LPG RUNS HOTTER?????

[Screwy]

When my GQ is on Gas it tends to run nearly a quarter hotter up the guage then when its on petrol.....

runs much cooler on petrol when A/C is on and off..........

DOES LPG make motors run hotter???

ive got colder plugs in it for the LPG...

is there anyway to fix this problem???

it will also explain y the MQ runs warm on gas also....

screwy

[-Scott-]

Yes, LPG runs hotter. I'm too lubricated to remember why, but I'm sure somebody else can explain.

Cheers,

Scott

[RaginRover]

Hmm, it shouldn't register that much difference IMO,

Yes it runs hotter, but if your cooling your system is up to it then it
you really shouldn't see that much difference.

Tom

[Screwy]

well,

on LPG, with the A/C on in the heat of late....

i get to 3/4 up the guage, when A/C is off its still at half...

when im on petrol, its abit over 1/4 and when AC is on on petrol its about half....

its running just abit warmer and just curious as to how to fix it....

screwy

[Tas_Dean]

Put a mechanical temperature gauge on the vehicle for a couple of days. The actual difference in temperature might only be a couple of degrees.

Cheers, Dean

[elgordomuygrande]

LPG burns at a higher temperature. When your cooling system is up to par there's no problem. Run it as hot as possible without boiling. If it's constantly running the red line and there's enough cooling fluid and ignition is timed to run on LPG then install a electric fan.

Cheers, Ron

[ozy1]

i did a search and it says on LPG it will run approx 10 degrees hotter

[Screwy]

yeh i beleive this is correct OZY....

the prob is that with the A/C on and the 33's..... That extra 10 degrees is starting to pose a problem.

Previously without a/c and 31s the temp was ok, ran warm on LPG if i flogged it but not bad..... its always behaved itself on petrol

Ive also got a 10 inch thermo on the front of the condensor that i wired onto a switch rather than onto the pressure switch for the a/c...

so this is on whenever i turn the a/c on and it helps... but not quite enough

[Shorty40]

Dont use the AC - wind ya window down

[Screwy]

Dont use the AC - wind ya window down

This problem has been going since before the A/C.........

just not quite as high...

its still gotton hot a few times wihout A/C when i try to hold 120km/h for too long

[V8Patrol]

Jeffricals, Jeffricals, Jeffricals.....

Of course it gunna run hotter ..... LPG does that ! ....... BUT ALSO....

You've increased the engine load buy fitting bigger rubber..... therefore adding to the problem........
Then you drive it @ 120kph and expect all to be sweet .......

Jeffricals, Jeffricals, Jeffricals.....

Fit a mechanicle guage for starters ....this will give you an ACCURATE temp reading instead of a "guage" of roughly how "hot" its opperating.

IF that doesnt show a minor differance between the LPG and ULP then you have a issue else where that needs to be resolved, it may be a problem caused by ........

Blocked radiator..... remove, power flush, and refit then test.

Corroded radiator fins ... replace or recore radiator.

Faulty thermostat .... replace after testing if nessecary.

Poorly adjusted fan belt ....tighten.

Placement of "items" in airflow path .... remove driving lights n test.

excisive throttle use ...... replace large nut behind the steering wheel !

These simple checks are for an overheating motor....in YOUR case its only whilst on LPG.....I would get a TUNE UP done on the system as the first thing to do....and while they are tuning it ( going back to the start .... ) get em to fit a MECHANICLE TEMP GUAGE .

Oh Jeffricals , Oh Jeffricals , OH Jeffricals

[Davidh]

Doesn't LPG require different timing? If it's too advanced the engine will heat up?
Seem to remember something like that when i had a falcon on lpg.
With the older cars you had to tune the engine for either LPG or petrol, and one would suffer.

I think i've even heard of some later model dual fuel systems that change the timing when you flick over between petrol and lpg.
That's the engines without distributors though.

Anyone confirm this?

[Tas_Dean]

Doesn't LPG require different timing? If it's too advanced the engine will heat up?
Seem to remember something like that when i had a falcon on lpg.
With the older cars you had to tune the engine for either LPG or petrol, and one would suffer.

I think i've even heard of some later model dual fuel systems that change the timing when you flick over between petrol and lpg.
That's the engines without distributors though.

Anyone confirm this?

I had a V8 HX Holden ute on dual fuel, and when I got my mate (a bloody good mechanic, who does a lot of LPG work) to tune it, he asked me if I wanted to run it on petrol much. I said no, so he tuned it specifically for gas. He adjusted the timing to Approx. 17 BTDC on Idle, and explained to me why. Petrol for that vehicle ran at about 6 BTDC (advanced), setup for dual fuel you would run about 10-12 degrees, and LPG requires somewhere around 17 degrees, due to the burn characteristics. When setup for dual fuel, and engine is timed to run "OK" on both, but not great on either! This relates largely to why a lot of dual fuel cars don't get very good economy on either fuel. Timing problems is also a cause of excess heat!
As for engines that change the timing between gas and petrol, I don't know for sure but I imagine that factory dual fuel vehicles probably do, through their ECU. You could possibly also buy an ecu aftermarket to do this.

