Radiator flushing on the GU 4.2????

Submitted: Sunday, Apr 17, 2005 at 19:57
ThreadID: 22143 Views:9404 Replies:12 FollowUps:16
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Okay; so here's the latest decision I've made to try to curb the overheating 'trol......

Following everyone's advice a few days ago (thanks everybody), I've decided to buy a new thermostat (it's says it 76.5 deg) and instal. Unfortunately, the gasket the Nissan bloke sold me doesn't look like it'd fit, so I couldn't do it this weekend. (They sold me one with 4 holes in it which is sort of rectangular in shape but with one end cut off at about 45 degrees, whereas the thermo housing is round shape with 3 holes in it).

I've also decided to flush all the coolant out and replace with pure rain water + 2 bottles of REDLINE's product called "Water Wetter". I've ordered the pink one (no smart arze comments you blokes!!!! hahaha) which is for both diesel and petrol vehicles and contains a rust inhibitor. The blurb says that it cools much better than water on it's own and even better than a coolant-equipped engine. From what I can gather, commercial coolant actually detracts from the cooling systems ability to do it's job...... I reckon if I've been guilty of putting too much coolant concentrate in the donk and this could be part of my problem.

Anyway, I know there is a drain plug somewhere on the back of the block somewhere. Does anybody with a 4.2 Nissan know exactly where this plug is and whether it's best to access it from above, or below the motor. I think it's somewhere mear the turbo, but if anybody can confirm this I'd be grateful.

I'm also unsure how to know when the flushing process has been completed and if all the town tap water I use to do this flushing job will get itself out of the system, or will I need to "waste" a certain amount of rain water to flush the krappy town water out before I fill up??

Thanks again for your responses....remember, the sooner you all can help me solve this problem, the sooner you won't have to put up with my long-winded, silly questions.

Cheers everybody,

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Reply By: Pezza - Sunday, Apr 17, 2005 at 20:46

Sunday, Apr 17, 2005 at 20:46
G'day Roachie,

Not having a lot of luck down there are you, mate I can't help you with the drain plug but I may be able to help with the overheating problem.
A mate of mine had a stage 2 upgrade done to his 4.2 GU trayback, the poeple in toowoomba that did it, whom I have heard good reports about for a while now, mentioned to him about how they have cured the inherent overheating problems in some GU's ( my mate didn't know about this problem until then) while they were explaining to him what they had done to his.
Remembering the problem you are having I queried him some more on this.
Now I'm not sure of the exact details but apparently it has something to do with the compression ratio in the intake manifold caused by the boost of the turbo. The factory has got it wrong but hasn't bothered to do anything about it because there weren't enough customers complaining.
Not sure if you already know about this and have already tried this avenue or not, thought it might be worth mentioning.
If not give me a quick hello on my email, pezzamail@bigponddotcom, so I can return their contact info for them, I don't want to free advertise for them as similar companies support this site, I realise they are a little ways from you but it might just be worth a phone call. ( and maybe a good excuse for a tanning holiday to the perfect sunshine state later )
On a different note, I have solved my sub fuel tank pump problem which you tried to help me with a while ago, after trying several elimination processes to narrow the fault down, including buying a new switch, nothing worked, so I went the good old fashioned way and ran a wire from the battery to fuse box to seperate switch on dash to pump, I now switch it on to pump fuel across and switch it off when it's empty. Real high tech eh? I now also have the bonus of being able to utilise the whole 40lts.

AnswerID: 107149

Follow Up By: Member - Roachie (SA) - Sunday, Apr 17, 2005 at 21:07

Sunday, Apr 17, 2005 at 21:07
G'day Pezza...... a man who does things the same way as me, eh? Fitting a new switch is probably the best solution to get around your sub tank problem.....but I'm a bit surprised you can get 40 litres out of it; that's a real bonus. I guess you just have to be careful to remember to turn the switch off when you finish.....also, might be a good idea to switch the pump on for 10 seconds or so every morning when you start up and are waiting for the motor to warm up a bit, just to keep the seals lubricated (which is what the standard system does; except it does it EVERY time you start up....could be 10 times a day).

Thanks for the idea about the turbo boost.....once I get the 3 gauges fitted up I'll be able to tell what boost I'm running and will probably need to get the pump and/or timing slightly adjusted.

