Injectors

[Jim Roe]

I have a 1979 43 DC with 671T's. The injectors had never been touched until last week when a mechanic decided to do a valve adjustment. I was starting to get a little smoke and he thought that an adjustment would do the trick. He also did an acid flush of the sea water system because I was having an overheating problem with my port engine.

Now when I start the engines I get a huge amount of smoke (the kind that drives everyone out of a marina). The smoke does diminish substantially after running for a minute or so. After much examination I believe the smoke is a fuel issue.

My question is: Can an adjustment back to the previous settings work or is it time to bite the bullet and replace injectors? Also, I have read previous threads about rebuilt injectors and it appears that there is a real chance of getting bad injectors. The mechanic I used is not DD mechanic and I can not seem to find one around this immediate area.

Thanks for any help you can give me.

Jim

 

[Genesis]

This is probably not an injector issue.

Did he set the rack or just the valves? If the latter he probably set the throttle delay and may have either set it a bit too loose (resulting in more overfueling on a cold start) or it may have been too tight from the outset and now is "correct".

There is nothing in a valve setting alone that should have caused this. Either the job was botched or something else (e.g. the general tune and throttle delay) was reset, and if the latter, it may not be "wrong"; you may have been set up incorrectly in the first place and now are correct (e.g. tune)

Exactly what was the scope of work performed?

 

[Canuck Dennis]

If repalceing injectors, always insist on "tested injectors" not unusual to have a dud.

 

[Avenger]

Smoked a little before, smokes a lot now, and somebody fiddled with the rocker adjustments. I can't see it from here, but I would have to guess he set the injector heights wrong. What color is the smoke? If it's white I'd get the timing re-checked.

 

[Genesis]

He SAID the valves were adjusted.

If that's ALL that were adjusted, you'd have to REALLY screw up the valve adjustment to get that result.

If, however, the entire tuneup was done, well, it was done wrong. Call said mechanic back and have him do it correctly.

IF (and only if) the injectors were REPLACED, there may be a bad one. But if they weren't removed, well, how'd one (or more) go bad?

Set wrong, yes.

 

[Canuck Dennis]

If possible, never, never have a mechanic work on Detroits who is not DD certified or trained, they are a very complex piece of engineering though mechanics say, oh, yes a DD screamer, anyone can work on those, true, but most make a mess of it.

 

[Genesis]

Bah.

DDs are simple to do routine tuneups on.

The procedure is in the shop manual and if you follow it step by step you will wind up with a properly tuned engine.

It WILL take quite a bit of time the first few (bunch?) of times, as setting the rack requires a "feel" that only becomes reasonably fast over time. Your FIRST rack will take all day. You do 'em enough, its an hour for the same result. Valve clearances and such are no different on a Detroit than they are on any other engine. If you can competently use a feeler gauge and swing a set of wrenches, you can tune a Detroit. The "mystique" factor is IMHO total garbage.

 

[Jim Roe]

Thanks everyone. I passed on your comments to the mechanic and he will work on her tomorrow. I will let you know how it all comes out.

Jim

 

[REBrueckner]

Around NY, 485HP 671TI I see smoke so much at cold start the boats sometimes "disappear" in it!!...literally....My experience is the higher HP TI's smoke a lot more at start...It appears the bigger the injectors the more fuel they dump ...

I had my 1972 8v71TI, only 435 HP, injectors tuned a few years ago. I had noticed a touch more smoke with cold engines, whitish gray, and since they had not been done in maybe 1500 hours and maybe eight years I owned the boat, I figured likely they had not been done for another eight yrs prior to my ownership when some engine work had been done. They run clean after warm up.

After tune up one engine was about the same, the other smoked just a bit MORE while cold...and seemed just a touch harder starting...It started at 70 degrees the way it now does at 72 degrees. (Just my observation.) I had the mechanic come back to check he used the injector gap recommended here....he checked several injectors and that was the setting...is it 1260? Whatever, it was ok ...

It's now about three years later and the engines behave the same....I'm sorry I had anything done to them...

Now this is the same experienced mechanic that has worked my DD's for twenty five years, three different boats...nobody else gets to touch my babies!!! I watched him and his partner for two weeks rebuild/refurbish my babies when I bought my YF.

You can reach your own conclusions...mine is that likely my starboard engine injectors might be approaching the time for a rebuild....nobody knows how long they have been in there untouched and how many hours may be on them....

The injector source recommended here, maybe by Brian and others, has worked well...(I forget the company name, anyone???) I recommended that source to my local mechanic and he finds those rebuilt injectors reliable, less expensive and better than his prior source....

Would gray bottle Diesel Clean make any difference??....I used some last year and this again at the end of this year at the "low dose" level and have not noticed any difference.