90 series prado overheating (1 Viewer)

[GotAn80]

My father's 2001 prado is overheating when towing his 3 ton caravan through the hills.
He's recently put in a transmission cooler which has stopped the trans from overheating but the engine is still getting hot. The gauge has never gone into the red but has gotten close. Engine has never boiled, doesn't blow smoke.

It's got a fairly new radiator in it, a new thermostat, aftermarket trans cooler, 3" exhaust, new oil in the trans fresh coolant in the radiator and there's no oil or water where it shouldn't be.

Other than the overheating it performs as it should. What are your thoughts on what could be wrong or need to be done?

 

[JDM Journeys]

Which engine?

 

[GotAn80]

Which engine?

1kz

 

[JDM Journeys]

It's possible that it is being pushed too hard in terms of heat built by combustion. Before any kid of towing, a pyrometer should be the first on the list in my opinion. It will indicate a potential overheat long before the coolant temp gauge starts rising. Then you can take steps to reduce the heat. Its amazing how gear choice and a slight change in throttle position can affect egt's dramatically. Altitude also affects diesel combustion as well - more smoke and less power as you go higher. And thus more heat.

You may in fact have cooling needs as well, but I'd start with egt before anything else. Towing with a diesel can build incredible amounts of heat quickly. I live in the rocky mountains and consider an EGT gauge as required equipment...

 

[JDM Journeys]

One other thing you didn't mention is the fan clutch. It is a viscous locked fan and as they get old/worn they can't push as much air as when new.

 

[GotAn80]

It's possible that it is being pushed too hard in terms of heat built by combustion. Before any kid of towing, a pyrometer should be the first on the list in my opinion. It will indicate a potential overheat long before the coolant temp gauge starts rising. Then you can take steps to reduce the heat. Its amazing how gear choice and a slight change in throttle position can affect egt's dramatically. Altitude also affects diesel combustion as well - more smoke and less power as you go higher. And thus more heat.

You may in fact have cooling needs as well, but I'd start with egt before anything else. Towing with a diesel can build incredible amounts of heat quickly. I live in the rocky mountains and consider an EGT gauge as required equipment...

Thank you for your indepth and speedy response. After installing an egt gauge what could you suggest installing for cooling?

 

[JDM Journeys]

I hate to throw parts at something needlessly.

I'd start with basics. Recent rad: Was it bled properly? An airpocket could be a cause of overheating.

New thermostat? OEM? Installed correctly?

If the rad checks out, I'd be suspecting the fan clutch, since almost everything else is near new... There is a way to test them that's pretty universal. Quick google should yield results.. they are rebuildable using fluid from hobby shop, but again a quick search will yield more details...

 

[GotAn80]

I hate to throw parts at something needlessly.

I'd start with basics. Recent rad: Was it bled properly? An airpocket could be a cause of overheating.

New thermostat? OEM? Installed correctly?

If the rad checks out, I'd be suspecting the fan clutch, since almost everything else is near new... There is a way to test them that's pretty universal. Quick google should yield results.. they are rebuildable using fluid from hobby shop, but again a quick search will yield more details...

Thank you. I'll update with the outcomes

 

[GotAn80]

Update: fan clutch was replaced with a new one egt gauge hasnt been installed yet since we would have to travel quite far to find someone who knew what they were doing with one (most people nearby wouldn't actualy know what it is, plans are to have one installed at some point)

Vehicle is now getting hot even on the straights while towing 3 ton, suspected head gasket? Guesses are it was like it quite some time before getting the exhaust done and gotten worse over time.

 

[KiwiBogan]

I thought the max towing capacity for the 95 series was 2.5 tonne? (mine is anyways). Maybe thats half the problem? My caravan is at about 2.5 tonne when we're fully packed and although my Prado pulls it ok, I defitnately wouldnt wanna be adding anymore weight than that. I feel like 2.5 tonne is at the limit of safety. And thats with electric brakes on the van....

