My problem is that when driving on the highway at 100-110kph the car runs great until I have a hill to contend with, then the temp climbs to above 3/4 on the gauge, then as I go downhill again, the temp returns to just below half on the gauge and stays this way until I get to another hill.
TD27T overheating
- Thread starter ajcmbrown
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squeak81
Member
Have you tried flushing your radiator? Sounds like there could be crap in it. Also has the car always run coolant in the system? Check the impellars on the water pump.
it seems from everything I have read on other sites and this one, that the cooling system seems to be working at close to capacity when in good nick, but when all is not at its best then problems are encountered.
The word "overstressed" comes to mind.
I like the idea of a bigger/thicker radiator and better water pump so that the cooling system is only working at 7/10ths instead of 10/10ths if that makes sense.
I may be wrong but a car travelling at 100kph should not be relying on the fan to cool it;
The velocity of air going through the radiator at that speed should provide plenty of cooling for almost all conditions.
Fans should only be needed when there is insufficient air flow such as when in 4x4 or in traffic.
Ironically this is when my car behaves itself and never even looks like getting hot.
I cant help thinking that there is not enough airflow for whatever reason, ie bullbar or some other obstruction but I cant see any obstruction.
Perhaps the fuel is not enriching under boost and creating a lean condition.
There is a diaphram on the injector pump and I dont know what it does but there is a vaccuum or boost line that is broken, maybe if I knew where that went it may solve my problem.
With some daylight on the weekend I will get under it and try to work out where it goes to and its purpose.
The word "overstressed" comes to mind.
I like the idea of a bigger/thicker radiator and better water pump so that the cooling system is only working at 7/10ths instead of 10/10ths if that makes sense.
I may be wrong but a car travelling at 100kph should not be relying on the fan to cool it;
The velocity of air going through the radiator at that speed should provide plenty of cooling for almost all conditions.
Fans should only be needed when there is insufficient air flow such as when in 4x4 or in traffic.
Ironically this is when my car behaves itself and never even looks like getting hot.
I cant help thinking that there is not enough airflow for whatever reason, ie bullbar or some other obstruction but I cant see any obstruction.
Perhaps the fuel is not enriching under boost and creating a lean condition.
There is a diaphram on the injector pump and I dont know what it does but there is a vaccuum or boost line that is broken, maybe if I knew where that went it may solve my problem.
With some daylight on the weekend I will get under it and try to work out where it goes to and its purpose.
"Have you tried flushing your radiator? Sounds like there could be crap in it. Also has the car always run coolant in the system? Check the impellars on the water pump."
This has been covered in previous posts.
This has been covered in previous posts.
squeak81
Member
With the radiator in mine it would over heat very quickly over 2500 rpm. I sent the old one in after i did a flush as it was still being a pain and the core was shot. I am replacing with new copper core over weekend.
The fan only cuts in when idelling or below 1500 rpm i think. But when you said the fan spun freely when car was hot gave some of us the idea that the clutch has packed it in.
The fan only cuts in when idelling or below 1500 rpm i think. But when you said the fan spun freely when car was hot gave some of us the idea that the clutch has packed it in.
I keep reading that the viscous coupling only works when the temparature rises above normal, in other words the silicone oil in the coupling gets thicker with heat instead of thinner like normal oil, this locks the fan so that it does not freewheel and pulls more air through the radiator, but since my car only gets hot at highway speed, can the fan possibly pull more air than is already being forced through the radiator?
I wouldn't have thought so, but as I said, I could be wrong.
I think my next step is to pull the water pump and if thats ok I will explore the fuel enrichment since it only happens under boost when more fuel is needed and more heat is produced by the turbo.
Apart from the water pump which I havent checked yet, I can't see any "cooling system" reason for getting hot with the possible but unlikely exception of the thermostat housing bypass.
The radiator appears to be clean inside, not blocked on the outside, water flows freely through it, it has a new thermostat, the belts are in good nick and tensioned correctly, there is no air in the cooling system, nothing blocking the radiator other than a normal bullbar, no driving lights, no other restrictions to airflow.
