Hi all,

I believe I have the gas leaking from the two reducers (one for each bank) into the cooling system.

One I purchased the car a little over a month ago the lpg ecu wiring still had a small amount left to do I believe the chap had upgraded it for a newer system and possibly had it running on it but took some wires off for whatever reason.

He had recently serviced both reducers himself but whether they were done right obviously is the big unknown.

Anyway I got it up and running and the map that is on it seems mostly fine, maybe slightly rough on idle I do mean slightly but since then I noticed even after sitting for 12+hours over night the coolant hoses stay pretty hard instead of returning to soft as the system cools down plus water level is tank is pushed down as soon as I release pressure when cold the it returns to the right level.

So I thought I’d remove the ecu fuse today and just run on petrol for the day and see if the coolant system stays pressurised tomorrow and even after cooling for a few hours today let alone 12+ they have gone back to soft so feel pretty confident that it’s gas leaking into it.

Not getting any visible bubbles in the tank when running off gas though maybe it’s leaking into it once off? And not actually losing coolant it seems.

Now the two reducers are what look like old Bigas ones other than them saying Bigas there is no obvious markings to suggest what model they are as it doesn’t say RI-21 on them or anything shut off valve is also separate to them so not built in.

I suppose if I could find the right parts I could service them myself but addmitdley I wouldn’t know if I’m doing it right either. I do reckon the better option would be replace but with a single vaporiser that way I don’t have all the extra coolant hoses running across the top of the intake and what not making it look at least a little neater.

Though that would definitely mean replacing the various copper lines to the reducer from shut off solenoid (currently T piece to each reducer one either side of engine bay.) though I wouldn’t even know where to begin with bending and fitting the copper pipe.

Local ish to me there I supposed to be an lpg conversion place but they never seem to pick up the phone so if they are still in business who knows.

Kinda leaves me in a catch 22 as I can’t find anywhere else nearby and I don’t know anyone personally that knows lpg. I’m not far from Coventry which is where the one I’ve been trying to contact is based. Does anyone know of any good businesses around the West Midlands? Hell I don’t mind travelling further a field of the prices are good and it’s not gonna be a place that tries saying everything needs replacing.

Hell I’d travel all the way to Norfolk or Yorkshire if necessary.

Simon, LPGC on here (and on www.lpgforum.co.uk) is just off the A1 near Doncaster. He will no doubt see this and reply shortly. Sounds as if you have correctly identified the problem and it may be due to a bodged attempt at rebuilding the reducers (or they are simply knackered). There will no doubt be a single reducer that Simon will recommend. Are we talking GEMS (pre-99) or Thor (99 onwards) motor?

Thor 4l.

Do you know if LPGC does the work aswell? Hell doncaster would work pretty well for me as I often have to pass by that regularly to see my kids up in Wakefield so would definitely be a bonus for me.

Yes, he's a full time LPG installer (although does spend a lot of his time putting right other people's installs).

Gilbertd wrote:

Simon, LPGC on here (and on www.lpgforum.co.uk) is just off the A1 near Doncaster. He will no doubt see this and reply shortly. Sounds as if you have correctly identified the problem and it may be due to a bodged attempt at rebuilding the reducers (or they are simply knackered). There will no doubt be a single reducer that Simon will recommend. Are we talking GEMS (pre-99) or Thor (99 onwards) motor?

I'm here ;-)

I agree it's going to be one or both of the reducers leaking gas into coolant, most likely just one,

My go-to reducers are MagicJet (Compact version and Extra version), those produced over the last few years all have a very wide range of pressure adjustability, either version (Compact or Extra) would be a good choice of reducer for a P38 in terms of both physical and technical and they're reliable.

If 2 reducers are fitted the gas outlets need to be T'd together. There's only one pressure sensor so if one reducer feeds one bank and the other reducer feeds the other bank the pressure sensor will only read pressure from one bank and the other bank could be getting very different pressure. It wouldn't cause any leaks or coolant pressurisation but would cause different fuelling to individual banks.

Does the system have a Bigas ECU (probably AEB2568?) and Bigas injectors?

I'm in South Elmsall, between Wakefield and Doncaster.

You are correct it is an aeb2568.

Current fuel map wise it it’s ever so slightly rough on idle and maybe slightly lacking power up a very steep hill if I was only doing 20-30mph when starting to go up at any other time to me at least it seems no different than when it’s on petrol even booting it from standstill up to 100mph it pulls very well.

Currently I have the copper pipe coming from the tank into the engine bay, that goes into a shut off valve which I had to replace the solenoid on which a bigas m20/m84 solenoid fitted so presumably that is also a bigas shut off but there are no markings on it whatsoever.

It then goes from the solenoid into a T piece to each reducer then out of one reducer it goes it one set of injector rails, and obviously the other reducer to the other injector rail (there is also a filter on each of these lines). Only one of the reducer seems to have a temp sensor in the body, the the gas outlet to the one without it in the body has the a temp sensor inline just before the injector rail.