Thanks mate

FollowupID: 364128

Follow Up By: ADM - Monday, Apr 18, 2005 at 12:24

Monday, Apr 18, 2005 at 12:24
You are correct Pezza

The turbo on the GU creates to much back pressure in the manifold and as a result of that it is not able to dispurse the heat. This is the reason MTQ (DTS) have their turbo upgrage were the exhaust and comp wheels are replace to relieve the pressure. After speaking to Peter at the Towoomba branch he advised they have done many for the government and apparently they do not have a heating problem any more.

It may pay to give them a call and they can explain this in more detail.

FollowupID: 364179

Follow Up By: Pezza - Monday, Apr 18, 2005 at 12:53

Monday, Apr 18, 2005 at 12:53
Yep, that's the mob I was talking about in toowoomba, s'pose I shoulda just named them, didn't want to do the wrong thing by the site, live and learn eh.
Tony was the bloke I was told to see, seems there is a few up there that can help, might be worth a call Roachie! Good luck.

FollowupID: 364181

Reply By: Andrew (Whyalla) - Sunday, Apr 17, 2005 at 20:51

Sunday, Apr 17, 2005 at 20:51
Dont forget to shout it a new radiator cap. Only a genuine Nissan one that has the correct pressure for your engine.
AnswerID: 107152

Follow Up By: Member - Roachie (SA) - Sunday, Apr 17, 2005 at 21:02

Sunday, Apr 17, 2005 at 21:02
Thanks Andrew, I did buy a new one from a auto shop when we were on our way to Cape York last year. It wasn't a genuine one but did have the same pressure setting as that marked on the original. I thought the original one was suspect at that time, but it turned out to be the hose was sealing on the outlet of the new radiator, so coolant would flow into the expansion bottle, but upon cooling down, the radiator was sucking air instead of coolant.
Thanks for the input....much appreciated
Cheers mate
FollowupID: 364124

Reply By: warthog - Sunday, Apr 17, 2005 at 21:32

Sunday, Apr 17, 2005 at 21:32
G'day Roachie,
The drain plug for the block on the td42t is at the back of the block (near the bellhousing) on the passenger side. If you look at the motor from the area of the passenger side bonnet strut you will see two bolts on the side of the block near the back, past the back of the dump pipe. The drain plug is the upper one.
I can't believe that motor of yours is still overheating with that massive radiator in it!?. Must be the hose sucking in or overfueling. We have just been to Ruby gap towing the camper trailer through the river bed in low range and no worries, air con kept going and temp guage stayed normal. Hope you solve it soon. Cheers.
AnswerID: 107165

Follow Up By: Member - Roachie (SA) - Sunday, Apr 17, 2005 at 21:37

Sunday, Apr 17, 2005 at 21:37
Thanks mate, It's never been a problem at idle or crawling over rocks or up steep hills in low range etc....only when pushing along at the speed limit with the camper on.
I did notice yesterday that I hadn't bothered to re-fit the plastic air dam underneath the radiator a few weeks ago when I re-fitted the 4-ways steering damper that had karked it and had to be replaced. So that could have contributed to the issue last weekend I guess, as that air dam seems to have a real beneficial effect in aiding the air flow over the radiator.
Thanks for the bolt locations too.
Cheers mate
FollowupID: 364135

Follow Up By: warthog - Sunday, Apr 17, 2005 at 21:51

Sunday, Apr 17, 2005 at 21:51
Might be the air dam. If you've got a winch as well as your bull bar there's probably not much room for air to get through to the radiator. My air dam was gone when I bought the car 2nd hand. The mechanic at work recommended making one out of conveyor belt rubber which I sourced from Blackwoods. I recently put a safari intercooler on and was worried about it blocking airflow to the radiator,even though it could have been a sight bigger for the price, so out with the hole saw and 4 52mm holes in the poxy alloy bar either side of the speed camera identification plate.
FollowupID: 364142

Follow Up By: warthog - Sunday, Apr 17, 2005 at 21:53

Sunday, Apr 17, 2005 at 21:53
Sorry, my mistake that last bit should have read revenue camera identification plate.
FollowupID: 364143

Reply By: trendy - Sunday, Apr 17, 2005 at 21:39

Sunday, Apr 17, 2005 at 21:39
Hi all, in relation to the radiator cap I am led to believe Nissan changed the pressure rating on the caps for the td42 to try and cure the overheating in my vehicle. This did not help but I would talk with your local nissan service dept. to make sure you have got the right one.
AnswerID: 107167

Follow Up By: Member - Roachie (SA) - Sunday, Apr 17, 2005 at 21:44

Sunday, Apr 17, 2005 at 21:44
Yeh mate, I've gotta go back there tomorrow to get the right gasket, so will see what they reckon then......not too hopeful though.
FollowupID: 364140

Reply By: Member - 'Lucy' - Monday, Apr 18, 2005 at 01:04

Monday, Apr 18, 2005 at 01:04
Roachie you idiot!

