300D W124 loosing power when engine hot - PeachParts Mercedes-Benz Forum

hummer253 · #1 08-14-2003, 04:07 AM

After about 2 horus of driving I loose power. I have to floor the accelerator for it to downshift so I can get power to run smoothly again. But from the start to about 80% near flooring the accelerator I get nothing at all.

I also tried this on PARK and NEUTRAL = same thing. One more thing I noticed is that when I turn off the engine and STRAT It again the engine just turns and turns. I will start again aafter about 3 tries.

I suspect it's something related to the INJECTION pump not giving enough fuel when it's running hot.

I rest the car with HOOD open for 5-10 minutes and everything back to normal again.

Checked all the linkages to Inj. pump, transmission, accelerator cable and they were all OK.

I will have the tank drained and replace PRE and MAIN FUEL FILTER just to be sure - BUT IF my filters are dirty is it possible that they de-clog when engine is not that HOT?

Will appreciate feedbacks and tips!

Thanks!

1985 300D W124
Philippines

Rick Miley · #2 08-14-2003, 09:49 AM

This could be a clogged fuel tank vent. When it happens, open the fuel filler cap and listen for air rushing in.

lrg · #3 08-14-2003, 07:48 PM

The 603 engine has a fuel preheater that routes the fuel through metal tubes that run into a water jacket in the left (driver's side) rear of the engine. There is a small (about 1" diameter and 2-3" length) cylinder located on the lower middle of the block on the left side which contains a thermostat that routes the fuel past the preheater when the engine warms up fully. Look for the four fuel hoses connected to it. They're pretty simple but you may have an obstruction in the thermostat or fuel lines around it. The thermostat housing can be removed with a couple of screws and easily taken apart to check for obstructions. While you're at it make sure all the fuel lines are clear too. It's probably a good idea to replace the O rings that seal the thermostat housing so it won't leak. (Mine did which is why I know how to remove it.)