Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 16-08-2014, 16:45   #31
Registered User

Join Date: Aug 2010
Posts: 74
Re: Rough Idle on Caterpillar 3208 Suggestions?

Don't get frustrated and focus on the basics. You've got a good engine that doesn't smoke, seems to have good compression, and runs well once above idle. Don't let anybody talk you into pulling the injectors, or, even worse, the injection pump (at least not yet).

It sounds like you have bled the low-pressure side of the fuel system, but you need to also bleed it all the way to the injectors. I don't have any experience with your particular engine -hopefully someone will respond with the detailed procedure, but generally once you are past the injection pump you can no longer use the manual lift pump like you have been doing -you need to have someone turn over the engine with the starter to finish bleeding all the way to the injectors.

You seem to imply that there are no 'good' mechanics available to you. The thing that separates the good ones from the mediocre ones is their ability to provide good diagnostics. Luckily, If you decide to seek help, I think a mediocre mechanic can handle this -just be sure to insist he concentrates on these simple fuel issues first.
__________________

__________________
Yukon Cornelius is offline   Reply With Quote
Old 16-08-2014, 16:54   #32
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 17,068
Re: Rough Idle on Caterpillar 3208 Suggestions?

They run, so idle them up and loosen each injector line one at a time, let it squirt some fuel out and re-tighten them, have a rag to catch the squirt and only loosen one at a time, when you loosen one, the engine will quit running on that one cylinder as of course it's not getting fuel so don't worry when it runs rough with the line loosened.
This is real, real basic Diesel stuff, real sure someone on your dock knows how to do this, just ask around. Once you see it done, you'll think is that all there is to that?
__________________

__________________
a64pilot is offline   Reply With Quote
Old 17-08-2014, 07:05   #33
Registered User
 
whatever's Avatar

Join Date: Mar 2009
Location: on the boat
Boat: Jefferson Motoryacht 45' Whatever!
Posts: 149
Re: Rough Idle on Caterpillar 3208 Suggestions?

Responses to previous suggestions...No glow plugs..If bleeding from high pressure side is cracking all the injector nozzle nuts, have done that before and have done 6 of the 8 on port motor just the other day, but will all 8 again. Will also inspect vent tube and try without filler cap on fuel tank. I am also going to put a pony tank to circumvent the main tank with fresh fuel. Will respond with results or subsequent psychiatric admission! Used to be a Shrink, now I understand the true feeling of conflict. Thanks to all you guys that have been trying to help us plug along thru this nightmare and provide hope and encouragement!!!
__________________
whatever is offline   Reply With Quote
Old 17-08-2014, 07:43   #34
Registered User
 
whatever's Avatar

Join Date: Mar 2009
Location: on the boat
Boat: Jefferson Motoryacht 45' Whatever!
Posts: 149
Re: Rough Idle on Caterpillar 3208 Suggestions?

One other thought...it has been puzzling to both the Admiral and myself thru all this, is we have a 12.5 Westerbeke genset that runs from the same fuel supply. If the fuel is bad, or there is air in the fuel lines, wouldn't the genset run bad as well? Or is it not as sensitive as the motors? Would this somehow indicate that it is "possibly" the injectors or the fuel injector
pump(s)? That has been our thought all along, as one had mentioned previously both start acting up so close together was so hard to believe for us as well!
__________________
whatever is offline   Reply With Quote
Old 17-08-2014, 08:44   #35
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
Re: Rough Idle on Caterpillar 3208 Suggestions?

I don't think both pumps and your injectors on both engines went bad at the same time. That is why I think you have an air leak in the system. Could be wrong, its difficult to diagnose a problem on the internet. However, they are great engines and should last a long time.

As for cracking the injector lines, I don't think that is necessary once the engines are running. If you can run the engines above 1,000 rpm and they are smooth and clean I don't think you have an engine problem per se. Do hook up the pony tank and let us know what happens.

Oh, about the genset. It runs at a higher rpm and at a specific rpm. It might not idle so well either.
__________________
The Blue Dot Campaign. This Changes Everything.
DeepFrz is offline   Reply With Quote
Old 17-08-2014, 08:59   #36
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 17,068
Re: Rough Idle on Caterpillar 3208 Suggestions?

Gen set also has a different fuel line and return line too, I bet
__________________
a64pilot is offline   Reply With Quote
Old 17-08-2014, 09:21   #37
Registered User
 
whatever's Avatar

Join Date: Mar 2009
Location: on the boat
Boat: Jefferson Motoryacht 45' Whatever!
Posts: 149
Re: Rough Idle on Caterpillar 3208 Suggestions?

This is the Admiral here...So DeepFrez you don't think we have to crack the nuts on the injectors? We thought that was also needed to ck for bad injector. Now I am assuming the pony tank is to bypass any air leaks instead of possibility of bad fuel? And yes the Genset has different line and return line, so that would indicate maybe not the fuel? unless because of what DeepFrez said running at higher rpms and it does that from the getgo.
__________________
whatever is offline   Reply With Quote
Old 17-08-2014, 09:27   #38
Senior Cruiser
 
Sailmonkey's Avatar

Cruisers Forum Supporter

Join Date: Sep 2009
Location: Houston
Boat: '76 Allied Seawind II, 32'
Posts: 5,787
Re: Rough Idle on Caterpillar 3208 Suggestions?

Like I said earlier in this thread, and have experienced on my own boat, you've either got dried out hoses or dried out packing on the fuel valves. These usually won't leak fuel, but will introduce air.

