Turbo working or not?
 

I am wondering if my turbo is working on my 300td. I never hear any noise coming from the engine that sounds like a whining like I have heard on trucks.
How does one know if the turbo is working? The car is running well and has lots of power. My mechanic once told me that you will never hear the turbo because it is so well engineered. Can any one hear the turbo on their 300td?

It is normal to not be able to hear the turbos on these cars. If you want to check the turbo remove the U tube between the air filter and the turbo compressor inlet (engine off). The turbo wheel should spin freely and have barely any play side to side or in and out. If you really want to make sure the turbo is working there is a line running from the back of the intake manifold to a switch on the firewall, then to the ALDA on the injection pump. Disconnect this line (and clean all the black goo from it while you are at it, search for "cleaning banjo bolt"). Test drive the car with the line disconnected. Low on power? The turbo is working fine.

On these cars, if you can hear the turbo there is a problem.

If your 0-60mph time is 14-16 seconds your turbo is working normally. If its 18-20 seconds its either not working or something else is causing it not to perform.

Yeah if the car takes 20+ seconds to 60 and feels like it has no power or pickup....then its not working.

Very very rarely do the turbo's fail.

I can hear the whine of the turbo on my wagon. It's not loud, but I can hear that it's working. Before I put my new hood pad in, I could really hear it. I like the sound of it.

I can hear my turbo whistle at about 2800 rpm and up. It has been like that since I bought it in 2006 w/216,000 miles. Same turbo noise at 258,000. Ther is no end to end play that I can feel, and very little side to side play on a cold engine. Shaft spins easily.

I was able to hear the turbo on the 300SD.
I could not hear the turbo on the SDL until I changed the breather tube and the foam surrounding it disintegrated. Now I can hear it when going up a hill.

I will try the speed tests today. My 300TD is the famous 1985 model with the crap oxidizer that was a recall because it would trap too much crap and clog. I had the exhaust manifold replaced and the turbo to and earlier pre-trap oxidizer version. That made a world of difference in the acceleration and power. Also I was worried the trap oxidizer could have damaged the turbo because I have heard stories about the ceramic element sand blasting the turbo as it breaks down with age.
Thanks for the replies

Well now I am wondering if it is working properly because getting on the freeway from a dead stop today took more like 20 sec. not 14. I may have to take off the U-tube and see what is going on. It could also be that the engine is not tuned to optimally. Maybe I should change the air filter which I haven't looked at in 6 months. It can get gunked up with oil. I haven't changed the fuel filters for a couple of years either. Weakest link theory.

Turbo boost gauge
 

The 617 turbo diesels have a port at the rear of the intake to check boost pressure. I think the thread is M10x1.0 or M10x1.25. Someone please correct me if I'm wrong on the size. The wastegate is factory set to open around .7 bar give or take

Here is an edited listing of materials to make a test gauge for turboboost.

I made a test gauge out of the following materials:

8 feet of 3/16" air brake tubing
one 90 degree quick connect for air brake tubing
one compression fitting for 3/16 brake line
one gauge that reads bar and psi
short length of 3/16 brake line with metric fittings (8" piece)
one coupling to connect quick connect to gauge
smigen of JB Weld
tubing cutter

1: Attach the quick connect to the coupling

2: Attach the coupling to the gauge

3: Attach the tubing to the quick connect

4: Using the tubing cutter, cut one of the ends off the brake line. Use a smigen of JB weld to seal the fitting to the brake line. This prevents any air leaks. DO NOT seal the flared end. Insert the cut end into the compression fitting and tighten.

5: Insert the other end of the tubing into the remaining compression fitting and tighten.

6: Let the JB Weld dry for several hours.


There you have it, a gauge to check boost pressure. See the attached photographs

Alan

Thanks for the plans. I'll give it a try.
If you want it done right you have to do it yourself.
Randy

There is absolutely no reason to make such an elaborate setup.

Find the ALDA on the top of the injection pump. Get a vacuum T and install it in the line to the ALDA. Connect the gauge to the T and route the tubing for the gauge into the cabin so that you can read the gauge while driving.

I occassionally hear a high-pitched chirpy bird-like noise, which I think might be the turbo, at the top of the gears range (just before the transmission shifts to the next gear). Turbo? Problem? The car performs fine...lots of power, 0-60 is 14-16 seconds...never really timed it but it seems powerful. Fast enough to pass Prius' on the hwy, etc.

I stand corrected. As stated by His Majesty, Sir Brian Carlton points out there is no need to make a tool that will last a lifetime of use.

Most of these fellows need to make one test to confirm or deny the presence of boost. They are not going to use the setup in the future. So, what's the fastest way to get a result..........your approach...........or a simplifed approach that doesn't require any fabrication?

i recently had my alternator replaced. since then, i can hear my turbo. sounds wheezy everytime i accelerate. the car gets going, but not with as much power as it used to. not sure if there could be any connection between having new alternator put it (i tried to do it myself, but couldn't get the nuts to budge. after hours under the car, i took it to mechanic.) and the turbo suddenly making noise. my mechanic says sometimes it's not wheezing, it's just spinning, that they do that sometimes, should still work fine. but why suddenly? and i really have noticed lack of power. thanks for any thoughts.

All turbo cars i've ever owned u can hear especially from a stop u should be able to feel the lag in the turbo too.

hmm. ok, well this is a new sound. I've had this car fro 3 years and am sensitive to every new sound. so, i'm wondering why after years of a quiet turbo, i suddenly here it "spinning" (sounds like wheezing/air leak to me). this combined with noticeably less power makes me think something is actually wrong.

Boost leak from the u-tube ends?

A leak on the inlet tube would not reduce power. It sounds more like an exhaust leak between the manifold and turbo.

You CAN hear the turbo in the '87 300D if, ...

I was looking for a "buzz" in my '87 and in the garage, held the brake down and ran the engine speed up a little, a little more, ... the rear tires lit up (??!!) and it surprised me so I let off quickly. As the engine RPMs dropped immediately, I noticed in the quiet garage the sound of the turbo spooling down.

It is usually drowned out by outside noises, engine mechanical noises, and road noise. Never heard it before or since then (and never tried that again).

yes, forced induction, that's what i am thinking too. the tube that connects the two has been taped in a few places. i will replace it this week and see. is there another place between the two that i can check? thanks
(again, the sounds, like a wheezy whirring, increasing in pitch in exact relation to acceleration, decreases when coasting or slowing down. seems directly related to accelerator).