Injectors?

[MikeP]

I know this topic has been well covered in the past and there have been a lot of comments re bad "new" (rebuilt) injectors. But I was wondering what the most current view is re where/what "brand" of injectors to buy.

I want to install "new" N90s (8V71Tis) but would like to have the best chance at getting 16 good ones at the first try!

 

[saltshaker]

I know this topic has been well covered in the past and there have been a lot of comments re bad "new" (rebuilt) injectors. But I was wondering what the most current view is re where/what "brand" of injectors to buy.

I want to install "new" N90s (8V71Tis) but would like to have the best chance at getting 16 good ones at the first try!

Why do you want new? Most mechanics prefer having yours rebuilt by a reputable shop. My mechanic in NJ and in Fl wouldn't warranty any injector issues unless we went that route. From what I've heard from others I can see why. I would PM Scrod or see if he jumps in here as he can rebuild yours or sell you new or rebuilt ones. He did a Cummins for an extremely picky friend of mine who was very happy with the results. Others here have used his services with great results.

 

[geofish]

I would try a recomended injector shop and have your existing injectors cleaned/repaired and tested rather than go to a big reman outlet. Lots of time they just need a good cleaning and will work like new saving you some money. Even if you want to go up/down in size a good shop will have some on hand and if you do have a problem the shop is close and you can make an exchange quickly with no BS. There is something to be said for a smaller shop where there is accountability with every worker and they meet the end user.

Good Luck
Geo

 

[JLR]

Mike - Interstate McBee is what I used to replace the Reliajunk when I needed to replace all 12 Reliajunks before and immediately after the rebuild in 2005. Still carry a spare McBee and have not had to use it.

 

[MikeP]

Thanks

The only issue I would have with having them checked/rebuilt is the time involved. I guess I should check to see what the turn-around time is to do that. I'd prefer just having injectors on hand so it's just an in/out one day thing. The McBees sound like good possibility.

There may be nothing wrong with the injectors in place but the engines do smoke at idle with a strong fuel (burn your eyes) smell. It has always done that and so do all the other 8V71TIs I see at the marina but I have finally become convinced from posts here that they CAN be smokeless and I suspect it's an injector issue. Rack/timing is correct. Engines don't smoke at all under full or partial power - only at idle and they start instantly from cold.

I'm absolutely NOT a believer in throwing parts at a problem but since the engines run very well, start immediately, and have excellent compression, injectors seem a logical deduction. OTOH, if someone has another suggestion, I'm all ears!

 

[DCMY #92]

I've always replaced mine with DDC Reliabuilt injectors from one of Florida Detroit Diesel's shops. They usually test my injectors while I wait, then exchange the bad ones for rebuilts off the shelf. I've carried a spare injector and never had to use it. After several years in the box it also tested bad.

Its a good idea to have them test the rebuilt units off the shelf before you leave the shop. They sometimes don't test good out of the box.

I've used Interstate Diesel for repair/overhaul of gen set injectors and pumps, but never tried them with DDCs.

 

[rsmith]

I bought a set of cores on EBay and used them for exchange so I always have a fresh set on hand.

 

[Genesis]

You're in MD, yes?

TIs have much poorer charge-air temperature control than TAs; the intercooler is sea water cooled and in cold water this contributes to a very cold air charge going into the cylinder. At high output this is good (colder, more-dense charge = more molecules of oxygen in the cylinder to burn the fuel with), but at low output (and especially at low power output) it contributes to poor combustion and thus lots of smoke and "stinkies", especially at idle with cold sea water in the intercooler.

I never had trouble with the "Premium" Reliabuilt+ injectors, but that's my experience. Others differ. All things being equal and having either the equipment or shop to do a quality inspection and rebuild I'd rather do that, as a local guy who has to stand behind his work beats a faceless corporation every time.

Over time the tips do erode a bit, especially if you run biocides (which are halide compounds and are rough on precision things -- like the holes in the injector tip) and that contributes to a poorer spray pattern and thus less-efficient combustion. This, plus output volume, can be tested on an injector test stand and if necessary the injector(s) that are out of spec can be rebuilt while leaving the others alone. I favor this path if, and only if, you have either the equipment or someone local who you trust does.

Make sure your rack balance is dead on along with injector height and valve clearance. All of those are critical and they don't have to be off much at all to produce smoke and odor at idle. It's also easier to check that than to pull the injectors.

If you're dead on with the clearance, rack and injector timing then I'd see if you can find a local place that can test the existing injectors on the bench for spray pattern and delivery volume. This way you're only changing the ones that are out-of-spec, and you can also test the replacements before they go back in the boat, and you've got a face-to-face interaction with the guy who says "they're good" or "they're not."

 

[rsmith]

Thanks

The only issue I would have with having them checked/rebuilt is the time involved. I guess I should check to see what the turn-around time is to do that. I'd prefer just having injectors on hand so it's just an in/out one day thing. The McBees sound like good possibility.

There may be nothing wrong with the injectors in place but the engines do smoke at idle with a strong fuel (burn your eyes) smell. It has always done that and so do all the other 8V71TIs I see at the marina but I have finally become convinced from posts here that they CAN be smokeless and I suspect it's an injector issue. Rack/timing is correct. Engines don't smoke at all under full or partial power - only at idle and they start instantly from cold.

I'm absolutely NOT a believer in throwing parts at a problem but since the engines run very well, start immediately, and have excellent compression, injectors seem a logical deduction. OTOH, if someone has another suggestion, I'm all ears!

