Interesting running hot question - PeachParts Mercedes-Benz Forum

rg2098 · #1 04-22-2006, 02:05 PM

It seems almost immediately after swapping my injector nozzles out my 300 is running very hot. It has always run at 83 C and never higher then 90 C in stop and go with the A/C. Ever since swapping those nozzles its running at 95 and now 105 C. No overheating, it stays rock steady at 105 now but I am still very concerned. I don't think its a cooling system issue as it was so immediate and jumping the aux. fan does nothing to bring the temps down. Could the new injector nozzles cause this dramatic of a temp change?

pawoSD · #2 04-22-2006, 03:35 PM

Are you sure you didn't damage/disturb the wire running across there for the temp sensor for the gauge? Maybe its just not reading the right temp.

rg2098 · #3 04-22-2006, 05:12 PM

Quote:

Originally Posted by pawoSD

Are you sure you didn't damage/disturb the wire running across there for the temp sensor for the gauge? Maybe its just not reading the right temp.

Its possible the temp sensor went bad, the wire is brand new along with the GP harness. I could be wrong but the engine feels like it is indeed throwing off more heat. I need to borrow one of those IR temp gauges from someone to check for sure.

tram · #4 04-22-2006, 05:15 PM

Your injectors also need a couple hundred miles to "seat".
Actually, disturbing the connection for the gauge sounds like a good theory to me. You may not have been getting an accurate reading before.
To me, WHERE it runs- as long as it is in normal range and holds steady- isn't a huge concern. But, I want that gauge there to tell me if I suddenly have a problem or not- IE, suddenly pegging at hot.

rg2098 · #5 04-22-2006, 09:34 PM

Quote:

Originally Posted by tram

Your injectors also need a couple hundred miles to "seat".
Actually, disturbing the connection for the gauge sounds like a good theory to me. You may not have been getting an accurate reading before.
To me, WHERE it runs- as long as it is in normal range and holds steady- isn't a huge concern. But, I want that gauge there to tell me if I suddenly have a problem or not- IE, suddenly pegging at hot.

I'm pretty convinced that the gauge is accurate. The wire is brand new as of 3 or 4 months ago and it is possible the sensor is going bad but I doubt it. I've spent enough time in the hot engine compartment adjusting the trans bleed valve to get a feeling for operating temp and it feels significantly hotter. It's been driven a couple hundred miles since the injectors were done and it got worse. It started running at 95-100C immediately following the injectors and now its running at 100-105C as of yesterday. I have a back up vehicle for the next week and a half (grandmothers Buick Roadmaster was running hot until I just replaced one of the cooling fans) so I would like to get this under control.

pawoSD · #6 04-22-2006, 09:51 PM

How old is your radiator?

Brian Carlton · #7 04-22-2006, 09:57 PM

Do you notice any difference in driveability?

Meaning, is it more "sluggish". Does it require more fuel to achieve the same acceleration as before the nozzle change?

It's quite the conundrum.........I'll tell you that. There would be no way that I could fathom a nozzle change raising the engine temperature so dramatically, but, if the spray pattern of the new nozzles is off badly.......for some reason........the engine won't make power and will develop significantly higher wasted heat.

Another possibility..........the new nozzles pop at a different point than specified and the timing is retarded beause of this fact.........the driveability should noticeably suffer.