gq overheating problem>td42 turbo?? anyone fixed it yet?

[fnqcairns]

Diesels are very different to petrols; you over-fuel a petrol, and it cools it down; over fuel a diesel, and it WILL overheat. Simple as too much throttle going up a hill, and this WILL occur. Flooring it in these conditions just over-fuels it, and overheats it. It's NOT a petrol. Also, playing with the injector pump yourself to increase fuel exacerbates this problem.

I agree 110% on this one. Petrols and diesels are two completely differnt beasts, and there is definately a difference needed in driving style. The way i drive is to find the acceleration fringe and then back off a fraction. Revving diesels never really seems to help too much either.

The whole time I had the Mav', I don't think I revved it over 3000rpm!! Why? Cos' it doesn't need to! A n/a TD42 gets max at about 2000rpm.

Same here for me too - i don't rev my car over 3000 RPM in either N/A or turbo form. My dyno sheets show peak torque at 1370 RPM, and peak power at 2550 RPM when my GQ was N/A.

Exactly right!! Why the hell would you rev the crap out a TRUCK ENGINE?? The power and more importantly torque are developed SO LOW in the rev range, there is NO POINT in revving the crap out of it. If you want to rev, get a TB42/45/48!!

depends on the definition of rev the crap out of, even in my n/a 4.2 if each gear change is made so the next snatches gear at or near max HP RPM then it's a far more sprightly car to drive (almost keeps up with traffic light traffic:).

If anyone has ever towed more than a tinny or light camper with one of these they will also know the advantages behind taking the 4.2 (but it can relate to any other diesel) up to near 3600rpm before a gear change.

I will also pick 3300rpm to hold this engine for a period before being forced back to 2nd gear at to around the same rpm to hold again...if i did not do this on occasion i would be stuck to chugging along in 1st way before due time.

It's gear changes that force the engine back to low in the rev range under load to build up again that hurts them, the accelerator will also tell the story of what rpm it would most rather be doing for the load.

[coxy321]

Whenever i tow stuff in my GQ it is usually a tandem with a car on it, or a tandem full of wood - i still don't rev my motor any harder.

Picking the right gear for the speed, and allowing the engine to "unload" before going up a gear also helps (ie. not changing up while the engine is still trying to accelerate). I generally only go as high as 4th gear when towing a load too - i only use 5th if there's a down hill or flat.

[bigbluemav]

Whenever i tow stuff in my GQ it is usually a tandem with a car on it, or a tandem full of wood - i still don't rev my motor any harder.

Picking the right gear for the speed, and allowing the engine to "unload" before going up a gear also helps (ie. not changing up while the engine is still trying to accelerate). I generally only go as high as 4th gear when towing a load too - i only use 5th if there's a down hill or flat.

Exactly!! If max torque is under 1500 RPM and max power under 2500 RPM, why rev it 45% MORE than that? No benefit!!

[love ke70]

so that when you go to the next gear your in the middle of the power curve. 32-34 is not silly revs, and the more airflow you get the lower the EGTs...

[fnqcairns]

And because it's not running a stationary generator or powering a trawler, it's to be driven, every engine will tell the person what it wants and is capable of.
I dawdle mostly but when there is work to do the td4.2 does it much better with a few extra rpm and there is most likely less harm done because of it. Just watch the egt's they always tell a story.

[Troll00]

I am chasing this bastard of an issue as well, and currently running:

- PWR Radiator
- PWR 6x10 w2a intercooler
- High-flow thermostat (waste of time)
- All baffling back in place (ARB bar)
- Garrett BB turbo @16psi

This is on a '99 TD42T GU wagon.

Without the camper in tow, the needle doesn't move. Once towing there is long periods of heat build up and to say the AC cannot be used when towing.

I currently think it is the inter-cooler isn't up to the task. The front IC rad is sitting behind the XGT's and just isn't dissipating enough heat. So any sign of a hill and the intercooler starts storing the heat form the inlet air and stops doing its job. I need my EGTs under 350oC to use the AC, and under 450oC on a hot day to stop overheating.

