the test pipe before and after it was installed. The machine shop did a super job; it fits perfectly.

Jeremy

jt20 · #13 06-01-2008, 01:55 PM

What was the cost for the test pipe?
Did you have to bring the plates to him, or did he have matching stock?
Can you post pics of your cat removed (esp. the exh.mani to cat gasket area)?

You were able to get ALL of your bolts off without heat? I am having a very difficult time.

Looks great, congrats!

Jeremy5848 · #14 06-01-2008, 06:13 PM

This morning I couldn't stand it any longer and made a gasket from a business card for the turbo oil feed line where it attaches to the turbo so I could get the car finished and drive it. I'll get the proper gasket from the dealer this week. I squirted some oil into the feed hole before installing the line (as someone advised on another thread here) so that the turbo wouldn't start dry.

So the car runs great and, since you really can't see the test pipe under the turbo, still looks original. I would say that there's not a whole lot more power but we weren't expecting that, right? Mercedes federial is rated at 123 HP while Mercedes californicatus is rated at 118. The engine does seem to be more responsive -- the turbo spools up quicker and the car is more responsive at engine speeds of 2000-3000 RPM. This is especially noticeable on the freeway. When one presses on the loud pedal in 4th gear at 50-60 MPH, the car actually responds rather than "we'll get back to you." My real hope is for improved fuel economy. Current around-town mileage on B100 biodiesel is only 20-21 and about 24 on the road. I hope to gain at least 3 MPG. We shall see.

I supplied the flanges (cut off of a matching trap cat at Pick and Pull -- they wouldn't sell the entire trap cat) and two right-angle bends made from 2 inch exhaust pipe. The machinist went to the auto parts place (conveniently next door) and got a 2 to 2-1/2 inch adapter to use for the square flange (it's slightly too large for 2 inch pipe). He also got a splice for the middle (between the two right-angle bends) at the same place. Using a splice was stronger than butt-welding the two pieces of pipe, he felt.

So it took 2 flanges, 2 pieces of pipe, and 2 adapters to make the thing. He charged me for four hours of shop time at $100 per hour (one of the disadvantages of Northern California -- labor is expensive) plus $5 for the parts and I paid $10 for the exhaust pipe. Total $415 plus fuel for 6 trips to ask "is it done yet?" spread over three weeks. He did an excellent job, with no error that I could see or measure. I suppose the tolerance is no more than +/- 1/16 inch or 1 millimeter.

I did not have to use heat to get any of the bolts out. The engine was stone cold. I used PB Blaster and let it soak in for awhile. The trap-to-turbo bolts were tight and the left rear hard to get at. I used a crowfoot wrench on that one and it was just barely strong enough. At least one of the manifold-to-trap bolts had to come off from below, maybe two, I don't remember. They were a real b*tch. I experimented with various combinations of sockets and extensions before I finally got one that fit and gave me decent leverage.

I hope the attached pictures will help you. If you want hi-res versions, shoot me a PM with your email address and I will send them to you.

Note that the manifold-to-trap junction does not use a gasket. This has been verified by others on this forum. I put anti-seize on all of the bolts when I reassembled. The stuff I used is heat-resistant and silver-colored. It was made by Loc-Tite and sold into the motorcycle market for use on BMW air-cooled twin headers. My can is over 30 years old and I still haven't used it up. I replaced all of the gaskets and o-rings and hope that I have stopped a couple of minor oil leaks.

Jeremy