metricadjustable

Hello all. Newbie poster, have been lurking and learning, thought i'd toss something out for advice.

I own a reliable '92 Chev S-10 4.3l 4x4 w/overdrive automatic, and 200,000 odd kms on the clock. Considering her history of abuse and her age, everything works rather well, except for an annoying problem with the first start of the morning.

When i start the truck cold and put her in reverse to back out of our driveway, the transmission (?) emits a clattering, loud enough to be heard across the street. The racket diminishes when you release the brakes and roll back, but increases when the brakes are re-applied. The best way to describe the noise is as if there was something caught in the engine fan, yet it can be felt through the cab. When this is happening, the transmission doesn't seem to be slipping any in reverse.

Once you put her in drive, the noise disappears, and after about five minutes, cannot be reproduced by reversing. The rest of the day is (relatively) quiet in all gears, forward or reverse, 2 or 4 wheel drive, hi or lo range.

There is no sign of the engine fan actually striking anything, no sign of the engine shifting, no unusual leaks or visibly loose/damaged anything. Fluids are up to level, and clean; the transmission filter is just over a year old. The driveline is as tight as can be expected with high mileage, no unusual vibrations.

Has anyone with a similar truck heard of anything similar?

old_master

Welcome to the forum!
Could possibly be a cracked flexplate.

inafogg

yes it could be if you put it in drive instead of reverse does it still make the noise??

maxwedge

Welcome to AF. Common issue, the fan is hitting the radiator shroud as the engine torques, you should see the marks on the fan and shroud.

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metricadjustable

Thanks for the ideas, everyone..

The same racket doesn't happen in drive.. and there aren't any visible marks on the rad fan shroud, that was my first thought. The engine doesn't seem to shift appreciably when i first put it in reverse.

I've got time now to check further; she blew a front brake line yesterday (the one that crosses along the front crossmember). Just my luck.

Is there any reliable way to inspect the flexplate without pulling the transmission and transfer case?

...and if it were a flexplate issue, would it disappear when the vehicle warmed up?

maxwedge

I'd stay with the fan here, I've seen dozens like this, have some one look under the hood as you power brake it some in reverse.

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inafogg

there is inspection plate that can be removed(couple bolts)you may be able to see with it removed.you may need to rotate engine