Engine Tapping/Knock Sound @ cold idle only

[deliman]

Since winter began my Delica has had a little bit of unstable idle in the morning when it's cold and knocks/taps quite loud only when it's cold. Once it's warmed up for the day it's fine.

I was told by a mechanic that it's either one or more of the injectors are clogged and isn't delivering the correct of fuel.

The injection pump has been rebuilt and timing reset, new air and fuel filters, reg. oil changes.

Any ideas? This is a 93 Model Exceed

[delicat]

So what about the injectors as suggested by your mechanic?

For winter I'm running lighter oil, 5w40 and it helps with the smoothness. I'll change it back comes summer time. My brother in Montreal changed his for 0w50 (synthetic) and that has helped him as well.

Let us know how it works out!

[Golf Cart]

David is right

The loud tapping that eventually goes away is just the cold oil taking longer to get up to the rockers. 5w40 switch over should eliminate the tapping, and a block heater will help with that rough running in the morning.

Mine does the same thing and the injectors are fine. Both my other diesel vehicles do the same and they both have brand new injectors. Could also be a tiny air leak and the engine is just pushing the air through the system. Try upping the idle to about 900 to 1000 rpm once your oil has circulated and let it run for a few minutes before taking off. I adjust mine up until the engine smooths out. It may creep up on you as it warms up. A few times I've fired it up in the morning, gone back in to get my stuff only to find the idle is up to 1400 rpm when i get back out.

Cheers