I have a 1991 300E that will run fine for about 20 minutes then die and not re-start until waiting for the engine to cool off, then it is the same thing again. The engine temp and oil pressure seem to be fine when it dies. Does anyone have an idea what might be wrong.

I would start to by checking why the car dies. 3 things make an engine run. Compression, spark at the right time and fuel air mixture. We can rule out the compression because the car restarts. Do you loose the spark or fuel? If you loose the spark you most likely have a heat soak problem. When one of the spark producing componets gets hot it fails. I once fixed a 89 300se with a similar hot engine failure that was the crank angle sensor. This car would only die on hot days with the A/C running. Good luck. John

I have had a very similar problem with my older model 300. I found that I had to replace my fuel lines as I was getting air into the system while operating at normal ranges. If idling it would last for hours with driving perhaps 20 minutes.

do a search on crank shaft position sensor.

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Whether you think you can or cannot, Either way you're right!. by Henry Ford.

Its a common problem on the 300Es. The circuit board in the fuel relay probably has a crack around one of the pins soldered to the board. You can fix it yourself with a dab of fresh solder or you can purchase a new relay here from Phil. The relay is about the size of a pack of cigarettes and is located behind the battery in the little partitioned firewall compartment.

You will need a magnifying glass to see the fine circular crack in the solder. The crack will encircle a pin that protrudes through to the back of the circuit board. ( you need to take the cover housing off the circuit board) The crack occurs around a pin of one of the heavier sets of relay points soldered to the board.

The problem occurs when riding and engine vibration cause the heavier components of the circuit board to stress the solder holding them to the board. Fatigue cracks develop and after the engine gets hot, heat from the engine causes the metal of the circuit board to expand. The expansion opens the crack and electricity is cut off from the effected relay. Consequently the engine no longer gets fuel and stops running.

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Earl



1993 190E 2.3
2000 Toyota 4x4 Tundra