Now here's a mystery for the 240 experts that has me stumped...

A month or so ago I was driving through the mountains of Colorado. It was a dark and windy night, 10 p.m. and 7 degrees above zero. I started hearing a squealing (bearings?) sound from the engine of my 1984 245. I stopped to look, but with the dark and wind, I couldn't tell if the sound was coming from the power steering pump, the A/C compressor, the alternator, or ?. It was really loud by this point. I did notice that the power steering fluid was low, so bought some and topped it off, hoping for the best.

Being 50 miles from home, I decided to chance it the rest of the way.
The squealing continued, but didn't get any worse.

The next morning, I started it up to pull in the garage to have a look. It ran fine! Quiet as a mouse. I cautiously drove it to work, and amazingly (to me at least) it continued to run fine for another month.

Then.... last night (again cold and windy) I heard a pulsing sound from the engine, felt an odd vibration in the stick shift, and then suddenly something screamed (under the hood) and the engine locked up. I yanked the car off the side of the road, shut it off, and opened the hood. It was dark, but by the light of the silvery cell phone I could see that the belts were fine. I restarted the engine to see what was sticking...lo and behold, there was no unusual sounds....for about 5 seconds, then it started screaming and it was obvious that something had seized between the crankshaft, A/C compressor, and power steering pump. It was too dark to see exactly what. Given the darkness, temperature, and my mood at the time, I locked up the car and had a pleasent walk home.

This morning, I went back and, without starting it, loosened the power steering pump and took off the belt. I cut off the belt between the A/C compressor and the crankshaft since it's no small job getting those 6 (?) bolts off the front of the water pump. (Note, it's light now, but about 23 F).

Here's the mystery. Both the power steering pump and compressor spun freely. I didn't even notice any binding or bearing grinding. I'm stumped. Any thoughts would be much appreciated.

Thanks!
Mike in Colorado

Hello, try to turn the CLUTCH portion of the ac compressor. I am sure that it is starting to lock up from your discription of the problem.The pulley runs free on a bearing, but when the ac is powered the clutch pulls in and runs the compressor. B.G.

I don't think that anyone mentioned this yet in this thread. If so, my apologies in advance.

The Crank Pulley is a Harmonic Damper, and its rubber bond can loosen.

That's the lowest pulley on front of engine. Attached to crankshaft.
Pulley is actually three components bonded together.
Inner metal ring, middle rubber ring, outer metal pulley ring.

When the bond lets go the rings can move relative to each other. Sometimes crank pulley will work its way forward or rearward (belts will no longer be parallel to pulleys). Sometimes it will slip rotationally and so the ignition timing mark will be off (this doesn't affect the actual ignition timing unless you use the mark to adjust timing after it slips).

It's possible for harmonic damper to squeal when the rubber bond slips.
If it slips enough it won't drive the alt and water pump. Predictable results.

You can get the part from fcpgroton.com or I'm sure from other sources also.

Installation of harmonic damper will involve using the "rope trick" from the timing belt change procedure in the FAQ. However with a standard tranny maybe you can hold the crankshaft still by setting the e-brake with tranny in gear. If not, use the rope trick.
--
Sven: '89 245 NA, 951 ECU, expanded air dam, forward belly pan reaches oem belly pan, airbox heater upgraded, E-fan, 205/65-15 at 50 psi, IPD sways, no a/c-p/s belt, E-Codes, amber front corner reflectors, aero front face, quad horns, tach, small clock.

Did you try starting it after removing the belts?

I'm shooting in the dark, but my bet is on a seized AC compressor because of the intermittent nature of the problem. Faulty (old and crumbling) wiring on your '84 is causing the clutch to engage the compressor. As with many of the funky wiring symptoms, this only happens when the conditions are right.

Let us know when you find out.

-Will
--
850 / Mini

that's what i was thinkin. the compressor is probably shot and the clutch is intermittently engaging.

Will,
I forgot to ask before...can I either replace or put dielectric grease on any of that wiring to eliminate that possible source? Also, .can you be more specific about which wiring, or will it be obvious to me which wiring goes to the PS pump and compressor?