I am in the process of replacing the w2a with a top-mount, anyone want a bolt-on PWR w2a kit?

- David.

Do an oil cooler first and lower your psi you will see the difference

[bigbluemav]

Diesels are very different to petrols; you over-fuel a petrol, and it cools it down; over fuel a diesel, and it WILL overheat. Simple as too much throttle going up a hill, and this WILL occur. Flooring it in these conditions just over-fuels it, and overheats it. It's NOT a petrol. Also, playing with the injector pump yourself to increase fuel exacerbates this problem.

I agree 110% on this one. Petrols and diesels are two completely differnt beasts, and there is definately a difference needed in driving style. The way i drive is to find the acceleration fringe and then back off a fraction. Revving diesels never really seems to help too much either.

The whole time I had the Mav', I don't think I revved it over 3000rpm!! Why? Cos' it doesn't need to! A n/a TD42 gets max at about 2000rpm.

Same here for me too - i don't rev my car over 3000 RPM in either N/A or turbo form. My dyno sheets show peak torque at 1370 RPM, and peak power at 2550 RPM when my GQ was N/A.

Exactly right!! Why the hell would you rev the crap out a TRUCK ENGINE?? The power and more importantly torque are developed SO LOW in the rev range, there is NO POINT in revving the crap out of it. If you want to rev, get a TB42/45/48!!

depends on the definition of rev the crap out of, even in my n/a 4.2 if each gear change is made so the next snatches gear at or near max HP RPM then it's a far more sprightly car to drive (almost keeps up with traffic light traffic:).

If anyone has ever towed more than a tinny or light camper with one of these they will also know the advantages behind taking the 4.2 (but it can relate to any other diesel) up to near 3600rpm before a gear change.

I will also pick 3300rpm to hold this engine for a period before being forced back to 2nd gear at to around the same rpm to hold again...if i did not do this on occasion i would be stuck to chugging along in 1st way before due time.

It's gear changes that force the engine back to low in the rev range under load to build up again that hurts them, the accelerator will also tell the story of what rpm it would most rather be doing for the load.

But considering the near FLAT torque curve of a TD42/TD42T......the difference between torque at 1500 and 2000 is minimal! A peaky engine like a ZD30, maybe, but NOT a TD42.

[love ke70]

so why not utilise that flat torque curve and rev the engine where it makes more power and is less stressed.
even the specs say peak power at 3600RPM for the GU and 4000 RPM for the GQ

[bigbluemav]

Yes, but aren't we talking about torque, not power?

Max torque is WAY LOWER. Torque is what pushes it through the gears. Who drives through soft sand at 3600-4000rpm? I do it about 2000rpm with a TD42 and 3000rpm in a ZD30, 'cos that's where the TORQUE is.

[love ke70]

the torque is virtually flat, you said it yourself

[bigbluemav]

the torque is virtually flat, you said it yourself

Yes DERRR, so it NEGATES the need to REV the crap out of it!

[fnqcairns]

Have many people actually driven an N/A td42? The low point where the max torque comes in is neither here nor there on this engine unless in low range towing tree trunks.....possibly, power higher up in the rev range is what makes the engine, don't miss out on it based on an assumption only, 3600 will do no harm ever and probably be kinder than lugging along spinning slow when there is no need.

The engine comes alive at about 3000 give or take a little and then thunders toward 3800-4K. How can that be given it's torque spec??

Disclaimer by thunders above i do mean the most impressive part of the engines power band is right here in 3rd gear, and by impressive I mean a td42 type level of impressive:)

[jem jem]

did i mention its Auto and its 3tonn everyday, arb deluxe bar,winch with tennis ball size holes drilled in front for extra air.... 3000rmp is like almmost max can go to36-4000rpm but it just blows fuel out the back.
no offence taken.

