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Discussion Starter · #1 ·
Hi all, First off, done the searches and still no answers to my problem. (a lot questions similar and discusions but....)
The 4wd is a GU 99 4.5 petrol on LPG, auto with external cooler, with 4.33 diff ratios on 285/75 A/T.

* The problem is it use to over heat on hills/slight inclines on hwy when the out side temp was 35deg+ but now (18mths later) its doing it 25deg+ :mad: at any speed.
This were I get confused when doing driving tests to confirm whats causing it.
First test on a flat road i can drive in second gear at 3500rpm and get no over heating but when half way up the and incline it starts to over heat in the same gear at the same rpm at the same speed.
Second test, OD off in 3rd gear at 2300rpm on the flat no over heating but when half way up the incline it starts to over heat again at same speed rpm and gear.*

Ok, I know what can cause over heating and have checked pullys, vicous (sp) fan, coolant (have changed twice) 2 yr old radiator looks very clean inside viewing from fill hole, outside of radiator as well apart from few bugs. Thermosate seems to be doing its job, no bubbles in coolant to show signs of a head gasket leak, no coolant loss and has been very clean each time i changed it, hoses ,and all seems to be good. Over heats on gas and petrol too and low range.
The auto was to blame was my first thought but both the radiator guy and auto trans guy dont think its the cause so im stumped.
Maybe the water pump not working fast enough but it it comes back to a load thing from the driving tests.
Hoping to get this sorted soon cause Im doing a trip up to Darwin from Melbourne in April.

Any ideas
Cheers
Glenn
 

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NISSAN GU PATROL
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Mate i have the 4.5 also, my temp always stays on Half, gas or petrol.

If you really have checked everything you have me stumped also,

Airlock in the Cooling System?
Maybe your guage or temp sensor is to blame ?
Hows the heater core? that could also cause overheating.
Does it feel like it drives normal, Does it have loss of power ?
Brakes Draging ?
Blocked Cat/Exhaust?
Blocked Intake, Is the Air Filter Clean?
Plugs/Points/Leads?
Correct Engine Oil?
Or maybe your carrying extra weight ?
 

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Id look at at the threads on "ecu talk" it gives useful data in degrees Celsius and most other operating parameters. The standard nissan temp guage is if fairly sensitive and not a real good indication of whats going on.

I think BruceTB45 gave a detailed account of what he was seeing on the guage vs "ecu talk" when towing a big load up a hill in his 4.5petrol.

keep us posted if you find a solution. My 4.5 sits a frag under half regardless of what its doing or outside temp. Im in the process of ordering the ecu talk, so I can get an idea of what else is going on. Im about to fit 285's so it will load up the engine no doubt.
 

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The nutty professor
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ever had the radiator internally rodded and cleaned out ? , if you have then the only other thing i can suggest is to run a slightly hotter thermostat to slow the flow of coolant down , this combined with the greater differance between ambient air temp and coolant temp means it is easier to remove a higher percentage of heat , i have had great success in the past with controling temps just by running a hotter thermostat, cooler thermostats only ever made the problem worse
 

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I know you said you checked the viscous fan but have you pulled apart and checked, refilled? On an old MK I had it too overheated in the simliar fashion to your desrcibing - ie.. under load, not revs. The radiator bloke pulled the viscous coupling aprt, filled with fluid and presto my overheating issues were gone.

Now, my 80 series had an overheating problem but that was due to an internally clogged raditor. It would only overheat on an unltra long climb with load on the motor - new radiator and problem gone.
 

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She's apples
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Another vote for the radiator.

Mine did a similar thing, never got hot until it went up an incline. It turns out the radiator was blocked internally.

It had been cleaned out 18 months beforehand but the coolant wasn't properly flushed and when mixed with the new coolant seemed to block it up.

Got it cleaned/rodded again and hasn't overheated since(approx 2 years).
 

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I've been having a similarly costly and frustrating experience with mine. I have now done; New radiator, New radiator Cap, New thermostat, New Fan Clutch, All new hoses, New Fan Blades, complete cleanout of the condenser, System power flushed and new radiator rodded (was 20% blocked after 3 months). Has cost me close to $1500 and Not a single change from when i started!!!!!

