Reply
 
Thread Tools Search this Thread Display Modes
 
Old 05-11-2022, 08:58 PM   #1
Member
 
Randomwake's Avatar
 
City: Campbell river
Vessel Name: Random wake
Vessel Model: 76’ CHB 34’ tricabin
Join Date: Oct 2021
Posts: 12
Oil diluted

I have a 120hp Lehman, I sampled the oil after 200 hrs, all wear components were good. But there was some fuel dilution happening. The engine does run a bit cold 155-160 but it seems that it’s not crazy low for these motors. Anyone else have minor dilution issues? Or fixes?
Randomwake is offline   Reply With Quote
Old 05-11-2022, 09:19 PM   #2
Guru
 
kchace's Avatar
 
City: Brookline, NH
Vessel Name: Blue Heaven
Vessel Model: Albin 43 classic double cabin, twin 135 Lehmans
Join Date: Sep 2013
Posts: 2,118
I had it on my Stb 135. On a 120 you have the benefit of a separate oil supply for the injector pump. This takes the pump off of the list of possible causes. Typical fuel dilution on a 120 can come from any injector piping leaks under the valve cover (main line, fuel return line) or a poorly functioning or leaking injector. I did some pressure testing of the fuel return rail and found no leaks. In my case, my fuel dilution also showed up on a annual oil sample and slowly increased each year. I replaced the injectors with a freshly rebuilt set and subsequent oil samples proved the dilution was no longer happening.

Ken
kchace is offline   Reply With Quote
Old 05-11-2022, 09:24 PM   #3
Guru
 
psneeld's Avatar
 
City: Ft Pierce
Vessel Name: Sold
Vessel Model: Was an Albin 40
Join Date: Oct 2011
Posts: 25,471
3800 hrs and no dilution even though I typically ran around 1650-1700 RPMs.... usually my temp was up around 180.
psneeld is offline   Reply With Quote
Old 05-11-2022, 09:57 PM   #4
Guru
 
Soo-Valley's Avatar
 
City: Gulf Islands, BC Canada
Vessel Name: Soo Valley
Vessel Model: Grand Banks 36
Join Date: Jul 2019
Posts: 2,816
The lift pump may be a source, and if it is then a sign it may be ready to fail.
__________________
SteveK AKA Soo Valley
You only need one working engine. That is why I have two.
Soo-Valley is offline   Reply With Quote
Old 05-11-2022, 11:35 PM   #5
Veteran Member
 
City: Michael
Vessel Name: Piaro
Vessel Model: Rinker 24
Join Date: Apr 2022
Posts: 29
Quote:
Originally Posted by Soo-Valley View Post
The lift pump may be a source, and if it is then a sign it may be ready to fail.

If it is a mechanical fuel pump, this is the culprit in the majority of cases.the diaphragm gets a pinhole in it, which results in a (usually) slight drip of diesel fuel into the crankcase. This is a serious issue not because of loss of lubrication due to dilution but it will raise the oil level in extreme cases to where the piston skirts dip into it and deposit it on the cylinder wall which can result in a runaway engine that you cannot shut off. You can often get an advance warning something is wrong when after setting a day or 3 the engine has to crank and crank to start the first time and afterwards starts normally. Consider replacing with an electrical fuel pump.
Piaro is offline   Reply With Quote
Old 05-12-2022, 09:19 AM   #6
Senior Member
 
Tator's Avatar
 
City: Bainbridge Island/Petersburg Alaska
Vessel Name: Oz
Vessel Model: Bluewater 40' RPH 1979
Join Date: Feb 2015
Posts: 433
When I had the problem on my 120 it was because of a leak on the return rack under the valve cover. I had removed the rack to replace the injectors with re-builts and hadn't replaced the copper washers. Took it back off and put new washers in-problem solved.

Tator
Tator is online now   Reply With Quote
Old 05-12-2022, 09:37 AM   #7
Valued Technical Contributor
 
DavidM's Avatar
 
City: Litchfield, Ct
Join Date: Aug 2012
Posts: 6,287
Not necessarily related to fuel dilution, but 155-160 is more than a bit cold. This engine may not have a thermostat, but if it does, check it and probably replace it. You should run about 180.

What is the fuel dilution pct on the oil analysis?

David
DavidM is offline   Reply With Quote
Old 05-12-2022, 09:54 AM   #8
Veteran Member
 
City: Michael
Vessel Name: Piaro
Vessel Model: Rinker 24
Join Date: Apr 2022
Posts: 29
Quote:
Originally Posted by Tator View Post
When I had the problem on my 120 it was because of a leak on the return rack under the valve cover. I had removed the rack to replace the injectors with re-builts and hadn't replaced the copper washers. Took it back off and put new washers in-problem solved.

