740 GLE Major Hesitation

740fromhell · Post by **740fromhell** » 04 Aug 2006, 07:58

I am a mechanic but I have never worked on a Volvo before until I recently got a great deal on a 1986 740 GLE coupe, non turbo 4 cyl. that I am going to completely restore. Great car, until she broke down on me.

Had massive problems stemming from the hall sending unit in the distributor. It failed while driving and shut down the ignition system going about 50 mph, destroyed my timing belt (needed replacing anyway) and blew up some minor electrical components.

I've replaced all the parts with working (and tested) used or new parts and made sure the timing was set as well as the distributor set in right but now the car has a slightly rough idle as well as virtually no power in first gear (automatic). Could be possible that the timing is off slightly as I did it by ear and eye instead of with a timing light (I'm old fashioned).

Starts right up without a problem. Reverses without a problem but heres the deal: In Drive the tach slowly shows rpms and then towards the end of the power band goes into 2nd and becomes a speed demon. 0-25 in 15 seconds, 25-55 in 5.

This is the first Volvo I've ever had the pleasure of working on. Anyone have any ideas? Please help!

wojeepster · Post by **wojeepster** » 04 Aug 2006, 18:17

They are great cars. I think you will like them. Why not set timing with a timing light and go from there. I assume it was running ok before your problem started. A couple of tools I find indespensible. The wiring diagram from volvo technical publications (about $27) It shows circuits power on and power off, location of all relays, grounds etc. expensive but worth it. "How to diagnose and repair automoble electrical systems" by terry martin (about $16) The best book I have ever read on this subject and I have read a bunch. He is light years ahead of everyone else.

https://www.amazon.com/gp/product/076032 ... 38?ie=UTF8

740fromhell · Post by **740fromhell** » 04 Aug 2006, 19:58

just rechecked my timing visually and no problem there although the idle pulley was a little off (adjusted that and still the same problem with the rough idle). will try replacing the spark plugs soon but im starting to wonder if the catalytic converter might have been damaged when the tow truck set the car down (uphill driveway)... that or possibly the tranny needs some work. ive looked at the tranny and it seems to be the original on the car.

im going to cross my fingers and hope its the catalytic converter. if anyone has any ideas on something i might be missing then please let me know.

cosmiclobster · Post by **cosmiclobster** » 22 Aug 2006, 22:29

740fromhell wrote:I am a mechanic ... Had massive problems stemming from the hall sending unit in the distributor. It failed while driving and shut down the ignition system going about 50 mph, destroyed my timing belt (needed replacing anyway) and blew up some minor electrical components.

This is the first Volvo I've ever had the pleasure of working on. Anyone have any ideas? Please help!

What makes you think the hall sensor has anything to do with why your timing belt got destroyed? If any electrical part of the ignition system fails while driving at any speed, it will just be like you switched off the key. Some drag from the engine being turned as the car slows rapidly but not much else. I dont see how that could have anything to do with the timing belt

Are you sure the timing belt wasn't half dead to begin with?
As for no power in 1st and too much in 2nd, I would check your tranny fluid level. That's the only thing I know of that would make such a big difference between 1st and 2nd