turbo charger question for 300sd
 

Hello,

Whats the test prodcedure for checking the operation of the Turbo.

I have now power on a hills?

Please help

Brian

Could you rephrase that? :confused:

Well, no power on hills could be number of things, but the first thing I would do is replace the fuel filters.

300sd turbo diagnotics
 

Hello,

I need to know what test on my Turbo for correct operation.

e.g.: when I test my waste gate valve with my minivac I get zero vacuum. Is it leaking?

i have a 300 sd
 

i have a 300 sd turbo but I have not touched the turbo... I have
just finished replacing a turbo on a saab. I have done 3 turbos so i
have limited experience. You waist gate is designed to open and let
the exhaust bypass the turbo to keep it from producing to much boost.
So on a saab the computer opens an electronic valve on top of the radiator and it allows vac to flow to the diaphram that pulls the waist gate open.
The benz would have a simular set up. If your waiste gate were stuck open then you would not have any boost and you would have decreased performance. Most turbo inspections occur by disconnecting the exhaust. You can visually check the waist gate then (see if it is stuck open or closed) and you can stick your finger in and wiggle the turbo fan shaft. (you are looking for excessive play) which indicates the bearings are going bad. You can also check the exhaust area for oil which indicates a bad seal.

But First,
Change both fuel filters,
clean the banjo bolt on the back of the engine.
clean the strainer in the fuel tank.
adjust the valves,
Do a diesel purge,

save the turbo for last....:D

There is no vacuum in the wastegate, it's works with pressure.

....and check the throttle linkage to make sure it is opening fully. On my 300D the nylon bushing in the firewall was wasted and even with my foot on the floor I was only getting about 1/2 throttle opening. Just a thought.

Though I would change the fuel filters as a general precaution. As a aside, has anyone noticed how fuel filters tend to get plugged up sooner these days? I remember going 30k between fuel filter changes twenty years ago. Today it seems that I have to change them once a year.

ok
 

ok, i have never replaced a turbo on a mercedes... so that
I feel these benz turbos are pretty solid compared to other turbos.
In fact I have owned 3 benz's and I have never had the need to touch
one of the turbos...I have had to replace head gaskets, rebuild engines and
now I am rebuilding a transmission but never had a turbo problem.

So do all the other stuff first. Clean the banjo bolt, fuel filters, etc

Then after all that if your still concerned about your turbo, remove the
boost side plumbing and wiggle the impeller looking for shaft play, remove the exhaust side plumbing and check the waist gate see if its locked open or shut, then look for oil sepage. Leave the manifold to turbo connection alone, and leave the oil intake and outlet alone.... (check the oil return lines where it fits into the oil pan for leaks... and check the O ring on the breather where it sits) Above all this there is actual boost preasure test but I would leave that to a pro...

On turbos, the metal around the waist gate will some times crack or split.
These splits are considered normal if the waist gate still works and the crack is not to long...

The test procedure for the turbo requires a boost gauge. You can either get one that mounts in the car or you can get one like a mechanic would use. If you have the type thats mounts in the car you can do the test all by yourself. Its also interesting to look at while your driving.

http://mb.braingears.com/126_DISC1/program/Engine/617/09-425.pdf

Adjusting your waste gate is a pain if you have a Garrett. Do a search for that here. I also think Diesel Giant has a good DIY page on it.

As others here have said, check your banjo bolts, change your fuel and air filters, etc... as well

300sd turbo diagnostics
 

Hello again,

Thanks for all the input.

I have since checked the Alda lines which are OK. Including the Alda.

I have checked the waste gate valve for operation, I applied an air hose to the input, you can here it clunk in and out with the pressure from the hose.

However, how do check for the waste gate valve itself for leaks?

Do I need to remove and physically check for this?

This car takes off nice in 1st gear, but when you get to the 2nd gear
[ probrably around 2000rpm ] it will not accelerate . You have to let off the peddle a bit, then it changes up.

It has trouble accelerating up those long uphill runs.

Please advise

Brian

I had the a same problem with my 81 300SD. Its your boost protection valve.
It is the little unit on the the firewall with vac lines going to the alda and the
intake manifold. My SD would not go up hills for @#$& !!! I took the BP valve
from my friends 300 CD and bang.... It was a whole different car. If you know
someone with the same turbo diesel engine, just switch it with yours. You
will tell right away if that is your problem. Also the BP valve on a 300 D or CD
looks a little different then the SD's, but it will work the same. Jay

81 300SD Black 132M "Sold":greedy:
81 300SD Blue 139M "Sold":greedy:
81 300SD Blue 246M
82 300SD White 202M
84 300SD Burgundy 168M "New":)
85 300SD Gray 267M "New" "Has damage to the rear":(
84 190D Red 111M "New":)

vac
 

so the waiste gate is vac controled... is that correct...

it normally is on a garrett....

300sd turbo diagnostics
 

Hello again,

I have now tried bypassing the protection device on the firewall, and blocking off the WasteGate valve pressure line.

Didn't make any difference to the performance.

I also stuck my PSI gauge on the output from the manifold, in the pressure line to the ALDA. I measured a constant 8 psi. I believe Mercedes gives 0.7 bars ~ 0.8 bars [10 psi ~12 psi].

Does anybody think this is enough difference to effect my performance.

I also tried tightening the inlet manifold bolts.

The Turbo itself appears sound no cracks, oil leaks, or end play in the bearings.

Does this point to a leaking Waste Gate Valve and or a Inlet Manifold gasket. e.g carbon buildup on the valve seat etc

Any and all comments please.

Thanks

Brian

PS: Thanks for your input so far.

No.