Screeching noise on cold start - turbo?? too heavy oil??

[krazzz]

It has gotten colder here the last few weeks and my Volvo has started making a screeching/squealing noise for the first few minutes when I start it up. After it warms up the noise goes away. It appears to be coming from back of the engine near the turbo. I am thinking that my oil is too heavy as I have been using 10w-40 from the summer. Do you think that is the case and will going to 5w-40 take care of the problem? My car has 155k on it and otherwise drives fine.

[StoningtonXC70]

Could be your supplemental air system blower...they make a hellacious squeal when they are on their way out.

Does the noise change character when you goose the throttle or is it relatively constant?

[JRL]

Same answer as the other site

[krazzz]

The noise is mostly constant does not seem to be related to rpm however it only makes the noise for the first minute or two until the car starts to warm up. I don't usually take off until the noise stops. I was thinking that it was the turbo and I didn't want to spool it up too fast before it was warmed up. I will try and see what happens when I gas it. I am a little relieved that it is sounding less like the turbo and more like the SAS. Someone on a different forum mentioned that it is possible to bypass the SAS and I am thinking about giving it a try. What are some ways to diagnose the SAS?

[StoningtonXC70]

Get yourself a mechanic's stethescope at your local auto parts store, and poke around with it (carefully) when the noise is present. The SAS blower is mounted under the battery tray but you should be able to get the scope sensing rod on it or close to it. You can also listen around other suspect sources, such as the turbo.

A mechanic's stethescope is a very handy tool for sorting out unusual noises such as the SAS blower. You can also make do using a long screwdriver as a listening rod, hold the shaft end on or near your suspected noise source and press the handle against that little bump of your ear lobe just in front of your ear canal to couple the sound to your ear. Marine engineers used to keep a set of long "listening rods" in their engine rooms to listen to various bearings on their pumps, turbines, and reduction gears in this fashion. Nowadays these rods have been largely been replaced by fixed and portable accelerometers whose outputs drive machinery monitoring spectral analyzers.

if it turns out that the SAS blower is your problem, you can just unplug its power leads as a short term fix. They freeze up due to corrosion from moisture that accumulates in them from exhaust gas back leakage through a check valve in the blower discharge line to the exhaust manifold. The blower is used to supply a blast of air into the exhaust gases on cold starts to help the cat converter come up to temperature more quickly, sort of like using a bellows to heat up a fire in a fireplace.

The Volo SAS blowers are quite pricey (about $300+) to replace, but running without one will not affect driveablility. You will most likely get P0410 OBD II check engine codes thown every once in a while, which could impact your ability to pass an emissions test, however, I recently passed a CT emissions test after having to reset a P0410 about a week before I brought the car in for a test. The test results did return an "SAS system not ready" flag, but apparently this was not considered enough of a problem to flunk the overall test.

Another possibility that is much more serious is that your timing belt tensioner is failing. You should be able to localize that noise with the stethescope to the vicinity of the timing belt cover on the right side of the engine. DO NOT continue running the car for even a minute if you determine that the tensioner is failing. When it goes, your engine will jump time and end up trashing your valves. You are then looking at a 3 kilobuck plus head replacement/rebuild. Have it towed in for repair rather than risk it failing on the way to the shop.

[krazzz]

From what you guys are saying it sounds like the SAS. Hope so, I have to drive 600 miles with it on Friday and I am away on business until Friday so it doesn't leave much time to rectify the problem. Stonington mentioned to just unplug it as a temporary fix. I live in a state that doesn't do vehicle inspections and lets just say the car is only used for "offroad racing and not intended for street use." Could that be a long term fix without causing any problems with the car? Does it affect gas mileage other than the first few minutes of a cold start? I'm not concerned about the check engine light staying on. I have a code reader and usually check it every time I change the oil.

[StoningtonXC70]

Come to think of it, try unplugging the SAS blower before you cold start the car as a diagnostic test. If there is no screeching noise at start up with it disconnected, you have confirmed the source of your problem, and also affected your temporary fix! If the noise is still there, on a positive note, you have eliminated the SAS blower as the source. On a negative note, you have to keep looking for the problem and it could be a lot more serious. If you get to this point, its time for the stethescope to try to pinpoint the source. Good luck.

You should have no noticeable performance effects from running without the SAS blower other than the throwing of the OBDII P0140 code, or perhaps some similar related ones, although I have only seen the P0140.

