Hey y'all. My '91 740 (4cyl, normal aspiration, no abs) wagon has started having a little problem that I didn't see in the FAQ or in my searches of the forums.

Every once in a rare while (maybe once every 3 weeks) when I start it up the SRS light will stay on and the engine makes a horrid and very loud squeal / screech noise. Sounds worse that a slipping belt and bad enough that the first couple times it happened I shut the engine off right away. Sounds more like the starter is not disengaging, but it's too loud to locate easily. If I shut it off and start it back up, no problem, both the noise and the light are gone. This has been going on about 4 months and seems pretty random.

It hasn't stopped me from putting 19k miles on the car since January, but I am concerned that it may be a symptom of something I should fix before it has me on the side of the road muttering under my breath.

So far, here is the mechanical work I've done on it in the past 6 months:
+flushed AT fluid (old fluid was almost black, thick, and stinky when it came out -- new fluid still looks good after a few thousand miles)
+put in new plugs (old plugs had white tips and a little black soot around the outside, haven't pulled the new ones yet to see how they are faring)
+switched over to Mobil1 pure synthetic oil (looks great, loses ~1 quart every 6k miles or so, on 15k rotation)
+cleaned throttle body (nasty dirty)

Mechanic has done:
+new heater hoses (*#%@#! things blew 500 miles from home at 2am in an ice storm. Didn't overheat, but I did lose all the fluid. The mechanic said the system pressure tested ok -- paid "out of towner" prices...ouch)
+new flywheel rpm sensor (this one I could not diagnose for the life of me. Was flooding and stalling out at idle once it got good and hot, then refusing to restart (flooded). Thankfully my mechanic here in Columbia, SC is reasonably priced... and fast!)

Oh, and this is my "to-do" list for the next month:
+replace fuel filter & flame trap
+clean throttle body again (engine is pretty sluggish, especially uphill)
+new shift link bushings (shifter is a little loose, might as well do it)

None of the above seem likely to be the cause of this Noise+SRS Light problem, which just makes me all the more concerned about it.

I'm relatively new to tinkering with Volvos and would much appreciate some speculation as to the "likely culprits" from the more seasoned Volvoans here.

Any ideas? I looked around the forums and FAQ and the SRS stuff I could find seemed rather different from this problem. Thanks much in advance for your insights & advice!

-Pat