When I first got the car it seemed like the throttle was a little off int he way the motor reacted but now that I have it home next to the 240 I can tell you thast this engine is really, really slow to respond to throttle inputs.

On the 240 if you tapt the pedal the motor jumps with it, ont he 300 if you tap the pedal you might get a couple of higher revs but that is it. I can floor it and then wait two secionds for it to spool up significantly.

Is this normal for the 300's? Seems like I am really underpowered too, as I bet the 240 can keep up with this 300 in almost all categories. Has a slight miss but I can't figure out what is causing it yet.

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

When was the last time a valve adjustment was done? Timing chain checked for stretch?

Also, have all fuel filters been checked / replaced? You have 1 screen at the fuel tank, one prefilter at the fuel pump down by the hand primer, and the canister filter between the PS pump and the block.

Finally, once that has been done, IP pump toming may be an issue-

These cars are not terribly fast, and there are members on this discussion that acually prefer a 240D with a stick to a 300 with an automatic. The extra cylinder on the 300D non-turbo is almost cancelled out by the power losses thru the automatic transmission.

__________________
Nate Stanley
(Currently Benzless)
1985 F-250 6.9l 170K
2009 SCION XB 36.5K
2003 LS430 78K
2012 Kubota B 2320

Thanks Nate.
Did the valves yesterday. I should have checked stretch but didn't, duh...
I am ordering filters now and will get them in this weekend. I have abad feeling that this one and my 240 are due for chains.
Once I get the filters in I will check the chain for stretch and see what that does for my timing.

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

A little update and I'm starting to have these premonitions...

Anyway, it appears that in the morning when very cold the engine fires right up and the car has pretty good power. But................ as soon as it warms up it starts losing power and by the time it is up to 80C it has less power than my old 240.

I'm guessing a cracked head or maybe block.

Now to shoot out some ideas for consideration...
I am not seeing any water consumption yet.
Car starts very easily when quite cold 16 degrees F this morning and 6 seconds of cranking had her going with NO glow plugs.
Blowby is minimal.
Anyone have any thoughts on this?

Chain may be stretched really bad as I seem to remember the chain tensioner rail being way extended from the side of the engine. I can't believe I didn;t check the chain when I was in there...

Other than that what other signs might I be looking for to verify cracked block or head?

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

Regarding the fuel strainer in the tank, has anyone ever cleaned or changed one of these? Is this even considered regular mantenance?

If so, one would think there'd be an easier way than draining the tank.

Any thoughts or reccomendations?

__________________
Gil

2004 ML350
1984 300CD; Ivory (sold)

You didn't mention the hoses. Most often the radiator hoses will get very firm with a cracked head or block, and stay that way after shut down...

I have been chasing this problem with a slight miss for some time and doing a lot of chanign things out as of recently but though I'd try to see if there were more ideas fromteh group.

I have changed my injectors around with another used set and I thought I was on the right trak but after closer measurement I am back to the same rough spot just about idle. it seems to me that one cylinder is not getting full power. I can also hear the proverbial nailing and upon tracing with a screwdriver I would swear it is now number 1 that is giving me this beautiful tone....

I have also noticed that when manually moving the throttle a slight adjustment in the will cause a fairly wild adjustment in engine speed. It also does not spool up immediately like the old 240 does. What i mean by this is that when I tap the throttle in the 240 the engine jumps with the tap and comes right back down to idle. In the 300 it seems to have a slightly delayed or sluggish run-up and then settles back fairly slowly.. It is also not very consistant. I can move the throttle to the same position a second time and the revs wil be different than the previous time in the same position. i'm thinking the IP has internal damage of some kind. the car sat for a long time before anyone tried to start it and i seem to remember someone saying that the IP can be damaged if you push on the throttle before turning it over when it has been sitting a long time.

Ideas are what I need at the moment.

the next thing I have planned is to try and replace the IP with one that I can get off another car but this is a pretty big project and if anyone has any other ideas before I bite into this poject I would appreciate it.

BTW - this is the 80 300D with no rack dampener and no chain stretch and lots of compression.

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique