had to tow the 72 home today

[jd4300fel]

Took my daughter out for an icecream, on the way home cruzin down the highway, I was only doing 50 or so. I asked my daughter if the truck was sounding louder than normal and she said yes. It sound like one of the mufflers was falling off or loose. I kept my eyes on the gauges and everything was where they are suppose to be. We went another nine miles and it was stayin about the same going through town it started to make a horrible noise like someone was rattling a coffe can with loose bolts in it.
This truck has always blew blue smoke at startup and then it clears up. A week or so ago I was low on oil I added a qrt and everything seemed to be fine. I am hoping to bull the valve covers off today or early this week, I am not sure what I will find. This truck was currently just used to go for a quick drive it's not my daily driver so that is a good point.
the truck has a 400 big block.

[Boog]

So did it quit running or did you shut it down for safety sake? Does it still do it at idle? If there are no spikes or dips in the oil pressure and engine temp it may not be anything real serious.

[matthufham]

head gaskets going out, or rings. did the muffler fall off or not?

[jd4300fel]

A few more details oil pressure seemd to be steady, I shut the engine down once I was able to get the truck to the side of the road less than a 1/2 mile at low speed. there is almost n rattling noise at idle but once you tap the gas peddle it's loud.

[Boog]

There are lots of things that could cause the noises. Several come to mind. Loose torque converter bolts, broken flexplate, loose flywheel dust cover, fan blades cracked or rubbing the fan shroud.
Is the engine still running smooth or has a miss developed?
You may need another pair of ears to go under the truck while someone revs the engine to help narrow the search.

[N2GMTrux]

The blue smoke at start up is caused by your valve stems seals being worn out, which are located on your exhaust and intake valves. Like everyone has stated there could be many different problems with the engine. But if all your gauge were looking normal then check your valve adjustment. I had a similar problem and it was a clicking or tapping noise. I could hear at idle and at high speed rev's. GOOD LUCK!

[71swb4x4]

Auto tranny? It could be the flex plate, or loose bolts between the flex plate and the torque converter.

[jd4300fel]

question would doing a compression check be worth anything ?

[IvelDesigns]

i don't see how that could hurt. at least then you could rule out a head gasket, rings, and valve seats.

[shortbed70]

Rockers backing off maybe or timing chain or???????? Noises suck!