Was getting the system power flushed on the weekend and after a 2 minute drive and a temp of 93, the guy said somehting isn't right here! So got out his IR themometer and according to the top hose the coolant was only 82 degrees. He was kind enough to lend me his themometer for the weekend. So i took the truck for a thrash up the freeway, sitting in second at 3300rpm for about 10km (35 ambient), by the top, ECUtalk was telling me 110 degrees, by the time i got out and opened the bonnet it was 107, and the temp in the coolant top hose was 97 degrees. I've ordered a new temp sender from Nizzbits and we'll see if that does the trick. Finger crossed as this is realling giving me the s*&%s. Another member had the same issue with mystery overheating and it tturned out to be temp sender.

Mine was displayig similar symptoms to yours. My advice, as others have said would be take it somewhere and get the radiator rodded and the block power flushed, they can also test the thermostat. If that doesn't work start withthe simpler and cheaper item like the temp sender, radiator cap, then looks at the fan clutch water pump.

Let us know how you get on.
Cheers
 

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I've been having a similarly costly and frustrating experience with mine. I have now done; New radiator, New radiator Cap, New thermostat, New Fan Clutch, All new hoses, New Fan Blades, complete cleanout of the condenser, System power flushed and new radiator rodded (was 20% blocked after 3 months). Has cost me close to $1500 and Not a single change from when i started!!!!!

Was getting the system power flushed on the weekend and after a 2 minute drive and a temp of 93, the guy said somehting isn't right here! So got out his IR themometer and according to the top hose the coolant was only 82 degrees. He was kind enough to lend me his themometer for the weekend. So i took the truck for a thrash up the freeway, sitting in second at 3300rpm for about 10km (35 ambient), by the top, ECUtalk was telling me 110 degrees, by the time i got out and opened the bonnet it was 107, and the temp in the coolant top hose was 97 degrees. I've ordered a new temp sender from Nizzbits and we'll see if that does the trick. Finger crossed as this is realling giving me the s*&%s. Another member had the same issue with mystery overheating and it tturned out to be temp sender.

Mine was displayig similar symptoms to yours. My advice, as others have said would be take it somewhere and get the radiator rodded and the block power flushed, they can also test the thermostat. If that doesn't work start withthe simpler and cheaper item like the temp sender, radiator cap, then looks at the fan clutch water pump.

Let us know how you get on.
Cheers
When warming up the car, does ecutalk show the correct temperature for the thermostat opening? (usually 82C). From what you wrote above, it sounds like it thinks 82C is 93C and a new sensor will fix your "problem". A thing to watch is the temperature will overshoot a bit just after the thermostat starts to open and then settle down to about 82C. The factory thermostat doesn't fully open until 90C (correction, 95C from manual) , so I think the temperature is meant to go into the 90's once you get the old beast working.

I just did an experiment which you might find useful to repeat.
1. Measured outside temp 20C, TB45 not started since yesterday. Ecutalk reports temperature 18C. This test is a first check of the temp sender.
2. Start engine and run at 1500 rpm. Ecutalk shows the coolant temp steadily increases for 5 minutes to 84C. Some time earlier the thermostat starts to open and cold coolant starts to flow into the block from the radiator. As that cooler fluid flows through the block, the temp drops to 76C at 6 minutes from engine start then starts increasing again. It cycles around a bit and stabilises around 82C as the thermostat opens and closes. This test is a second check of the thermostat and temperature sender.
 

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Thanks for you're response Bruce. The evidence on the weekend support the theory of a faulty Temp sender however the thermostat and temperatures reported by ECUtalk appear to be about right. My current school of thought is that the temp sender is reporting incorrect values increasing exponentially as the temp rises. So at 82 its only out about 5-5 degrees (ie reading 86-87) but a good 10 degrees at 97 (ie reading 107).
From memory, whilst driving, the temp hits about 87 the starts to drop but only down to 81, then stabalises 84-86 on a cool day. I would have to re-run the test to confirm with your results. But i thought given the evidence and how much i've spent "whats another 88 bucks" to rule out one more thing! Expensive way of doing it but i'm getting closer...

Do you happen to know what temp the mechanical fan is meant to kick in at? Mine engauges at about 92 according to ECUtalk. The ECU turns the electric fan on at 97 and the aircon cuts out at 104. Do these values sound right?

