Start my 93 after 2 weeks not running it, had it plugged in for a couple of hrs.
But when i fired it up it was extremely quiet. it was a warm day and all.
but it was quiter than any other time after hrs of running
has any one experienced this before. I have thought that there was a slight difference when running on the one tank or the other.
have not started it again yet to see if it still sound very quiet/

 

Do you know where the advance lever is on the left side of the IP, with engine running push the bottom of the lever in toward the IP, it should react with stumbling and possible smoke...white. Release the lever see if it returns to a normal running condition with clatter, if not I would double dose the fuel with a suitable additive, then drive it to see if it makes any difference. The advance piston may be sticking, you can push it in but it decides when to return.

 

no not familiar with the advance lever or IP, what does acronym IP stand for,

thanks

 

Injector pump. Go look on the driver's side of the injector pump, when you open the throttle it moves an arm on that side which pushes the advance piston in (the piston is down near the bottom of the pump) fire it up, and use a screwdriver or somthing to push the bottom of the arm in and see what happens.

 

Visit this gallery of info......... check out some pics.

28385&cat=500&thumb=1

 

thanks for the info. found the advance lever and it seems to be working ok.
but who knows what it was doing the other day
also when i started it, the sound is more of a normal 7.3 still a little more quiet
than usual, maybe warmer weather and all. but it sure has a good clatter going when weather is running just slightly cooler.
I'll run it and add some additive and watch the advance lever

 

I was just going to say, I have been through 3 IDIs. the first was a normal sounding 7.3, the second was at the time really rattly sounding (again a 7.3) that made the first one seem REALLY quiet when i fired it back up. The 3rd is an insanly obnoxious 6.9. It makes the other 2 sound like gassers! So any chance you have been driving other diesels? LOL

 

since new my 88 7.3 has always made more noise when cold compaired to when hot. if i plug it in in the winter, i do not wake anyone up when it starts. but try to start it without plugging it in, and the rattle will wake up the whole neighberhood. thats part of the reason it is named the rattletrap

 

Howdy,

The noise you hear is of course compression ignition "knock". Completely normal for all (earlier) diesels. (the newer ones are pretty quiet by comparison due to electronic injection and strategically timed pre-injection)

This "noise" (not noise to some of us!) varies with timing. retarded timing in a warmed up diesel will be pretty "quiet" like you observed.

Most (or all) IDI (Indirectly Injected ) diesels have some form of automatic or manual advance control to advance the timing for cold starting. late 70's-mid 80's VW diesels had a "cold start" **** that when pulled would advance the injection timing about 6 degrees for cold starting. The engine would start if you didn't pull it out but it would either run very rough(and smoke like a *&%^) or it would run and shake and shudder. If it was really cold it wouldn't start at all!

IDI diesels like the up to 93 GM 6.2/6.5L and up to 94 FORD (Navistar) 6.9/7.3L use basically the same Stanadyne DB2 mechanical injection pump. It has an auto advance feature that will advance the timing for cold start up and then retard after warm-up. If you listened while idle warm-up you would hear the sound change when it retarded...You can usually notice the advance because it "rattles" much louder when cold. We're only talking a few degrees here though.... so it if's not timed properly or the autoadvance is not working (or stuck) it'll either be hard to start and ok when warmed up (and quiet) or it'll be loud and will stay loud. If it's timed too far advanced it'll go from really loud to just loud!

In either case timing is pretty critical for an indirect injected diesel. Just a little off, (several degrees) can cause a "no-start" condition.


A lot of early FORD 6.9/7.3 diesels are not timed correctly because people with wrenches messed with the timing (and either didn't have a luminicity probe or didn't want to take it to someone who did). They set the timing by "ear". It can be done....but it's not very accurate! Trial and error timing doesn't work well with IDI diesels!!





Cheers,

Rick

 

The ones i have were all timed by a shop actually, I just retarded the 6.9 myself and it quieted it up a fair bit but its still alot louder then the first 7.3 I had. Actually it was pulled from the truck to make room for the 6.9.

 

My dad always said "if it ain't broke don't fix it"