300TD Tapping Sound

[ClarkT]

My 1987 300TD wagon seems to have a little less power and a little more unburnt fuel in the exhaust than I'd expect. It's been this way for months. Yesterday I was checking around the injectors and noticed a tapping noise coming from the #3 cylinder. I tried bleeding the fuel line, and when I had it removed for a moment a loud knock came out of the same cylinder.

With the fuel line back on the tapping returned. Are these symptoms of a fouled injector? bad rings? injector pump?

What would you do?

Best Regards,
Clark Thompson

 

[mjtray]

Sounds like one of your injectors has given upthe ghost....have you tried running some injector cleaner through it.....nprmally quite a loud knock....the Americans call it nailing.

If the noise is a tapping like an old type writer its likely to be a hydaulic tappet that is on its way out. I have one on my 300D which disappears if I rev the engine past 2500 revs. If its a noisy tappet its not too much of a problem.

I'm going to try some Wynns hydraulic tappet cleaner and see what happens.

 

[landover]

If the engine is running on all cylenders it is probably a hydralic lifter.

 

[dieselman]

My 1987 300TD wagon seems to have a little less power and a little more unburnt fuel in the exhaust than I'd expect. It's been this way for months. Yesterday I was checking around the injectors and noticed a tapping noise coming from the #3 cylinder. I tried bleeding the fuel line, and when I had it removed for a moment a loud knock came out of the same cylinder.

With the fuel line back on the tapping returned. Are these symptoms of a fouled injector? bad rings? injector pump?

What would you do?

Best Regards,
Clark Thompson

Do you mean you had the fuel ine off or just cracked free for a second.
If it's just cracked free then the knock will be due to the injector not squirting properly due to reduced pressure and sucking air into the pipe when the injection pulse collapses.

As Mjtray said, run some injector cleaner through it, if that doesn't work then have the injectors tested.

 

[ClarkT]

Thanks to you all.

I added injector cleaner yesterday when I filled up, and it already runs noticeably smoother. It still seems like a lot of unburnt fuel in the exhaust when I'm idling, but I'll give the injector cleaner a week and see how it does.

Regards,
ClarkT