I will probably replace the water pump as a form of insurance since I dont know how old it is and could be the original, in which case it would be overdue anyway.
And thanks all for the suggestions, keep em coming in case there is something obvious I haven't considered.
I wouldn't have thought so, but as I said, I could be wrong.
I think my next step is to pull the water pump and if thats ok I will explore the fuel enrichment since it only happens under boost when more fuel is needed and more heat is produced by the turbo.
Apart from the water pump which I havent checked yet, I can't see any "cooling system" reason for getting hot with the possible but unlikely exception of the thermostat housing bypass.
The radiator appears to be clean inside, not blocked on the outside, water flows freely through it, it has a new thermostat, the belts are in good nick and tensioned correctly, there is no air in the cooling system, nothing blocking the radiator other than a normal bullbar, no driving lights, no other restrictions to airflow.
I will probably replace the water pump as a form of insurance since I dont know how old it is and could be the original, in which case it would be overdue anyway.
And thanks all for the suggestions, keep em coming in case there is something obvious I haven't considered.
Hey squeak81, would you mind updating after you replace the radiator?
I just remembered something that happened a couple of years ago that "might" be causing my problems, my Navara wold not start one morning and after a little investigation I found that the battery hold down clamp had become dislodged and the battery had moved far enough left for the power steering pump pulley to cut a slice out of the bottom of the battery, this caused battery acid to be sprayed all over the engine bay (looks like sh1t) and I was thinking that if the acid got onto the radiator fins and corroded some of the fins, then perhaps that is preventing heat transfer.
I will pull the radiator out and take it to a radiator shop and see what they say.
Given what others have said about Navaras being prone to overheating, it could be something this simple but not obvious.
I just remembered something that happened a couple of years ago that "might" be causing my problems, my Navara wold not start one morning and after a little investigation I found that the battery hold down clamp had become dislodged and the battery had moved far enough left for the power steering pump pulley to cut a slice out of the bottom of the battery, this caused battery acid to be sprayed all over the engine bay (looks like sh1t) and I was thinking that if the acid got onto the radiator fins and corroded some of the fins, then perhaps that is preventing heat transfer.
I will pull the radiator out and take it to a radiator shop and see what they say.
Given what others have said about Navaras being prone to overheating, it could be something this simple but not obvious.
squeak81
Member
We had the same problem. Bought the ute and was told by previous owner that the battery exploded and the acid went every where (yep looks like shit too). So let you know how i go over weekend. My old radiator seemed fine but the core was shagged. Took it in to a radiator shop and they stripped it down after a pressure test.
My TD27 fan used to cut in at highway speeds when I was towing in summer (and on some days, when I was unloaded too), a fan that big at 3400RPM (and then some for the pulley ratio) makes a fair racket.
Yeah pumping air in would make a difference at highway speed, it's not a very easy duct for the air so any help is good. Mine would get up to about 1/3 on the temp guage, fan kicks in to bring it down to about 1/5, then it climbs again, it's the circle of life.
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Good thing that the new pump will come with a hub included I guess.
I cant say I have ever heard the fan kick in, but I am deaf according to my kids....Haha.
I should take it for another good drive with the radio off and window down to see if I can hear it.
I wonder if air deflectors like what is used underneath vans like Mits Express, Mazda E2000 would help at all, I had a van once that had the deflector broken off and it would overheat at anything over 60kph because the airflow was completely missing the radiator.
Perhaps that would alleviate some of my issues.
I cant say I have ever heard the fan kick in, but I am deaf according to my kids....Haha.
I should take it for another good drive with the radio off and window down to see if I can hear it.
I wonder if air deflectors like what is used underneath vans like Mits Express, Mazda E2000 would help at all, I had a van once that had the deflector broken off and it would overheat at anything over 60kph because the airflow was completely missing the radiator.