Tator

Back in olden days we were taught to heat the copper washers dull red then drop them in some water and then file them until you have an unbroken circle of shiny copper. Nowadays I have a compartmented box with an assortment of new washers but I still toss the old ones into a small cardboard box in case I need an add sized one. Of course I never do so the box just sits around as a good luck charm to ensure I have a new one the proper size.
Piaro is offline   Reply With Quote
Old 05-12-2022, 11:20 AM   #9
Member
 
Randomwake's Avatar
 
City: Campbell river
Vessel Name: Random wake
Vessel Model: 76’ CHB 34’ tricabin
Join Date: Oct 2021
Posts: 12
Quote:
Originally Posted by DavidM View Post
Not necessarily related to fuel dilution, but 155-160 is more than a bit cold. This engine may not have a thermostat, but if it does, check it and probably replace it. You should run about 180.

What is the fuel dilution pct on the oil analysis?

David
It was 5%, I do have replacement thermostat but the supplier recommends 170 degree thermostats….. I didn’t think it was worth switching and making a mess for 10 degrees.

These boats also have potential for poor coolant flow to cylinder #6 which cause excess heat and wear in #6. Which is why I assume the OEM replacement is now 10 degrees colder than the original OEM.
Randomwake is offline   Reply With Quote
Old 05-12-2022, 11:27 AM   #10
Guru
 
psneeld's Avatar
 
City: Ft Pierce
Vessel Name: Sold
Vessel Model: Was an Albin 40
Join Date: Oct 2011
Posts: 25,471
Who is propagating that these engines still, currently, widespread, etc, etc....have a no. 6 cylinder cooling problem?

When I asked American Diesel about the plug and flushing procedure...they said it was overblown and not to worry.

Believe less than 10% of what you read on the net and research the crap out of that 10%.
psneeld is offline   Reply With Quote
Old 05-12-2022, 11:41 AM   #11
Member
 
Randomwake's Avatar
 
City: Campbell river
Vessel Name: Random wake
Vessel Model: 76’ CHB 34’ tricabin
Join Date: Oct 2021
Posts: 12
Why else would they recommend a 170 thermostat, coldest setting I’ve ever heard of. In the manual optimum temp is 195, however in the same manual it recommended 180 thermostat??
Randomwake is offline   Reply With Quote
Old 05-12-2022, 11:44 AM   #12
Guru
 
rgano's Avatar
 
City: Southport, FL near Panama City
Vessel Name: FROLIC
Vessel Model: Mainship 30 Pilot II since 2015. GB-42 1986-2015. Former Unlimited Tonnage Master
Join Date: Oct 2007
Posts: 4,321
How many engine hours did it take to get to 5%?

As a long time caretaker of a couple of these fine engines, I concur on all of the above advice.

When I had a serious dilution problem on my port 120, I was told one methodt to troubleshoot would be to hook up a bicycle pump (one with a pressure gauge) to the return fuel connection at the back right side of the head and pump it up to 10-20 PSI. I didn't ever get to that sort of pressure because while trying to I noted fule bubbling up out of the top of the banjo connection at the number two injector. Turned out to be the injector itself. I always used new copper crushing washers on the return banjo and at the bottom of the injector well.
__________________
Rich Gano
FROLIC (2005 MainShip 30 Pilot II)
Panama City area
rgano is offline   Reply With Quote
Old 05-12-2022, 01:43 PM   #13
Senior Member
 
GoldenDawn's Avatar
 
City: Brentwood Bay, BC
Vessel Name: Golden Dawn
Vessel Model: Krogen 42
Join Date: May 2011
Posts: 228
I had this issue and it was the copper washers near the banjo nuts in the fuel return. I replaced them and problem solved. I also learned that I could have annealed (heat up v hot with a torch, let cool slowly) them.
__________________
John Harper
Golden Dawn, KK42-82
GoldenDawn is offline   Reply With Quote
Old 05-12-2022, 08:32 PM   #14
TF Site Team
 
slowgoesit's Avatar
 
City: Puget Sound
Vessel Name: Muirgen
Vessel Model: 50' Beebe Passagemaker
Join Date: May 2019
Posts: 1,892
Quote:
Originally Posted by GoldenDawn View Post
I had this issue and it was the copper washers near the banjo nuts in the fuel return. I replaced them and problem solved. I also learned that I could have annealed (heat up v hot with a torch, let cool slowly) them.
Actually letting copper cool SLOWLY tempers it, it does not anneal copper. Copper acts the opposite of steel or iron in this respect. So, to SOFTEN (anneal) copper, you heat it up to the appropriate temp, then quench it quickly in either oil or water as discussed above.
Letting it cool slowly results in the copper being HARDER, not SOFTER.
__________________
Vessel Name: Muirgen
Vessel Model: 50' Beebe Passagemaker
slowgoesit is offline   Reply With Quote
Old 05-12-2022, 10:41 PM   #15
Senior Member
 
