LPG questions for all you with LPG'd V8's

[JulesV8]

Afternoon everyone,

I spend most (if not all) of my time on the discovery pages but was tols about this section of the forum so thought I would say hello and ask some questions.

I have a 1996 3.9l v8 efi disco 1 and have had a sequential multi point autogas system fitted back in july.

On my way home a couple of nights ago the gauge blipped to tell me it had run out of gas, even though it still had 3 bars left on it. I wondered why then thought that the gas had frozen. A member on the disco page advised me to look at the coolant level which was low...problem solved it now works a treat...or so I thought.

It would appear that I have a slight coolant leak but I dont know where its going. Does anyone know if I can use something like rad weld to bung the system up? the other question relates to "air pockets" and how to get rid of them.

My thrid question relates to a slight smell of gas in and around the vapouriser when the engine is turned off, ie, I park up and can smell gas. Now does anyone know if the system "vents" itself when not in use or should I "soapy water" the system and watch for bubbles.

I'm returning around 150 to 165 miles per gallon of gas which seems within the limits of my twin 36l underslung tanks (which equates to anywhre between 13 and 14 mpg) which there again sounds about right.

All answers and advice greatfully received.

Thanks all,

Jules

[SimonHobson]

I have a 1996 3.9l v8 efi disco 1 and have had a sequential multi point autogas system fitted back in july.

On my way home a couple of nights ago the gauge blipped to tell me it had run out of gas, even though it still had 3 bars left on it. I wondered why then thought that the gas had frozen. A member on the disco page advised me to look at the coolant level which was low...problem solved it now works a treat...or so I thought.

It would appear that I have a slight coolant leak but I dont know where its going.
OK, it's a Rover V8 - there's an old joke about there being two sorts of Rover V8, those that need their head gaskets doing, and those that have had them done recently :D A few questions to help diagnose it :
Do your coolant hoses go hard quite quickly after startup ? If you release the pressure from the header tank when it's fully warmed up, does it re-pressurise ? If you take out the spark plugs, does one (or more) of 1, 2, 7, or 8 look different to the rest - either 'steam cleaned' or rusty ?
These are all signs of the head gasket blowing from one cylinder to the water jacket. If this is the case, then the only cure is to do the head gaskets (do both, it's not worth it to just do one). What could well be happening is that as soon as you start from cold, air is put into the cooling system - and this will collect at the high points including the reducer. I think the 3.9 is a lot better than the old 3.5 carb engine I had in the 110, but the air will still collect in the reducer and can even cause the pump to airlock.

Does anyone know if I can use something like rad weld to bung the system up?
It might help, a bit, for a while - but really, it just will not seal against the cylinder pressure.

the other question relates to "air pockets" and how to get rid of them.
If your reducer is plumbed in parallel with your heater then it could be difficult. Pinching a heater hose while revving the engine a bit could help clear the reducer.

My thrid question relates to a slight smell of gas in and around the vapouriser when the engine is turned off, ie, I park up and can smell gas. Now does anyone know if the system "vents" itself when not in use or should I "soapy water" the system and watch for bubbles.
It shouldn't be venting. If there's a slightly loose joint then it would leak under pressure. It could be that with the engine stopped, a bit of gas gets through the reducer and increases the pressure a bit in the low pressure side - but it's pressurised anyway to (typically) about 1 bar in injection systems. I would use leak detector, or if you haven't got any, soapy water to look for leaks - but wash any soap off afterwards as it can cause corrosion.

I'm returning around 150 to 165 miles per gallon of gas which seems within the limits of my twin 36l underslung tanks (which equates to anywhre between 13 and 14 mpg) which there again sounds about right.
13 to 14mpg sounds about normal. Some get more, I reckon I'm doing well to get 13 - but then a 110 has the aerodynamics of a small bungalow and I'm not renowned for my weak right foot :biggrin:

[JulesV8]

Hi Simon,

Thanks for the advice. I dont think my head gasket has blown reasons being.
- At the last service all the plugs were fine
- No loss of power
- No white smoke

Saying that, nothing is impossible so I might as well bite the bullet and pressure check the cylinders. I'll also check for the re-pressurisation of the header tank (is that what you call it?)

I actually think that the leak is in or around the heater matirx. I have an un-identified excess of water in the passager footwell in the winter and I do believe that there is a leaky pipe to the matirx or the matrix itself is shot.

thanks for the advice regarding the rad weld, I may give it a try though I need to find the time to take out all the dash and check the matrix situation.

Its soon due for a service so I'll get the vapouriser checked over for leaks and will probably invest in some spray to check for leaks.

as for the MPG, I think I can get better though I need to change the oil in the diffs and have just changed my tyres, which should help...there agian its all down to having the time to do all these things. I think I'll be using my paternity leave for all these jobs.

