Hey Guys,

Every once in awhile I can hear a faint ticking noise when coasting at lower RPMs with the windows down. It's not that loud, and I've always thought it was possibly a noisy injector, until I realized last night the injectors wouldn't be firing if I wasn't giving the truck any gas.

The sound seems to be coming from the left side of the truck, and I usually only hear it if I'm close to a concrete barrier on the driver's side or driving through a tunnel. The frequency of the sound is slow enough that I'm thinking it's only one cylinder leaking, as I've had cracked manifolds in previous cars and the ticking noise was not only more pronounced but also much more frequent.

I only hear the noise when coasting, and as soon as I get on the gas, it either goes away or the noise of the engine completely drowns it out. I can even accelerate hard towing a load and not hear the noise at all.

I'm going to crawl under the truck tonight and take a look at the manifolds to see if I can spot a leak somewhere, but I thought I'd see if any of you guys have any ideas of what it might be and what I should look for. I already replaced the up-pipes about a year ago when I changed the clutch, and the noise didn't get any better or worse, so I don't think they are the culprit.

Thanks!

 

Could be the gaskets where the manifold and exhaust bolt together. Been known to burn out. 1 ea side and just use a long extension and a socket, unbolt and slide new one in, replace bolts while youre at it.

 

Mine doesn't have any gaskets where the exhaust manifold bolts to the up pipes. Do you mean the up pipe gaskets under the turbo collector, Passin Thru? I have leaking up pipe gaskets and I hear the ticking noise, they are a bit** to replace with the motor & trans in the truck.

 

I crawled under the truck tonight and took as good of a look as I could at the exhaust manifolds and all of the components. I was surprised at how tight everything was packed in there, and it looked like an exhaust manifold job would be a nightmare in these trucks!

Everything I could see looked good and I didn't find any soot marks or other obvious signs of leakage anywhere. That's not to say I don't have a leak somewhere on the manifold that isn't visible though.

I may just have to wait until the noise gets worse before I can actually track down and fix the leak, although I might have to wait awhile, since it hasn't gotten any louder in the three years I've owned the truck!

 

Stick your hand down behind the turbo at the up pipe joints and see if your fingers get soot on them. Sounds to me to up pipe gasket leaks, very common.

 

I'll give that a try this weekend when installing my new brake controller. I doubt it's the up-pipe joints, as the pipes and gaskets were all replaced a year ago this month with no change in the noise. Although I've learned long ago that one should never assume that because you recently replaced something that it's still not the problem!

 

Ya, I know what you mean. I put the brass donuts in just recently from beans and they are leaking.