[DEZ]

Yes, but aren't we talking about torque, not power?

Max torque is WAY LOWER. Torque is what pushes it through the gears. Who drives through soft sand at 3600-4000rpm? I do it about 2000rpm with a TD42 and 3000rpm in a ZD30, 'cos that's where the TORQUE is.

I had my na td42 on the beach on the weekend. Now sand was very soft, in high range i could get to 3rd at 2000rpm with a lot of throttle and it was labouring. Drop to 2nd revs raised to 3000 and i was barely touching throttle. Differnt situtions call for differnt gears and revs.

[love ke70]

the torque is virtually flat, you said it yourself

Yes DERRR, so it NEGATES the need to REV the crap out of it!

so if the torque is flat, and you need more power to get up a hill, or through some very soft sand etc, where are you going to find it? higher in the revs, HP = (rpm x T)/5252.

you enjoying choking your motor and ill enjoy driving mine sedately when i have the power i need low down, and enjoy the revs when i need them

[Clanky]

For those overheating, valve settings and inj pump timing can have a profound affect on exh temps.
If all else is well it is an easy check

[maccapacca]

Hey Clanky, what injection pump setting do you recommend, does anyone else have a answer?

[coxy321]

Hey Clanky, what injection pump setting do you recommend, does anyone else have a answer?

Factory spec'd timing for me.

On the whole rev/torque/power thing, i'll rev my engine if i need to - but i still stand by what i said earlier about finding revs over around 3000RPM to be unproductive. Thats just me though. Everyone's different.

When my car was N/A, max HP was peaking at about 2500RPM.

[love ke70]

Hey Clanky, what injection pump setting do you recommend, does anyone else have a answer?

Factory spec'd timing for me.

On the whole rev/torque/power thing, i'll rev my engine if i need to - but i still stand by what i said earlier about finding revs over around 3000RPM to be unproductive. Thats just me though. Everyone's different.

When my car was N/A, max HP was peaking at about 2500RPM.

so if your running factory spec timing, all you can adjust is the fuel screw yes?
so why do we pay to get something dyno tuned unless we're getting a pump done? was something i had been wondering, how the timing would effect the power i make.

i was paying attention on my way home from work today, to my RPM. had to pull off at the bottom of a steep hill (sign says 20%) took off once i got off the phone, 1st up to 3000, then in second ran it out to about 3500, although it starts to feel a little flat by that point, its still accelorating, and hits 3rd at 2000rpm, if i had of changed early it would have bogged down and i woulda been rowing my boat back to second, so i dont understand how you other guys are saying you dont rev the motor?

this is in my work ute, which weighs in around 2.8 tonne on a daily basis, so i can understand why it struggles, how do other guys drive them without revving them that far and not bogging down on hills?

running 13psi, non intercooled, wound up fuel and D-gas, EGT's hit 550 on a 30 second power run if its all already hot, so its not short of power...

[Clanky]

I just use the factory timing as its a touring truck with a fairly standard pump apart from a bit of extra fuel and boost compensator. You can vary the timing a little by trial and error but you need to be careful as it changes the EGT and fuel comsumption.

For a (VE type) TD42 GQ it 0.74mm +/- 0.02 which is equivalent to 6deg BTDC
GU TD42 is 0.626 +/- 0.02

If you had a modified pump you would need to go with the spec set by the modifier.

[coxy321]

In regards to pump timing etc, if i ever get someone to play with the fuel (which doesn't happen often), i'll get them to check the timing as well. Whatever the dyno technician thinks the pump needs, they can dial it in as they want on the day, that way there's no "if" or "but" about the setup. When i get my arse down to dieseltech, i'll be getting fuel, pump timing and also valve clearances done, just to be sure to be sure.