Thanks for all the advice and will update as soon as.

Ta
Jules

[SimonHobson]

Thanks for the advice. I dont think my head gasket has blown reasons being.
- At the last service all the plugs were fine
Did you have this problem at your last service ?

- No loss of power
- No white smoke
You wouldn't see either of those in the early stages.

Saying that, nothing is impossible so I might as well bite the bullet and pressure check the cylinders. I'll also check for the re-pressurisation of the header tank (is that what you call it?)
Well it will cost nothing to check :rolleyes:

I actually think that the leak is in or around the heater matirx. I have an un-identified excess of water in the passager footwell in the winter and I do believe that there is a leaky pipe to the matirx or the matrix itself is shot.
It's not unknown, I had a matrix fail in the Disco - it had never been crimped properly (aluminium matirc with plastic headers) and when it got hot and pressurised it would leak - but it didn't do it solo, just when I was towing my mates motor to a Hill Rally. We had to bypass the heater, and it was cold and wet up in Scotland :eek:

[JulesV8]

Hi Simon,

Yep, I did thats why I think its the matirx but as you say, it wont hurt to check the head, best do it know if there is something wrong before I fry the engine.

Thanks for the advice,

Jules

[CCKW353A1]

3.9 V8's do suffer with what appears to be leaky head gaskets but are frequently loose(at the top) cylinder liners as the fire ring of the gasket sits out board of the wet cylinder liners. With heads off look for a black line showing the join between block and liner on the steam cleaned cylinder. If you find a loose liner its replacement engine time or big ££££££££££££'s for flanged liners to be fitted to your engine.

[SimonHobson]

If you find a loose liner its replacement engine time or big ££££££££££££'s for flanged liners to be fitted to your engine.
Yes, I had a 4.6 engine sat in my garage for a while with a slipped liner - which is why I got it cheap. I had decided that Turners seem to have the best option - top hat liners with O-ring at the bottom like a wet liner engine. Sadly I decided that I wasn't likely to have a spare 1 1/2 grand for a set of their liners in the foreseeable future and let someone else have it who had blown his up (let go BIG time at about 7 1/2 thousand RPM :eek:)

[sharpy1980]

Afternoon everyone,

I spend most (if not all) of my time on the discovery pages but was tols about this section of the forum so thought I would say hello and ask some questions.

I have a 1996 3.9l v8 efi disco 1 and have had a sequential multi point autogas system fitted back in july.

On my way home a couple of nights ago the gauge blipped to tell me it had run out of gas, even though it still had 3 bars left on it. I wondered why then thought that the gas had frozen. A member on the disco page advised me to look at the coolant level which was low...problem solved it now works a treat...or so I thought.

It would appear that I have a slight coolant leak but I dont know where its going. Does anyone know if I can use something like rad weld to bung the system up? the other question relates to "air pockets" and how to get rid of them.

My thrid question relates to a slight smell of gas in and around the vapouriser when the engine is turned off, ie, I park up and can smell gas. Now does anyone know if the system "vents" itself when not in use or should I "soapy water" the system and watch for bubbles.

I'm returning around 150 to 165 miles per gallon of gas which seems within the limits of my twin 36l underslung tanks (which equates to anywhre between 13 and 14 mpg) which there again sounds about right.

All answers and advice greatfully received.

Thanks all,

Jules

Is yours an Auto? I,ve got a 96 V8i Auto multi point lpg with twin 36l tanks and I get around 140 miles at best so you're doing well, I had slight water leak from the thermostat and the water collected between the cylinder heads of which alot evaporated but I now have another leak from behind the water pump housing (looks a scary job), also I get a gas smell under the bonnet after switching off and have tried soapy water with no joy so was thinking of getting it serviced. Oh the other thing mine leaks water into the footwell but only after using the air-con (not likely at the moment lol).

[SimonHobson]

Oh the other thing mine leaks water into the footwell but only after using the air-con
Check your condensate drains. On the early ones, the drains come off the bottom of the evaporator unit with rather fragile pipe stubs - which break off :rolleyes: Even if they don't get broken off, it's easy to kick the pipe and pull it out of the hole where it goes through the bulkhead.

In either case, the condensate* just dribbles on the floor.

* When you cool air, the amount of water it can carry reduces. Cool it enough and water starts to condense. Unless the air is very dry (like in current frosty conditions), you'll get condensation on the evaporator as it gets 'damn cold'.

[V8_Disco]

Not uncommon for the heaters on discos to develope a leek after an LPG convertion most people plum them into the heater pipes (its a sensible place!) but it can upset the heater with all the wiggaling in the engine bay ... I have heard of 3 cars this has happend to (though one of those was a p38)

Aidan