 

[GotAn80]

I thought the max towing capacity for the 95 series was 2.5 tonne? (mine is anyways). Maybe thats half the problem? My caravan is at about 2.5 tonne when we're fully packed and although my Prado pulls it ok, I defitnately wouldnt wanna be adding anymore weight than that. I feel like 2.5 tonne is at the limit of safety. And thats with electric brakes on the van....

Yes your correct in what you are saying they do have a rating of 2.5 ton. However his has a stronger tow bar setup, 3 inch exhaust and has been dyno tuned. The overheating has been resolved the previous owner had replaced the radiator with a cheap knockoff that wasn't working properly. Before being tuned and having the exhaust done your right 2.5 ton would be the limit however after the exhaust, tune and being a brand new caravan with the latest tech you hardly notice the van on the back.

 

[KiwiBogan]

Yes your correct in what you are saying they do have a rating of 2.5 ton. However his has a stronger tow bar setup, 3 inch exhaust and has been dyno tuned. The overheating has been resolved the previous owner had replaced the radiator with a cheap knockoff that wasn't working properly. Before being tuned and having the exhaust done your right 2.5 ton would be the limit however after the exhaust, tune and being a brand new caravan with the latest tech you hardly notice the van on the back.

Ahh glad you got it sorted. I'm very interested to know more about the "tune" he's had done. I'd give my left arm for a bit more uphill driving and towing power but can't seem to find much reports from people that have tuned a 95 series (only 120 series and up).

I've also had a 3" exhaust upgrade, 3 bar map sensor and boost T pushing 18psi.

 

[GotAn80]

Ahh glad you got it sorted. I'm very interested to know more about the "tune" he's had done. I'd give my left arm for a bit more uphill driving and towing power but can't seem to find much reports from people that have tuned a 95 series (only 120 series and up).

I've also had a 3" exhaust upgrade, 3 bar map sensor and boost T pushing 18psi.

The tune is the best thing that cars ever seen. Was done at kaipoi repowers in christchurch, not sure if your from the south island but she goes up Arthur's pass with no troubles towing 3.5 ton and the highest the aftermarket egt gauge gets going up was 750. Used to struggle sitting at 90kmph but after the tune it can overtake people doing 90 with the van on the back. Any questions just ask I'm more than happy to answer them as best I can

 

[KiwiBogan]

The tune is the best thing that cars ever seen. Was done at kaipoi repowers in christchurch, not sure if your from the south island but she goes up Arthur's pass with no troubles towing 3.5 ton and the highest the aftermarket egt gauge gets going up was 750. Used to struggle sitting at 90kmph but after the tune it can overtake people doing 90 with the van on the back. Any questions just ask I'm more than happy to answer them as best I can

I'm from Dunedin (Mosgiel) originally but live in South Australia these days. Wow, it has been about 23 years since I last drove Arthur's Pass in my old bedford van...

750 deg C EGTs is pretty high I thought? I spoke to my local tuner a year or so ago and they don't like EGTs getting over 500-550 deg C!

So how was it tuned exactly? I've been told that the ECU can't be tuned on these. Only with the addition of a chip. This is where I'm stuck with my decision. Unichip, DP Chip, Dtronic, Roo System's, other?...

 

[GotAn80]

Cant remember what the gauge reads in but we've been told to back off at 900. I own an 80 series landcruiser and I was told the same when I bought it (Their both mounted preturbo). It was dyno tuned and I'm pretty sure they put a Unichip in it.

 

[KiwiBogan]

Cant remember what the gauge reads in but we've been told to back off at 900. I own an 80 series landcruiser and I was told the same when I bought it (Their both mounted preturbo). It was dyno tuned and I'm pretty sure they put a Unichip in it.

Right gotcha! So I'm looking about $2500-$3000 to get that done on mine last time I checked. Sounds worth it though! Cheers for that!

My EGT probe is mounted on the dump pipe as that's where the exhaust manufacturer placed the hole for it. Whenever my truck starts to overheat on those hot days towing up hill, usually EGTs are at about 550 and water temp get up to about 80% (Max. before I back off the pedal). I think my engine would go pop if I took it over 600 haha .