Perhaps that would alleviate some of my issues.
I seem to have solved my problem, its amazing what a fresh pair of eyes can show you.
While sitting in my garage on the phone looking at the front of the Navara I noticed that the bullbar obscures around 60% of the radiator, so I took the bullbar off and went for a drive, 40 kms and no real sign of overheating but got a little high at times, a friend looks at the front of the car and says "is that an intercooler?" I said not thats an airconditioner condensor.
He says "shit its blocked" "no it isn't" I say, but on closer inspection with my glasses on I realise he is correct.
So...I cut two holes in the front of the bullbar about 200mm x 100mm directly in front of the radiator, blew the A/C condensor with a jet washer and now my overheating problems are a thing of the past.
Just to be sure, with almost a tonne on the back up a very long hill heading south out of Canberra, the temp got a whisker over half on the gauge.
So to all who helped with suggestions, information, I thank you all again and I promise to wear my glasses before posting again.
While sitting in my garage on the phone looking at the front of the Navara I noticed that the bullbar obscures around 60% of the radiator, so I took the bullbar off and went for a drive, 40 kms and no real sign of overheating but got a little high at times, a friend looks at the front of the car and says "is that an intercooler?" I said not thats an airconditioner condensor.
He says "shit its blocked" "no it isn't" I say, but on closer inspection with my glasses on I realise he is correct.
So...I cut two holes in the front of the bullbar about 200mm x 100mm directly in front of the radiator, blew the A/C condensor with a jet washer and now my overheating problems are a thing of the past.
Just to be sure, with almost a tonne on the back up a very long hill heading south out of Canberra, the temp got a whisker over half on the gauge.
So to all who helped with suggestions, information, I thank you all again and I promise to wear my glasses before posting again.
D
Dave
Guest
Nice work.
Easy cheap fix to.
Easy cheap fix to.
Yeah it was a cheap and easy fix Dave, thanks for your suggestions and help in trying to sort my problem for me, this is what makes forums like this invaluable.
20 years ago everyone was on their own, if you had a problem, you had to work it out or take it ot a "specialist" in that field.
The Mazda E2000 van that I mentioned in a previous post had been owned by a company that had spent thousands with "specialists" trying to sort out the overheating problem, cylinder head reco, new radiator, ultimately the engine was replaced, when it was as simple as a wind deflector that had broken off somehow. I think from memory the repair cost me about 12 bucks.
These problems are not always rectified like this but it sure is good when a bit of careful inspection (glasses!) valid suggestions and thought are applied for a great result.
20 years ago everyone was on their own, if you had a problem, you had to work it out or take it ot a "specialist" in that field.
The Mazda E2000 van that I mentioned in a previous post had been owned by a company that had spent thousands with "specialists" trying to sort out the overheating problem, cylinder head reco, new radiator, ultimately the engine was replaced, when it was as simple as a wind deflector that had broken off somehow. I think from memory the repair cost me about 12 bucks.
These problems are not always rectified like this but it sure is good when a bit of careful inspection (glasses!) valid suggestions and thought are applied for a great result.
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squeak81
Member
Glad you got it sorted with near to no cost. I replaced the radiator in mine the other day and fixed the problem here.
If you need any more help mate we are here.
If you need any more help mate we are here.
could have bad oil flow, japanese diesels are known for getting pretty sooted up theres a product ive seen in magazine called "cost effective" thats meant to flush out your engine pretty well, goes for around $100, would be worth a try... heres a link for you
Cost Effective Maintenance - Flushing Oil Concentrate
Cost Effective Maintenance - Flushing Oil Concentrate
UPDATE: it seems that my overheating issues are not completely rectified.
Maybe the weather was just cooling down when I last posted in April 2011, but with this summers high temps, I have noticed that my cooling system is not 100%, probably 85%.
On long hills my temp gauge slowly climbs higher and higher, not as bad as before but it still happens.
I believe it is the housing that bolts to the front of the cylinder head.