Cheers Bruce
 

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Interesting stuff, I thought it may be worth throwing my two bobs worth in as well
I am chasing similar problems with the car getting hot on long climbs as well
Just did Bruces check with EcuTalk on my TB45E

Car not started since yesterday
Ambient temp around 24c EcuTalk on start showed 24c
Run at 1500 rpm @ 5 minutes 68c
@ 10 minutes 71c
@ 15 minutes 78c
@ 20 minutes 77c
Decided to go for a drive and kept the car in second gear at 3,000 rpm for 10k's and temp didn't go over 84c
So for mine I'm starting to wonder if it even has a thermostat or one thats too cold, I have never checked this
Not trying to hijack the thread but willing to test with whatever I can to contribute to a solution
 

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. <snip>...

Do you happen to know what temp the mechanical fan is meant to kick in at? Mine engauges at about 92 according to ECUtalk. The ECU turns the electric fan on at 97 and the aircon cuts out at 104. Do these values sound right?

Cheers Bruce
Here are some snips from the manual and your results look close to spec to me.

1. Your aircon cut out is 104C factory specs are 105C-109C cut out, cut back in 102C-104C

2. Your aircon fan turns on at 97C and the factory spec is 95C

3. Your engine driven fan clutch engages at 92. I couldn't find a spec and I can't remember mine but I think it was about 94-95C but I can't be sure.

In summary all that sounds like all present and correct sir!

I have also attached the specs for the temperature sender if you want to check yours and the specs for the the thermostat. I was wrong in my last post - the thermostat doesn't fully open until 95C.

Now mine is a manual, from your name I guess yours is an auto. The auto trans will dump a lot of heat into the cooling system when the torque converter is not locked like when climbing hills. A lot of auto owners hook up an external trans cooler and disconnect the internal circuit to the radiator. One of the reasons they do this is for reliability to avoid leaking water into the transmission if a leak develops. Another trick is a torque converter lock circuit (search) which is often used for towing to reduce heat and improve fuel useage. Incidentally the manual trans car has 2 electric thermofans rather than the one on the auto trans.

Finally you mentioned that the new radiator was 20% blocked after 3 months. Did somebody mix coolant types at some stage? A good block flush that you have just had might be the answer unless the rad has blocked again.
 

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Interesting stuff, I thought it may be worth throwing my two bobs worth in as well
I am chasing similar problems with the car getting hot on long climbs as well
Just did Bruces check with EcuTalk on my TB45E

Car not started since yesterday
Ambient temp around 24c EcuTalk on start showed 24c
Run at 1500 rpm @ 5 minutes 68c
@ 10 minutes 71c
@ 15 minutes 78c
@ 20 minutes 77c
Decided to go for a drive and kept the car in second gear at 3,000 rpm for 10k's and temp didn't go over 84c
So for mine I'm starting to wonder if it even has a thermostat or one thats too cold, I have never checked this
Not trying to hijack the thread but willing to test with whatever I can to contribute to a solution
Have a look at the thermostat specs I just posted - it looks like you have the "tropical spec" thermostat 76C. It does have the advantage that it is fully open by 90C instaed of 95C for the standard thermostat. Maybe a previous owner was chasing the same issue?

Pongy, is yours an auto by any chance?
 

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Have a look at the thermostat specs I just posted - it looks like you have the "tropical spec" thermostat 76C. It does have the advantage that it is fully open by 90C instaed of 95C for the standard thermostat. Maybe a previous owner was chasing the same issue?

Pongy, is yours an auto by any chance?
You could be on the money there Bruce, I wonder if would be worth changing
And yes it is an auto
 

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You could be on the money there Bruce, I wonder if would be worth changing
And yes it is an auto
And does it use an absurd amount of fuel? Wondering if it is too cool to run efficiently.
 

