Jump to content

BSS and Diesel Vacuum Gauge


dmr

Featured Posts

I have been having a stubborn to diagnose intermittent engine problem for months and have now pretty much pinned it down to slight air leakage at the first fuel filter, a spin on filter.

I think that at a certain level of clogging the filter sucks in a little air well before any starvation symptoms appear. I would quite like to fit a suction side vacuum gauge, like this one:

 

https://www.amazon.co.uk/Pressure-Gauge-SODIAL-30inHg-Barometer/dp/B01IGS8OJ6/ref=sr_1_fkmr2_2?keywords=diesel+vacuum+guage&qid=1578086328&sr=8-2-fkmr2

 

Will this fail the BSS????? The issue is that we don't know what is inside it, it might have a plastic component which could have the same risk as a plastic drain plug? But as its on the suction side and will be at a higher level than the fuel tank the risk should be minimal?

 

What does the forum think?

 

..............Dave

Link to comment
Share on other sites

Inside that gauge will be a bourdon tube one end of which is sealed and attached to some gears whch in turn actuate the pointer. The bordon tube is designed to flex under the effects of pressure or vacuum and is usually made of a copper alloy. The gears are usually of brass on steel arbours running in brass plates. All a bit like the internals of a clock without as many parts. None of which should cause any issues.

 

On balance I think I'd replace the filter assembly, do you really need the extra complication?

If in doubt K.I.S.S. is the best rule to follow.

 

 

  • Happy 1
Link to comment
Share on other sites

58 minutes ago, Man 'o Kent said:

Inside that gauge will be a bourdon tube one end of which is sealed and attached to some gears whch in turn actuate the pointer. The bordon tube is designed to flex under the effects of pressure or vacuum and is usually made of a copper alloy. The gears are usually of brass on steel arbours running in brass plates. All a bit like the internals of a clock without as many parts. None of which should cause any issues.

 

On balance I think I'd replace the filter assembly, do you really need the extra complication?

If in doubt K.I.S.S. is the best rule to follow.

 

 

I know that's how proper old brass gauges work but I can't believe that a £3 gauge could have proper little gears inside, I was thinking about some "bendy plastic engineering", but then again the Chinese do make stuff unbelievably cheaply.

 

I think part of my problem was that the the filter got part-plugged much sooner than my normal filter change interval so a gauge would give a nice indication of filter condition. In fact if it allows me to extend the filter change interval it might even pay for itself one day.

 

...............Dave

1 hour ago, jonesthenuke said:

Fit the gauge with an isolating valve and say you will normally run with the valve closed?

 

 

Thought of that, but its three more potential leaks in the vacuum side of things. Would be easier to just remove the gauge on BSS day, like taking all the stuff out of the gas bottle locker ?

 

..............Dave

Link to comment
Share on other sites

Perhaps I'm getting befuddled with my age (over 21) - but, sdurely folks shouldn't build a lot of kit just to detect a problem after it has occurred?? The problem is - the filter's blocked - remedy - change filters regularly??

Proper filters are inexpensive. Check  at each oil change (?how) / replace at each engine oil change.

With a modern car that's serviced regularly (haha) filters get changed - whether or not they're needed.

 

Therefore why not with a boat engine system.

(paerhaps it's many years of servicing my car(s), that the answer is obvious....

Not for others mebe.

 

You / we're all blurry doomed... 

Link to comment
Share on other sites

I suppose that as I have been an engineer specialising in instrumentation I just like measuring things.

 

I usually change fuel filters at 600 hours and they always "look" clean. This has worked fine for over 12000 hours without issue. If I had changed the filters at engine service interval (200 hours) then I would have thrown away 80 serviceable fuel filters. My current issues are probably because two consecutive fuel filters have plugged in much less than 200 hours so even a more frequent change would not have worked.

With hindsight it sort of makes sense, In an effort to check the state of the fuel tank I had likely stirred up some particles which had gone into the filter.

The more I think about the variables of getting diesel into a boat the more I think changing filters at any arbitrary interval is a bit simplistic.

 

................Dave

Link to comment
Share on other sites

2 minutes ago, ditchcrawler said:

Lots of fuel filter set ups have a differential pressure gauge across them  https://www.asap-supplies.com/racor-fuel-pressure-gauge-rk19669

 

Yes, I looked at that but thought the £3 Amazon device might be more cost-effective. Actually I might splash out and go for the £8 Amazon jobbie ?

 

How can Racor justify £143 for a basic mechanical pressure gauge?.

Note that these do not need to be particularly accurate, we are just looking for a significant increase in vacuum.

 

...............Dave

Link to comment
Share on other sites

1 hour ago, dmr said:

I know that's how proper old brass gauges work but I can't believe that a £3 gauge could have proper little gears inside, I was thinking about some "bendy plastic engineering", but then again the Chinese do make stuff unbelievably cheaply.

 

Surely the gears don't matter, since they don't contain the fuel. As long as the bourdon tube itself is metallic it should be fine. The prospect of having the casing, dial and gears melt in a fire shouldn't be of concern to the BSS.

For £3 I would buy it and check the internals before fitting.

Link to comment
Share on other sites

2 hours ago, dmr said:

My current issues are probably because two consecutive fuel filters have plugged in much less than 200 hours so even a more frequent change would not have worked.