In your overheated befuddled state, you must have staggered into either a TOYOTA or JEEP dealership when trying to source the thermo gasket. Maybe you over indulged in that fabulous home cooking Annette serves and have the 'halucinations'.

Mate! nothing is square with four bolts holes and an end cut off at 45deg's unless you have had a feed of Kadina 'blue copper' mushrooms. Especially the next line - I'm going to use pink water wetter. I mean to say, how much wetter than water can you get.


Seriously (I'll try to be) I was talking to a gentleman in QLD tonight about the exact same problem that you have.

He tells me that he to has heard, been advised that the internal turbo design that nissan engineered for the vehicles you both have is flawed.

Also that MTG (DTS) in Toowoomba have a fix for the problem where they use the existing turbo housing and re engineer the internals.

What the exact physics of it all is I have no idea. Maybe worth a call to them before you go to all the trouble of flushing and putting in the pink gin.

Have a good one mate

AnswerID: 107188

Reply By: NathanK - Monday, Apr 18, 2005 at 10:29

Monday, Apr 18, 2005 at 10:29
i used to have trouble with overheating on my V8 Discovery (turned out the rad was 70% blocked and needed rodding which fixed it completely!!), and a family friend works for redline Oil and put me onto their Water Wetter - the pink stuff - additive.

tell you what, it definitely works! the disco ran a noticable amount cooler on WW than on Tectaloy or other additives.

have you considered getting your rad rodded? if she's run hot, there's a good chance a lot of crap that sits at the bottom of the block gets stirred up when overheating and is shot thru into the rad and blocks the tubes up.
AnswerID: 107212

Follow Up By: Member - Roachie (SA) - Monday, Apr 18, 2005 at 13:57

Monday, Apr 18, 2005 at 13:57
Thanks Nathan. I would hope this radiator doesn't need rodding yet as it's less than 12 months old, but I suppose if it's taken on a gutful of crap from the block, than maybe it is already suffering......

Thanks for the words of comfort about the wett water too; I must say I have had some reservations about doing away with the traditional coolant.


FollowupID: 364189

Reply By: awill4x4 - Monday, Apr 18, 2005 at 19:19

Monday, Apr 18, 2005 at 19:19
Roachie, I certainly hope your radiator doesn't need rodding out as it's a complete alloy fabricated radiator and the only way to do it is to grind/cut out the weld, then get it rodded out and then reweld the endtank on. It's certainly not a 5 minute job.
I'm running a similar PWR core on my petrol/LPG GQ but I fabricated and welded the radiator myself and have no overheating problems.
My best advice to you for flushing out your cooling system is to use some radiator flush (I've used Tectalloy Muckowt with good results). Follow the instructions to the letter and time it so that you can get your radiator reverse power flushed by a competent radiator specialist after it's recommended running time in the cooling system.
You will be amazed by how much gunk is removed by the reverse flush. Then just get them to fill with tap water and drive it around for a day or 2. Then drop the water and remove the plug in the block and flush out through the radiator hose and refill with coolant and distilled water.
I'm using Tectalloy 100+ which is a 50/50 mix.
As an afterthought. Are you using the factory shroud? I think on the PWR ones I've seen there isn't any provision for it. On the one I built I made sure I could fit the factory shroud, the only part I have problems with is the bottom half with its small clip on section which is too close to the crank pulley, so I left that part off.
Regards Andrew.
AnswerID: 107274

Follow Up By: Member - Roachie (SA) - Monday, Apr 18, 2005 at 20:21

Monday, Apr 18, 2005 at 20:21
Thanks for that insight Andrew.
I couldn't get the shroud back on, but PWR does put the lugs there for it to be fitted. I actually cut the shroud off horizontally about 4" from the top so that I could refit the top bit, just so that fingers would be protected from the fan blades. I still have the bottom half and may have to work out a way to get it rejoined and try to modify it so it will fit; even if I have to leave the bottom flap off. I always thought that with the extra fan at the front which I have fitted, the air flow over the fins would be okay. Overheating has never been a problem at low speeds, only when pushing hard or into a strong headwind.

Back to the drawing board I guess.

Cheers mate

FollowupID: 364244

Follow Up By: Truckster (Vic) - Monday, Apr 18, 2005 at 22:59

Monday, Apr 18, 2005 at 22:59
So you dont have the complete shroud on your rad ??

There is your problem.