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And does it use an absurd amount of fuel? Wondering if it is too cool to run efficiently.
No, fuel use is about average from what I can gather
23-25 litres per hundred on LPG around town
Running around town on a hot day the temp will sit between 84-90c but if I make it work hard towing or going up long hills it has gotten to 110c which is starting to get into the worry zone I reckon
 

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Don't want to get anyone side tracked but:
My TB45 on gas doesn't appear to have a cooling issue, but on long drives and recently on a track, the bonnet feels hot (or very warm, whatever you prefer) to the touch, a mate of mine actually asked about it. My eye goes over the temperature gauge often enough and all seems fine (around half, mostly just under, lower if high speed driving in cool conditions). I can feel radiant heat from the gear stick area too after driving long distance at high speed. Now being a 4WD novice, this might all be fairly normal to you, but thought I'd check if something could be wrong or ways to work what it is.
Cheers!
 

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Don't want to get anyone side tracked but:
My TB45 on gas doesn't appear to have a cooling issue, but on long drives and recently on a track, the bonnet feels hot (or very warm, whatever you prefer) to the touch, a mate of mine actually asked about it. My eye goes over the temperature gauge often enough and all seems fine (around half, mostly just under, lower if high speed driving in cool conditions). I can feel radiant heat from the gear stick area too after driving long distance at high speed. Now being a 4WD novice, this might all be fairly normal to you, but thought I'd check if something could be wrong or ways to work what it is.
Cheers!
Most of my 4wheeling has been in my old petrol TB42 shorty. The gear lever always got too hot to touch down on the metal part when sand driving on a hot day. The temperature gauge also never changed from normal. I got into the habit of lifting the bonnet when I stopped in the sand, just to keep some of the heat off the batteries and other electrics like my homemade ignition and battery isolator boxes. Having said that, in 19 years I have never had a problem that stopped me on the road apart from a clutch slave cylinder (missed a 2 year clutch fluid change - bad maintenance by me).

I think some of us may be jumping at shadows, especially with our you-beaut ecutalk displays. The factory made their temperature gauge so that it shows normal over quite a wide range that occurs in normal driving. I think it doesn't move between about 75C and 100C roughly. Remember that the cooling system is pressurised and normally has about 33% coolant and I think the bulk boiling point is roughly 127C. The aircon cutout is 107C and I think that gives us an idea that operating up towards this level is normal, especially if we are towing in hills and it is a hot day.

91 Maverick XLT TB42 manual
98 GU Patrol TB45E manual
 

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Discussion Starter · #18 ·
thanks guys, but i still dont understand why my car can rev at 3500rpm in 2nd gear on the flat road and stay at normal temp(will also over heat on hill) BUT will over heat at 2200rpm in 3rd on a hill.(but also good on the temp on the flat)
can anyone explain this please? and is there anything I can eliminate with these type of symptoms e.g I was told by the radiator guy if it is a radiator problem when it starts to over heat slow down 20 kph and the temp should reduce,but which is not hapening.
Also Does the torque convertor lock with the OD off (3rd) on the auto??
Cheers
 

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Hmmm interesting guys, and thankyou for the responses. You've made me nervous again bruce with those figures. Sender is on its way, so i'll try it anyway(might just add to the extensive list of non-faulting cooling system parts i'm gathering). That picture you posted bruce looks a bit different to what i expected. Is the cooland temp sensor the one on/next to the thermostat housing?

Going back to what you have said Glenn and i'm speculating here a bit, but my overheating occurs when under load aswell. I kind of ruled out tune as a cause because it runs great on petrol and still overheats. Which brings us back to the auto placing load on the system. When i did my "freeway tests" i had it in second purposely so the converter was locked, which implies little heat input as a result of the transmission. But could the cooler be blocked? Would it be safe for the transmission to bypass the in-radiator tank and see what happens?
 

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Hang on scrap most of that, i got myself confused (couple of reds down) Yes all these numbers will appear in spec becasue they are, but the problem is the temp sender is reporting the incorrect temp to the ECU. From my tests;

Temp (ECU talk) ------ Actual temp(thermo gun on the top hose)
82 ------------------------ ~78
86 ------------------------ ~82
93 ------------------------ ~86
107 ------------------------ ~97

Thus it will cut out the aircon when ECUtalk reads 104 but temp is actually ~95 and turn the fan on when ECU talk reads 97 but the temp is actually only ~90, hence the apparent but non existant overheating! Does that make sense.

All will be revealed tomorrow when i put in a new sender. Fingers crossed!
 
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