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 Post subject: BRC System Question
PostPosted: Mon Aug 21, 2017 7:02 pm 
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Joined: Thu Aug 23, 2012 12:54 am
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Hi, hope someone can help.

I have a BRC System fitted to my car which I have had for nearly 8 years. About every 2 years (I do about 30k miles per year) I have to get the Reducer changed as the diaphragm in it splits meaning when the engine is switched off for over 5 minutes Gas leaks into the inlet Manifold meaning it takes a few turns of the key to restart it.

There is a small bore vacuum pipe from the Throttle Body to a Y piece and one pipe goes off to what I think is a Map Sensor and the other pipe goes to the Reducer to operate the rubber diaphragm when you put your foot down, its this pipe the gas leaks back through when you stop the car.

So my question is, until I get the Reducer changed again, can I just clamp the pipe from the Y piece to the Reducer to stop this problem and if I do so will it cause problems or any damage?

Thanks


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 Post subject: Re: BRC System Question
PostPosted: Tue Aug 22, 2017 9:40 am 
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Location: Yorkshire
You'll have problems with running on gas properly if you clamp it.

You're aware the vac pipe connects vacuum to one side of the diaphragm so you're likely also aware a spring pushes in the opposite direction against the diaphragm... the balance between the spring and vacuum on one side of the diaphragm and gas pressure on the other side determines diaphragm flex, diaphragm flex controls a valve which meters gas into the system, in this way the setup keeps gas at a certain level above manifold pressure. We can adjust the spring pre-load to adjust 'certain level'.

If there's a slight leak in the diaphragm gas can pass slowly from the pressure side to the vacuum side but with the leak being only slight vacuum is maintained, so reducer pressure is about normal but the engine gets a bit of un-metered gas via the vac line (which continues to flow when solenoids are off until gas from the vapour lines has escaped via the vac line, causing the long cranking problem). If you block the vac line pressure in the vac side would slowly rise until it reached the same pressure as the pressure side but this won't happen because the only force acting on the diaphram now would be the spring pressure, which will keep the diaphragm flexed to allow more gas through, so pressure wouldn't stop rising until (potentially) tank pressure is reached but way before that point the engine would stop running properly on gas. At such high pressures there is potential to do further damage to the reducer itself and perhaps also potential for damage to other components like injectors, because there can come a point where pressure is high enough to have liquid gas exiting the reducer which then evaporates where it shouldn't be evaporating, super-cooling effected components, changing tolerances, making seals and soft parts brittle, etc. This point can be reached even though well before this point the vehicle wouldn't be running well on gas at all.

Even if pressure didn't continually rise if you blocked the vac pipe it would still mean the reducer wouldn't deliver gas at pressure relative to manifold pressure. Instead reducer pressure would be constant (and most likely referenced to near atmospheric pressure). Depending on other aspects of the installation, the injectors might not be able to meter gas properly at the higher pressure (relative to manifold pressure) at low loads particularly at idle and on the over-run even if the ECU properly calculates and compensates for the higher pressure.

I find BRC sequential system reducers to be better than the average sequential reducer in terms of reliability, certainly wouldn't expect one (or almost any other reducer for that matter) to need a new diaphragm every 2 years. Aspects than can damage reducers include operation at too cold a temperature (insufficient heater water flow / changeover temp set too low / booting the throttle when it has just switched to gas with warming for cold engine), under-rated rated reducer for the spec of the vehicle (should have fitted a more capable / bigger reducer), too high or even too low a pressure setting (could see the diaphragm flex in a way it shouldn't or parts of the reducer not work together as the design intended). Perhaps contamination (engine oil or similar making way to the reducer diaphragm via the reducer vac line) could also be included in that list.

What is the condition of the diaphragms when you remove them?

Simon

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 Post subject: Re: BRC System Question
PostPosted: Wed Aug 23, 2017 9:21 pm 
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Joined: Mon Jan 23, 2012 12:21 pm
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Your best short term work around is to switch back to petrol about a minute or so before you stop the engine - this will allow the remaining pressure to bleed off and be burnt in the engine rather than filling the manifold with the engine stopped. Best long term solution is to fix it properly obviously!

Simon - I don't think hes replaced the diaphragms, sounds more like hes got an installer to change the whole unit to me?


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 Post subject: Re: BRC System Question
PostPosted: Thu Aug 24, 2017 8:26 am 
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Brian_H wrote:
Your best short term work around is to switch back to petrol about a minute or so before you stop the engine - this will allow the remaining pressure to bleed off and be burnt in the engine rather than filling the manifold with the engine stopped. Best long term solution is to fix it properly obviously!

