603 Turbo operation questions

[locry]

ok, so this is my first turbo 603. I don't have a firm grasp about its operation,

here's what i THINK i know about it, turbo spins from exhaust gasses, turns the intake compressor, pressurizing the intake tract... IP gets a "positive pressure" signal from the intake tract triggering an extra dose of fuel.

Correct?

what's the ALDA? how does it work? I know i still have the TRAP oxidizer, will have to change it out. Where's the EGR? is it the assembly that's hooked up to the trap? there are vacuum lines from the intake going to what seems to be a relay, 2 relays? what are they for? how do they function?

sorry for all the questions... I just want to know how EVERYTHING downstream/upstream the exhaust works. What can be eliminated(EGR), to improve performance... more importantly, having a good understanding of how everything works and how everything is put together makes it easier for me to troubleshoot if anything comes up. Thnaks guys! i know there are a lot of experts here.

[locry]

one other thing... IF ever the turbo fails and is irrepairable, can it be disconnected and bypassed safely? would it work exactly like an NA 603 would? coz my first 300D was non-turbo...

and how does the waste gate work? anything that needs replacing in there?

[riethoven]

Many good fundamental questions. You can use the search function and probably find answers to all your questions. Users GSXR, dieseldiehard, Brian Carlton and sixto have vast real world experience with these engines.

I am in the middle of putting a head on a W124 and their posts have been invaluable. From a practicality standpoint I would think that it would be cheaper to repair a turbo than to convert it to a non turbo.

[TheDon]

Originally Posted by riethoven

I am in the middle of putting a head on a W124 and their posts have been invaluable. From a practicality standpoint I would think that it would be cheaper to repair a turbo than to convert it to a non turbo.

yes, why go back a step

[locry]

i was just wondering what the difference is between a non-turbo 603 and a turbo 603 besides having the turbo. I'm guessing they have the same IP, except that the turbo IP is equipped with an ALDA and calibrated higher.(just read the ALDA thread )

so, IF i HAD to remove the turbo (let's say a replacement is unattainable), theoretically, can i just install an NA exhaust manifold (which is readily available) and go from there?

[TheDon]

a turbo rebuild is fairly straightforward if the compressor/turbines are still in good shape.

about the IP , the 617's have different IP's for the turbo and non turbo models, mainly internal differentiations, it could be the same for the 603 turbo/n/a

[BOMC]

if you have the 124 with the 603 like me, here is a vacuum diagram (1st) that may be useful and two that cover turbo function (2nd) and the turbo set-up (3rd) . you seem to have the basic operation of the tubo correct.

the alda, the way i think of it, is a fuel mixure device, it richens the fuel ratio corresponding to the pressure inside the intake manifold. as pressure builds the mixutre richens. there is a pressurised line going from the intake into a solenoid (in diagram, 'Y30') then into the alda device. if this is the relay you mention, then it serves to cut off boost pressure in the event of an overboost condition by closing and having the alda produce a mixture relative to low or no boost pressure being sensed. BTW this solenoid gets coked with soot and is a common cause for lost boost or poor performance.

as for the EGR, it is commonly held here that it can be removed or its vacuum line plugged with out negative affect. there is hovwever an ARV (air recirculation valve) that is on the turbo, but seeing that you still have the old trap it is probably advisable to keep it hooked up since it is responsible for making the charged air hotter so that the trap can 'regenerate' properly.

there are abundant posts dealing with ARV and EGR "modification", check these out.

[dieseldiehard]

Originally Posted by locry

i was just wondering what the difference is between a non-turbo 603 and a turbo 603 besides having the turbo. I'm guessing they have the same IP, except that the turbo IP is equipped with an ALDA and calibrated higher.(just read the ALDA thread )

so, IF i HAD to remove the turbo (let's say a replacement is unattainable), theoretically, can i just install an NA exhaust manifold (which is readily available) and go from there?

NO, the turbo engine won't run hardly at all without a turbo.
I've tried this, After removing the crossover pipe from a perfectly running 603 turbo the car couldn't even get out of a snails path.
The solution is to fix the turbo or find a NA engine

[Hit Man X]

Exactly, just fix it properly. I drove a 603 with a plugged ALDA (no boost) it was comically slow.

[dieseldiehard]

Your car still has the Nasty Trap Oxidizer on it??
If so make an appointment at the nearest dealer to have the trap removed under MBNA Open Campaign (fancy word for recall). I have the OC# if they play dumb.
If your turbo has been damaged as a result of the TO coming apart and hitting the turbo then they will replace the turbo along with the job, and you should also get a new exhaust line, tip to stern, with a new Cat oxidizer mid chassis.

Originally Posted by locry

ok, so this is my first turbo 603. I don't have a firm grasp about its operation,

here's what i THINK i know about it, turbo spins from exhaust gasses, turns the intake compressor, pressurizing the intake tract... IP gets a "positive pressure" signal from the intake tract triggering an extra dose of fuel.

Correct?

what's the ALDA? how does it work? I know i still have the TRAP oxidizer, will have to change it out. Where's the EGR? is it the assembly that's hooked up to the trap? there are vacuum lines from the intake going to what seems to be a relay, 2 relays? what are they for? how do they function?

sorry for all the questions... I just want to know how EVERYTHING downstream/upstream the exhaust works. What can be eliminated(EGR), to improve performance... more importantly, having a good understanding of how everything works and how everything is put together makes it easier for me to troubleshoot if anything comes up. Thnaks guys! i know there are a lot of experts here.

[locry]

thanks for all the replies guys!!!

so what are the major differences between an NA 603 and a turbo one?
just the IP?

[sixto]

Originally Posted by dieseldiehard

If so make an appointment at the nearest dealer to have the trap removed under MBNA Open Campaign (fancy word for recall).

locry is in Manila, closest MBUSA dealer is in Honolulu... maybe Guam

Sixto
93 300SD

[sixto]

I don't know about impossibly slow. I drove the 93 with no boost and it got to 80 on the freeway with more to give. It accelerates a little better than a semi Could be one of the rare benefits of the 3.5.

If you have to live with a 603 with no boost, route the air cleaner outlet directly to the crossover pipe and tweak the ALDA for a little more go.

A turbo rebuild is cheap enough that there's no point getting the engine to work without a turbo.

locry, look around for a Euro turbo exhaust manifold. Even a 3.5 turbo exhaust manifold should work. That way you won't need to worry about the trap or EGR.

I expect a normally aspirated 603 will have an ALDA for altitude compensation (the original purpose of the ALDA). The ALDA and/or IP might not have the range to compensate for 1 bar of boost.

Sixto
93 300SD

[gsxr]

Originally Posted by locry

So what are the major differences between an NA 603 and a turbo one? just the IP?

NO!!! The turbo motor has totally different pistons, bottom end, etc to handle the extra power & heat. You cannot take a NA motor, slap a turbo on it, and expect it to survive for long. The turbo motors have oil cooled pistons, oil squirters, different exhaust valves (I think), and a bunch of other things besides the IP.

[sixto]

How about the cam? If the NA and turbo cams are the same then I expect a turbo engine with no turbo will run just like an NA engine.

Sixto
93 300SD