Oh, and you don't mean the clutch that I engage to shift gears, do you? I assume that there is some internal clutch in the compressor? Forgive my ignorance, but I'm learning about how each part works just after it breaks! I've learned a lot so far, but other than replacing the belts recently, this is my first encounter with the A/C system.

Thanks again,
Mike

there is an electonic clutch on the front of the compressor. when you turn on the ac unit it engages and locks the clutch (like letting out the clutch pedal does when you drive...except this engages a compressor not the transmission)

This is good information! A learning experience indeed. I've been wrong before, but if you've driven 50 miles without the PS and AC belts and haven't had the howler monkey symptoms then I'd be focusing on the PS and AC.

The load on the alternator belts increases as you put more load on the electrical system. So if it doesn't squeal when you've got the high beams on, radio going and the blower fan cranked then it's a safe bet the alternator isn't your problem.

I suspect the AC system because the symptoms are somewhat intermittent, like the running of the AC compressor during normal operation. The PS pump runs all the time. That's not to say that something massively wrong inside the PS pump couldn't do the same thing. -I don't know.

You got it, I was referring to the clutch internal to the AC compressor. I don't have much more than a basic knowledge of how the AC works. Try searching the archives or the 700/900 FAQ. I bet you'll find information there to diagnose and put this to rest.

Are you getting a good upper body workout driving around without power steering?

Good luck!

-Will
--
850 / Mini

p/s symtoms are usually sudden immediate in not mistakable. just my experience. a dead pump on a running car usually produces a notable result.

Will
Thanks for replying. I did try to start it, and it runs great (assuming that having no power steering or A/C is great!) What I mean is, the engine runs fine (I've driven 50+ miles over 3 days and it seems like it has more power than usual).

A few more things that might help the diagnoses. I was running the A/C, to help defrost the windshield, when the squealing/vibration started . Also, the power steering pump, the compressor, and the water pump all spin freely now. (I;m sure something seized the other night because 1. The engine sounded like it was really overloaded while sqealing occured, even with the clutch didengaged) and 2. when I tried to start it with the hood up, I saw the belt over the PS pump shuddering and not moving before I shut it off again.

It really seems like everything spins freely, then something locks up temporarily. Does that sound typical for either the PS pump or compressor? Occasional, non-binding squealing, then eventual lockup?

-Mike

Have you insepcted the rubber mountings that hold the accessories? Were the belts tight?

The noise might have simply been belt noise. I find that loose belts act up at nighttime. Why, because of the load of the headlights.

Good Luck!!

Goatman,
Cool name... regarding rubber mountings for accessories, I'm not sure which ones you mean...do they look something like engine mounts?

Regarding the belts... I just replaced them recently, and they were definitely tight. Also, I've had belts squeal... this was more like an engine shuddering, screaming band of howler monkeys trying to rip up the engine. I yanked if off the road within 3 seconds or it would have died on me.

Tell me more about these rubber mounts if you have a minute..

-Mike

i would start with new belts after feeling the alternator and jiggling the fan (water pump). Also, did you get any lights on the dash or did the temp shoot up? If those check out it may have just been a bad belt. Power steering pumps sound like a band of crickets on a summers eve when they start to go.

I was thinking of new belts to see if it seizes again... but if it does, can this hurt the engine while I'm trying to get off the road to shut it off?

As for lights, nothing. It was driving fine, then odd thumping/vibration through my hand on the shifter, then all of a sudden screaming and engine shuddering. I didn't notice high temp, but don't remember looking for that.

From you decription of the PS pump going bad, that's helpful. This was more like a band of angry howler monkeys really POed at the same time. More likely the compressor?

-Mike

Have you checked the alternator or water pump, those are the most common faults.

Also is your car an automatic? The throwout bearing in a manual gearbox can squeal too. Check the timing belt idler as well. Those are most common.

Good Luck!!

I haven't checked the alternator specifically yet, but it's been silent since I removed the PS and the compressor belts (I've driven 50+ miles without either). Does that mean it's okay? Or do alternators intermittently squeal, then not?

I jiggled the fan (that's how you check the water pump, isn't it?) and it feels as solid as when I replaced all of the belts a month or two ago, and no leaking fluid, so I assume that's okay?

It's a manual tranny, replaced about 3K ago.

Can you tell me how to check the timing belt idler?

Many thanks,
Mike