Screwy (and anyone else using lpg), decide if you are going to run mostly gas or a split between both, and if you decide that you are going to use mostly gas, get your engine tuned accordingly. If you know how to adjust timing yourself, it's pretty easy to wind the advance back down if you get stuck and have to run petrol for any length of time. This arrangement suited me fine! You don't have to have a timing light to do this, but one would be advisable when readjusting for gas. There is any amount of information out there on tuning "by ear", and this is fine for preventing engine damage, though you may not be getting full economy by being a couple of degrees out.
And going back to what I said earlier, get a "mechanical" temperature gauge fitted (even if it is a borrowed one temporarily) to give you a rough idea of actual temperature, as the difference on an "electric" gauge such as those fitted to a vehicle could be as little as 2 degrees between quarter and three quarters!
P.M Me or post back here if you need any more information.
Regards, Dean

[Screwy]

Kingy, Kingy, Kingy....

Done all the above, including change thermostat and flush etc etc.....

and its still abit warm.....

Though from wat i can tell, its running better on petrol.....

I may get it tuned for LPG and see how that goes, id say that may be the main problem.

[J Top]

One of the reason for the lack of power on gas is the lower volumetric efficency, as petrol enters the chamber as a liquid which is a more condensed form of fuel than the gas, therefore the gas being a greater volume, there is less room for air so less power.
The petrol entering as a liquid has a greater cooling effect then the gas.!
In NZ we used to fit a unit called a Dual Curve. This unit retarded the timing on petrol when you first wired it up, so you reset the timing on petrol and when you changed to gas it advanced again,
HOWEVER, when you advance your initial timing you increase your total advance as well, which with lower power and higher temparatures and
head wind and incline etc,etc means that full throttle is required to move and you can have extreme combustion chamber temperatures and valve and piston failures.
The Dual Curves used to limit the total advance to safe levels.
J Top

[elgordomuygrande]

One of the reason for the lack of power on gas is the lower volumetric efficency, as petrol enters the chamber as a liquid which is a more condensed form of fuel than the gas, therefore the gas being a greater volume, there is less room for air so less power.

Also the fact that the ideal air-fuel ratio of LPG is slightly higher so that the lesser volume of air that's in the cilinder is sufficient for even lesser LPG to be completely burned. Hence, although the caloric( energetic) value of LPG being higher than petrol, actual power will be less ( at least with a conventional LPG system)

Timing has to be advanced due to lower burning speeds of lpg.

[outlandy]

Engines that are converted to run on LPG only are actually supposed to run cooler. This is to do with cam and ignition timings. My Commode runs on straight gas and the initial advance for gas is 16Deg BTDC but only 22 at full noise. So you are just trying to get a happy medium with your tuning and will never get it ideal unless you convert it. In saying that Most 4x4's arent suited because of range and storage issues on gas but staright gas would be perfect for a comp fourbie

[Shorty40]

My GQ is now running straight gas and it runs considerably COOLER than it did on petty

Im not sure if it is meant to, but I dont imagine it will cause any problems running cool

[adam.s]

Engines that are converted to run on LPG only are actually supposed to run cooler. This is to do with cam and ignition timings. My Commode runs on straight gas and the initial advance for gas is 16Deg BTDC but only 22 at full noise. So you are just trying to get a happy medium with your tuning and will never get it ideal unless you convert it. In saying that Most 4x4's arent suited because of range and storage issues on gas but staright gas would be perfect for a comp fourbie

I'd imagine with the advanced ignition, gas would want to run hotter, but then you gotta remember its a gas being stored as a liquid, shouldn't it chill the intake when it's converts back to gas ?

At least that would explain why.

Around town my guage sits about 40% (normal), on the highway I think it creeps up to 50%, thats on a long highway drive - I've only got a 4speed, so she revs a bit high

[V8Patrol]

its a gas being stored as a liquid, shouldn't it chill the intake when it's converts back to gas ?

LPG is in vapour form well before it makes the inlet manifold......

Thats why the "converter" is there, to convert LPG from the liquid state as held in the tank to a vapour state which is then fed to the engine.

-----------------------------------------------------------------------------------

Duel fuel setups arent efficient, its simply a compromise of systems and one setup will usually be slightly better than the other setup.
Only a "sole gas" or "sole petrol" system will give performance, & economey, fitting a duel setup will deminish the petrol side of things and the LPG will never run at its full potential untill the petrol side of things are removed.

