Tonight while running on lpg sat in traffic my RR started misfiring on &
off then seemed ok. Then traffic moved and as I tried to move off it
started spluttering, almost stalling. I quickly flicked over to petrol &
it was fine. A few more 'tests' on the journey proved that it is only on
gas that it happens. I'm having to top up the rad with coolant as the
dash light keeps coming on - I've pinpointed that to the expansion tank
cap- I can hear it escaping when hot, so I'll get one of those in the
next few days. The engine isnt overheating but I wondered if the two
things could be related seeing as the pipework flows through the gas
assembly. I know the gas level indicators are usually a way out but I'm
easily 60/70 miles from being empty (I use the trip meter to guage it)
There are no obvious faults (hanging wires etc)

Or any other ideas anyone please.

Dave

From a point at sea, to the circles of your mind, this is Dave
Wheatley:

Tonight while running on lpg sat in traffic my RR started misfiring on &
off then seemed ok. Then traffic moved and as I tried to move off it
started spluttering, almost stalling. I quickly flicked over to petrol &
it was fine. A few more 'tests' on the journey proved that it is only on
gas that it happens. I'm having to top up the rad with coolant as the
dash light keeps coming on - I've pinpointed that to the expansion tank
cap- I can hear it escaping when hot, so I'll get one of those in the
next few days. The engine isnt overheating but I wondered if the two
things could be related seeing as the pipework flows through the gas
assembly. I know the gas level indicators are usually a way out but I'm
easily 60/70 miles from being empty (I use the trip meter to guage it)
There are no obvious faults (hanging wires etc)

The vapouriser takes heat from the cooling system to stop it from
freezing as the gas turns to liquid (latent heat of vapourisation and
all that). If the water level drops to the point where none is getting
to the vapouriser then it will start to ice up. The effect is similar
to carb. icing, which some petrol engines used to be prone to.

I guess at low engine speeds, when stuck in traffic, the coolant is
not circulating very fast, which may exacerbate the low level.

If it happens again, switch to petrol for a few minutes to give the
vapouriser time to thaw out, then see if it is still doing it.

Also, I'm a little concerned by your exapnsion cap theory. The cooling
system will be pressurised, but the cap is meant to allow air out
above a certain pressure (and back in again if the pressure drops too
low as it cools). However, if you are not filling the water level
higher than the maximum level mark, and it is still chucking it out,
then something is amiss (on my car I can remove the cap altogether and
not lose any coolant). Try a new cap by all means, but it may be
something more than this. I'd be happy to hear I'm talking bollox
here.


--

Stewart Hargrave

A lot faster than public transport


For email, replace 'SpamOnlyToHere' with my name

From a point at sea, to the circles of your mind, this is Austin
Shackles:

On or around Tue, 02 Sep 2003 09:11:11 +0100, Dave Wheatley
enlightened us thusly:


Hi,
I've not had this car long but when I went to get it insured I had to
have the gas system checked by an approved installer - the only problems
they found were some retaining clips & a water pipe to the vapouriser?
(from your description). SINCE then I have had to keep topping up the
water and the low water level light comes on- by this I mean it needs
topping up every day or 2! Not bucket loads, maybe a cups worth. So, my
thoughts were either an air lock or air leak(because of the high pitched
noise from the cap) so the system isn't pressurised properly. I admit I
don't understand the LPG systems at all, but I understood that water is
used in the process.

It was fine before this pipe was replaced, I top the expansion tank up
to just above the mark that's in it. Of course the place that ok'd the
system & did the pipe don't want to know unless I pay more....'it was ok
when it left here.....' you know how it goes.

I'm just trying to find somewhere to start with the problem, I guess it
can be anything down to a bloody crimp connector being loose, but, this
loss of coolant together with the problem makes me suspect that.

get it compression tested (or do it yerself, if you have the kit and the
knowhow). V8s are a bit prone to head gaskets going. catch it early, and
it's a tolerably easy fix. your pressurising and water loss sounds to me
like a marginal head gasket.


Austin has voiced my thoughts about a head gasket, but I was trying to
avoid depressing you too much before you had eliminated other causes.

But thinking on:

1) Maybe it is an airlock. Some cooling systems are quite prone to
such things. When the installer fitted the new hose there would have
been some coolant loss, and an airlock may have been caused then.

2) However, what could be happening is that exhaust gases are being
forced into the cooling system through a blown head gasket. This
forces water out, hence the drop in coolant level. But a cupfull of
coolant is not a great deal, and I would be surprised if loss of this
small amount would cause your vapouriser to freeze. Maybe the gas in
the cooling system is now causing a lock that stops hot water getting
to the vapouriser. Often the vap. heating is taken off the supply to
the heater - next time it starts spluttering, try turning the heater
on and see if it still works.

