GQ Patrol 4.2 diesel sluggish towing?

Submitted: Monday, May 09, 2005 at 11:25
ThreadID: 22797 Views:2924 Replies:8 FollowUps:0
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Hi guys,

Recently became the owner of a 92 GQ 4.2 ltr diesel manual. She's in great nick and has only done 145 000 kms. Around town I'm getting 12.4lt/100kms and the truck feels quite responsive.

Had my first towing experience on the weekend and was really disappointed. Towed my boat (approx 1600kg, 18.5 foot fibreglass with a 90hp outboard) to Jurian which is about 270kms from Perth and averaged 21lt/100kms. The top speed I was getting was between 90 and 100 kms/hr in forth gear and there was nothing left - my foot was to the floor. Any hint of an incline and she'd drop to 80kms/hr. (Perth to Jurian is quite hilly - they're not huge gradients but they were enough to hurt)

After a while I realised that having my foot flat to the floor wasn't helping much - I could back off about a quarter throttle and my speed stayed the same - which may account for all the fuel I used!!

Temp gauge normally sits just below a quarter – while towing it was up just over half.

Is this sort of towing performance normal? It's my first diesel and I guess I don't really know what to expect.

Just had new air filters put in it and a full service.

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Reply By: flappa - Monday, May 09, 2005 at 11:29

Monday, May 09, 2005 at 11:29
I would suggest thats pretty close to normal.

Thats why a lot of Owners opt to put a turbo on it , mostly for towing purposes.

My parents did exactly that after buying their 4.2 Diesel Mav.

Towing performance was ordinary , so put a turbo on it.

Made a HUGE difference.

At the time , $3500 well spent.
AnswerID: 110412

Reply By: sang - Monday, May 09, 2005 at 11:42

Monday, May 09, 2005 at 11:42
Hi Karlos,
I have a Landcruiser Troopy with 4.2 diesel (naturally aspirated) and tow a 22 ft van (2200 Kg) and the truck is heavily laden to over 3000 Kg. All up I am moving over 5 tonnes. Get around 20-21 l/100k. On the flat, I manage 110 Kph, but normally tow at 90-100 kph. Any gradient will drop the speed down to 80-90 kph. A bit more gradient will see me into 3rd or 2nd gear, down to 60-80 kph. You get used to it and most of Oz is flat anyway. Always lookout for folowing vehicles, pull over and let them pass.
AnswerID: 110416

Reply By: 80scruiser - Monday, May 09, 2005 at 12:05

Monday, May 09, 2005 at 12:05
The 4.2's have a fuel filter in the pump as well which can get blocked.
Remove the fuel inlet pipe to the pump and you will see a filter down the hole. Pull it out and give it a clean. You will be surprised at the junk that gets in there.
AnswerID: 110419

Reply By: Member - Karl - Monday, May 09, 2005 at 12:46

Monday, May 09, 2005 at 12:46

As others have stated that sounds pretty much right for a normally asperated diesel. I have a 1991 80 Series Landcruiser which I added an aftermarket turbo. I would notice that when towing my off road trailer full of camping gear and family in the truck my speed was pretty average; however, it improved dramtically with the turbo.

The turbo shouldn't make much difference to your fuel usage from what you are getting now except that once you are towing, overtaking, cruising up Greenmount etc you use less fuel because you don't have your foot flat to the floor - which is when you use fuel in a diesel.

There are a couple of good places in Perth that fit turbos - Robson Bros in Belmont is one that comes to mind. They get a good wrap in Western 4 Wheel Driver magazine.

AnswerID: 110429

Reply By: floyd - Monday, May 09, 2005 at 13:00

Monday, May 09, 2005 at 13:00
Have the injectors been serviced? Have the valve clearances been adjusted since new. I would start with this first. Much cheaper than a Turbo. Having said that I got one fitted to my hilux and it now tows like a petrol 6 cylinder. Turboing a 6 cylinder diesel will give it the torque of a V8.
AnswerID: 110432

Reply By: Member - Brian (Gold Coast) - Monday, May 09, 2005 at 18:19

Monday, May 09, 2005 at 18:19
I have just started towing recently with my 95 TD42 and realised all the things you have!
Sounds like yours behaves exactly like mine.... SWMBO and I are budgeting to fit a turbo to ours now...

As yours is your first diesel, for what its worth I have learned a couple of things about diesels......
Change oil filters with every oil change
Service every 5000 k's
keep your cooling system clean.... including the fins on your radiator and air con condensor, I regularly remove and clean the radiator, and while it's drying I have enough room to hose out the fins on the condensor. Be careful not to bend the fins over with over-zealous hosing though..... going off road usually raises dust and that dust usually settles in your radiator and becomes an air blockage!
AnswerID: 110494

Reply By: Vinnie - Monday, May 09, 2005 at 21:33

Monday, May 09, 2005 at 21:33
G`Day Karlos

I got the same vehicle and the same response when towing as you do. You can either get a tubo fitted and that realistically will set you back around 4 grand or do what I do.........take a little longer to get there!!

AnswerID: 110531

Reply By: Karlos - Tuesday, May 10, 2005 at 01:20

Tuesday, May 10, 2005 at 01:20
Thanks for all your responses and advice guys - much appreciated. Definitely going to look at a turbo.

AnswerID: 110568

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