Just get a five gallon jig of diesel, a short length of fuel hose and run from the jug to the secondary (include the lift pump) and see if the problem disappears.
__________________
Sailmonkey is offline   Reply With Quote
Old 17-08-2014, 09:34   #39
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
Re: Rough Idle on Caterpillar 3208 Suggestions?

Don't over think the problem. Just take it one step at a time. See how it runs with a pony tank and then we go from there. It could well be what sailmonkey says. Its as good a guess as any right now.
__________________
The Blue Dot Campaign. This Changes Everything.
DeepFrz is offline   Reply With Quote
Old 17-08-2014, 09:39   #40
Registered User
 
whatever's Avatar

Join Date: Mar 2009
Location: on the boat
Boat: Jefferson Motoryacht 45' Whatever!
Posts: 149
Re: Rough Idle on Caterpillar 3208 Suggestions?

SailMonkey as far as we can tell, all fuel hoses except for the return lines are either copper or steel. Not sure where any packing would be either on the fuel valves. We will be hooking up a pony tank, and will report back results when that is done..DeepFrez that is my(Admiral) problem exactly and the Captain tends to run that direction as well, over analysis
__________________
whatever is offline   Reply With Quote
Old 17-08-2014, 09:58   #41
Moderator
 
HappyMdRSailor's Avatar

Cruisers Forum Supporter

Join Date: May 2008
Location: North Mississippi
Boat: 48 Wauquiez Pilot Saloon-C22 Chrysler Sunpiper- 19 Potter-Preparing to cruise w/my girl
Posts: 5,980
Re: Rough Idle on Caterpillar 3208 Suggestions?

Quote:
Originally Posted by whatever View Post
SailMonkey as far as we can tell, all fuel hoses except for the return lines are either copper or steel. Not sure where any packing would be either on the fuel valves. We will be hooking up a pony tank, and will report back results when that is done..DeepFrez that is my(Admiral) problem exactly and the Captain tends to run that direction as well, over analysis
Sealing the stem (for the handle) of the (any) ball valve

One air leaky in in the system = your problem symptoms...

A day (pony) tank should take about 10 min to set up max...
__________________
In the harsh marine environment, something is always in need of repair...

Mai Tai's fix everything...
HappyMdRSailor is offline   Reply With Quote
Old 17-08-2014, 10:00   #42
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
Re: Rough Idle on Caterpillar 3208 Suggestions?

I hope you do have one piece of flexible fuel line at the engine. The line from where the steel line leaves an attachment point on the hull structure to where it attaches to the engine needs to be a flexible line or the steel line will develop cracks.

Over thinking a problem is something I struggle with as well. When one is faced with something new, something way out of one's experience, it can be daunting to take that first step. What is the old saying? Oh yeah, "Get off your buts and do it".
__________________
The Blue Dot Campaign. This Changes Everything.
DeepFrz is offline   Reply With Quote
Old 17-08-2014, 10:25   #43
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
Re: Rough Idle on Caterpillar 3208 Suggestions?

Here is an interesting article that may help with your problem or with future problems. Written by my mechanical guru.
The Vacuum Gauge Tool - Professional BoatBuilder Magazine
__________________
The Blue Dot Campaign. This Changes Everything.
DeepFrz is offline   Reply With Quote
Old 17-08-2014, 12:11   #44
Moderator
 
sailorchic34's Avatar

Cruisers Forum Supporter

Join Date: Feb 2011
Location: SF Bay Area
Boat: Islander 34
Posts: 4,815
Re: Rough Idle on Caterpillar 3208 Suggestions?

I'm with DeepFrz. Your injectors are most likely fine. You mention that with manifold valve closed, engine ran smooth at idle. when Open the idle varied. So look at the valves and upstream between manifold and tank(s) for the vacuum leak. That's where it is.

Could easily be a valve stem leaking or a slightly loose fitting or cracked hose. It's not the tank vent if the generator runs fine.
__________________
sailorchic34 is offline   Reply With Quote
Old 17-08-2014, 18:07   #45
Registered User
 
Stu Jackson's Avatar

Join Date: Jan 2011
Location: Cowichan Bay, BC (Maple Bay Marina)
Posts: 6,389
Re: rough idle on Caterpillar 3208 Suggestions?

Quote:
Originally Posted by motion30 View Post
One of my 3208s does that , especially when cold. I can bump the throttle up a little bit and it smooths out.
+1,000

1000 rpm max for transmission issues is way too low. 1200 to 1300 for my Universal with a Hurth. Anywhere the engine "feels" comfortable is just right, either set it on the throttle adjustment stop bolts or with your hand at the binnacle. Your rpm is being reported by either the alternator or a mech sensor on the engine, and it ain't "perfect."

I think you're over complicating this a whole lot.

But then again you said you were a shrink!

Good luck.
__________________

__________________
Stu Jackson
Catalina 34 #224 (1986) C34IA Secretary
Cowichan Bay, BC, (Maple Bay Marina) SR/FK, M25, Rocna 10 (22#) (NZ model)
Stu Jackson is offline   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Volvo 2040 Rough Idle when Cold ben373 Engines and Propulsion Systems 5 03-08-2014 08:27
Rough idle and cuts out when going into gear nonamebrand Engines and Propulsion Systems 12 09-07-2014 08:20
Lombardini rough idle daveNZ Engines and Propulsion Systems 12 08-03-2014 10:25
Caterpillar 3208 10 rpm difference between engines Krawdad Engines and Propulsion Systems 15 29-11-2012 21:11
Engine idle woes-Will not idle after warm Pa La O La Engines and Propulsion Systems 5 24-09-2006 13:13



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 00:51.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.