[hogie50]

The air pump connector is just in front of the battery tray below the LH headlight. It is clipped to the inner panel and is a grey color and about 2" long and an inch wide. Disconnect this and you will probably get a check light with the P0410 code for emission error. Reset and you probably won't get a problem for a while or you can get an intermittent check light. I bought a re-built air-pump on e-bay from a guy who replaces the bearings for approx. $130. Has worked fine so far. I also drilled a small hole on the casing below the intake side of the pump impeller to allow water to drain should the valve fail again. You guys must get a bargain on Volvo parts in the US. I was quoted a 'special price' from our local dealer of $450 CDN!! Normal price is $600 CDN! Valve is $200 CDN.

If you replace the air pump, you MUST replace the valve as that is the cause of the pump failure (valve jams open and allows moisture to drain down to the pump which is at the lowest point. Good job Volvo!

[krazzz]

Thanks hogie for the detailed description of the location of the connector. If unplugging the pump has no ill effects on the car I don't plan on replacing it. I can live with the light coming on now and then.

[StoningtonXC70]

So Krazz - how did you make out with the troubleshooting?

[krazzz]

I just got back into town tonight. I unplugged the pump and started it up, it didn't make the noise but the car had been driven a couple hours earlier so I'm not sure the engine was cold enough. Tomorrow will be the big test. I'll let you know.

[krazzz]

Well its not good. I started it up this morning with the pump disabled and it still made the noise. However, I was able to do some additional diagnosis and eliminate a few things. It is NOT the turbo. I listened around the engine compartment with the stethoscope but it was very hard to hear where it was coming from. It was easy to tell where it was NOT coming from so I was able to eliminate the turbo and other accessories such as the alternator and power steering pump. It seems to be more on the top end but I couldn't determine left, right, front or back. It is RPM related. When I gave it a little gas the pitch would change with the engine speed but the noise stops completely over ~1,200 rpm. Due to the high frequency the noise seemed to dance around and resonate everywhere. I do feel comfortable that after running for about 3 minutes the noise completely goes away. I can start the car a couple hours later and the noise does not come back. The only time you can hear it is when the car has sat overnight. I ordered up the timing belt kit with the tensioner and water pump. Since I am driving from PA to MI tonight I had the parts overnighted to my destination. (I know I shouldn't be driving it at all but I am leaving my 8 month pregnant wife in PA and I don't want anything to happen to her while I am gone.)
I might also pull the valve cover next time I start it and see if I can hear anything clearer that way.

[StoningtonXC70]

I strongly recommend that before your trip you pull the cover off the timing belt and sprockets, and try to eliminate or confirm if the problem is with the timing belt tensioner, by inspection and monitoring with the stethescope on cold startup. If it is indeed the source, I would be very concerned about it suddenly failing at some point, either on a cold startup or even afterwards while you are driving. I had some warning (about 10 minutes) when mine went, but I did not realize it was the tensioner. As I recall, it was making an intermittent screeching noise that was RPM sensitive, and it was not obvious that it was coming from under the timing belt cover. I assumed it might have been the alternator. Bad assumption as it turned out.....

Do you know when the tensioner was last changed, if ever?

[krazzz]

I have no idea when/if the tensioner was replaced and that is why I am doing it this time. The timing belt was done at 77k and now it has 152k so it is due. What does it take to pop that cover off? On my S90 it had some quick clips and it would pop off in seconds. With a quick glance I didn't see any fasteners for my V70.

[StoningtonXC70]

Krazz. just came across this thread on Sweedspeed.com...same problem as yours...turned out to be the timing belt idler pulley....

http://forums.swedespeed.com/showthread.php?107292-screeching-noise&p=1116314&viewfull=1

[hogie50]

There is a 10mm or 12 mm bolt about 3-4 inches from the top edge of the cover and approx. in the middle. I find it easiest to remove the header tank and lift it out of its slider clip by lifting straight up. You may need to undo the small overflow/return pipe to lift it up. no need to remove the lower pipe.

Once you have removed the bolt the cover lifts straight up and off.

When re-fitting be sure to get the top corners fully engaged or the cover will buzz and (as in my 850) crack the bolt hole surround.

I'm not sure what year your car is, but this works for an 850 through to a 98 V70 for sure. I think the 99-2000 is the same but not 100% sure.

Good luck!

[krazzz]

Well the parts came in today. I plan on doing the job tomorrow. I'll update with what I find.

[krazzz]

UPDATE: Problem fixed!! It was the idler pulley for the timing belt. It was pretty stiff and was causing all of the noise. I did the full timing kit with the tensioner and water pump. Should be good for another 70k which will get me up to 220k. If I am lucky enough to need to replace the belt again I will be ecstatic!

[StoningtonXC70]

Good going!. You dodged a big bullet, smart to go the whole 9 yards with the water pump along with the tensioner and belt.

[Volvoagain]

I had a similar noise and it projected thus hard to find. It was a pulley on the timing belt that was seizing upon cold start up. Caught it just in time as belt was dragging across while it was seizing.