Overheating problem NL

[Ian Sharpe]

Hi guys, hoping someone ca n help me out here.

I first noticed the Paj was getting hotter than usual a couple of months ago when I was doing some low range (both transfer cases in low) , pulling some timber out on a hill that I had cut down for firewood.

The temp got up to 98-100 , I thought , hot day , really low gearing, not much air flow. It went back to normal once I stopped that work.

But in the past 4 weeks its back worse. It got up to 105-108 whilst idling at the shops on a very hot day (36 deg)

Went down to under 90 once I started to move.

So things I have done since but to no avail.

1. Checked temp with different gauge & sender, no change
2. checked thermostat, was working Ok. Replaced with new one anyway.
3. Replaced radiator, no change
4. replaced viscous fan (it seemed locked on) with a Davis Craig thermo, no change
5. Pulled off headers & welded cracks, also checked cat, it was ok. Ran it with muffler not connected , no change.
6. Took it back to the guys that rebuilt the motor 2 years ago, thinking maybe water pump. Lost faith in them once they said it was running Ok & at 77 deg. Thats funny I said , my digital gauge says 93 & the thermostat is 82 deg.!
7. Plumbed in a Davis Craig electric water pump, no change. could actually see the water flowing in the radiator from left to right but I suspect it may be only circulating the water through the upper manifold & not the block. If I take the EWP off I cannot see any movement of the water at all.
8. Changed o2 sensor, no change.

SO any thoughts before I get someone to strip down the front end & replace the water pump? Can they fail? it doesnt leak or make any bad noises etc.

cheers guys

[stumagoo]

water pumps can fail - though its not a normal thing, happens when either the bearings go and they leak but normally can still pump, or if they have poor water used in them and it corrodes the blades of the pump, this would normally happen along with other components deteriorating - core plugs, radiator, heater core etc. if the originaly water pump was suspect and reused it may be a possibility but its unlikely.

Other possibilities is a partially blocked radiator and water galleries inside the engine. and the dreaded head gasket possibility. there are more but you have covered the bulk of them. remember stock waterpump wont flow until thermostat opens.

[Ian Sharpe]

Other possibilities is a partially blocked radiator and water galleries inside the engine. and the dreaded head gasket possibility. there are more but you have covered the bulk of them. remember stock waterpump wont flow until thermostat opens.

I also ran it without thermostat no difference. I doubt head gasket as I can see no bubbles & also I dont seem to lose any water. Blocked galleries inside engine could be a worry though.

[Jeffwatkins]

I also ran it without thermostat no difference. I doubt head gasket as I can see no bubbles & also I dont seem to lose any water. Blocked galleries inside engine could be a worry though.

Don't know about water quality in Braidwood but in a job I had many years ago I used to test the water quality in some country towns. Cootamundra/Leeton/Wagga etc were really bad as is a lot of WA is. The coils in the diesel fired burners clogged and developed pin holes. But with you being on a farm my guess is you have tank water. Do you use that in your radiator?

[geopaj]

So, to clarify, it's only getting hot when idling or when going slow in low range?

This would suggest that the cooling system has capacity to cool adequately if/when thee is enough airflow.

I'd strongly suggest you revisit the viscous fan and shroud and remove all the add-ons (electric fans are known to not produce as much airflow as a mechanical fans).

[Ian Sharpe]

Don't know about water quality in Braidwood but in a job I had many years ago I used to test the water quality in some country towns. Cootamundra/Leeton/Wagga etc were really bad as is a lot of WA is. The coils in the diesel fired burners clogged and developed pin holes. But with you being on a farm my guess is you have tank water. Do you use that in your radiator?

yeah tank water

[Ian Sharpe]

So, to clarify, it's only getting hot when idling or when going slow in low range?

This would suggest that the cooling system has capacity to cool adequately if/when thee is enough airflow.

I'd strongly suggest you revisit the viscous fan and shroud and remove all the add-ons (electric fans are known to not produce as much airflow as a mechanical fans).

no, I can be scooting along the highway , hit an incline & up she goes, eg the day I took in into Queanbeyan to have it checked by the engine guys, it was 3 degrees ambient, Up doughboy hill & it hit 98. Goes back to under 90 when under not much load.

The thermo fan does work ok, & cools it down once it comes on. WHen i put on the thermo, I actually refitted the bottom section of the shroud that had to come off if you put a body lift on the NLs. SO now I have full shroud where before I didnt.

Seriosuly giving me the s***s, big time, especially after all the $$ I have pit into this thing.

[geopaj]

So, to clarify, it's only getting hot when idling or when going slow in low range?

This would suggest that the cooling system has capacity to cool adequately if/when thee is enough airflow.

I'd strongly suggest you revisit the viscous fan and shroud and remove all the add-ons (electric fans are known to not produce as much airflow as a mechanical fans).

no, I can be scooting along the highway , hit an incline & up she goes, eg the day I took in into Queanbeyan to have it checked by the engine guys, it was 3 degrees ambient, Up doughboy hill & it hit 98. Goes back to under 90 when under not much load.

The thermo fan does work ok, & cools it down once it comes on. WHen i put on the thermo, I actually refitted the bottom section of the shroud that had to come off if you put a body lift on the NLs. SO now I have full shroud where before I didnt.

Seriosuly giving me the s***s, big time, especially after all the $$ I have pit into this thing.

Sorry, it's a bit hard to diagnose via the internet.

Have you done the "basics" such as checking the air con condenser for mechanical airflow blockages (ie mud, bugs, etc) ?

[Ian Sharpe]

Sorry, it's a bit hard to diagnose via the internet.

Have you done the "basics" such as checking the air con condenser for mechanical airflow blockages (ie mud, bugs, etc) ?

yeah , did that when I had the radiator out.

guess I'll have to get the front end torn down & pump replaced.

[damo03]

Can you get to a cooling specialist? They might be able to determine the cause? Sounds weird that it's suddenly a problem. My NL never goes who've half even in traffic at 40deg with aircon on.

[Ian Sharpe]

Can you get to a cooling specialist? They might be able to determine the cause? Sounds weird that it's suddenly a problem. My NL never goes who've half even in traffic at 40deg with aircon on.

yeah im booked in to natrad next week.

[MTN-KAT]

yeah im booked in to natrad next week.

Hi Ian, pls tell, what was the result of Natrad visit and what was the cause for the "intermittent" overheating. With thanx.

[Ian Sharpe]

Hi Ian, pls tell, what was the result of Natrad visit and what was the cause for the "intermittent" overheating. With thanx.

they replaced the water pump with a complete pump including the housing. All seems good now, however the 'old' pump looked OK, but he said that the risk you run if you only replace 1/2 of the pump (which did happen) is that the tolerances can be out of whack & the pump may not perform 100% .

All seems good now but the outside temps have dropped now too. Guess next summer will tell.

cheers