'87 W124 300TD performance?? - PeachParts Mercedes-Benz Forum

lewisnolt · #1 03-30-2011, 08:18 PM

Hello, I just bought an '87 300TD wagon; I want to open up the intake and exhaust. If I get rid of the stock air intake and the sensor/flap thing under the air box and put on a cold air intake, will I get any check engine lights or problems of any sort? Also, does anyone make a bolt-on cold air system for this car or do I just fab something? I just adjusted the ALDA, and was pleased with the bottom-end results. I'd also like to remove the EGR and put on a 3" exhaust with like a Magnaflow muffler or something, and eventually turn up the IP. How much can I do before I'm gonna puke the trans? Any input on all this would be helpful. Thanks!

aaa · #2 03-30-2011, 08:36 PM

Quote:

Originally Posted by lewisnolt

check engine lights

No.

You can't turn the IP up enough for the trans to be a worry.

dieseldiehard · #3 03-30-2011, 09:06 PM

Quote:

Originally Posted by lewisnolt

Hello, I just bought an '87 300TD wagon; I want to open up the intake and exhaust. If I get rid of the stock air intake and the sensor/flap thing under the air box and put on a cold air intake, will I get any check engine lights or problems of any sort? Also, does anyone make a bolt-on cold air system for this car or do I just fab something? I just adjusted the ALDA, and was pleased with the bottom-end results. I'd also like to remove the EGR and put on a 3" exhaust with like a Magnaflow muffler or something, and eventually turn up the IP. How much can I do before I'm gonna puke the trans? Any input on all this would be helpful. Thanks!

Well, removing the air intake won't buy you any additional power, the first thing you have to worry about is the Trap Oxidizer, if it has one. Search for Nasty Trap Oxidizer. If the factory recall was done to bypass the NTO with a straight pipe it will have a diesel cat under the car and that little item represents a power loss of a few percent, to which I can attest

Otherwise you are now going to have to spend big money with a modified IP and injectors along with a bigger turbo (55 trim to start or a HOLSET if you can find one) but if you do go that route, please be sure to install a Exhaust Gas Temp gauge (EGT)

Don't bother messing with a larger exhaust or any odd mufflers, it won't buy you anything (yet).
Look at what the guys in Finland have done with this engine (say the words diesel HOT ROD!) and you will find lots of ideas:
W124 300DT - 11.92 1/4 mile
and
The Baddest Mb Diesel I've Ever Seen!!!!
DDH

vstech · #4 03-30-2011, 10:36 PM

welcome to the forum! we're a helpful bunch, but we also don't mince words.

a cold air intake will not help you in any way.
actually, the current stock intake IS cold air. and well designed. that flap can fail closed, but it's not likely.
nothing wrong with 3" pipes, but it won't help much with power aside from the lack of a cat! and putting in a bypass of the cat with stock pipes will be equal improvement.
HOWEVER, if you are planning to massive boost the motor, 3" will be more able to handle bigger boost/fuel.

also... keep in mind that the stock head is a weak point. cooling system is primary to keeping it from blowing itself up.

WELCOME TO THE FORUM!

1stbenznc · #5 03-31-2011, 12:54 AM

Good to see you with us!! Welcome! The previous posts are spot on. These cars cannot be easily modified like a gasser with intake and exhaust. Nor can you throw in a 100hp tune like my diesel Excursion to modify the fuel delivery, timing etc.

You are basically held hostage by how much your mechanical Injection pump can deliver and injectors squirt. It starts adding up fast to modify the IP. You may be able to get one from a later model 350 which I believe has a bit more flow. You would then need to get a bigger turbo to keep up with the extra fuel delivery.

The stock air filters are huge and breath pretty well. Save your money there. You can get rid of the flapper and put a straight pipe there.

I would first get it running to its optimal performace and fix and safety items (sloppy suspension, brakes, SLS, etc beore making it go too fast.

Get a boost gauge. You should have about 11-13 psi and run 0-60 in about 12-13 sec for the wagon.

Good luck!

babymog · #6 03-31-2011, 04:12 PM

All above correct in my experience.

The exhaust will be fine until you have put larger elements in your IP and a significantly larger turbo on. Deep-six the cat for a little improvement. Ditto with the intake, you can eliminate the airflow meter box and replace it with a pipe for negligible improvement in flow, but the current filter system and its cold-air feed from the fender is better than a crappy cone-filter sucking hot air and dust from under the hood.

On this forum a photo with a cone filter in it is an instant don't buy the car signal.

jonbobshinigin · #7 04-01-2011, 02:32 AM

The pump from a 3.0 and 3.5 are the same, they adjustments simply different. If one is to do a full load adjustment/turn the pump up, it would not matter which pump you had. As someone else said...first step should be make sure the whole car is mechanically 100%. Especially the cooling system!

babymog · #8 04-01-2011, 06:13 PM

The 3.5L pump has a different torque capsule, makes for a stronger launch.

johnscars · #9 04-03-2011, 03:47 PM

Hey Guys, not trying to hijack this thread, it's a related question. Yesterday I was investigating a new and big oil leak (think BP) from the turbo's oil return tube - it is leaking where it bolts into the engine block. To make it easy to get at the top of the turbo oil return tube, I removed the manifold crossover and the wastegate - and was surprised to find a lot of carbon build-up between the two. (Approximately 1" hole diameter blocked 10+%). Does that build-up hurt performance? I'd cleaned it thoroughly about 15,000 miles ago (287k, now 304k) when I rebuilt the turbo and head.

Also, any source(s) used or new, on that turbo-oil return tube? After removal, cleaning, inspecting, re-installing - it is still leaking a lot of oil. Anyone see this problem before?

