That Chevy S10 rattle may be crappy welds

[gxi]

Hello Mr. Editor! Perhaps you could turn this into an article or sticky or something. Seems to be a common problem. My 1991 S10 Pickup 2.5L 5-speed had an intermittent rattle that seemed to be coming from under the drivers side floorboard. I was sure the tranny was doing something weird. Turned out to be a heat shield on the top of the front exhaust pipe, just below the manifold mounting. It only had little spot welds holding it on, and they'd broken. It was somewhat formed to the pipe, in a narrow space next to the bottom of the engine (which it was shielding, obviously), so it didn't fall off of its own. I pried it off with a ball joint separator. Rattle gone!

[MagicRat]

Welcome to AF

We appreciate your insight, but I should add such heat shields are usually in place to improve safety, vehicle function or both. IMHO removing such a shield is not "fixing" your truck. Sure the rattle is gone, but now it has another problem..... something may get damaged or cease to function because its getting too hot.

Like most manufacturers, GM makes serious efforts to equip their vehicles for extemes. In this case, perhaps your truck, being driven in the winter with light loads will do fine without a heat shield.

However, add summer temps, and/or heavy hauling/towing, your exhaust will get toasty-hot and you will discover what that now-missing shield was actually doing. If this shield was wrapped around your converter, an engine problem, such as an ignition miss or over-rich condition will get your converter very hot very quickly.

Perhaps you will overheat the starter, so it won't start when warm... perhaps you will melt something, or boil the fuel in the fuel line. Perhaps you will just set your carpet on fire, which is always exciting.

I would suggest you retrieve that heat shield and put it back on. A quick repair for a rattling heat shield is just to wrap a couple of inexpensive metal hose clamps around it and snug them down. The rattle will be gone and the heat shield will still be in place. Try that, and hopefully you can fix your truck without creating new problems.

[gxi]

Oh yeahhh... hose clamps! I was planning on fixing that b4 hot weather returns, by welding it back on - which means removing the exhaust pipe of course - but hose clamps! Brilliant! Love this forum!

[j cAT]

Originally Posted by gxi

Oh yeahhh... hose clamps! I was planning on fixing that b4 hot weather returns, by welding it back on - which means removing the exhaust pipe of course - but hose clamps! Brilliant! Love this forum!

when the shields rattle I use some stainless steel wire. .030-.050 inches dia. . wrap around the stainless steel heat shields and no more rattle.

the reason those shields are over the cat converter is if the engine missfires or unburned fuel gets to the cat converter they can get so hot they will glow red. I have seen vehicles catch fire with this ...

the other reason is the shields keep the pipes hot and this reduces exhaust back pressure..

[gxi]

Originally Posted by j cAT

when the shields rattle I use some stainless steel wire. .030-.050 inches dia. . wrap around the stainless steel heat shields and no more rattle.

the reason those shields are over the cat converter is if the engine missfires or unburned fuel gets to the cat converter they can get so hot they will glow red. I have seen vehicles catch fire with this ...

the other reason is the shields keep the pipes hot and this reduces exhaust back pressure..

Thanks, another good idea. Actually, this is "on the top of the front exhaust pipe, just below the manifold mounting" as I mentioned. Or am I quibbling? Anyway, having thought about it (oww, my head), I reckon that the reason it's spot-welded on so that it was apparently raised slightly above the pipe was so that air could flow in between, and so that the heat shield would be cooler than the pipe. Obviously. So I think I'll JB Weld a couple of "spacers" of some sort on the bottom of the heat shield, and then remount it, probably with big hose clamps. Had I thought of all that to begin with, I could have simply slipped the objects underneath the shield and then clamped it down, instead of prying it off. Would've saved hassle. Oops.

[j cAT]

Originally Posted by gxi

Thanks, another good idea. Actually, this is "on the top of the front exhaust pipe, just below the manifold mounting" as I mentioned. Or am I quibbling? Anyway, having thought about it (oww, my head), I reckon that the reason it's spot-welded on so that it was apparently raised slightly above the pipe was so that air could flow in between, and so that the heat shield would be cooler than the pipe. Obviously. So I think I'll JB Weld a couple of "spacers" of some sort on the bottom of the heat shield, and then remount it, probably with big hose clamps. Had I thought of all that to begin with, I could have simply slipped the objects underneath the shield and then clamped it down, instead of prying it off. Would've saved hassle. Oops.

I have to do this to the 1994 s10 PU. rattles on that shield near engine.