It all comes down to setup and engine tune for that chosen setup.

Kingy

[Patroler]

yea i'm running strait gas and initial advance of nearly 20 degrees, but the advance curve is a lot flatter than what it would be on a petrol car.
All i did to work out where to set the timing is fit a good vac gauge, advance timing at idle until vacuum maxes out and starts to drop, then retard the timing around 1 in/Hg from the max vacuum figure you saw.
That came out of an LPG fitters hand book i copied, it won't solve the steep anvance curve that the motor would have from standard tho, you'd have to get the dizzy adjusted

[p76rangie]

Petrol motors need to run hotter to change the fuel to vapor. You should set up a gas motor to run cooler as it is already vapor. You should run a colder thermostat. LPG will technically give you more power if it is set up properly and if the petrol companies do not water it down too much with butane. It is setting up the car to run on both fuels that causes the issue. Butane will generally sink to the bottom of the tank. Therefore if you fill up your car with at a service station with a near empty tank, you will tend to get lower octane fuel.

[Screwy]

What are all of the symptoms of a blown head gasket on one of these motors??? TB42......

just got a feeling

[MKPatrolGuy]

What are all of the symptoms of a blown head gasket on one of these motors??? TB42......

just got a feeling

When dad's blew, his oil looked like a chocolate milkshake.

[V8Patrol]

Depending on "where" the gasket is blown as to the visual sighting....
IE: water in oil, water loss through exhaust, water loss through radiatorcap/ resiviour bottle

Blown Head Gasket Symptons:

1/ Slow overheating: usually takes anywhere from 1k to 300ks for the temp to rise above normal and continue on to the hot mark.

2/ Internal heater: runs hot then cold, air pockets can sometimes be heard running through the heater.

3/ low oil pressure: extra temperature decreases oil viscosity thus decreasing the "pressure reading" on the guage.

4/ excessive water vapour: usually visiable at cold startup from the exhaust ( left over water in the exhaust system from previous drive)

5/ Radiator reserve bottle: either dead empty or way overfull, the dead empty bottle is a result of what water that was in the bottle being boiled off over a longer period of driving, while an overfull bottle is the start of that process.

6/ Continously refilling radiator: If you need to "top up" the water on a dailly basis or every couple of hours and there is no visiable signs of a leak then the water is getting out elsewhere.

7/ Engine has trouble turning over: Usually this happens during a "cold start", ....... overnight the water has been forced into the clyinder under radiator pressure, then when you try n start it the water is compressed but as we all know ya cant compress water so the motor simply slows down at that point where that cylinder is being forced to try and compress the water in it, this is called "Hydrolicing" and if you have a strong starter motor or a reduction driven starter then the worst case scenerio is a bent rod........ yep major rebuild !!!

Where does the water go ???? :

A/
Usually the gasket blows between a water gallery and the actuall engine cylinder..... What happens then is that on the induction stroke tha water is sucked into the cylinder along with the air/fuel mix, then its combusted, then the vapour is sent out with the exhaust gases...hance excesive water vapour through the exhaust.
Also during this cycle, the combustion & exhaust strokes force some of the exhaust gas back into the water gallery therefore displacing the water thats in the cooling system, this water that is displaced is forced out of the radiator and the total overall water amount in the cooling system is reduced....all be it slowly.

B/
In some instances the gasket blows between the water gallery and an oil gallery, this will result in water loss into the oil system and the "chocolate colored oil" as described in an above post. The oil will also be "thinned down" thus reducing is abillity to lubricate correctly and therefore lower oil pressure on the guage.
Long term driving in this state will result in the oil being turned to what I can best describe as "airated thickened cream" on the dipstick or oil filler cap...... its much worse inside the rocker cover and sump and if left unrepaired WILL result in engine damage..... IE new rings/bearings etc etc.

C/
A rare one is a water leak out of the engine at the point where the head joins the block....this will be visiable and will leave a pool of water on the ground or a water "trail" down the side of the block.

Testing for a Blown Head Gasket:
Remove the radiator cap and look for "bubbles" in the water
Remove the sparkplugs...one will be ultra clean !!! thats the cylinder thats blown
Get a CO2 test done at the local mechanics joint.
Get a cooling system pressure test done at the local mechanics joint.

Getting home if ya blow a head gasket:
So you've spotted the symptons and realise you've done a head gasket and ya miles from home....relax unless its a water into oil leak, you'll make it easilly if its a water into the cylinder leak
Firstly let the engine run and top up the water SLOWLY....
Secondly DONT tighten the radiator cap up all the way as you would normally do, instead tighten it to the first stage and leave it there. This will allow the exhaust gas to escape through the cap rather than displacing the water. The cap should feel "loose" but not fall off when the first stage of tightening is achived.
thirdly, reduce ya speed by 10-20%, an engine running at 80kph runs cooler anyway, there is less RPM so therefore there is less CO2 being forced into the cooling system
And finally, throw in a can of "BARS LEAKS" or similar product into the cooling system.

