question: fuel filter vacuum gauge

The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
See posts with no answers
S

seattleboatguy

Senior Member
Joined
Nov 2, 2013
Messages
327
Location
USA
Vessel Name
Slow Bells
Vessel Make
Marine Trader 38
I have twin 135hp Fords on my Marine Trader 38, and I am thinking about installing a vacuum gauge on the fuel filters. I don't need a remote display at the helm; just something to check in the morning before I take off. My original idea was to buy some $3.99 vacuum gauges on amazon and stick them on a T on the discharge side of my Racors. But, I see there are super duper gauges for the Racor T handle fitting that sell for $60 to $80. Is the super duper option really worth that much more money?

1.jpg
 
Go to McMaster-Carr and get some liquid filled ones. The liquid dampens the pulsations from the lift pump. I bought some a couple of years ago, I think around $25.
 
Vacuum is Vacuum, but use a decent gauge as BobH mentions. No need to do the Racor specific application. Mcmaster is an excellent source for all this stuff...

McMaster-Carr
 
the one on my boat works fine but it doesn't have a drag needle to hold the highest reading till reset. I think that would be handy.
 
Steve said:
the one on my boat works fine but it doesn't have a drag needle to hold the highest reading till reset. I think that would be handy.
Click to expand...
I have never messed with one of these vacuum gauges, but I would think that the vacuum would be the same whether the engine is running or not. Is this what you are seeing in your boat?
 
IMO they are a waste of money for a low fuel flow engine like a Lehman. You rarely see any significant vacuum reading until the filter element is completely clogged up. Even then you may not see that much vacuum on the gauge.
 
If you install a gauge don't get the ones that go on top of the racors. When you change filters the Tee handle gets dropped. Slippery fingers diesel and all end them fairly quickly.

The problem with these gauges, when installed between the primary and secondary is you don't know if the secondary is getting clogged. You should actually install it after the secondary. Then again, if you keep up with your primary changing the secondary shouldn't need changing. (Much)

You will see a buildup of vacuum when the filters get clogged. The vacuum goes away when you shut off the engine. They do sell the gauges with a 'set needle' that stays at the maximum, but this only works if you remember to re set it each time. Better to have a gauge to read when running the engine. You have to get all the air out of the line when installing. air is compressable. and alters readings.

Having a gauge on each filter is great. You get an idea which tank has the bad fuel. My boat has a common vac gauge after the primarys so I cant tell which tank is bad, so I have to change both.

I have seen as much as 7 lbs vacuum on mine when I had bad fuel. But the engine starts making telltale hiccup noises and slight rpm fluctuations. But I know it's coming, with confirmation from the gauge
 
Have "the" gauge. But why worry unless there isn't sufficient fuel flow for full power?
 
markpierce said:
Have "the" gauge. But why worry unless there isn't sufficient fuel flow for full power?
Click to expand...
I'd sort of like to know before I go through woods hole with 7 knots of current, rocks and ferrys to dodge if the fuel is got a high vacuum or not.

Totally predictive. Nothing like an extra thing to help me decide if/when filters need changing.

When I run on clean filters I show around 1 to 2 lbs vacuum. When it starts to clog up it moves slowly to 3 or 4 lbs vac. Time to change 'em before it's an issue.
 
Is there an electronic "read it on the bridge" version?
 
Fuel blockage doesn't happen all that quickly unless your engine(s) suddenly stall. Applying "full power" occasionally (every time out/daily when underway is a good test of fuel flow.
 
If you install a gauge don't get the ones that go on top of the racors. When you change filters the Tee handle gets dropped. Slippery fingers diesel and all end them fairly quickly.

The problem with these gauges, when installed between the primary and secondary is you don't know if the secondary is getting clogged. You should actually install it after the secondary.
Click to expand...

Whaaaat?!!

1) I don't know what engines you are talking about, but you will find that the secondary is often, if not always on the pressure side of the fuel pump. So you need a pressure gauge over there if anything. I haven't seen otherwise, but then again I have far from seen them all.

2) The gauges replace the T-handle. In God knows how many filter changes, klutzy old me has had zero problems with this, and I am an expert at creating problems.

I have seen as much as 7 lbs vacuum on mine when I had bad fuel
Click to expand...
What kind of engine? 7 is very low and well into the green zone for every diesel I know of.
 
Last edited:
caltexflanc said:
Now gee, why would they do that??
Click to expand...


You are correct. I have two secondaries. I forgot about the one just upstream from the fuel pump. For some reason the PO had another secondary after the primary's but before the lift pump. Perkins 4.236


When I was bringing her home last summer off Erie Pa the engine was making funny tonal hunting sounds. The vacuum was in the vicinity of 10 lbs. This summer after a rough trip it went to 7 and I changed them. Fuel filters are cheap. Wife and Grandkids aboard with engine problems.... Priceless. It's different with just myself as mechanic and Captain. Without an engineer I tend to err on the side of caution.

Wish I had a picture of my gauge. It is on a hose, which the PO ran up out of the engine room and fastened it along the edge of the companionway. Barely noticeable. But it is nice to be able to glance down to see how the Vac is holding. Or not. Without lifting hatches. Really, if you had to lift a hatch, would you? Or would you just keep running until it stopped? It would be like having Temp gauges under the deck. Pretty useless down there.
 