Maybe the weather was just cooling down when I last posted in April 2011, but with this summers high temps, I have noticed that my cooling system is not 100%, probably 85%.
On long hills my temp gauge slowly climbs higher and higher, not as bad as before but it still happens.
I believe it is the housing that bolts to the front of the cylinder head.
Hey.
My Td27t sits on about 1/3 nearly all the time. When ive been hurting her for an extended period of time - it may go up to half.
Contrary to some of your previous posts...if your diesel is running lean it should not lead to overheating...if your diesel if running rich it will create more power, higher exhaust gas temps and bulk heat.
you would need an EGT guage installed in the exhaust to check this. Otherwise you can have the car put on a dyno and ask the dyno operator to do an EGT test...they will be able to tell you if its burning excess fuel and creating to much heat..
the td27t has a boost compinsator, to allow for more fuel to be added on boost so it makes power. You can adjust this with a simple screw setup, but id sugest not playing with this unless u have an EGT....
the other dead giveaway is black smoke, have a mate follow you while your loading her up and get a description of how much smoke she is blowing. she should only blow a small amount under load, but if its coming out in a thick stream you may be running to rich/have a leaky injector.
I have seen your posts about your clutch fan, did you replace this?
It should not be overly easy to spin when your engine is hot. The oil in the fan works based on tempture, the theory is that when you radiator heats up, the oil in the clutch heats up and locks the fan up to cause it to go faster - pulling more air through the radiator and cooling the fluids down.
On Davies crag website you can do some reading on it, i think without additional head most are rated to 40 percent friction, going up to around 65 70 percent with heat around 75-85 degrees.
the dirty diesel should not create SFA heat idling or under no load work, when she is on boost and loading up - she will start to fell the heat and this will be one of the times it will rely on the heating system.
when i got the car, its radiator had barely any fins but it still worked fine, unless you towed something - just an example.
i replaced my radiator with a decent one and this went away.
anyway....you need to ensure your radiator has no blockages/missing fins and is in general good working condition. Then you need to make sure your clutch fan is working, this is harder to test.
Regardless of whats been said, the clutch fan is the only thing PULLING the air through the radiator. when your cruising along the airflow generally will deflect around your front-bar/bull bar/ac condenser and not make its own way to the radiator - its needs to be forced and directed there. The clutch fan does this for you.
if all these basic things are in order you might have to dig deep.
i see you have good coolant/replaced thermostat, this is good.
did you replace the water pump? this is a good idea to.
next things ?
the td27t has a oil cooler i believe....check this, make sure the coolant and oil flow is not impeded....if the oil is getting stuck and HOT it will cause the engine to heat up/causing the coolant to heat up to......this is a big issue with the SD33 patrol diesel engine - lots of threads online about this.
Headgasket? have you had a compression check? is it eating water? is it putting compression into the cooling system?
im starting to run out of ideas here, so hopefully you have fixed the issue by now
regards, Christian
My Td27t sits on about 1/3 nearly all the time. When ive been hurting her for an extended period of time - it may go up to half.
Contrary to some of your previous posts...if your diesel is running lean it should not lead to overheating...if your diesel if running rich it will create more power, higher exhaust gas temps and bulk heat.
you would need an EGT guage installed in the exhaust to check this. Otherwise you can have the car put on a dyno and ask the dyno operator to do an EGT test...they will be able to tell you if its burning excess fuel and creating to much heat..
the td27t has a boost compinsator, to allow for more fuel to be added on boost so it makes power. You can adjust this with a simple screw setup, but id sugest not playing with this unless u have an EGT....
the other dead giveaway is black smoke, have a mate follow you while your loading her up and get a description of how much smoke she is blowing. she should only blow a small amount under load, but if its coming out in a thick stream you may be running to rich/have a leaky injector.
I have seen your posts about your clutch fan, did you replace this?
