83 300d no power after 80mph and engine temps rise past 100
 

I drive an '83 240d that I swapped a 300d turbo out of an '82. The doner car had lovecraft and he was using veggie. The car at this present time has the ALDA removed, plenty of pep in lower gears(oddly no smoke, which worries me) but will not go above 90mph period. I can get to 90, back off the pedal and the car will maintain the speed (don't do this for too long as I get a shake that I believe is cause by a bad ball joint) but when I floor it, I hear the turbo spooling significantly more but the speed does not change. The 240 was able to reach 80-85mph so I know the tank filter is fine. I removed the lovecraft, changed the fuel filters, the clear one and the cartridge, and I put in some Lucas injector cleaner in one tank of gas, sea foam in another, and now diesel Kleen in my current tank. The car used to only reach 85, now I can hit 90-92. Speedo is calibrated properly (tested with a gps). Also, I work about 25 miles from home mostly highway, if I keep my speed under 75 the car is happy, anything over for more than 5 minutes and the temp goes from 80-85 to 95-100. Once it gets there it stays and doesn't go up but it doesn't seem right. Any ideas?

* Temps cruising between 75-85 can rise as far as 100-105 I do not know of it go higher as the 80 mark is my comfort zone and 100 means something is wrong so I drop back to 70

What are your rpm's at that speed and what is your gear ratio? Are you sure you're not just running flat out at that speed? Is the accelerator linkage opening all the way?

I havent hooked up the tach yet but I know the engine isn't maxed out. The tach is my next project. As far as the linkage, all seems tight, no play when the throttle is down all the way. When I reach 80 and start to ease off of the throttle the peddle is about halfway back when I'm able to maintain that speed. My old 300 felt exactly the same at that speed but I was able to get her up to about 115ish (never tried for too long as the cops are bad down in south fl)

I ment tach not speedo, sorry about that

What''s the gear ratio? 240d's are typically geared much lower than 300d' so it's no surprise there's a difference in top speed. Have you checked the linkage by holding the pedal to the floor and having someone check to make sure the linkage is at the stop on the IP?

Tranny and drive shaft are out of the 82, not sure of the ratio but they were original out of that car, just rechecked the linkage and that is good. The weirdest thing with this car is the lack of black smoke. None on startup, none on heavy acceleration and from what I understand, without the ALDA the main complaint is the heavy smoke. Possibly a bad IP? I can't figure out any other problem that would show these symptoms besides a fuel issue

The thermostat opens at 80 degrees, so if your gauge is registering under 85 at cruise something is wrong. Having an 80 degree thermostat doesn't mean your gauge should be showing 80.

Having the needle at 100 means something isn't optimal but it isn't a reason to be concerned. Anywhere between 90 and 110 is perfectly acceptable and won't cause any problems for the motor.

Play is not the issue.

You need to have someone in the car pushing down on the pedal while you check that the linkage that actuates the pump is at full stop. Try it yourself by hand first to see it at its full travel, then have someone push down on the pedal from the driver's seat.

what exhaust piping did you use? what differential? the GEARING is in the differential, not the transmission... in top gear, both 240 and 300 transmissions are the same 1:1 but the rear on a 240 is 3.69:1, and the rear on a 300 turbo is either 3.07:1 or 2.88:1 depending on year... that's a huge difference.
also, what radiator did you use?

Sorry bout that, still learning but looks like that's the culprit. The differential wasn't changed if I remember correctly. The exhaust is off of the 300 and the radiator also off of the 300 with the external fill tank

http://img.tapatalk.com/42e57410-6f09-3383.jpg
So this bushing is a little worn giving the IP a little play

Gearing
 

Best case (a 300D with a 3.07 diff) is 83% of 300D speed in a 240D with its 3.69 gearing. Worst case (2.88 diff) is 78%. So you're doing good to reach 90 MPH and no wonder the temp is rising, the engine is probably running flat out. You need to find a 300D differential, preferably one from a 1985, which has the higher (2.88) ratio.

Jeremy

Get the instrument cluster from the car you get a better ratio rear end out of. The speedometers are calibrated to the individual ratios of the rear ends.

Just to make sure the ratio is still the 240ds. It is present on the differential flange I think or nearby. You do want another differential to get the revs down. Or the car will be screaming at you forever.

They are not speaking of that.

Way down on the Fuel Injection Pump is the Throttle Arm. When you step on the Accelerator Pedal the Throttle Arm on the Fuel Injection Pump has to go all the way foward to the Stop Screw with no space between the Lever and the Stop Screw.

If the Arm does not reach that stop your Engine will not reach higher rpms.