Hello, all.

I just flew to Houston and drove my new '93 240 wagon back to NC. 1400 miles and it did great. However, I have a couple of questions.
1) It has a B230FD engine (round tooth timing belt), and the owner's manual recommends changing it every 100,000 miles. The Volvo shops around here stick with 50K. It is okay to run it to 100K before changing it?
2) When letting the gas off at highway speeds OR turning the OD off when going down hill OR sometimes on bumpy roads, there is a groaning noise (more of a feeling than a noise) under the front of the car. It almost sounds like a bushing needs replacing. Could it be a motor or transmission mount?

Thanks ahead of time!
Denis

Re: groan. Both actions you mention involve weight shifting forward and the front end diving slightly. How about when you first touch the brakes? Also, try bouncing the front corner of the car.

Hi John,
The noise doesn't necessarily occur when I first touch the brakes. However, I didn't think about bouncing the front of the car, which I'll do tonight. It doesn't handle or ride poorly though.
Denis

"It is okay to run it to 100K before changing it?"

Sure. Volvo recommends it, and the rounded teeth essentially prevent the "snagging" of the former square tooth against a swuare groove in the sprocket (which resulted in a snapped belt).

And if your t-belt breaks, the engine is unharmed.

"...sounds like a bushing needs replacing. Could it be a motor or transmission mount?"

Hmm. Happen any other time, such as corners, upshifting, downshifting (not just OD), or under acceleration? Does it feel as if it's from one side or the other?
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Don Foster (near Cape Cod, MA)

Hi Don,

I was hoping to hear someone say that about the belt!

The noise doesn't happen when I enter or leave corners. It feels like it's coming from the right side of the car. The first time I heard the noise I grabbed the tops of the front tires and shook the heck out of them and didn't feel anything out of the ordinary.

It doesn't appear when I'm accelerating, but thinking about it, when I let off the gas at higher speeds (70-80) it really rattles.

Denis

"...it really rattles..."

Is it a quiet, subtle groan or a rattle?

If it's a rattle, examine the ever-popular heat shields around the exhaust pipe and catalytic converter. They're guaranteed to rattle -- the rattle starts small and gets worse with time (as over months). You can chisel off the heat shields and never look back.

If it's a groan (particularly one that you feel), then you might look for evidence of the exhaust system or something else touching the undercarriage or chassis as you decelerate. Slowing down (in contrast to accelerating) puts an opposite torque on the engine, so it tips slightly in the other direction.

This might have implications about the motor or tranny mounts, as you initially asked.
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Don Foster (near Cape Cod, MA)

I'll check the exhaust system too.

I forgot to mention that I sometimes hear the noise when start the car. I doubt that would have anything to do with suspension, but as you say, it's a torque thing and may after all that the motor mounts and/or tranny mount are suspect.

"...sometimes hear the noise when start the car..."

Ever watch the engine bounce around when it first fires?

Anyway, if you hear the noise when you start the engine -- which means car not moving -- then it largely eliminates tires, bearings, suspension, driveshaft, brakes.
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Don Foster (near Cape Cod, MA)

Well, after horsing around with the car for awhile and discovering nothing, I took it to an independent Volvo shop. On a lift they discovered that the left motor mount isn't tight and when the engine is started, it rocks more than it should. The other thing they noticed is that the left bushing for the front sway bar is worn and the hole is ovaled. At least it's nothing serious!

They were surprised when I told them at 70mph the cars gets around 28mpg and 24mpg at 80. Maybe that it's a California car it has a different gear in the back or something?

The car also has a B230FD motor, which according to the manual and some other posts here, indicates it has a 100,000 mile timing belt. However, the shops here insist it be replaced at 50,000 miles. What's the scoop?
Denis

"...the left motor mount isn't tight and when the engine is started, it rocks
more than it should..."

Good news, easily fixed.

"...the left bushing for the front sway bar is worn and the hole is ovaled..."

Also good news and very easily fixed.

"...it has a 100,000 mile timing belt. However, the shops here insist it be replaced at 50,000 miles. What's the scoop?"

The standard Volvo timing belt (B21, B23, B230F and FT) have square cogs (teeth). The sprockets have matching square-cut grooves. When the belt stretches slightly, over time, it can become loose enough so that the sharp edge of a cog can misengage the mating groove in a sprocket, and the belt rides up -- stretching too far and snapping.

The newer design (on your engine) with the rounded teeth and matching rounded grooves permits the belt to "self seat." Even if it stretches slightly so that the teeth and grooves don't exactly align, they will still engage themselves and seat properly. This means the belt won't be stretched and snap, even if it's a bit loose.

If you do your own t-belt replacements, it won't hurt to do them at 50k mile intervals (as is encouraged for the old style belt). However, if you pay a shop to do your maintenance, you can wait the recommended 100k interval.

At least that's my take on it.
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Don Foster (near Cape Cod, MA)

Hi Don, that makes sense about the belt, and I like your take on the belt replacement! I'll definitely do my own and save the $300 a shop would charge me.
Thanks for your help!
Denis