89 Mighty Max runs fine but gets louder after 10 mins
I have an 89 Mighty Max that has 140,000
miles on it. It starts right up and runs fine.
I notice after about 10-15 minutes driving it
starts getting louder. The best way o can
describe the sound is like a loud exhaust
sound like a hole in the exhaust. I've
checked the exhaust and there is no hole.
The weird thing is it goes away about 5
mins later. Any ideas ?