sosiko

hello everyone!
this is my firs post on this forum.

I have a issue with slightly reduced power after engine overheat on 97' E420. coolant pipe had bursted while going aggressively on uphill. temp gauge was slightly over 100 and all coolant was lost. after fixing the pipe and refiling with fresh coolant I have noticed that at medium to low throttle engine has little bit less power. this is mostly noticeable below 3000rpm. at higher revs I can feel that power is restoring. engine has not changed sound after overheat and it doesn't consume oil. could you suggest what to check.

thank you

Hirnbeiss

How high did the temp get, or how long was the engine operated with no coolant?

sosiko

hi, thanks for reply
temp could be 100-110c (210-230f). gauge was below red area. it was narrow road and it took me about one minute after low coolant warning to stop and turn of engine.

sosiko

I've have got an idea. can it be (low power at low revs) because of damaged O2 sensor? yes it is designed to resist exhaust heat, but it was heater pipe damaged at the back of the engine and water could have splashed on O2 sensor. this sensor measures oxygen inside and outside.

thank you

ymaghs

Similar things happened to mine. I have a 97 E420 and I had overheat due to blown water pump and once blown radiator after falling into a ditch. I have been getting diagnostic scanner errors like Fuel system 1 and 2 Closed Loop Fault and the P0410 Secondary Air Injection Fault.

It drives nice for a while but after about 20-30 minutes of driving around town the car gets noisy and loses 30-40% power and loses drive smoothness. The same happens immediately after I turn on the AC. If anyone has any ideas or advice it would be appreciated.

Plutoe

Sounds like you damaged your secondary injection pump when your poor driving habits put the car in a ditch-----correct the fault and try to stay out of ditches!!

ymaghs

Thanks for your reply and advice. It wasn’t really falling into a ditch, it was one of those, you know, sudden mini valleys that the LA roads department has put on some roads that if you don’t know they are there in advance, you fly over their top and land into their valley ditch.

In fact this noise problem and loss of power used to happen even before falling into the ditch and blowing the water pump, but not so much. I even thought it might be the fan clutch over spinning because at times it sounds like and overworking SUV or Truck fan¸ and I even suspected the trans might be slipping causing power loss.

If it was the secondary air injection pump then why does it come after 20-30 minutes of driving, whereas the air pump is supposed to kick in right after cold start and then turn off in due course of driving?!

After the water pump started leaking I was driving for a couple days until it was fixed watching the temp and water level carefully. And after the Rad puncture I only drove 3 -4 miles back to the garage while refilling water along the way. I don’t think temp ever went over 95-100.

My worst fear is still that the over-heatings may have affected the topology of the Cylinder and/or Piston/rings and/or head, and the change getting too much after engine warms up. What do you think?

Since this phenomenon get worse when turning the AC on I also strongly suspect that the AC compressor bearing or the pump itself might be gone too? What do you think?

ymaghs

Thanks again for your reply Plutoe. Doesn't the fuel system closed-loop fault mean there is a leakage somewhere? or does it mean incomplete burning somewhere?