New heads and auto box coolers ?

[Paulpen]

Sorry for all the questions

From looking around at a few vehicles I've seen some with the heads replaced and some that have not yet been done.
I was wondering what people prefer in their opinion - a vehicle that's running fine that may need one in the future or a vehicle that's had one replaced but with a head of unknown origin ?

Also if getting an automatic is it worth investing in a separate cooler for the fluid ? I'm planning on using if for short trips daily but will occasionally used to tow a car trailer and caravan.

Thanks in advance

 

[silvercruiser]

My colorado is now on 174 thousand miles and runs lovely. when i bought it five years ago i replaced the radiator so that i knew the transmission cooler/warmer was fine. i have also replaced the thermostat/coolant and pump all with toyota genuine parts. i dont think there is a problem with heads i just think if you dont look after the cooling system then as with most aluminum heads they crack when hot.

I personally dont like the separate coolers as the toyota design is quite good as it helps warm up the oil too and you do not get this with an external cooler. and the changing of the rad is a doddle of a job.

 

[Paulpen]

Never really seen it like that before but does kind of make sense !

Guess its more a weakspot than a reccuring fault !

 

[sae70]

As far as I'm aware the overheating woes associated with the auto 90/95 series is a larger issue with the TD's and not found so much in the D4d's. I'm not aware that anyone ever found a diffinative answer as to why the TD models are so prone to overheating, except that Toyota may have inadvertantly designed the cooling system with little or no room for the vehicle getting older and putting on a few miles. People have looked at all sorts that I've read about to cure or improve the possible issues that may cause the overheating from replacing the rad for a new one, replacing the water pump, flushing the system through and replacing the thermostate all as a just in case any of these may be the cause of the overheating troubles.

My understanding of the reasoning behind fitting a separate stand alone cooler for the auto box is to remove the heat load of the auto box from the finely balanced engine cooling circuit. It's only more recently I've read people talking about the intergrated OE auto box cooler failing and the auto box oil becoming contaminated with water. I've have to say that if Swampy had not come with a separate auto box cooler fitted I would have probably not fitted one myself!

The single most effective thing that I've read about notably improving cooling on an older higher mileage 90/95 series was either servicing or replacing the Viscouse fan coupling. Some thing that in the most part gets overlooked as just working because it's going around.

if Swampy had been an older high mile 3.0TD auto without a separate auto box cooler fitted I would have probably fitted a new rad and either replaced or serviced the viscouse fan coupling.

Don't quote me and I'm very happy to be corrected, but I don't think that they have a problem with the head. They seem to have a finely balanced cooling system that can in some cases easily overheat causing head damage.

You could always buy a manual as they don't appear to suffer from the overheating woes of the auto. Probably because the cooling system on the manual is not having to cope with the heat load of the auto box cooler as the viscouse fan coupling slowly becomes less efficient with age.

 

[jbecks]

I have a BM supercooler and will be fitting it this weekend to bypass the toyota oil heater, as I'm not keen on intergrating the oil cooler with the radiator, as it was most likely chosen as a cost issue having coolant around 80degrees celius is not really cooling the tranny or your atf heating the coolant! and your going to be putting extra load on the gearbox by towing.

Toyota redesigned the heads for the later 1kzte engines, but not sure when exactly apparently you can tell as the valves are longer or something I was reading up about it. My view is some of the heads cracking May be from a failed head gasket, as many other engines that have a cast iron block with ally heads also are prone to cracking when a hg fails, ie the 4.7 v8 in grand cherokees.

I would just buy a truck on condition and if the head ever fails, replace it with a amc head. Don't doget there are thousand and thousands of 1kzte engines kicking around so the issue may not effect as many trucks as you think. And every car ever sold has an achielles heal! If it was a land rover it would have 10!

 

[grantw]

As far as I'm aware the overheating woes associated with the auto 90/95 series is a larger issue with the TD's and not found so much in the D4d's. I'm not aware that anyone ever found a diffinative answer as to why the TD models are so prone to overheating, except that Toyota may have inadvertantly designed the cooling system with little or no room for the vehicle getting older and putting on a few miles. People have looked at all sorts that I've read about to cure or improve the possible issues that may cause the overheating from replacing the rad for a new one, replacing the water pump, flushing the system through and replacing the thermostate all as a just in case any of these may be the cause of the overheating troubles.

