chirping sound peterbilt

try greasing the two square rubber blocks that the hood rests on when closed,

 

I dont use grease cause when your cleaning the windshield or wiping down the visor or horn covers, you might get caught leaning against those rubber blocks that you "greased". What I do is cut the tip of an old sock from the toes (about 3 inches) and slip it over the rubber blocks.

 

Motor mounts and cab mounts will also make a chirping sound. I see you changed the motor mounts but you might check the bolts.

What I do (old mechanics trick) is put brake fluid in a oil squirt can and spray down the mount and the bolt holding it. If the noise goes away and then comes back after you wash or run through the rain you found your problem. I also own two 95 Pete's.

And yes it could also be the head but like others have said do the cheap stuff first.

I also used to own a T600 with a N14. The previous owner said he would get a chirp sound on a hard pull. If I remember right he said they ended up changing the injector cups to solve the problem. It was doing it shortly after the motor was overhauled.

 

Kenworth's can do the same, I use dry lube, you can get it in a little stick. Be careful using brake fluid, will take your paint off real quick of your not carefull.

 

I actually use "SYL-GLYD" a silicone based grease the petroleum based grease will swell the rubber and make it worse. But that's still messy and temporary I had to replace the hood hinges (2) and both front cab bushings and replaced the rubber blocks with aftermarket neoprene blocks, to get it to stay quiet.

 

I'd say headbolts and gaskets then if they are blowing bubbles

 

sad part is, if it ends up being a head gasket and the engine has a lot of miles on it. just replacing the head gasket will be a temporary fix. usually with age the deck of block gets worn and you have to redeck block. which isn't cheap!

 

I had to put 3 new heads on my N14 because the coppers were bad and new heads were only $200 more. It had more blow by after that but ran it for 5 more years.