The injector rails are valtek 30 I believe. The settings on the map are also set as valteks under the injector section so I believe I’m correct in identifying them.

Reducers are both bigas but not other identifying marks to say which model of reducer.

Out of the injector rails on the other side for pressure I believe they go into a y piece which then goes into the one part of the aeb25 map sensor, obviously out of the it goes into another T in straight line on the T if that makes sense it goes on to a nipple intake for map pressure and out of the remaining part of the t a vacuum line comes out and then spilts via a Y piece one to each of the pressure part of the reducers.

Rough idle could be due to any or a combination of worn injectors, points of gas entry in plenum too far from engine valves, calibration.

But your immediate problem is the reducer(s) leaking LPG into engine coolant.

Most reducers have 12mm gas outlets, Bigas reducers normally have 10mm gas outlets.
Most injectors have 12mm gas inlets but Bigas injectors normally have 10mm inlets and 10mm inlets are available for V30 injectors.
10mm to 12mm inline pipe connectors are available.
If your install has 10mm reducer outlet(s) and 10mm injector inlets you may need to either change injector inlets to 12mm or use a 12mm to 10mm inline connector when fitting a reducer that has 12mm outlet. Since 12mm pipe is better available than 10mm pipe (and you may need to reroute piping to use just 1 reducer) and since most injectors are only available with 12mm inlets it would be better to change piping to 12mm if you're changing the reducer.

I think I understand the pipe routing you've described. The installer may have intended the pipe between injector rails (with the T to the AEB025) to act as a pressure balance pipe. But if that pipe is narrow diameter it may not be able to flow enough enough to balance pressure between rails in some conditions (e.g. big difference in pressure output of reducer, certain engine loads).

Lpgc wrote:

Rough idle could be due to any or a combination of worn injectors, points of gas entry in plenum too far from engine valves, calibration.

But your immediate problem is the reducer(s) leaking LPG into engine coolant.

Most reducers have 12mm gas outlets, Bigas reducers normally have 10mm gas outlets.
Most injectors have 12mm gas inlets but Bigas injectors normally have 10mm inlets and 10mm inlets are available for V30 injectors.
10mm to 12mm inline pipe connectors are available.
If your install has 10mm reducer outlet(s) and 10mm injector inlets you may need to either change injector inlets to 12mm or use a 12mm to 10mm inline connector when fitting a reducer that has 12mm outlet. Since 12mm pipe is better available than 10mm pipe (and you may need to reroute piping to use just 1 reducer) and since most injectors are only available with 12mm inlets it would be better to change piping to 12mm if you're changing the reducer.

I think I understand the pipe routing you've described. The installer may have intended the pipe between injector rails (with the T to the AEB025) to act as a pressure balance pipe. But if that pipe is narrow diameter it may not be able to flow enough enough to balance pressure between rails in some conditions (e.g. big difference in pressure output of reducer, certain engine loads).

Okay dokey I’ll try and get out there with a Caliper and see what we’re working with. I found your number on Google and have dropped you a text message saying I could do a WhatsApp video call if you would like that way you can see what we are already working with.

For the benefit of others who might be interested in reading this and for my own notes...

Had a Whatsapp chat with Khemitude today, showed me around the engine bay during the video call. It's got a (relatively recent) AEB badged AEB2568 with old Bigas reducers and Valtek type30 injectors. The 2 injector rails are each fed from a separate reducer, no balance pipe. The gas inlet points on the are in the 'old skool' position on the Thor plenum so quite a distance from petrol injectors and engine inlet valves. This also means that each rail feeds 2 cylinders on one cylinder bank and 2 cylinders on the opposite cylinder bank, and without a balance pipe this means it's likely 2 cylinders on each bank get higher pressure gas and hence richer mixture than the other 2 cylinders on the same bank.

Plan is for the OP to come to me maybe next week. I'll replace the 2 old reducers with a new MJ one and calibrate it as well as can be.

Just had an old mk2 (facelift) Jeep Grand Cherokee 4L straight six here with a very similar problem... The Bigas reducer was leaking gas not to the cooling system but to the gas output, so when the system was turned off gas pressure rose to >3bar and was ballooning gas pipes. I replaced the Bigas single reducer with a MJ reducer. One of the Valtek type34 injectors wasn't working at all (coil OK but no output of gas) on number 1 cylinder, so I left it set to run on 5 cylinders on gas with number 1 on petrol until the owner has replaced that injector himself. It also has an occasional lambda signal shorted to heater circuit problem, so the owner is going to replace the pre-cat lambda sensor.

Turns out it's one I converted in 2008 but I originally fitted a closed loop mixer system (back then I'd offer customers the choice of a mixer system or sequential system and the mixer system would be a bit cheaper), so the front end components have been changed since I originally converted it.15 years ago. Heh, first thing I said when looking under the bonnet was "Wow your ECU is just hanging and resting against the engine". He says "Well you fitted it". I said "I didn't fit this mate lol". My original receipt (which he brought with him) showed I'd fitted the mixer system but it now had the sequential system fitted.