My understanding of the reasoning behind fitting a separate stand alone cooler for the auto box is to remove the heat load of the auto box from the finely balanced engine cooling circuit. It's only more recently I've read people talking about the intergrated OE auto box cooler failing and the auto box oil becoming contaminated with water. I've have to say that if Swampy had not come with a separate auto box cooler fitted I would have probably not fitted one myself!

The single most effective thing that I've read about notably improving cooling on an older higher mileage 90/95 series was either servicing or replacing the Viscouse fan coupling. Some thing that in the most part gets overlooked as just working because it's going around.

if Swampy had been an older high mile 3.0TD auto without a separate auto box cooler fitted I would have probably fitted a new rad and either replaced or serviced the viscouse fan coupling.

Don't quote me and I'm very happy to be corrected, but I don't think that they have a problem with the head. They seem to have a finely balanced cooling system that can in some cases easily overheat causing head damage.

You could always buy a manual as they don't appear to suffer from the overheating woes of the auto. Probably because the cooling system on the manual is not having to cope with the heat load of the auto box cooler as the viscouse fan coupling slowly becomes less efficient with age.

That is just about the best summary I've ever read on this. You've obvioulsy done alot of research on it!

 

[wobbly]

I think that the cracked heads and contaminated gearboxes both have one thing in common - the radiator, so putting in a replacement on an older truck is a good preventative measure.

A cheap rad will be a couple of hundred pounds, genuine toyota seens to be about £450?

The viscous fan coupling is a very good point, have seen this cause problems on 3.4 petrols.

Putting in extra temp gauges is an option, showing head, atf temps etc.

There will be 3 LC's at the pub meet tonight, its the pub on the right just before Thornfalcon on the Taunton-Ilminster road, ask for Pete if you can make it.

Pete

 

[silvercruiser]

Toyota redesigned the heads for the later 1kzte engines, but not sure when exactly apparently you can tell as the valves are longer or something I was reading up about it. My view is some of the heads cracking May be from a failed head gasket, as many other engines that have a cast iron block with ally heads also are prone to cracking when a hg fails, ie the 4.7 v8 in grand cherokees.

well my Colie is one of the last before they switched to the d4d so this could explain why ive had no problem. but i like to think it the servicing and loving care it gets

 

[Paulpen]

I think that the cracked heads and contaminated gearboxes both have one thing in common - the radiator, so putting in a replacement on an older truck is a good preventative measure.

A cheap rad will be a couple of hundred pounds, genuine toyota seens to be about £450?

The viscous fan coupling is a very good point, have seen this cause problems on 3.4 petrols.

Putting in extra temp gauges is an option, showing head, atf temps etc.

There will be 3 LC's at the pub meet tonight, its the pub on the right just before Thornfalcon on the Taunton-Ilminster road, ask for Pete if you can make it.

Pete

Only just seen this chap - went for a beer and a haircut after work

Guess it was the Nags head pub ?

 

[wobbly]

That's the one!

Back to the Blackbrook Tavern next month.

On way back from Topshamm yesterday spotted a T reg Colorado on a dealer forecourt, dark green, £3,990.00

Can work out where it is if you are looking at them.

Pete

 

[Paulpen]

Always looking but out of my budget

I'll deffo be at the next one

 

[sae70]

That is just about the best summary I've ever read on this. You've obviously done a lot of research on it!

Thank you Another thought I had after typing all of that is that maybe the D4D's don't suffer from the overheating issue simply because they are not yet old enough to have allowed the viscous fan coupling to become that much less efficient to allow the engine to overheat when used under extreme conditions

 

[Jon Wildsmith]

having coolant around 80degrees celius is not really cooling the tranny or your atf heating the coolant!

The coolant at the bottom of the radiator by the atf element should be significantly cooler than that unless it is overheating.

 

[jbecks]

The coolant at the bottom of the radiator by the atf element should be significantly cooler than that unless it is overheating.

It it is cooler but not as cool as I would want, then you also have the issue of the atf heating the coolant. It's predominately down to cost as to why toyota used this method instead of a separate oil cooler.