1995 850T wagon – Engine suddenly died on freeway

[Seamonster]

My 1995 850 Turbo wagon just lost engine power on the freeway and I could use some suggestions as to the cause. I’m not super car-savvy, but I am handy (maybe the most “serious” thing I myself have done on my 850 was to replace an oxygen sensor). I have ramps, jack stands, and a wide selection of not-very-specialized tools.

I’ll present the situation chronologically so as to limit any wrong-headed ideas about causality that I may have. Some symptoms may be unrelated to others, which means you get to have fun playing “spot the red herring”.

The day before going on a 450+ mile freeway round trip this past weekend, I checked fluids, tires, etc. All was fine except I noticed that the serpentine belt was fairly worn. I ordered a new belt online (which will arrive in a few days), and since I had to make the trip regardless, I bought some belt dressing and sprayed a bit on the old belt, by way of “insurance.”

About 150 miles into the trip, the Check Engine light came on. Two fault codes were reported (via the one-button, one-light interface):
2-4-1 EGR system flow fault, and
3-1-4 Camshaft position sensor.
Assuming those to be emissions-related so not immediately critical, I continued on the trip and the car behaved fine otherwise.

On the return trip two days later, after driving ~150 miles and still ~80 miles from home, I heard a very faint chirping sound, like there was a small cricket in the glove box. I recall thinking, “Hmm, I wonder if that’s the beginning of the end of the serpentine belt,” as it was sort of a super quiet version of the loud squeal that a worn belt can make.

Only ten minutes later, while going 70 MPH, the engine suddenly lost all power. I might have heard a sudden noise, or maybe I imagined it, as the power loss was abrupt. As I coasted down a convenient offramp, I noticed that I still had dash lights and headlights – which suggests, I think, that the alternator should still be okay. But as I got to the bottom of the ramp, I noticed there was no power assist for brakes or steering.

I opened the hood thinking I’d find the serpentine belt in shreds. But no, it was still fully intact. Visual inspection revealed no dangling cables, nothing obviously loose or broken.

Then and now, when I turn the key to start the engine, I get whir or hum, but no cranking. So I still have battery power, the starter itself probably works(?), but it seems the engine is somehow locked up (I don’t want to say “seized” because that’s more specific than what this might be).

Looking at the Troubleshooting tips in the manual and in Haynes, I don’t see a set of symptoms that seems spot on.

Could the problem be electrical in some way? Failure of what component? What would fail so suddenly at speed?

Is it conceivable that, having sprayed a bit of dressing on the serpentine belt 350 miles before, the belt could somehow have seized (e.g., due to differential flexibility)? I don’t know how I can test this because I don’t know how to manually turn the motor – the car, now trucked home, can’t be easily rolled, as it’s in a low area that’s uphill in both directions. Should I try getting the front end on jack stands by jacking up one side at a time?

Is there anything I can try to “reset”? I tried clearing the fault codes but for some reason they won’t clear. In the past when clearing codes, it has sometimes taken me a few tries to get the button pressing right – the sequence and duration of presses can be tricky. But now I’m either doing something consistently wrong, or the computer somehow knows that something is wrong enough that it won’t let me clear the codes(!)

I can’t see the timing belt without opening its housing, but I don’t suspect it because it was replaced only 30,000 miles ago.

Any ideas on how I can better focus my thinking would be much appreciated.

I figure that in any case I should install the new serpentine belt when it arrives in two days. Hopefully by then I’ll know what I’m dealing with.

Thanks,
Kraig

[j-dawg]

Have you checked the camshaft position sensor? Failure of that component could render your car inoperable. This may be that rare case where the code the car is giving you actually leads you right to the problem.

[Seamonster]

j-dawg,

That would be great news. At a glance, it looks like replacement of the camshaft position sensor should be easy – just two screws and a connector. I didn't think that could be the trouble because my wife's Saab had the same failure yet her car continued to drive fine – it only had to be replaced for emissions reasons (at least that's what I understood at the time; we were just dating then, and she had her own mechanic deal with it).

Given the fault code, I should replace the sensor regardless. Is there any sort of adjustment or "fine tuning" I have to do with it, or is it plug n' play?

Thanks,
Kraig

[j-dawg]

To be honest, I don't know how important the cam sensor is. I would guess that both the crank and cam angle sensors are needed to at least start the car: since the crank turns twice per four-stroke cycle, the car needs to know which stroke it's on. But I dunno.

[Seamonster]

Since I did get the fault code for the camshaft PS, I've gone ahead and ordered a new one (via 2nd day air). But if anyone has read through my 850‘s symptoms and thinks the no-start problem might be something other than the CPS, please chime in, I'm all ears. Either way, I'll update this thread when there's news. -- Kraig

[abscate]

The fact that the engine isn't cranking right is not good news.

I think you broke your timing belt. The fact that it was done 30k ago probably means inferior parts were used, and that explains your crickets

Remove the two screws on the plastic cover on top of the engine, pop off the t wo clips and take a look at the hidden belt underneath and make sure it's intact. I'll try and find a pic

The lights, headlights, stuff is all irrelevant. That's what happens when your engine shuts down.

[FLXC90]

Sorry to pile on, but the crickets may have been your idler or tensioner, or water pump. If the cam timing had jumped one or two teeth initially, it would throw the code but still run. If the belt skipped again at say, 70 mph, it's not good news. Do you know if the tensioner and pulleys were also changed 30k ago? and how many miles on it now?

However, all is not lost, the valves and head may need replacement, but the bottom-end may still be okay. And all the confidence you need to tackle it yourself is here in the forum.

Let us know what you find

[Seamonster]

Abscate called it: the timing belt broke. It had only 30k miles on it. But that’s how far the car has gone in the past 8 years (from 135k to 165k), so maybe age itself was a factor.

I’ve read varying things about how serious the engine damage will necessarily be. The fact that I heard little or no noise when the belt broke, and it was sudden, suggests that it didn’t have a chance to slip a few teeth and start wrecking valves and such. I mean, if there were serious engine damage I would have heard some real metal chaos happening, right?

So is it conceivable that I could install a new belt and all would be okay? Percentage wise, how likely is that the case? If so, I can follow directions and get the car’s front end up on jacks stands, so I should be able to work it out. (Then I’d also install my already-purchased serpentine belt and camshaft position sensor.)

I don’t have a clear sense of how much valve damage can be sustained before a car won’t run at all. But if it would be possible for me to get the car back to “merely functional” without spending many hundreds of dollars, that would be good enough for me.

If the no-major-damage outcome is plausible, can anyone recommend the best “how to” web page for doing the timing belt on a ‘95 850? There are a lot of write-ups out there but it’s hard for me to tell at a glance to tell which might be best.

And should I start a new thread emphasizing the timing belt situation?

Thanks for sharing this, uh, *adventure* with me.

- Kraig

[Scholz]

Every timing belt breakage story I've read on these engines has included valve damage. as to the metal on metal noise I snapped a timing belt on a honda DOHC engine and it went dead silent. like nothing... in gear. trashed 3 valves. So I don't think you really need to hear it for the damage to be done.

[abscate]

Crap on rye, I really, really hoped I was wrong on this one...