Simon - I don't think hes replaced the diaphragms, sounds more like hes got an installer to change the whole unit to me?


Good advice Bri.

And yes I now see it does read like the whole unit was changed.

Simon

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 Post subject: Re: BRC System Question
PostPosted: Tue Aug 29, 2017 6:02 pm 
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Joined: Thu Aug 23, 2012 12:54 am
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LPGC wrote:
You'll have problems with running on gas properly if you clamp it.

You're aware the vac pipe connects vacuum to one side of the diaphragm so you're likely also aware a spring pushes in the opposite direction against the diaphragm.........

Simon


Sorry about the delay in replying, been extremely busy and then had trouble getting back on here, thanks for the replies.

Its an Astra H 1600 and I had a BRC Fly System fitted in 2009 by CLS Dual Fuel in Durham, about 20 miles from me.

The Reducer they originally fitted was a BRC Genius 1200. This went just under 2 years so was replaced under the 2 Year Warranty. They replaced it with another BRC Genius 1200 and that lasted about 2 years as well. This time they replaced it with a BRC Genius 1500 and this one has lasted just over 2 years.

I bought the car with 5500 miles and its now done 250,000 miles as I use it as a Taxi doing over 30,000 miles a year so I’m getting about 60,000 – 70,000 miles out of each reducer before the Diaphragm splits. I don’t know what condition the Diapragm is in as they just replace the whole reducer.

From Cold it switches over to LPG at about 56 – 60c. I certainly don’t boot the car and always drive with economy in mind.

I am aware that there are kits available to replace the Diaphragm at about £20, I’ve seen a few on eBay. My concern about these is although it’s the cheaper option, if the quality is okay or will they go after a few thousand miles. Must be something that goes a reasonable amount of times as they seem to be selling a few, one even comes with an exploded diagram, and looking at the diagram it appears that there are that many parts I would probably end up doing something wrong. One of them being advertised on eBay suggests that the rubber parts including Diaphragm should be replaced every 50,000 miles.

Here is a link to one of them for sale on eBay: http://www.ebay.co.uk/itm/REPAIR-KIT-FO ... SwpDdVUHAN

Simon. I’m up near Middlesbrough and looking on my SatNav you are 79 miles from me. If I ordered the kit would you be prepared to repair it? If so can you inbox me a price for doing this please.


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 Post subject: Re: BRC System Question
PostPosted: Thu Aug 31, 2017 4:24 pm 
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There are few possible that could cause premature failure of all those reducers. If it is fitted too high in the engine bay or if it is plumbed in series with the heater matrix and the heater matrix is blocked that could prevent the reducer circulating enough hot water to keep it warm. If the installer fitted injectors with too small a nozzle size they might have compensated by increasing reducer pressure, which can put extra strain on reducer components including the diaphragm.

Some BRC systems have a few changeover settings - changeover delay duration from cold with anther setting that defines the cold temp, changevoer delay duration from hot with another setting that defines the hot temp.

Should be able to buy new original BRC diaphragms from Tinleytech, haven't checked your link but why buy pattern parts from Ebay when Tt is the official BRC importer... Not over complicated to swap diaphragms, sometimes the most difficult part is removing corroded bolts that hold the thing together but that shouldn't be a problem on a 2 year old unit. They should all last more than 50000 miles and a new reducer should come with a warranty anyway.

Worth bearing in mind that it's much quicker just to swap a reducer with another one than to repair the one you've got, You could save most money fixing it yourself, will save money if I fix the old one over if I supply and fit a new one but some of the money you could have put to a new one will be spent on me working on your old one.

I don't normally stock much new BRC gear but do have lots of second hand bits around including known good BRC reducers and injectors. You might want to come and have me look at your system including reducer position in the engine bay, the pressure it is set at, software settings & calibration, plumbing, etc, possibly fit a new diaphragm or swap your reducer for one I've got.

Edit - I am fully booked up for the best part of the next 3 weeks though.

Simon

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 Post subject: Re: BRC System Question
PostPosted: Mon Sep 04, 2017 5:13 pm 
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LPGC wrote:
There are few possible that could cause premature failure of all those reducers. If it is fitted too high in the engine bay or if it is plumbed in series with the heater matrix and the heater matrix is blocked that could prevent the reducer circulating enough hot water to keep it warm. If the installer fitted injectors with too small a nozzle size they might have compensated by increasing reducer pressure, which can put extra strain on reducer components including the diaphragm.


Thanks Simon, it would have to be in about 3 weeks before I could get down there.

