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CaptG · 14-06-2007, 15:26

I guess I will have to reserve judgement about the actual rpm until I can get handheld tach to confirm.
While I was running at max throttle in gear tied to the dock I captured a sample of the exhaust water. It seems to be loaded with black gritty stuff like carbon. Could it be that the extra power & revs she is making with the rebuilt injectors & pump is blowing out years of carbon build up from low speed running? Or is blowing carbon the result of too much load? ie. too much prop for the additional power after rebuild of IP. Keep in mind if I reduce rpm to the max she would make before IP rebuild there was no black sooty discharge from exhaust.
Tell me what you think.

Aloha..........Gerry

Maddog · 14-06-2007, 15:54

Is it hard and gritty? Like it came from the exhaust elbow.

CaptG · 14-06-2007, 17:18

Maddog...........Yes it is hard, gritty,& black. There is also some black smoke but not excessive for a diesel. The exhaust elbow is 6 months old & not clogged. As stated in last post if I back off to previous rpm( pre IP rebuild) it all clears up.

Aloha........Gerry

CaptG · 14-06-2007, 22:02

Aloha to all........I'm going to try a new approach on this problem. Let's start with what we do know to try to discover what we don't know. Here's what we do know.
1) The boat ,motor, tranny, & prop are original equip.

2) I've run the boat for the last 3 years..no smoke & no soot at full throttle. 1300rpm by my tach which I suspect is only reading half of actual rpm. That's what it's read since i've had the boat. (3 years)

3) The seals on the injection pump started leaking so I remove it & injectors and sent them to a highly recommended shop in So Cal for rebuild.

4) Reinstalled rebuilt pump & injectors.

5) Now I get another hundred rpm (1400 by my tach) & lots of soot & some black smoke @ full throttle in gear.

6) Only 2 events happened between running good with no smoke or soot and lots of soot & some smoke. a)The
pump & injectors were rebuilt. b) I reinstalled rebuilt pump & injectors.
Question...given all of the above doesn't it sound like the most likely problem might be retarded pump timing? It's the one thing that makes sense to me. What do you guys think? I value your input.

Aloha ..........Gerry

SkiprJohn · 15-06-2007, 02:18

Capn Gerry,

My Mercedes service manual says: Trouble - Engine is sooting strongly, emits thick black clouds of smoke - The cause is: 1 )Injection pump injects too early or too late or the Injection pump is not in order. 2)Retainer on the adjusting sleeve has become loose and changed feed volume or compression of individual cylinders is too low. 3)Wrong fuel or Leaky governor diaphragm. 4)Full load stop device worn after long operation of injection pump. 5)Engine sucks infiltrated air.

I think your pump might be out of time but I couldn't possibly be certain.

Kind Regards,

JohnL

Maddog · 15-06-2007, 07:55

Pump timing is beyond me. I would call the shop first and ask the same questions. Who did you use in So. Cal.? I live here and would be interested in who you used. PM me if you don't want to publish the name on the forum. If you are interested, I can suggest another shop.

SkiprJohn · 15-06-2007, 11:17

Capn Gerry,

The timing is a matter of pump installation and turning the pump on its mount to coincide with when no. 1 piston is tdc. It doesn't have much to do with who worked on the pump itself. You probably know that already!!

There is a pump shop here on the Big Island. About 5 miles from my house.

Kind Regards,

JohnL

CaptG · 15-06-2007, 16:01

Aloha guys...Well I spent my morning tweaking the IP timing. First went slightly advanced of the alighnment marks then slightly retarded of the marks. It got worse both ways so I went back to spot on the marks. Back to square 1. I talked to the guys at the shop & they think my tach is only reading half of actual rpm. With the 18x14 prop the motor is happy up to 2600 rpm but can't handle 2800 and starts to smoke & soot. Makes sense. I will know more after I get a handheld tach to verify actual rpm. In the meantime I'll just run her at the rpm Iv'e always run as she is perfectly happy at that rpm. I'll post back when I verify tach speed.
Thanks for all the help.
Aloha........Gerry

SkiprJohn · 15-06-2007, 16:59

Aloha Capn G,

My little Mercedes (same size as your engine) has two versions of the engine, industrial/commercial and auto/truck. The auto/truck version has a centrifugal injection timing device attached in front of the IP so that you can rev the engine to 3600 with no problem. My industrial version's governor is set at max 2534. I do believe that if I tried to push the rpms to somewhere above 2800 it would do the same as yours because the fuel pump timing is wrong for that speed because of the lack of that centrifigal injection timing device.
So maybe your engine is doing what it is supposed to do just as you say and the tach isn't reading correctly just as you suppose. That would certainly explain a lot.
Kind Regards,
JohnL

CaptG · 15-06-2007, 19:09

Aloha John.......I forgot to mention something very important to this whole issue in my last post. On the data plate of the pump there is a series of numbers. The last set of numbers is the setting code for the shop to set up the IP. There are different settings for different applications. The 1st 2 numbers of the last set have to do with the max amount of fuel that can be delivered per a given amount of time. Mine was originally a PH 25 but for whatever reason they set it at PH 30. The result is the slightly higher rpm @ full throttle. Apparently the navy has these boats propped right to the limit and the extra rpm was too much load for the old girl. Thus smoke & soot. I rigged a throttle stop to allow only the original rpm and she is running smooth with no smoke or soot.
Now I need to solve the tach issue if for no other reason than wanting to know if it is only showing half rpm. I guess I'm just going to hava to cough up the extra $40 for shipping a 6 ounce package to Hawaii from the west coast. What price paradise?
Thanks again to everyone for the input.

Aloha............Gerry

SkiprJohn · 15-06-2007, 22:07

"extra $40 for shipping a 6 ounce package to Hawaii from the west coast."

I wish I could have back what I've spent in exhorbitant shipping charges to Hawaii. I try to get folks to use USPS whenever possible.

JohnL

SkiprJohn · 15-06-2007, 22:27

Aloha Capn G,

This is a digital in eBay. There is a bunch of them by the same company. Maybe they can do a better job of cheap shipping.

eBay Motors: DIGITAL LASER PHOTO TACHOMETER NON CONTACT NIB TACH RPM (item 160126645033 end time Jun-16-07 13:14:39 PDT)

CaptG · 16-06-2007, 11:32

John........Mahalo for the info on the tach. Having the product name I was able to google it & found lots of hits. I ordered 1 on Amazon......$48 including shipping. When I get it & test the boat tach I'll post back with results. In the meantime I think I'll go catch my dinner. I think I'm ready for some BBQ mahi-mahi & a couple of cold brews.

Thanks for all the help.
Aloha........Gerry

CaptainK · 16-06-2007, 12:08

Quote:

Originally Posted by SkiprJohn

"extra $40 for shipping a 6 ounce package to Hawaii from the west coast."

I wish I could have back what I've spent in exhorbitant shipping charges to Hawaii. I try to get folks to use USPS whenever possible.

JohnL

Remind me not to ship anything to Hawaii!!