1985 Volvo 240 - just bought it - eratic idling - was bone dry
I just bought my friends 1985 DL for super cheap. It revs up and down trying to idle, and eventually will stall out after a minute of that. I can get it up to about 30 mph, but cant rev it without it dying. When i was driving it home I noticed it was overheating because it was dying and wouldnt let me get anywhere, so I pulled over added water to the radiator (it was bone dry) and started up again and it drove home with the erratic reving. Does this sound like a blown or warped head? He simply told me that the thing wouldnt go on the freeway, but didnt say anything about the erratic idling. He isnt big on cars so that doesnt surprise me. It only has 160,000 miles, so it should have lots of life left in it. Thanks so much for your help.
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Re: 1985 Volvo 240 - just bought it - eratic idling - was...
The coolant leak could be a blown head gasket. And the not going over 30 MPH could be from the catalytic converter being clogged. Do a compression test for the head gasket, and remove the O2 sensor from the exhaust and drive with the exhaust leaking out the hole. If the lower back pressure allows the car to go over 30 MPH then you know the cat. is clogged.
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repost with the spec differences beween the two engines Im a bit foggy here..Im thinkin one had or has intake restrictor plates under the intake for not letting hot gasses enter under the carb mount...
Sounds like you have a leaking vacuum line. If it has a hole or is cracked, it will leak or **** air causing the idle to be erratic. The vacuum lines or hoses should be traced down for any cracks or dry rot and replaced. The heat from the engine and the emissions causes the hoses to break down and a lot of people don't realize these should be replaced. The vacuum lines or hoses coming from the intake area is the main area to look at.
Check the wiring from the connector at the center of the firewall to the engine. Many 83/84 240's had problems with the insulation crumbling and the wires shorting out. These problems got worse when this harness was disturbed in any way. Let me know if this helps or if you need further info.
The coolant temp sensor sends signal to the ECU and the ECU adjusts the idle RPM. When the coolant is cold, the engine requires more fuel to sustain idle with thick oil (oil gets thicker & more viscous when cold). This makes the engine to idle at faster RPM but it should settle down to 850 RPM or so after the coolant warms up. The sensor is nothing but a thermistor; a device that changes electrical resistance according to the coolant temperature.
I just had a similar problem with my 1990 240DL and it turned out to be the fuel pressure regulator located on the forward part of the fuel rail in the engine compartment in conjunction with the mas air flow meter. Both were repalced and now the engine idles normally.