3) Is the new hose leaking at all? Are there any other obvious leaks?
Is leaking water getting sprayed onto any ignition components?

4) When the engine is warmed up, but spluttering on LPG, check how
warm the vapouriser is to the touch. It should be on the hot side of
warm.

5) Whilst you are there, try squeezing one of the radiator hoses. It
should be reasonably firm (the system is pressurised) but still
squeezable. If it feels very tight and hard to squeeze the system may
be over-pressurising (symptom of a blown head gasket).



--

Stewart Hargrave

A lot faster than public transport


For email, replace 'SpamOnlyToHere' with my name

On or around Tue, 02 Sep 2003 19:12:53 +0100, Stewart
enlightened us thusly:


Austin has voiced my thoughts about a head gasket, but I was trying to
avoid depressing you too much before you had eliminated other causes.

But thinking on:

1) Maybe it is an airlock. Some cooling systems are quite prone to
such things. When the installer fitted the new hose there would have
been some coolant loss, and an airlock may have been caused then.

On the V8, it can. some of them have an additional filler on the heater
pipes. But that wouldn't really cause a steady coolant loss.


--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"For millions of years, mankind lived just like the animals. Then
something happened which unleashed the power of our imagination -
we learned to talk." Pink Floyd (1994)

Austin has voiced my thoughts about a head gasket, but I was trying to
avoid depressing you too much before you had eliminated other causes.
I didn't expect a simple cheap answer...as I said I've not had the car
long, could explain the eagerness to sell?

But thinking on:

1) Maybe it is an airlock. Some cooling systems are quite prone to
such things. When the installer fitted the new hose there would have
been some coolant loss, and an airlock may have been caused then.
Funny thing is that when I went to fetch it back, while I was in the
waiting room I saw the 'engineer' come back from the test drive and
checked in the expansion tank - he dipped his finger in. I thought
nothing of it 'cos I didn't have any reason to at the time. The next
morning the light was flashing on the dash, since then it's done it
every morning until the engine warms up, so I add water and the next day
the expansion tank is below the line again.


4) When the engine is warmed up, but spluttering on LPG, check how
warm the vapouriser is to the touch. It should be on the hot side of
warm.
How far on the hot side of warm?? When I tried it after the 'spluttering
run' it was BLOODY hot!


5) Whilst you are there, try squeezing one of the radiator hoses. It
should be reasonably firm (the system is pressurised) but still
squeezable. If it feels very tight and hard to squeeze the system may
be over-pressurising (symptom of a blown head gasket).
The top rad hose is extremely hot, as can be expected I guess, but quite
easily squeezable. As are most of the hoses going to the heater and
vapouriser. I did check them although I don't know what I would have
deduced from the result!! I guess I was hoping that the simple answer
was a cooling 'problem' airlock or whatever causing the gas wobbly! as
it's fine on petrol and fine until warmed up.


Dave.

In message , Dave Wheatley
writes
Austin has voiced my thoughts about a head gasket, but I was trying to
avoid depressing you too much before you had eliminated other causes.
I didn't expect a simple cheap answer...as I said I've not had the car
long, could explain the eagerness to sell?

But thinking on:
1) Maybe it is an airlock. Some cooling systems are quite prone to
such things. When the installer fitted the new hose there would have
been some coolant loss, and an airlock may have been caused then.
Funny thing is that when I went to fetch it back, while I was in the
waiting room I saw the 'engineer' come back from the test drive and
checked in the expansion tank - he dipped his finger in. I thought
nothing of it 'cos I didn't have any reason to at the time. The next
morning the light was flashing on the dash, since then it's done it
every morning until the engine warms up, so I add water and the next
day the expansion tank is below the line again.


4) When the engine is warmed up, but spluttering on LPG, check how
warm the vapouriser is to the touch. It should be on the hot side of
warm.
How far on the hot side of warm?? When I tried it after the
'spluttering run' it was BLOODY hot!


5) Whilst you are there, try squeezing one of the radiator hoses. It
should be reasonably firm (the system is pressurised) but still
squeezable. If it feels very tight and hard to squeeze the system may
be over-pressurising (symptom of a blown head gasket).
The top rad hose is extremely hot, as can be expected I guess, but
quite easily squeezable. As are most of the hoses going to the heater
and vapouriser. I did check them although I don't know what I would
have deduced from the result!! I guess I was hoping that the simple
answer was a cooling 'problem' airlock or whatever causing the gas
wobbly! as it's fine on petrol and fine until warmed up.


Dave.