Last edited:
Vacuum gages tell us when we are near ready to change the filters keeping us out of trouble and saving time and money. These are 2" gages glycerin filled with snubbers to quiet down the fuel pulses adding accuracy and make reading easier (about $20 each). A new filter is at about 2 psi and it will begin to flutter the engine at about 12 psi - it takes about 600 gallons burned per engine before the gage will go from 2 to about 8-9 psi.


 
markpierce said:
Fuel blockage doesn't happen all that quickly unless your engine(s) suddenly stall.
Click to expand...

Engine(s) are there to keep the captain cool. Watch how un-cool he gets when they suddenly stop running.

Yes, been there done that. Fortunately there wasn't a thing to hit within 100 miles and the Ocean was flat, so I got it all sorted..... at 3am.
 
smitty477 said:
it takes about 600 gallons burned per engine before the gage will go from 2 to about 8-9 psi.

That all depends on whether you got nice, clean, fresh fuel last time you hit the fuel dock, how long it sat, what the wonderful world of biochemistry is doing in your tanks, and whether the sea state you're in is enough to shake something loose that grew a looooong time ago.

I've had it happen in hours.
Click to expand...
 
"That all depends on whether you got nice, clean, fresh fuel last time you hit the fuel dock, how long it sat, what the wonderful world of biochemistry is doing in your tanks, and whether the sea state you're in is enough to shake something loose that grew a looooong time ago."


Yes - of course it does I agree completely. It also has a lot to do with exactly which fuel filters you are running.
In a past boat I also have had filters plug within hours from new leading me to add vac gages to that boat as well - and on that boat I added two sets of gages on each engine one after a new bulk filter that I added and another after the Racors that were already installed. Those increased the time between filter changes by more than 400% until I could get the tanks much cleaner.
I find that the gages not only help with when to change the filters but also immediately rule out some potential engine problems when they are encountered.
I just mentioned the current real data point about 600 gallons since it always seemed better to change a filter when it needed it rather then based upon some other non related reasons such as seasonal or hours of use.
 
I have Racor mounted gages on both filters. They work fine. I usually see 0 on the large 30 micron unit, and 1-2 on the smaller 10 micron unit with new elements.
 

Attachments

  • fuel system (768 x 512).jpg
    fuel system (768 x 512).jpg
    129.1 KB · Views: 95
Oooh, shiny! While we're in this part of the engine room, how many of you have it set up so you can circulate fuel out of various tanks through the filters? IE a permanent scrubbing system with it's own circulation pump, ie you can do this at the dock?
 
The gauge is really useless at idle so unless you climb down to check it when running under a load the gauge will read low even when the primary is nearly clogged. Diesels use more fuel under a load then at the same RPM in natural (the governor does this to maintain RPM) so it is best to be able to view the gauge under normal operating conditions and note changes over time.

Rough seas mixing up the tank gunk, bad load of fuel, faulty primary fuel filter will all cause a rapid fuel starvation situation from a clogged filter (I have experienced all three) Murphy will see to it that this happens at a most inopportune time. On a non-inspected boat the line from the T to the gauge can be a 1/4" vacuum hose and can easily be snaked up to a visible location near the helm.

Just another tool in the tool box, I like mine and it works well, view-able at the helm and was not expensive.
 
Capt.Bill11 said:
IMO they are a waste of money for a low fuel flow engine like a Lehman. You rarely see any significant vacuum reading until the filter element is completely clogged up. Even then you may not see that much vacuum on the gauge.
Click to expand...

Yes. I never see my gauge move, even under load at cruising speed.

Jim
Sent from my iPad using Trawler Forum
 
jleonard said:
I have Racor mounted gages on both filters. They work fine. I usually see 0 on the large 30 micron unit, and 1-2 on the smaller 10 micron unit with new elements.
Click to expand...
I'm running 10 micron on primarys and 2 micron on secondarys. Trying to play catch up with years of crud.
 
We have them on our polisher, main and genset filters. I never really see the gauge move on the genset filters which are higher micron filters. For the polisher and the main we use 2 micron filters and the gauges surely indicate the condition of the element inside. It's nice looking at them during routine engine checks and I make it a habit to check the vacuum level on the main filters before coming thru an inlet if we've been out.

I would suspect those that don't see the gauge move much are using larger micron filters just based on our experience.
 
SCOTTEDAVIS said:
The gauge is really useless at idle so unless you climb down to check it when running under a load . . . so it is best to be able to view the gauge under normal operating conditions and note changes over time.
Click to expand...

That is where the drag needle comes in -- it stay set (until manually reset) at the highest reading the indicator needle reached. Very handy!
 
oscar said:
Oooh, shiny! While we're in this part of the engine room, how many of you have it set up so you can circulate fuel out of various tanks through the filters? IE a permanent scrubbing system with it's own circulation pump, ie you can do this at the dock?
Click to expand...

I built mine so I CAN do that by adding a piece of hose and a fitting, but I found that is not necessary with the system I installed.

I'm running 10 micron on primarys and 2 micron on secondarys. Trying to play catch up with years of crud
Click to expand...

I hear ya....been there also.
 
You must log in or register to reply here.

Similar threads

P
Racor filter - Wireless Vacuum Gauge?
Replies
13
Views
808
RickyD
RickyD
tcoop
Fuel Vacuum Question
Replies
24
Views
2K
Capt Ray
C
PhilPB
Fuel Filters
Replies
15
Views
2K
jleonard
jleonard
slowgoesit
  • Locked
For Sale: Racor 500fg, twin setup w/ vacuum gauge
Replies
1
Views
522
slowgoesit
slowgoesit
Barking Sands
Had to open up the port fuel tank..always something.
2
Replies
31
Views
3K
Barking Sands
Barking Sands

Latest posts

Back
Top Bottom