[Clanky]

so if your running factory spec timing, all you can adjust is the fuel screw yes?
so why do we pay to get something dyno tuned unless we're getting a pump done? was something i had been wondering, how the timing would effect the power i make

Yes and no. You can set the timing for HP or torque or a compromise ( factory) and a dyno might help find a sweet spot...maybe. Depends on your driving style, not your dyno style.
An electronic system can do this over a wide range which is why they can create good power throughout the rev range. At the risk of staying on the topic of this thread, this is why driving style and pump mods need to be carefully done or you will risk overheating

As for driving style for diesels, talk to some truckies. They use the full rev range (around 1500 - 2500rpm) to keep the engine in the sweet spot between gears.
Its best not to make them labour or rev the tits off them, but they are governed to a safe max rpm,(unless you want to play with this setting on the pump )

EGT can tell you a lot about how you are driving the engine (and how hard its working) I have had to drop a gear when towing, not because the engine was labouring, but just to drop the EGT's on a hot day. Hence we get back to the driving style argument again and the overheating issue.
I have never had to turn the AC off - I would rather go a bit slower than be sweating santas sack off. Although I hate it when a B-double hauls out and overtakes you going uphill!!!

[Clanky]

In regards to pump timing etc, if i ever get someone to play with the fuel (which doesn't happen often), i'll get them to check the timing as well. Whatever the dyno technician thinks the pump needs, they can dial it in as they want on the day, that way there's no "if" or "but" about the setup. When i get my arse down to dieseltech, i'll be getting fuel, pump timing and also valve clearances done, just to be sure to be sure.

Exactly right Coxy321. Wear in the pump can change the timing and fuel settings etc. Same with valves and injectors. Its normal routine maintenance on the diesel engine and all be contributors related to elevated temps

[coxy321]

Beaten by the code!

When you quote, make sure the content you want to quote is between the code eg [*quote="personsname"] blah blah blah [*/quote]. Don't include the asterix i put in there though. Try and edit those two posts for practice - you're spinning me out!

[Clanky]

Beaten by the code!

When you quote, make sure the content you want to quote is between the code eg [*quote="personsname"] blah blah blah [*/quote]. Don't include the asterix i put in there though. Try and edit those two posts for practice - you're spinning me out!

Ahh the quoting business is a bit clearer now. Also that "quote" button on the post helps out when a bloke actually takes notice
Thanks Coxy

[jem jem]

Ok, yeterday was a hot hot day, driving home from work with air con on at first... warmed up to half, turned air off, was sitting in traffic M5.. warmed up just over half, got the shit took next exit.. put foot down, got to just under Hot, pulled up while my mate grabed a sixPac of Jimmis... crept up a little more.... could here a slight bubbling sound... drove of got back onto menagle road , cruiseing bout 80-100ks started to drop. got home and it was just over half.....!! so i think my factory gauge is ok. but why why why does she get warm.......!!!!

[purplebus]

Ok, yeterday was a hot hot day, driving home from work with air con on at first... warmed up to half, turned air off, was sitting in traffic M5.. warmed up just over half, got the shit took next exit.. put foot down, got to just under Hot, pulled up while my mate grabed a sixPac of Jimmis... crept up a little more.... could here a slight bubbling sound... drove of got back onto menagle road , cruiseing bout 80-100ks started to drop. got home and it was just over half.....!! so i think my factory gauge is ok. but why why why does she get warm.......!!!!

it should start to cool down if you are stopped but the vehicle is still running. when the motor is warm open the bonnet and watch the fan when you turn the motor off. the fan should stop spinning when eng is stopped almost straight away, if it continues to spin it needs the viscous hub oil in it. with the eng is cold and stopped spin the fan by hand, then when it is warm stop it and spin the fan by hand again. it should have heaps more resistance on it when warm.

[jem jem]

i have changed that already. and the fan....... water pump, radiator ,hoses, putt twin oilcoolers for the auto. cant think wat else

[coxy321]

Almost sounds lke a thermostat, not regulating the flow properly.

Just because you've replaced all of the parts, just keep in mind that there is such a thing as DOA.

[jem jem]

will change on weekend....
thanx shoul i try it without one>???