It should not be overly easy to spin when your engine is hot. The oil in the fan works based on tempture, the theory is that when you radiator heats up, the oil in the clutch heats up and locks the fan up to cause it to go faster - pulling more air through the radiator and cooling the fluids down.
On Davies crag website you can do some reading on it, i think without additional head most are rated to 40 percent friction, going up to around 65 70 percent with heat around 75-85 degrees.
the dirty diesel should not create SFA heat idling or under no load work, when she is on boost and loading up - she will start to fell the heat and this will be one of the times it will rely on the heating system.
when i got the car, its radiator had barely any fins but it still worked fine, unless you towed something - just an example.
i replaced my radiator with a decent one and this went away.
anyway....you need to ensure your radiator has no blockages/missing fins and is in general good working condition. Then you need to make sure your clutch fan is working, this is harder to test.
Regardless of whats been said, the clutch fan is the only thing PULLING the air through the radiator. when your cruising along the airflow generally will deflect around your front-bar/bull bar/ac condenser and not make its own way to the radiator - its needs to be forced and directed there. The clutch fan does this for you.
if all these basic things are in order you might have to dig deep.
i see you have good coolant/replaced thermostat, this is good.
did you replace the water pump? this is a good idea to.
next things ?
the td27t has a oil cooler i believe....check this, make sure the coolant and oil flow is not impeded....if the oil is getting stuck and HOT it will cause the engine to heat up/causing the coolant to heat up to......this is a big issue with the SD33 patrol diesel engine - lots of threads online about this.
Headgasket? have you had a compression check? is it eating water? is it putting compression into the cooling system?
im starting to run out of ideas here, so hopefully you have fixed the issue by now
regards, Christian
Hi Christian, thank you for taking the time to try to help me with my problem.
So that we are not going back over old possibilities I think I should mention the following, my engine uses no water, has no water in oil, or oil in water, the radiator is clean and flows freely, the radiator cap and thermostat have been replaced with a new items, the water pump appears to be pushing plenty of water.
My problem was much worse before I cleaned the A/C condenser and opened the front of the bullbar that was obstructing the radiator, so I don't fully agree with the idea that most of the air goes around the front of the car, just drive with a plastic bag on your grille for a while to demonstrate what I mean. Davies Craig sold many thermo fans on the basis that engine driven fans suck power at higher revs and don't work efficiently at low rpms, like in traffic. They stated that a thermo fan works only when needed, not at highway speed, and kicks in when in traffic where air flow is minimal. In other words, a Davies Craig thermo fan would give the best of both worlds, no power robbing fan blades which are ineffective at highway speeds and plenty of cooling at low engine rpms, ie idling. I am always ready to take on new ideas or even different reasoning, but their original reasons seem sound to me.
Earlier today I posted about the thermostat housing that bolts onto the front of the cylinder head, not the alloy water outlet, the cast iron piece that the thermostat sits into.
Where the thermostat sits at the front of the head, there is a small housing that bolts to the front of the cylinder head that the thermostat sits in. I have pasted this theory below and would like your input on the theory.
"Looking down into this housing with the thermostat out, it appears to have a "seat" that the thermostat closes off when fully open to prevent the coolant from bypassing the radiator.
The "seat" area in my car is fairly corroded, and I have the same issue on long hills.
I believe that the coolant is designed to circulate around the engine block and head only until it heats up to operating temperature, when the thermostat opens and the disc on the bottom of the thermostat "should" close off this gallery.
If corroded like mine, this can no longer seat and allows some of the water to bypass the radiator and just circulate around the block and head, creating an overheat condition.
The good news is that this part is replaceable, I dont know how much or how available it is but since Nissan have sold millions of TD27's around the world, it should be available.
Has anyone explored this before?
if I have the wrong end of the stick, please let me know."
The idea of diagnosing the problem also appeals to me much more than replacing items until I think I have solved the problem.