Kingy

[V8Patrol]

The worst drive I've had with a blown head gasket was 1700ks to home....I backed the speed down in stages as the leak got worse and limped into my street doing an incrediable 40kph, I'd been at 40kph for over an hour at that stage !
The leak was in 2 cylinders being 5 & 7 and was that bad that when I removed the sparkplugs and added water it actually ran out the sparkplug holes !, mind you the leak early on was very slight and caused little drama...it did get worse as I did the distance tho.

The pistons were like new when I removed the head as were the valves and actual head, water has that effect !
I fitted new head gaskets and changed the oil and havent had a drama since.

Kingy

[Tas_Dean]

Getting home if ya blow a head gasket:
So you've spotted the symptons and realise you've done a head gasket and ya miles from home....relax unless its a water into oil leak, you'll make it easilly if its a water into the cylinder leak
Firstly let the engine run and top up the water SLOWLY....
Secondly DONT tighten the radiator cap up all the way as you would normally do, instead tighten it to the first stage and leave it there. This will allow the exhaust gas to escape through the cap rather than displacing the water. The cap should feel "loose" but not fall off when the first stage of tightening is achived.

Years ago when I was a poor (still am) young apprentice I blew a head gasket in my old 85 corolla. It was pumping the coolant out under pressure (compression into radiator).
I arranged to replace my engine at a mates workshop 200 Km's away. I got there by a very weird setup.
What I did:
I rigged two hoses up from the radiator filler, up to my drivers side mirror. To one of these hoses I rigged up a funnel (cutoff coke bottle), and I filled heaps of bottles of water and sat them behind the passenger seat. when the engine started to overheat, it would blow a large amount of water out, then overheat rapidly. So, to avoid stopping every ten kilometres to refill the radiator, I just opened my window and poured water down the funnel until it came out of the second hose!
Of course, my contraption was held in place with Duct Tape
I also found that I didn't use as much water, and the engine barely overheated at all, because I was able to keep the engine cooler by the addition of water periodically.

But I certainly got some very weird looks!

Cheers, Dean

[Tas_Dean]

The pistons were like new when I removed the head as were the valves and actual head, water has that effect !
I fitted new head gaskets and changed the oil and havent had a drama since.

Kingy

Yes, nothing like a good steam clean

Cheers, Dean

[longlux]

Jeffricals, Jeffricals, Jeffricals.....

Of course it gunna run hotter ..... LPG does that ! ....... BUT ALSO....

You've increased the engine load buy fitting bigger rubber..... therefore adding to the problem........
Then you drive it @ 120kph and expect all to be sweet .......

Jeffricals, Jeffricals, Jeffricals.....

Fit a mechanicle guage for starters ....this will give you an ACCURATE temp reading instead of a "guage" of roughly how "hot" its opperating.

IF that doesnt show a minor differance between the LPG and ULP then you have a issue else where that needs to be resolved, it may be a problem caused by ........

Blocked radiator..... remove, power flush, and refit then test.

Corroded radiator fins ... replace or recore radiator.

Faulty thermostat .... replace after testing if nessecary.

Poorly adjusted fan belt ....tighten.

Placement of "items" in airflow path .... remove driving lights n test.

excisive throttle use ...... replace large nut behind the steering wheel !

These simple checks are for an overheating motor....in YOUR case its only whilst on LPG.....I would get a TUNE UP done on the system as the first thing to do....and while they are tuning it ( going back to the start .... ) get em to fit a MECHANICLE TEMP GUAGE .

Oh Jeffricals , Oh Jeffricals , OH Jeffricals

I'd Just like to add the Radiator Cap(system can loose pressure if not working properly) & Water Pump(i've have this one cause probs on a vehicle before can get worn or worse lose a fin & not pump efficently) to this list

[Screwy]

OK,

Symptoms ive got:

It runs fine around town, doesnt overheat.............. BUT i occasionaly hear bubbles coming out of the overflow for about 10 seconds after the motor is killed........ even when temperature is fine.

Overheats lots at anything over 100 - 120 kms for more than half an hour....... also tends to lose water without leaking over about 6 hours of a trip....... i noticed the temp started getting very high and the heater tended to blow hot air off and on as if air pockets....

the LPG started to stutter on and off abit as if running out of gas, i think air pockets cause light amounts of iceing up in the converter........

and after driving 6 hours i popped the radiator and all that came out was steam and i put like 7 litres of water in it......

It overheated far worse on the way home but didnt lose the water cause i checked it at every servo this time.......

BUT was on the hot line all the way home

BUGGA