I had one engine doing the same thing a # of years ago. A lttle smoke at start up then just a slight tint in the exh when running. I ran it like that for 2 years and a little over 500 hrs. One day after trolling at 8 kts all day I cranked up to go home and the port engine looked like the mosquito sprayer truck. when we pulled the head off the cyl with the bad injector had torched one of the valves almost in half. You could see the spray patern on the top of the piston wasnt even and had a cooked look to it. One of the rings was broken in that cyl and the liner was warped to the point we had one heck of a time getting it out. Since all the other cyls looked good we just did the one hole and head. I no longer believe a bad injector will fix its self.

 

[MikeP]

Yes, I'm in MD...well, I'm not at the moment but I will be in mid April for about 8 weeks which is when I will do the work.

I understand the intercooler/fueling issue with the TIs at idle but I feel compelled to at least determine if there is any fueling issue here and at least make them as good as they can be. If they already are...so be it.

There is a diesel outfit - JG Parks - fairly close to the marina. I have never used them for anything other than buying stuff like antifreeze/filters, etc., but I'll talk to them about doing an inspection of the injectors/replacement of any bad ones. I don't even know if they do that but I guess if they don't, they would be able to recommend someone.

Based on the compression of both engines, I don't expect any sort of valve or other issues - the compression in all cyls of both engines last year was well within the specs of the DD service manual for the engines.

My only real concern is I don't want the boat down for an extended period so that's why I worry a bit about how much time it would take to have the injectors tested/replaced as needed. OTOH, I agree that the best thing would be to have them all checked and only replace injectors that are out of spec AND have the replacement injectors checked as well to ensure they are performing correctly.

 

[Avenger]

Local shops may have the capability to rebuild and test DD injectors, and it's certainly worthwhile to deal with someone you know if you want to have them tested, but unless they're rebuilding hundreds of them in-house it's generally not cost effective compared to product from a production builder like Interstate-McBee. They use quality parts and all of their remans are tested unlike a certain other reman product. So if you want to have them checked out and replace as required it would be reasonable to go local, and you can contact Interstate and see who's a dealer in your area.

On the very rare occasion that there is a warranty issue my experiences with Interstate have been good. I probably shouldn't talk about warranty because it creates the wrong impression, (and I also have to add the standard disclaimer that past performance is not a guarantee of future results) but we just submitted a claim for one injector from a set of 12. It had started to stick so a replacement was airfreighted per the customer's insistence. The failed injector was submitted later and Interstate not only warrantied it, they picked up the airfreight as well. They certainly didn't have to do that, especially considering that the injector installation had exceeded the one year warranty.

 

[captddis]

A bad Reliabuilt premium injector caused my #1L piston to seize to the liner with 253 hours on a total rebuild. I had the pleasure of rebuilding it again!!! 10k with my free labor.
I sent the them to Derek[Scrod] for testing and he found that a couple of the holes in the tip were never made and caused a bad spray pattern. Even though the engine did not smoke.

I went with Interstates from Derek for 1/3 of the Reliabuilt premium junkers. Get the Interstates and buy them from Derek.

 

[MikeP]

Sounds like good advice...

 

[jim rosenthal]

You might try Parks Diesel up in Kent Island... they are fairly close to PNYH.

 

[34Hatt]

You might try Parks Diesel up in Kent Island... they are fairly close to PNYH.

Or listen to the members here that have used Derek and have been Very satisfied!!!
Myself Included !!!

Or you can fishing

 

[saltshaker]

...Based on the compression of both engines, I don't expect any sort of valve or other issues - the compression in all cyls of both engines last year was well within the specs of the DD service manual for the engines.

My only real concern is I don't want the boat down for an extended period so that's why I worry a bit about how much time it would take to have the injectors tested/replaced as needed. OTOH, I agree that the best thing would be to have them all checked and only replace injectors that are out of spec AND have the replacement injectors checked as well to ensure they are performing correctly.

What prompted the compression test? That's a lot of work to do unless you suspect a problem. Also would have been a great time to change the injectors since they gotta come out to do the test.

 

[MikeP]

"What prompted the compression test? "

Frankly, it was simply because I wanted to know what the compression was. Call it a throwback to my engine building days when I could give you every spec on any engine I built.

At the time, I was convinced that the smoke/fuel smell at idle was a normal 8V71 Ti thing so having the injectors tested or replacing them didn't occur to me. But now, after hearing a fair number of statements on this site, including a video or two, that claim/show no smoke at idle, I want to look into it further. Yeah - it would have made a lot more sense doing it when I was pulling injectors anyway!

 

[saltshaker]

I can relate to that. It's nice to know what you're dealing with. Also some comfort in knowing you still have good compression after all the years you've owned her. Checking the injectors makes the most sense since you already set the rack. Been hearing too many horror stories about engine failures caused by a faulty injector.

 

[captddis]

"What prompted the compression test? "

Frankly, it was simply because I wanted to know what the compression was. Call it a throwback to my engine building days when I could give you every spec on any engine I built.

At the time, I was convinced that the smoke/fuel smell at idle was a normal 8V71 Ti thing so having the injectors tested or replacing them didn't occur to me. But now, after hearing a fair number of statements on this site, including a video or two, that claim/show no smoke at idle, I want to look into it further. Yeah - it would have made a lot more sense doing it when I was pulling injectors anyway!

What were your comp numbers?

 

[MikeP]

As I recall, the lowest was in the 530 range on a 475 min spec in the service manual. But I'm not on the boat and that info is in the log. I'll check it when I get to the boat next month.