Just to answer some of your points. The Reducer plumbing is plumbed into 2 T Pieces in the pipes going from the Engine to the Heater Matrix, don’t think theres a problem with coolant flow as theres plenty of heat inside the car when I turn the heating on.

The Injectors that were fitted are BRC Orange Injectors.

The photo in the link below is of the System Installed in my car. I took the photo some time ago hence why the Reducer in the top right of the photo looks new. Don’t know if you can tell from that if it looks to high or low but will be able to see when I bring it down in about 3 weeks.

https://i.imgur.com/IteZPLq.jpg


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 Post subject: Re: BRC System Question
PostPosted: Mon Sep 04, 2017 11:12 pm 
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Joined: Mon Jan 23, 2012 12:21 pm
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Location: Milton Keynes
smokie1010 wrote:
LPGC wrote:
There are few possible that could cause premature failure of all those reducers. If it is fitted too high in the engine bay or if it is plumbed in series with the heater matrix and the heater matrix is blocked that could prevent the reducer circulating enough hot water to keep it warm. If the installer fitted injectors with too small a nozzle size they might have compensated by increasing reducer pressure, which can put extra strain on reducer components including the diaphragm.


Thanks Simon, it would have to be in about 3 weeks before I could get down there.

Just to answer some of your points. The Reducer plumbing is plumbed into 2 T Pieces in the pipes going from the Engine to the Heater Matrix, don’t think theres a problem with coolant flow as theres plenty of heat inside the car when I turn the heating on.

The Injectors that were fitted are BRC Orange Injectors.

The photo in the link below is of the System Installed in my car. I took the photo some time ago hence why the Reducer in the top right of the photo looks new. Don’t know if you can tell from that if it looks to high or low but will be able to see when I bring it down in about 3 weeks.
https://i.imgur.com/IteZPLq.jpg



The crucial thing is if the reducer itself is hot (depending on the plumbing it may be in series or parallel with the heater matrix, only way to tell for sure is to follow the pipes).

It doesn't look too high to me as its below the level of the expansion tank, though this doesn't guarantee that you have a decent flow going through it, easiest way to check is either with the software (using the sensor to monitor the temperature) or take it on a decent run and check the temperature of the reducer quickly afterwards (it should be fairly hot - hot enough you don't want to touch it really and needs to be after its been under some engine load as well).

For example a kinked coolant hose would be enough to cause a problem if it was in parallel, or it becoming airlocked if you have a leak somewhere as well. if its in parallel then the heater may well work fine whilst little to nothing is flowing through the reducer.


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 Post subject: Re: BRC System Question
PostPosted: Wed Sep 06, 2017 10:14 am 
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Joined: Wed Sep 29, 2010 5:01 pm
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I agree with Bri that the reducer should be low enough in that position. Will say though that it's difficult to make out in the pic if the reducer water connections are both at the bottom end of the reducer. Where that's the case, combined with the reducer being relatively high up (even though it's by no means too high) there is a bit more potential for air/steam locks to appear within the reducer in certain situations (assuming it was bled properly when first fitted). Seen issues often enough that I'd avoid fitting a reducer that high with both water connections at the bottom, where done like that I'd at least expect to have to make special efforts to bleed the reducer such as disconnecting one of the pipes, removing expansion tank cap and back-filling the reducer using a length of pipe held above expansion tank level. Even if there were an airlock would expect it to eventually bleed itself given high enough engine revs to get some volume of water flowing through it. When I convert a car or fit new bits in the cooling system such as a reducer I run the engine with the rad/expansion tank cap off for a while, or remove the cap and give it a bit of a rev when the engine has cooled down enough after a drive, sometimes see bubbles flow into the expansion tank that might otherwise have been a bit of an airlock.

Just a could be - Sure that all gas that leaks into the manifold is from a split reducer diaphragm and not at least partially from a leaky LPG injector?
A lot of BRC systems are fitted with the reducer shut off solenoid some distance from the reducer, implying that when the solenoid is shut-off there is still quite a bit of liquid gas in the pipe between the solenoid and the reducer. With such a setup, if you have a leaky LPG injector the reducer can continue to flow all that gas (from the gas feed through the reducer into the inlet manifold) after the engine is switched off and since the engine isn't running there is no flow of heating water around the reducer to prevent it becoming very cold and prone to breaking reducer diaphragms. If there is one aspect of a BRC install that causes more problems than any other with injectors it is BRC valve lube systems of the type which pump lube fluid into the gas vapour feed to injectors (so lube fluid flows through LPG injectors) leading to injector gumming... and you do have a lube system of that type fitted.

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Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240


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