740 turbo kicks back at starting

[JonBlanchard]

My 1990 740 turbo wagon with greater than 250,000 miles (an estimate as the odometer doesn't work when it's cold) kicks back at starting, especially when hot.

It is hard to describe but sometimes when starting it feels like someone grabs a hold of the engine and it abruptly stops turning, then proceeds slowly. If I back off and start again it usually starts ok. It doesn't do this every time and it is noticeably worse when the weather and car are warm. Once it starts it performs normally.

I've had this car for many years and this problem has been going on for the last three and is starting to get worse. It has been through tune ups, new starters, batteries, and other repairs that have had absolutely no effect on this problem. Two separate Vovlo repair shops don't know what's causing it.

I throw it open to your collective intelligences.

[billofdurham]

Sorry for the delay in replying but I have been digging around trying to find an answer.

Are you showing any fault codes?

it feels like someone grabs a hold of the engine and it abruptly stops turning, then proceeds slowly.

On cars older than yours, without electronic timing control, this was usually a sign that the timing was out.

I would suggest that you read Kmaniac's topic at:
https://www.matthewsvolvosite.com/forums ... =2&t=16575

Pay particular attention to the part about the vibration damper on page 5.

More information can be found at:
http://www.brickboard.com/RWD/volvo/382 ... ments.html

Bill.

[JonBlanchard]

Thanks Bill, the last time my mechanic checked there were no fault codes and the last time I checked the timing was steady at 12 BTDC.

When one mechanic listened he said it sounded almost like there was pressure built up in a cylinder. How something like that would happen is beyond me. I am kind of leaning towards a bad ignition switch. Still, I'm stumped.

[billofdurham]

pressure built up in a cylinder

That's a new one on me but I'm not an expert.

Having re-read your original post I now see the part about it stopping then proceeding slowly. That obviously did not register first time around.

I am inclined to agree about a faulty ignition switch, as the electrical portion is known to deteriorate. Unfortunately, there is no good way to test them except to wiggle the key the next time it happens and see if it will turn over at the proper speed.

Bill.