From what I can tell, the cooling system components such as the radiator, water pump, fan belts, airflow, coolant, thermostat and temp gauge are all working correctly. The viscous coupling is perhaps questionable, but I still need convincing that it can cool an engine at 100 kph, after all what did manufacturers do before viscous couplings where available? They had blade fans fixed to the water pump shaft, some with as little as 4 pissy little pressed steel blades, some with 7 or 8 or more large flexible blades. They relied on airflow in front of the radiator except at low speeds. I agree with how a viscous coupling works, but was always of the belief that they are for high load at low speeds, where airflow is not present, the viscous clutch fan creates airflow.
I wasn't aware that a lean diesel does not create heat, but I agree that it seems logical that unlike a petrol engine, if it is unable to produce power, it is unable to produce heat.
I don't think my engine is producing any more power than standard, so running rich is unlikely, however the leaky injector theory idea has merit, since I have noticed black soot on my trailer sometimes.
Again, thank you for your time and ideas, Tony
So that we are not going back over old possibilities I think I should mention the following, my engine uses no water, has no water in oil, or oil in water, the radiator is clean and flows freely, the radiator cap and thermostat have been replaced with a new items, the water pump appears to be pushing plenty of water.
My problem was much worse before I cleaned the A/C condenser and opened the front of the bullbar that was obstructing the radiator, so I don't fully agree with the idea that most of the air goes around the front of the car, just drive with a plastic bag on your grille for a while to demonstrate what I mean. Davies Craig sold many thermo fans on the basis that engine driven fans suck power at higher revs and don't work efficiently at low rpms, like in traffic. They stated that a thermo fan works only when needed, not at highway speed, and kicks in when in traffic where air flow is minimal. In other words, a Davies Craig thermo fan would give the best of both worlds, no power robbing fan blades which are ineffective at highway speeds and plenty of cooling at low engine rpms, ie idling. I am always ready to take on new ideas or even different reasoning, but their original reasons seem sound to me.
Earlier today I posted about the thermostat housing that bolts onto the front of the cylinder head, not the alloy water outlet, the cast iron piece that the thermostat sits into.
Where the thermostat sits at the front of the head, there is a small housing that bolts to the front of the cylinder head that the thermostat sits in. I have pasted this theory below and would like your input on the theory.
"Looking down into this housing with the thermostat out, it appears to have a "seat" that the thermostat closes off when fully open to prevent the coolant from bypassing the radiator.
The "seat" area in my car is fairly corroded, and I have the same issue on long hills.
I believe that the coolant is designed to circulate around the engine block and head only until it heats up to operating temperature, when the thermostat opens and the disc on the bottom of the thermostat "should" close off this gallery.
If corroded like mine, this can no longer seat and allows some of the water to bypass the radiator and just circulate around the block and head, creating an overheat condition.
The good news is that this part is replaceable, I dont know how much or how available it is but since Nissan have sold millions of TD27's around the world, it should be available.
Has anyone explored this before?
if I have the wrong end of the stick, please let me know."
The idea of diagnosing the problem also appeals to me much more than replacing items until I think I have solved the problem.
From what I can tell, the cooling system components such as the radiator, water pump, fan belts, airflow, coolant, thermostat and temp gauge are all working correctly. The viscous coupling is perhaps questionable, but I still need convincing that it can cool an engine at 100 kph, after all what did manufacturers do before viscous couplings where available? They had blade fans fixed to the water pump shaft, some with as little as 4 pissy little pressed steel blades, some with 7 or 8 or more large flexible blades. They relied on airflow in front of the radiator except at low speeds. I agree with how a viscous coupling works, but was always of the belief that they are for high load at low speeds, where airflow is not present, the viscous clutch fan creates airflow.
I wasn't aware that a lean diesel does not create heat, but I agree that it seems logical that unlike a petrol engine, if it is unable to produce power, it is unable to produce heat.
I don't think my engine is producing any more power than standard, so running rich is unlikely, however the leaky injector theory idea has merit, since I have noticed black soot on my trailer sometimes.
Again, thank you for your time and ideas, Tony
