GU 98 dual fuel

Hi All,

early this week I started a thread asking about compatibilities for main tanks among different models of GU. My intention was to come back to the original configuration getting rid of the dual fuel system that actually run in my Patrol.

Some mates replied and gave their points. Finally I decided to keep the dual fuel so, thanks for all the suggestions.

However, the system is out of date an needs to be certified again, even because I need to pass the reg inspection here in WA. Tank will have to be replaced and I was wondering if it could be possible to fit another bigger than the one currently set (90 liters). I was surprised when the owner of the workshop who will take care of the job told me that, although there are bigger tanks they cannot be fitted. I didn't understood the reason why (my english by phone still has to be improved...), but I guess could be related to some legal rules. Anyway...

My question today for all the forum gurus is related to those "valve saver kits". Are they a worth thing to take into account, or is just a way to waste money for nothing?

It makes sense to add a system like this or just alternating between LPG and Fuel is enough to keep the valves healthy?

Thanks in advance,

Racked up 400,000 k on my last dual fuel 4x4 , never had an issue with the heads on either motor I had in that 4x4.
all I did was alternate as you have suggested between gas/ulp.
How long do you intend keeping car???
Head would need refreshing after 250k anyway,
All I can really say even though I've had a good run is "gas kills engines". Put a valve kit on it if you like, but not better than running ULP

I have a 98 4.5L GU with a 105 Litre Useable Gas Tank so they are available and can be fitted

Thanks BOB would have thought the 120ltr total would be available, got me beat why they always put the smaller tank in.
From memory its the same width just slightly bigger in diameter. you can rock them whilst filling to get extra, but not that much, 5ltrs maybe
Bummer you cant remove the AFL valve, would be great for touring

you can rotate tank 15 to 20 degrees and that alters the float level and gives you more gas

Wish I'd known that years ago, still keeps it legal too.
I've heard stories of taxis having them removed or bent, but not sure on that one

Thanks threedogs, sorry about my still poor vocabulary, but when you said "heads", did you mean cylinder heads or valve heads?

Quote:

---

Originally Posted by threedogs

Racked up 400,000 k on my last dual fuel 4x4 , never had an issue with the heads on either motor I had in that 4x4.
all I did was alternate as you have suggested between gas/ulp.
How long do you intend keeping car???
Head would need refreshing after 250k anyway,
All I can really say even though I've had a good run is "gas kills engines". Put a valve kit on it if you like, but not better than running ULP

---

Thanks BOB,

when you said "105 Litre Useable Gas tank" did you mean that this tank is bigger than 105 litres, but since they can be filled up to 85% - 90% its size is around 120 litres right?

Quote:

---

Originally Posted by Bob

I have a 98 4.5L GU with a 105 Litre Useable Gas Tank so they are available and can be fitted

---

Hi third 256,

But doing this thing... could be dangerous in terms of extra filling and exceeding the space that those tanks reserve for a gas expansion, right?

Quote:

---

Originally Posted by my third 256

you can rotate tank 15 to 20 degrees and that alters the float level and gives you more gas

---

Yes and yes to both questions the 120 lt tank fills to about 100lt, and heads wear out around the valves because of the gas,no lead in the gas to soften valve surface

Hi threedogs,

good point about the lead effects on wearing down the valve surface and even another parts of the engine (supposedly all internal parts of the combustion chamber). Obviously there is no justification on using lead due to its healthy consequences, but might be worth then to use some kind of substitute... especially because my engine is going to be soon 340.000,...

I bought this GU second hand. I paid 8 grands so, not bad at all, especially when is said that this TB45 are very tough. The rest of the car is pretty well it needs some after market replacement, but for sure in the same way that a new car... and at this moment I have a lot of fun with the project itself.

Thanks for your replies.

Quote:

---

Originally Posted by threedogs

Yes and yes to both questions the 120 lt tank fills to about 100lt, and heads wear out around the valves because of the gas,no lead in the gas to soften valve surface

---

I went to Melb this Weekend and filled up with Gas at Calder Raceway and it took 112 Litres to fill the Gas Tank from empty. Usually it only takes105 Litres.
I did not worry about the extra Gas as I still had 50 K's to go before I parked it.
I just recently put a Reconditioned Head on (290,000 K';s). This Head had the Inlet Ports enlarged which allows better breathing and has made a big difference in the Power.
I always run a Tank of Petrol through to every 4 tanks of Gas. Also my Patrol starts on Petrol and switches to Gas automatically after a short warm up.
Been tempted to put on a Larger Exhaust System but the Truck is only used once or twice a month for Camping and Fishing trips.
Should outlast me Ha Ha

Hi Bob,

there is a very interesting point in your comment but I suppose it should be placed in a completely new thread... this thing related to the Inlet Ports in your new Reconditioned Head.

I heard some time ago that one of the best ways to increase notoriously the power of an engine is to improve both, the air intake and the exhaust.

In my mind was always the image of changing the ducts for intake, with a new air box and maybe a snorkel, and also the extractors...

After reading your threads I realised that all this improvements would work better if in addition the ports for the intake but also the ones for exhaust are enlarged...

Nice point...

Quote:

---

Originally Posted by Bob

I went to Melb this Weekend and filled up with Gas at Calder Raceway and it took 112 Litres to fill the Gas Tank from empty. Usually it only takes105 Litres.
I did not worry about the extra Gas as I still had 50 K's to go before I parked it.
I just recently put a Reconditioned Head on (290,000 K';s). This Head had the Inlet Ports enlarged which allows better breathing and has made a big difference in the Power.
I always run a Tank of Petrol through to every 4 tanks of Gas. Also my Patrol starts on Petrol and switches to Gas automatically after a short warm up.
Been tempted to put on a Larger Exhaust System but the Truck is only used once or twice a month for Camping and Fishing trips.
Should outlast me Ha Ha

---

Quote:

---

Originally Posted by Anaurath

Hi Bob,

there is a very interesting point in your comment but I suppose it should be placed in a completely new thread... this thing related to the Inlet Ports in your new Reconditioned Head.

I heard some time ago that one of the best ways to increase notoriously the power of an engine is to improve both, the air intake and the exhaust.

In my mind was always the image of changing the ducts for intake, with a new air box and maybe a snorkel, and also the extractors...

After reading your threads I realised that all this improvements would work better if in addition the ports for the intake but also the ones for exhaust are enlarged...

Nice point...

---

Here are the Specs of the Reconditioned Head.

Set up to our Turbo and High Torque LPG spec's.
We start with a good secondhand cylinder head , then ,
Hardness test , Pressure test , Crack test , Strip , Chemically clean acid dip ,
K/Line valve guides , Serdi 3 way cut seats ,
Serdi flycut combustion chamber to unmask valves , Serdi throat ports ( also known as pocket port )
Second hand Valves , Valve springs , Retainers , Collets and spring seats are hot tank acid dipped
Valve are buffed , Valve stems linished , Kwikway reface valves , Kwikway tip valves
Comec machined with Diamond tip , final cleaned for assemble , valve spring pressure checked ,
Assembled with new valve stem seals


This was done by a Company in Victoria. PM me if you want the Name of that Company