Have you checked the coolant level in the rad itself. Undo the large nut
on top of the rad and fill up to within about 1 inch of the top. Replace
the nut, then top up the expansion tank.
--
hugh
Reply to address is valid

Austin Shackles wrote:
On or around Wed, 03 Sep 2003 08:58:14 +0100, Dave Wheatley
enlightened us thusly:


Austin has voiced my thoughts about a head gasket, but I was trying to
avoid depressing you too much before you had eliminated other causes.

I didn't expect a simple cheap answer...as I said I've not had the car
long, could explain the eagerness to sell?


4) When the engine is warmed up, but spluttering on LPG, check how
warm the vapouriser is to the touch. It should be on the hot side of
warm.

How far on the hot side of warm?? When I tried it after the 'spluttering
run' it was BLOODY hot!


not unusual for them to be too hot to touch. Mine runs OK like that. If
you take away the supply of coolant (which is actually heating the
vapouriser) it'll freeze in under a minute, especially under load.


5) Whilst you are there, try squeezing one of the radiator hoses. It
should be reasonably firm (the system is pressurised) but still
squeezable. If it feels very tight and hard to squeeze the system may
be over-pressurising (symptom of a blown head gasket).

The top rad hose is extremely hot, as can be expected I guess, but quite
easily squeezable. As are most of the hoses going to the heater and
vapouriser. I did check them although I don't know what I would have
deduced from the result!! I guess I was hoping that the simple answer
was a cooling 'problem' airlock or whatever causing the gas wobbly! as
it's fine on petrol and fine until warmed up.


compression test is worthwhile, picked up a dubious head gasket on me
sister's boyfriend's Range Rover.

If you end up lifting heads, make sure to check that the head's not warped -
not too expense to have it skimmed, unless you've already put it back
together...




I'll get the compression checked then first, see where to go from there.
There are 2 issues I have- spluttering when running gas & the coolant one.
Would the problems caused by a bad gasket be evident on both gas and
petrol though, rather than just the gas. Is the timing/compression etc
more critical when not using petrol thus causing the misfiring?

Dave

From a point at sea, to the circles of your mind, this is Dave
Wheatley:


4) When the engine is warmed up, but spluttering on LPG, check how
warm the vapouriser is to the touch. It should be on the hot side of
warm.
How far on the hot side of warm?? When I tried it after the 'spluttering
run' it was BLOODY hot!

That's hot enough, and indicates that I might be talking bollox from
start to finish. If it is that hot then it obviously isn't freezing.
Something else is causing the spluttering.

5) Whilst you are there, try squeezing one of the radiator hoses. It
should be reasonably firm (the system is pressurised) but still
squeezable. If it feels very tight and hard to squeeze the system may
be over-pressurising (symptom of a blown head gasket).
The top rad hose is extremely hot, as can be expected I guess, but quite
easily squeezable.

This doesn't eliminate a head gasket problem, but it mitigates against
it. The definitive answer is to get an exhaust probe put into the
expansion tank to see if any exhaust gases are present.


--

Stewart Hargrave

A lot faster than public transport


For email, replace 'SpamOnlyToHere' with my name

From a point at sea, to the circles of your mind, this is Dave
Wheatley:

There are 2 issues I have- spluttering when running gas & the coolant one.
Would the problems caused by a bad gasket be evident on both gas and
petrol though, rather than just the gas. Is the timing/compression etc
more critical when not using petrol thus causing the misfiring?

It does seem that the two things may not be related. If the vapouriser
is hot when it starts to splutter then it is not freezing due to
coolant loss.

A car running on LPG does give the ignition a harder time - the LPG
mixture is more resistant to letting a spark pass through it than a
pertol mix. If your high tension ignition components are not in good
condition then the spark can try to find its way home via other
routes. This often involves backfires in the inlet manifold, but can
involve rough running. On my Volvo I had to replace everything, the
plugs, the coil, the ditributor cap and rotor arm, and the HT leads.
But it did have a very destructive backfire habbit.

Does your answer above imply that you only lose coolant when running
on LPG? If so, maybe you have an overheating problem caused by poor
setup.


--

Stewart Hargrave

A lot faster than public transport


For email, replace 'SpamOnlyToHere' with my name

On or around Wed, 03 Sep 2003 14:38:44 +0100, Dave Wheatley
enlightened us thusly:


I'll get the compression checked then first, see where to go from there.
There are 2 issues I have- spluttering when running gas & the coolant one.
Would the problems caused by a bad gasket be evident on both gas and
petrol though, rather than just the gas. Is the timing/compression etc
more critical when not using petrol thus causing the misfiring?

dunno, but a comp test is easy and may show something.

Plugs and leads are another possibility, unless they've recently been
replaced. LPG requires a stronger spark (or putting it another way, it
takes more voltage to make a spark in an LPG mixture than a petrol mixture.


--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"All animals are equal, but some animals are more equal than others"
George Orwell (1903 - 1950) Animal Farm