With hindsight it sort of makes sense, In an effort to check the state of the fuel tank I had likely stirred up some particles which had gone into the filter.

The more I think about the variables of getting diesel into a boat the more I think changing filters at any arbitrary interval is a bit simplistic.

 

................Dave

Surely the first fix is to pump out as much crap as is possible from the bottom of the tank and stop the crud blocking your filters in the first place ?

If checking your tank stirs muck up what would filling it up with diesel do?

 

Link to comment
Share on other sites

1 hour ago, PaulJ said:

Surely the first fix is to pump out as much crap as is possible from the bottom of the tank and stop the crud blocking your filters in the first place ?

If checking your tank stirs muck up what would filling it up with diesel do?

 

With the benefit of hindsight I might almost understand was has happened.

I believe my diesel tank to be very clean, but I had the opportunity to do a home-made fuel polish. This produced very little muck but I now assume stirred up some slight sediment that was not captured by my fuel polisher but did partly block the first filter. I had rough running and replaced the filter. A month or so later  I got some more diesel. It is possible that this was not of top quality, or maybe it just stirred up the loosened sediment again and so blocked a second filter. There is a second issue in that I suspect there is a quality control issue on the filters which makes getting a good seal a bit variable, which leads to an air leak rather than starvation..

 

I think the lesson is that even if you believe you have a really clean diesel tank it can still contain stuff that in the right circumstance can be stirred up. This is why I like the idea of a filter vacuum gauge. The other lesson, especially for those who do a fuel polish right before a tidal passage, is that this might be counter-productive.

 

.................Dave

Link to comment
Share on other sites

I have a plastic tube tied t a stick. I dip this in the tank and siphon out the bottom of the tank.

 Sometimes I just get apparently clean fuel but other times I draw off water, anything up to several litres.  Also often get black blobs .  I have only once had the primary filter block with black sludge, that time I siphoned off quite a bit of water and sludge.  Didn’t go for the full polishing, but added some Marine 16 and repeated the siphoning a couple of times.

Normally the filter is clean, but I still change it regularly, they are cheap enough from Inlinefilters. But when I have seen some crud, it could appear to be drawing in air, but. It isn’t.  Are you sure it’s not just your filter clogging up? The filter shouldn’t block enough to give a significant pressure drop across it on a regular basis.  I would just try and get your diesel clean and check regularly for water, especially if you are getting the fuel from an unfamiliar source.

Link to comment
Share on other sites

6 hours ago, dor said:

Are you sure it’s not just your filter clogging up? The filter shouldn’t block enough to give a significant pressure drop across it on a regular basis.

He has stated that he always changes his filter at 600 hours rather than the recommended 200 hours and that he's been having this issue for months. I'd revert to changing at 200 hours and ensuring everything was tight.  Only then, if there a was still a problem, be looking for another cause. That wouldn't involve adding gauges and worrying about the effect on BSS because, although there are applications where measuring the pressure across filters is key, cheap and simple filters on common or garden small boat engines isn't it. 

Link to comment
Share on other sites

10 hours ago, dmr said:

With the benefit of hindsight I might almost understand was has happened.

I believe my diesel tank to be very clean, but I had the opportunity to do a home-made fuel polish. This produced very little muck but I now assume stirred up some slight sediment that was not captured by my fuel polisher but did partly block the first filter. I had rough running and replaced the filter. A month or so later  I got some more diesel. It is possible that this was not of top quality, or maybe it just stirred up the loosened sediment again and so blocked a second filter. There is a second issue in that I suspect there is a quality control issue on the filters which makes getting a good seal a bit variable, which leads to an air leak rather than starvation..

 

I think the lesson is that even if you believe you have a really clean diesel tank it can still contain stuff that in the right circumstance can be stirred up. This is why I like the idea of a filter vacuum gauge. The other lesson, especially for those who do a fuel polish right before a tidal passage, is that this might be counter-productive.

 

.................Dave

I had this problem with my primary filter when I first commissioned the boat, only slight contamination of the filter but caused the same problem. I moved the filter from the engine room to the stern within a yard of the diesel tank and not had a problem since. I think it was the combination of resistance in the filter and drawing the fuel 5 or 6 yards through a small bore pipe. If I did it again I would use a much bigger bore pipe for a start and still put the filter near the tank.

 

Link to comment
Share on other sites

31 minutes ago, ditchcrawler said:

I had this problem with my primary filter when I first commissioned the boat, only slight contamination of the filter but caused the same problem. I moved the filter from the engine room to the stern within a yard of the diesel tank and not had a problem since. I think it was the combination of resistance in the filter and drawing the fuel 5 or 6 yards through a small bore pipe. If I did it again I would use a much bigger bore pipe for a start and still put the filter near the tank.

 

I have only a very short run of 5/16 to the tank, and its a shallow tank so not much lift. I am using a fine first filter whilst many "experts" suggest a very course first filter, but its worked ok for a lot of hours....till now ?

 

An old workmate had a Ford Transit camper that cut out going up steep hills on very hot days, it took him years to diagnose it.....a hairline crack in the filter head let in air when hot, the steep hill needed more suck to get fuel from the tank up to the lift pump on the engine at the front.

 

.............Dave

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.