Havin' been thru this myself, its critical on 4.2's to have the shroud surrounding the complete radiator. Top and even the bottom section that is removed when doing a body lift.
FollowupID: 364266

Follow Up By: Member - Roachie (SA) - Wednesday, Apr 20, 2005 at 22:44

Wednesday, Apr 20, 2005 at 22:44
Thanks mate,
I've made some bits up and fitted them to the bottom section of shroud, so that once I take the top hose off to cut it and fit the new stainless steel section in the middle of it with temp sender etc, I will have another go at trying to get the whole shroud back into position.
We'll see how that goes!!!


FollowupID: 364498

Reply By: Member - Ed. C.- Monday, Apr 18, 2005 at 22:49

Monday, Apr 18, 2005 at 22:49
G'day Roachie,
One thing which doesn't appear to have been mentioned yet, and which is all too often overlooked when draining/flushing cooling systems & changing coolant types.... In case ya hadn't thought of it.....

Catch ya later.... Ed. C.
Confucius say.....
"He who lie underneath automobile with tool in hand,
....Not necessarily mechanic!!"

My Profile  Send Message

AnswerID: 107310

Follow Up By: Member - Roachie (SA) - Wednesday, Apr 20, 2005 at 22:46

Wednesday, Apr 20, 2005 at 22:46
Thanks for the reminder Ed....will make sure I flush and refill the heater and exchanger too.

FollowupID: 364499

Reply By: ianmc - Monday, Apr 18, 2005 at 23:06

Monday, Apr 18, 2005 at 23:06
Gee Roachie, you are giving Nissan a bad name. One would think they would give U another truck to keep U quiet but suppose that would get hot too.
Well maybe this is silly and not possible but its been done before. Your fan is not back to front on its hub, ie.,pushing instead of pulling in air??
AnswerID: 107312

Follow Up By: Member - Roachie (SA) - Wednesday, Apr 20, 2005 at 22:47

Wednesday, Apr 20, 2005 at 22:47
Thanks Ian,

Will make sure it's the right way round..

FollowupID: 364500

Follow Up By: Glenn D - Thursday, Apr 21, 2005 at 04:29

Thursday, Apr 21, 2005 at 04:29
Hi Ian,

If you had some reason for installing the fan back to front it will still " move " air in the same diretion

Still trying to work out if you are joking or not !

FollowupID: 364520

Follow Up By: Member - Roachie (SA) - Thursday, Apr 21, 2005 at 22:51

Thursday, Apr 21, 2005 at 22:51
Yeh, I figured he was having a lend of me, so just brushed it off.....

However, the other comment about being able to do 120k/h in reverse in 5th gear could never happen. Why? Well, the only way I can get my old girl up to 120k/h is if I've got a stiff tail wind blowing against the back of the barn doors and twin spares (which is a big, flat surface area on which the wind can 'push' with good effect). However, if I was going in reverse, 5th gear, the tail wind would be coming at me from the front end and would be much less effective because of the extremely well presented, aerodymatically-excellent, bonnet end. The only flat surface for such wind to hit on would be the twin Lightforce 240's. I would estimate my maximum top speed in 5th gear, reverse would be about 98k/h.
I will now go out to the shed and get some pliers so I can try to prise my tongue from it's current position (firmly pushed into the side of my cheek).
Cya all later
FollowupID: 364627

Reply By: Glenn D - Thursday, Apr 21, 2005 at 04:34

Thursday, Apr 21, 2005 at 04:34

Check to see if your fan is pushing not pulling air.Easy to check - engine will be turning opposite direction to normal. High range will only have one forward gear but five reverses!

AnswerID: 107628

Reply By: ianmc - Thursday, Apr 21, 2005 at 21:49

Thursday, Apr 21, 2005 at 21:49
Glenn D, well who is joking now. Well I have egg on face, just went out to ponder over this by looking at the Triton fan & I am wrong & you are right.
BUT, turn it around & the sccoop effect of the curved blades is rather reduced.
Well, sucked in Roachie. Bet he is still scratching his head!
Yeah the Stuart Highway with no limits would be fun in 5th reverse at 120kmph.
AnswerID: 107726

Reply By: ianmc - Friday, Apr 22, 2005 at 20:21

Friday, Apr 22, 2005 at 20:21
What Roachie, the trol wont exceed 120kmh?? Hasnt it got a turbo? Or are the blades in the turbo installed back to front too???
I wouldnt bank on that!!
Triton 2,5td handles 120kmh albeit with a few revs & plenty more afyer that but takes a while!
AnswerID: 107884

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