Dear friends,
many thanks for taking the time to read this post.
I have a prado 95 running a 1kz-te engine. we live on the coast and temperatures generally reach 34-36 degrees celcius daytime.
its got a peculiar issue and i was hoping to get some guidance on this group.
The car drives fine within the town and I can push it and it never overheats in tailback traffic or even when speeding around town.
On the highway a different story, the temperature gauge starts creeping up and we usually park on the side idling until it cools down. We have made some observations as follows:
1. if the aircondition is on and we are on the highway, after some distance of driving over 80kph and using the turbo the car tends to overheat. when we get somewhere and check, the top radiator return hose is quite stiff.
2. even with the airconditioning switched off, the car still overheats if driving at over 80kph and rev counter sometimes over 2000 revs.
On the return trip if I keep the speeds at below 60kph and the revs at below 1800-2000 revs, aircon switched off and dont overspeed, the car never overheats.
work done just recently less than 3 months ago:
1. cylinder head gasket replaced and head checked for cracks and bend( they checked with steel rulers and did not do a pressure test as they said there is no bend( the worshop engineers who do refacing etc did that..
1.2 radiator core cleaned with dipsticks to remove gunk.
2. full block reverse cleaned with radiator flush using a machine( glorified water pump, pushing water through in the opposite flow direction). the water was quite clean so no salt or dirt deposits in engine block.
3.water system flushed three times and very good quality coolant put in after that.
4. the gearbox oil was flushed and changed too.
the cooling system was pressure checked to not have leaks.
work done about 2 years ago when we had an overheating issue then as well.
1. radiator cleaned and cooling system flushed.
2. viscous fan coupling changed.
3. radiator plastic top removed and an aluminium top was welded on. radiator cap changed and checked
I am stuck and don't know what to do.
1, should I throw that engine out and replace with another refurbished 1kz-te engine( the current engine has done 286,000 kms(not sure if it was clocked before i bought it) and there is no smoking etc?
2. change the radiator? have heard that radiator channels do get clogged and narrow after about 10 years thus impeding coolant flow.
3. change the torque converter?
4. change/service the turbo?last turbo service was about 2 years ago.
5. am advised to lock the viscous hub so it runs at the engine speed( apparently in Kenya, they open the vicous coupling, cut gasket paper and seal it again. the silicon stays on one side and the fan keeps running at engine speed always)
6. could it be a clogged oil pump?
7. could it be a clogged sieve in the oil sump thus not getting enough oil pumped around when engine under load?
8. remove the aftermarket sump guards ( we are in Kenya and roads sometimes have rocks etc, so we put very heavy gauge fabricated sump guards) and have the engine washed thoroughly from the bottom of the car?
please assist if possible.
thanking you in advance for your help.
many thanks for taking the time to read this post.
I have a prado 95 running a 1kz-te engine. we live on the coast and temperatures generally reach 34-36 degrees celcius daytime.
its got a peculiar issue and i was hoping to get some guidance on this group.
The car drives fine within the town and I can push it and it never overheats in tailback traffic or even when speeding around town.
On the highway a different story, the temperature gauge starts creeping up and we usually park on the side idling until it cools down. We have made some observations as follows:
1. if the aircondition is on and we are on the highway, after some distance of driving over 80kph and using the turbo the car tends to overheat. when we get somewhere and check, the top radiator return hose is quite stiff.
2. even with the airconditioning switched off, the car still overheats if driving at over 80kph and rev counter sometimes over 2000 revs.
On the return trip if I keep the speeds at below 60kph and the revs at below 1800-2000 revs, aircon switched off and dont overspeed, the car never overheats.
work done just recently less than 3 months ago:
1. cylinder head gasket replaced and head checked for cracks and bend( they checked with steel rulers and did not do a pressure test as they said there is no bend( the worshop engineers who do refacing etc did that..
1.2 radiator core cleaned with dipsticks to remove gunk.
2. full block reverse cleaned with radiator flush using a machine( glorified water pump, pushing water through in the opposite flow direction). the water was quite clean so no salt or dirt deposits in engine block.
3.water system flushed three times and very good quality coolant put in after that.
4. the gearbox oil was flushed and changed too.
the cooling system was pressure checked to not have leaks.
work done about 2 years ago when we had an overheating issue then as well.
1. radiator cleaned and cooling system flushed.
2. viscous fan coupling changed.
3. radiator plastic top removed and an aluminium top was welded on. radiator cap changed and checked
I am stuck and don't know what to do.
1, should I throw that engine out and replace with another refurbished 1kz-te engine( the current engine has done 286,000 kms(not sure if it was clocked before i bought it) and there is no smoking etc?
2. change the radiator? have heard that radiator channels do get clogged and narrow after about 10 years thus impeding coolant flow.
3. change the torque converter?
4. change/service the turbo?last turbo service was about 2 years ago.
5. am advised to lock the viscous hub so it runs at the engine speed( apparently in Kenya, they open the vicous coupling, cut gasket paper and seal it again. the silicon stays on one side and the fan keeps running at engine speed always)
6. could it be a clogged oil pump?
7. could it be a clogged sieve in the oil sump thus not getting enough oil pumped around when engine under load?
8. remove the aftermarket sump guards ( we are in Kenya and roads sometimes have rocks etc, so we put very heavy gauge fabricated sump guards) and have the engine washed thoroughly from the bottom of the car?
please assist if possible.
thanking you in advance for your help.
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