GoldenDawn's Avatar
 
City: Brentwood Bay, BC
Vessel Name: Golden Dawn
Vessel Model: Krogen 42
Join Date: May 2011
Posts: 228
Slowgoesit - thank you for the correction!
__________________
John Harper
Golden Dawn, KK42-82
GoldenDawn is offline   Reply With Quote
Old 05-13-2022, 01:57 AM   #16
Guru
 
Lepke's Avatar
 
City: Between Oregon and Alaska
Vessel Name: Charlie Harper
Vessel Model: Wheeler Shipyard 83'
Join Date: Jun 2016
Posts: 2,700
In tests I've seen, diesels run better at higher temps. OEM makers usually recommend lower temps to warranty avoid boil over issues.
I run my diesel pu at 205° and get much better mileage and more power.
Lepke is offline   Reply With Quote
Old 05-13-2022, 07:43 AM   #17
Guru
 
City: Rochester, NY
Vessel Name: Hour Glass
Vessel Model: Chris Craft Catalina 381
Join Date: Aug 2019
Posts: 5,195
Quote:
Originally Posted by Lepke View Post
In tests I've seen, diesels run better at higher temps. OEM makers usually recommend lower temps to warranty avoid boil over issues.
I run my diesel pu at 205° and get much better mileage and more power.

It's true of most engines, gas or diesel. Running them hotter means hotter cylinder walls and better thermal efficiency, plus better fuel vaporization. It's generally a balance of running it warmer vs when it starts to cause durability problems, or for a gas engine, pre-ignition. And on some engines, it's hard to run the coolant warmer without making the intake air too hot (which hurts power and on a gas engine further reduces pre-ignition margin).
rslifkin is offline   Reply With Quote
Old 05-13-2022, 04:45 PM   #18
Senior Member
 
TowLou's Avatar
 
City: North NJ
Vessel Name: Bassey
Vessel Model: 17' Bass
Join Date: Aug 2016
Posts: 295
A diesel ignites with heated air from the compression (no ignition spark) and the atomization of the fuel the closer to 180 for water temp you can get the better. You could have unburnt fuel you could have a leaking injector or fuel pump as well. I have seen all 3 contribute to dilluted oil. The leaky injector actually increased the standing level in the oil pan it was that bad.
TowLou is offline   Reply With Quote
Old 05-16-2022, 02:02 PM   #19
Senior Member
 
City: Northport
Join Date: Jun 2018
Posts: 307
Quote:
Originally Posted by kchace View Post
I had it on my Stb 135. On a 120 you have the benefit of a separate oil supply for the injector pump. This takes the pump off of the list of possible causes. Typical fuel dilution on a 120 can come from any injector piping leaks under the valve cover (main line, fuel return line) or a poorly functioning or leaking injector. I did some pressure testing of the fuel return rail and found no leaks. In my case, my fuel dilution also showed up on a annual oil sample and slowly increased each year. I replaced the injectors with a freshly rebuilt set and subsequent oil samples proved the dilution was no longer happening.

Ken
Good summary. Thx
Alisske is offline   Reply With Quote
Old 05-16-2022, 05:22 PM   #20
Guru
 
rgano's Avatar
 
City: Southport, FL near Panama City
Vessel Name: FROLIC
Vessel Model: Mainship 30 Pilot II since 2015. GB-42 1986-2015. Former Unlimited Tonnage Master
Join Date: Oct 2007
Posts: 4,321
Do not forget a leaking diaphrgm in the diesel LIFT PUMP as a possible source of fuel dilution in a FL120. Never had an issue with it in many years running a pair of them. I have heard of people replacing that pump with an electrical fuel pump avoiding the issue altogether.
__________________
Rich Gano
FROLIC (2005 MainShip 30 Pilot II)
Panama City area
rgano is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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


» Trawler Port Captains
Port Captains are TF volunteers who can serve as local guides or assist with local arrangements and information. Search below to locate Port Captains near your destination. To learn more about this program read here: TF Port Captain Program





All times are GMT -5. The time now is 03:25 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012