I'm surprised at the amount of oil that is dripping - there must be a lot of pressure on that line. The 17mm bolt threads into the block with almost 1" of thread, and feels like it presses the flange tight, but it's still spewing more than 15 drops per minute. ...thanks -John

babymog · #10 04-03-2011, 04:58 PM

John:

You didn't mention a car, I'm going to assume you still have your '87 300TD?

The oil return tube, the one from the bottom of the turbo, has an O-ring seal at the joint of the two tubes. Is this where it's leaking or is it at the end? I believe that I have all of these parts (used) around here.

The gasket is another issue, at the turbo and at the block. Did you replace the gaskets?

You state that you removed the crossover tube and the wastegate. Do you mean the exhaust tube from the exhaust manifold to the turbo? Shouldn't be carboned inside other than a thin soot coating. The wastegate isn't removable from your original (KKK?) turbo, so I'm a little confused (again) with what you're referencing there.

johnscars · #11 04-03-2011, 05:43 PM

Yeah Jeff, same 87 300TD. Sorry for the confusion. The easiest way to describe the oil tube's location is hood-up to look down on the turbo between the 2 brass colored compression fittings. About 6" down You can see the top of the odd shaped flat plate with two 6mm allens 30mm apart. One of the allens is right between the brass colored connector joining the 2 exhaust manifolds. That odd shaped flat plate is the end of the oil tube. The tube is routed under the exhaust and into the engine block mid-engine with a 17mm bolt that presses the tube's flange into the block - like a gas compression fitting.

The gasket on the flat end was ripped, but not leaking. I removed it and applied some black RTV. I can also probably cut one to replace it. But it is the other end that is leaking.

The carbon build up was after the crossover tube joins the bracket - the unit to the front of the bracket - also held on with two 6mm allens - and it has a vacuum line running out forward. I found the carbon-build-up when I removed those two allens.

babymog · #12 04-03-2011, 08:34 PM

Be especially careful with RTV or any gasket maker there, if it makes it into the turbo oil supply it could cause damage, if it squeezes into the oil flow and blocks it, also potential damage.

This is the oil supply line to the turbo, not the return. More pressure. I don't know how to prevent a leak at the block end, perhaps a look at the EPC will show whether there is a seal there?

The crossover tube from the turbo to the intake plenum is often fouled with carbon, from the EGR just above the turbo. Most of us either block the vacuum-line to the EGR valve with a BB, or just put a blank gasket on before mouting the valve so that it can't foul the intake air. Nasty mess mixing sooty exhaust with oil vapors, a good way to create tar. You will probably find that the rest of the intake tract is equally caked with crud.

johnscars · #13 04-03-2011, 09:37 PM

Thanks for clarifying it's an oil supply-side problem, the oil leak is at the engine-block side of the turbo supply tube. RTV contamination is probably not a concern since I carefully applied a so-so thin skim that shouldn't create a problem.

Does anybody have a spare supply-side oil tube? I probably bent mine during the rebuild process when I FAILED to disconnect it from the block before trying to remove the turbo (yank it out). There, I've said it. I yanked it! (Digging a deeper hole - but hey, those Yankees got us all through 9/11 in a really big way!) I worry/suspect that mine developed a stress crack when I bent it back to fit into the block.

edited next day:
I found a used tube locally, ordered gasket from the dealer. Asked at dealership how a tube could go bad. Mechanic said look for wear at the flange - and sure enough on close inspection there is a hairline crack at the edge of the flared rim where it seals to the block (it could probably be expertly welded and refinished). New one works great. Taking it on a 500 mile ride to the SF Bay Area today.

Thanks -John

Hit Man X · #14 04-04-2011, 10:15 PM

I do not post in this section much, but I tweaked my 603 a while back and has been running quite nice.

First, make sure the car is running 100%. Flush/service all the fluids/filters for your baseline... this includes no fluid leaks and a solid suspension + brakes.

This is big... gut the cat under the car. Most people who drove these cars when new never ran them out to redline shift points to blow the cat out and/or did lots of city driving so the cat never really heated up enough to stay clean. I have fixed piles of 603s that could barely get out of their way with just gutting the cat (INCLUDING MINE).

I drove my car a few times with an open downpipe and the boost came on a hair faster but the sound was irritating as could be (as it should with no sound control). So unless you are going to upgrade the IP then the turbocharger, I would not waste my money on a new exhaust. Apparently the stock IP is good to about 165-175hp?

After that... have new nozzles installed in your injectors then balanced. The difference is amazing in how much more linear the power is delivered.

Max out the ALDA to your preference for throttle response. I will not debate removing it or not, I did but that is your choice. Once the top cap is removed you can simply loosen that lock nut (10mm?) and adjust the length of the screw with a 1-2" piece of hacksaw blade. Works great.

My boost is about 11-12psi from memory. I did not turn it up even after tweaking the IP a hair. That little KKK (K24 I believe) is probably more efficient at 11-12 than at higher levels. I never tested so just a guess.

I removed that AFM under the air filter long ago, actually used a 617 air intake tube and used sealant on both ends (W126, not sure if same for your W124). Just allows you to hear the turbocharger a bit more. Same goofy barn door deal on most BMW and Porsche of the '80s. The AFM is not really restrictive at full throttle on 200hp I6s that run to 6000rpm...

Just remember, these are economy cars. Therefore it costs more to make them 'zoom-zoom' than a performance car already setup to run well. A few minor tweaks will make them run better than most and still be enjoyable to drive. My SDL only needs a 2.47:1 diff now as it has enough power for my driving and my area, the 2.88:1 just really is not needed for me... now my 617, for how I drive the 2.88:1 is just about ideal.