Hi all,

I've recently gotten my (new to me) 1981 242 DL back from my mechanic, where I had quite a lot of work done:

New steering rack
Total belt job
Tons of new oil seals

The engine runs like a top now and doesn't leak a drop, but there is a scary behavior that I noticed even before I had work done:

Occasionally, when I go over bumps or round a sharp corner, the engine will hesitate, like totally lose power, then violently kick back in. Any ideas on what could be causing that?

I will note that the engine wiring harness has not been replaced.

Thanks for any ideas you can offer.

I remember other people mentioning the exact same thing - additionally that it would die on the highway - and the cause was that the charging cable from the alternator to the battery wore through its insulation where it runs under the engine.
I would check that first, it's an identified system weakness.

I would also make sure all your spark wires and ignition items are tight.

Do you notice if all your electrical systems die, or if it's just the ignition? Does your tach drop like a rock, or slowly with the engine rpm? Does the volt-meter (if you have one) drop too?

Good Luck and Post Back
William
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1990 740 Turbo, on its way to stock specs, maybe beyond

Great advice! Thank you. I will check that cable.

All ignition parts were replaced during this recent work I had done. I will go make sure everything is secure, but since the behavior was happening before and after the work, it's probably not that (unless I'm missing something, which is entirely possible).

My car has no instrument upgrades. Only a clock and speedo on the dash. Since I have owned it, the dash light have rhythmically pulsated as I drive down the road. I thought it might just be old car behavior, but maybe that's a sign of other electrical issues.

You wrote, "...the dash light have rhythmically pulsated as I drive down the road...."

That's a sure sign of voltage regulator problems -- lights are brighter when the alternator is putting out full charge, and are dimmer when the regulator cuts in to limit the charging.
Problem is, it's supposed to be subtle -- unnoticeable -- so when you can see it happening by the brightness of lights changing, that's a sign it's not working right.

I don't know whether you have a separate, external voltage regulator (mounted on the side of the engine compartment) or yours is built into the brush assembly inside your alternator -- spanning your model year, I've owned a 1980 (which I think was external, but honestly can't remember whether it really was, or I'm thinking of a still earlier car), and a 1984 (which is internal), but not a 1981.

Regards,

re "the dash light have rhythmically pulsated as I drive down the road." No, they're not supposed to do this. Usually an alternator issue - sometimes failing brushes. There are threads on it in the archives.
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240s: 2 drivers and some parts cars

I once had my ground on the alternator break on me. It was just touching enough to keep the car running but my headlights where dim and some of my other lights came on too I believe. The speedometer was slow too. I had some friends behind me on a 60 mph road and I couldn't figure out why they where going so slow.

I would look for a loose wire as others have posted. I had an 88 240 that was dying on turns and it turned out to be the connection (that I failed to tighten after reinstalling the battery) for the wire that supplied the 12v to the fuel injection relay via the red wire and 25 amp fuse.

Does the car continue to do this when the tank if full? If it stops doing it with a full tank I would suspect the rubber connection between the prepump and pickup tube (in the tank) has perforated.

Randy

Seems like the behavior happens no matter what the tank level is at. Right now it is within a couple of gallons of full and the hesitations have been happening since I refilled.

Did your mechanic test drive the car after all that work? Had you metioned the "mometary dying" symptoms?
Ask if he checked the motor mounts. Or you can, esp rt side under the oil filter. That one gets mushy and lets the engine drop low. How are your front shocks/struts? Do you hear any scraping or thumping noise in the engine compartment or front suspension, or transmision/driveshaft tunnel when you hit bumps or corner hard?
Your 242 could be scraping (shorting out) or pulling a wire or an elec connector, or maybe bouncing enogh to jiggle something that's already loose.

If you want to work on it yourself get the Bentley 240 Manual, 10 times as good as Haynes or Chilton and only twice the cost.

Steve

I didn't mention it to him, unfortunately. It had only happened a couple of times before I took the car to him (because the drive home to my house was on a very straight, flat section of Interstate). At the time I thought it might have been my imagination, but in town driving has increased the frequency of the behavior. The behavior will sometimes cease for long enough to be missed in a test drive. It's not totally consistent. One severe bump will result in nothing, while the next (even smaller) one can cause the hesitation.

I will go and check the motor mounts today. I'm not sure whether he examined them, but I would imagine he did. On a previous 240 I owned, he did replace a bad mount at the first post-purchase visit.

The front shocks were newly replaced before I bought the car. The ride is actually very solid (even sporty) compared to my former wagon. The suspension feels great.

I will order the Bentley manual immediately. I'm certainly willing to work on my car to the limit of my ability. Is motor mount replacement within the reach of an enterprising beginner?

I had a loose wire from the distributer that used to 'disconnect' when ever I turned right.

Sounds like you also need new motor mounts...

Klaus
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Why are Volvos so endearing? Its just a car.

I had a 7 series years ago that did that. it turned out to be an old alarm connection at the battery that was loose/bad. cleaned and tightened and all was good. whats connected to the side of the pos. batt. terminal? do you have to reset the radio security code?

I'm not sure about the radio reset. The previous owner installed an aftermarket CD player. I need to identify what's attached there. To my ignorant eyes, I'd say a wire leading to a really disorganized looking bird's nest of wires under a plastic box. Not sure if this was the original Swedish design of the result of poorly executed repairs over the years.

I'll try to snap a picture.

Lok at wiring especially the 25A underhood fuse. I've had similar problems w/ > 1 car and it was a bad connector each time.
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240s: 2 drivers and some parts cars

Thanks, I will check that out. Now to reveal my total ignorance: Is there a diagram available that shows where the fuse and associated wiring are in my particular car?

And I would recommend the Bentley 240 Service Manual (google for price deals) over the Haynes.

In my view, the part of the 83-93 manual that does NOT relate to your '81 would fit on a match book cover (slight exaggeration). It will address your:

• Fuel Injection (if it's K-jet/CI)
• Ignition (Bosch Electronic)
• Engine & Ancillaries (B21)
• Transmission (Manual w/OD or BW55 3-speed)
• Brakes (Girling front, Ate rear)
• and probably more I can't think of right now

IMO, although it has a number of typos, the Bentley manual is the one to have. Mine is dog-eared after 19 years. The only Haynes I'd recommend (if you can find a copy) says "1974 thru 1990" on the cover.

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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

Thanks for the suggestions. I found a cheap copy of the Bentley at a used bookstore here in Raleigh last night! I have a lot to learn. I'll keep my eyes out for a copy of that Haynes manual too. I've never been very hands on with my cars, but I want that to change, especially after my recent $1900 mechanic's bill, hehe.

Suggest you buy a Haynes manual if you're going to work on the car.

The fuse is near the battery, usually attached to one of the coil mounts. Follow the smaller red wire from pos post of the battery.

Not sure if that's correct on an 81 - I have 84-up cars.

It could be a bad ground, lose connection at starter/ battery/ alternator. Or at the fuel pump.

Read through the archives on related problems.
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240s: 2 drivers and some parts cars