Around a year ago, I purchased a set of new Monark Injectors along with heat shields for the 1984 300D. I took them to a well known diesel shop to pop test and calibrate them. I then installed them in the car. Here's the deal: when the car is cold, I hear a nailing sound, however once the car warms up the nailing sound goes away. I'm thinking of installing injector line heaters to see if it will make any difference......any ideas?

I recently installed Monarks and it took a few hundred miles for them to quiet down.

these Monarks have been in the car for 1000 miles and are still nailing when the engine is cold.

Are you using only Diesel Fuel?

I learned this on the forum. Low Injector opening pressures = slightly advanced timing. When Injectors are rebuilt they up the opening pressure and that retards the timing slightly.

You may need to re-time your Fuel Injection Pump.

Lower compression also will cause Injectors to Nail more than they would when the Engine is warmed up.
Late Valve timing effects compression; Timing Chain stretch causes late Valve and Fuel Injection timing (if the Fuel Injection Pump has not been previously re-timed).
Valve Adjustment also effects Valve timing and Engine Compression.

Cold Engine Nailing can also be caused by Glow Plugs not working as they should.

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84 300D, 82 Volvo 244Gl Diesel

thanks, I was wondering about timing for the fuel injection pump. I will check out the glow plug situation and perform a compression check as well, good idea. The timing chain was replaced at 150K, the car now has 240K on it now so it "should" be OK, but as we know there are no guarantees.......

If the common 617 IP timing procedure uses a drip tube at the IP; that is, downstream of the injector, how do you retime the IP? Advance until the nailing stops? Seems like an inductive timing device is the better way to go.

Sixto
87 300D

If done properly Drip Tube timing is not going to be the cause of nailing.

As the Timing Chain and Timing Gears wear the Fuel Injection Pump Timing becomes more retarded/Late. Regardless what is going on with the Injectors.

Oddly both retarded and too much advanced timing will both cause nailing.
I forgot to mention that Nailing can also be caused by Air in the system.

Everthing that hat "Nailing" in the title from my notes:
Nailing caused by delivery valve.
http://mbca.cartama.net/archive/index.php/t-19002.html
More Nailing List of causes
http://www.peachparts.com/shopforum/showthread.php?p=2304480#post2304480
Nailing stopped after solving air leak or removing air
http://www.peachparts.com/shopforum/showthread.php?t=298939
Pressure causes Nailing
http://www.peachparts.com/shopforum/showthread.php?p=2250046#post2250046
Mystery nailing due to messed up secondary filter
http://www.peachparts.com/shopforum/showthread.php?p=2265834#post2265834

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84 300D, 82 Volvo 244Gl Diesel

Oops, I meant the drip tube is upstream of the injector.

Sixto
87 300D

You were right before.
The Drip Tube would be upstream from the Fuel Injection Pump; but downstream from the Fuel Injectors.

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84 300D, 82 Volvo 244Gl Diesel

But how do you account for opening pressure when setting IP timing using the drip tube method?

Sixto
87 300D

Just like New Orleans is upstream of St. Louis!

Nailing a bit when cold, even when glow is working, is fine. It goes away when warmed up. My car is like this. I've advanced the timing a bit so that it does nail when cold. I like the power curve of where I've got the timing set.

I'm running Monark's set at the top of the range for pop.

I'd say you don't have a problem, or anything to worry about. So long as your power and smoke are fine.

If you retard your IP timing a bit, the cold nail will be less. You could also be reducing your power a bit.

Live on the edge!

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Cheers!
Scott McPhee

1987 300D

Is the timing chain considered a maintenance item? At how many miles should one be changed?

When you use the Drip Tube you remove part of the Delivery Valve and the Delivery Valve Spring and you remove the Fuel Injection Hard Line that connects the Fuel Injection Pump to the Injector.
So there is no opening pressure to account for.
When you use the Drip Tube to time you are timing the Fuel Injection Pump to the Crankshaft; this has nothing to do with the Injectors themselves.

(There is a Pressure Relief/Overflow Valve on the Fuel Injection Pump Housing and that regulates the Fuel Supply/Lift Pump Pressure. When you use the Drip Tube you need to pump on the Hand Primer and keep that pressure up and as even as you can or you are going to have a tough time.
See the instructions in the DIY Section on using the Drip Tube.)

The Injectors are somewhat like pressure relief valves. They hold they hold up the Fuel flow from the Fuel Injection Pump until the Injector Opening/Pop Pressure they were set to open at is reached.
So the though is that a low Injector Opeing/Pop Pressure allows the Fuel to be Injectied earlier/more advanced than and Injector that has a Higher Opeining/Pop Pressure.

A lower Injector Opening/Pop Pressure does not sound so bad except that the Fuel does not get Atomized as well at lower pressures so it is not going to burn as easily.

The above stuff concerning Injectors has an effect on when and at what rate the Fuel is going to burn. The Nailing sound can be a result of too much of the Injected Fuel burning at the wrong time.

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84 300D, 82 Volvo 244Gl Diesel

I can get confused sometimes.
Also lately I have been taking a lot of pain medications.

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84 300D, 82 Volvo 244Gl Diesel