Over heating

[BlackWidow]

Hi all,

I know that this has been covered before but I would like to run this past you guys before I take the head to find nothing.

Now then as some of you know I have had a problem for a while now and I have been to France doing the Massif and had a chance to do some serious observations. Now then on the drive down through France and back the truck never skipped a beet. I was doing speeds of 95 mph for hours at a Time up and down some long hills and the temprature gauge never moved. When climbing the Gorge de Tarn which is alot of changing revs and on and off the power she started to cook. I also found that as long as I kept the revs below 1700rpm the truck would not over heat no matter what I was doing either steep rocky climbs or gentle potters up and down the mountain. As soon as I pushed up to and over 2000rpm she would start over heating but on the open road I can hold it at 3000rpm without over heating. So basiclly the heavier the load on the engine the worse she is but....it semms to be proportional to loading and air flow through the engine bay. I did not loose any coolant except on one day when the truck over heated big time and I had trouble keeping it under control and I think that it may of boiled off rather than through a hole. And also other than a puff of blue smoke that Crispin spotted at Lincome nothing has come out the exhaust pipe.

The radiator is fairly new and I have replaced the thermostat (OEM) still no change. I have checked for gasses in the coolant but found none. The top hose is always hot but the bottom is a lot cooler, I was not able to do the test when over heating as it was so hot that I got a blister on my arm from just leaning on the wing. (sound familliar John ). I am not getting a woosh from the viscous fan that I would expect

Now my questions are for those that have had the cracked heads.

1. Was there any sign of gasses in the coolant.

2. What were your symptoms?

And in general

1. Is there an easy way to test the viscous fan whithout the need of 2 tacho meters to measure engine speed relivant to fan speed ie: the 80% of engine speed.

2. What is the best way to test coolant flow to find weeknesses on the KZTE engine (As unaturally the thermostat is on the cold side of the radiator).

Many Thanks in advance

Steve

 

[Steve H]

Hi, Steve. When the head went on mine I had no signs of overheating at all, just losing water. I even towed my caravan with the cracked head and didn't overheat. I did get a cloud of white smoke when starting up after a run. Just before I did the head, this got really bad and smoked nearly all the time as I drove home for the last couple of miles. You say that the fan doesn't seem to be making the right noises so maybe that's the place to start. Also Bob Murphy has fitted a lower rating thermostat to his truck and seems to have solved his overheating problems. Have a look at his thread

viewtopic.php?f=14&t=10530&start=0

 

[sae70]

I'd start with the Viscous fan after reading the used Prado review in this topic viewtopic.php?f=14&p=84820#p84820

Interesting read, only got to page two Will have to read the rest later, but interesting what he says about the viscous fans life of around 125,000 miles

Good luck Steve

 

[BlackWidow]

Thanks guys,

I think that I may go down the viscous fan route, but as you have seen I have brought Bobs link back to the fore and will wait for a reply from him.

Mr T. wants arround £270 for a new one.

That link was an interesting one Steve, mine has or is suffering from all listed ie overheating and rack. The rack I have sorted.

Steve

 

[sae70]

Mr T. wants arround £270 for a new one

Is that for the Viscous fan unit If so I wonder if Mr Rubie can help you out If not there's always the re-oiling option viewtopic.php?f=15&t=9715&p=67576

[youtube:2hsesmab]3ACx7GTCn7Y[/youtube:2hsesmab]

 

[AndyCook]

I topped up the silicone fluid in viscous fan recently.
this was after I was in lakes offroading and i couldnt heard it roar/whoosh on a long hot climb

after doing this servicing, i have been offroading in wales and defintely heard the fan kick in this time

 

[BlackWidow]

Funny you should show that I have found these and found them very interesting reading especially the first one Toyota seem to enginier there coolant systems to be just enough but any little discrepancy shows up qickly. Also the viscous coupling has a life span of around 200000 KM and mine is well passed that.

http://neuralfibre.com/paul/4wd/tuning- ... fan-clutch

http://www.offroad80s.com/how-to-top-up ... t1160.html

 

[Jon Wildsmith]

Chris mentioned you'd been having issues Steve, good job you didn't come to the Pyrenees, some very long climbs there. Does sound like your fan VC could do with a top up.

 

[BobMurphy]

I think that I may go down the viscous fan route, but as you have seen I have brought Bobs link back to the fore and will wait for a reply from him.
Steve

Oh Dear . . . I hope you're not waiting with 'bated breath for me to come up with the solution to your problem .

What happened to my 1KZ-TE and what I ended-up doing:

The temp gauge never moved from the centre line, until the day I was towing two horses over a long, steep hill (the A68 South of Edinburgh/Dalkeith).

On the return trip the gauge went into the red. I rolled the power off and it stabilised. Eventually I had to pull in and found a lot of coolant had been lost via the overflow bottle.

Thereafter, I lost a bit of coolant on a run, but the car ran (and towed) OK. Gradually, however, I started to get clouds of steam when re-starting from cold.

I put up with this for a while, then ordered a new head from Roughtrax and a radiator, gasket sets, head bolts and so on from Milners.

With the head off, it was obvious that I had been getting coolant into No. 4 cylinder, but there were no obvious holes in the head gasket.

After changing the head everything seemed fine, but eventually I started losing coolant through the overflow bottle again. I was suspicious of the 'pattern' head gasket I had used so replaced it with a genuine Toyota gasket. This time I used jointing compound above and below the gasket.

I also fitted the toyota 'optional' 76 deg thermostat, as I had never detected any warmth in the lower radiator hose with the standard 82 deg 'stat.

Since then, all has been fine and I have towed heavy horse trailers without losing any coolant. Also, there is heat in the lower rad hose, so the coolant is now circulating.

HOWEVER, Having read this thread and also the links, I realise that I have never heard my cooling fan cut in and out. I have 127,000 miles on the clock so I guess I need to top up the silicone oil. Who knows - maybe that was the cause of the overheating and eventual head failure all along

I didn't have the old cylinder head pressure-checked and I couldn't see any cracks, but I believe that is not unusual. All I can say is that my temp gauge didn't move until I had lost a lot of coolant - around 4 litres, so I didn't get any warning of impending doom.

As others have posted; the standard temp gauge isn't exactly accurate and some have fitted additional sender units in the top coolant manifold. This shows the motor getting very hot while the standard temp gauge is showing normal.

I am in the process (when I get on with it ) of fitting a thermostat into the top coolant outlet to see if that gives better control.

Now to order-up some silicone oil - Toyota SILICON OIL (18mil tubes), Part No. 08816-10001.

One day we will have this problem licked


Bob.

 

[BlackWidow]

No I was not hoping for solution to the problem Bob I was interested if the thermostat worked for you or not, it has not worked for me but I think that I have the 82 fitted not the 76.

All the reading that I have done on the viscus fan makes me think that is my problem but I am trying to cover everything just in case.

I never realy lost coolant, but as a coutionary measure I left my heaters on and I knew when I was over heating before the temprature gauge did as the blowing out heat got hotter before the gauge even moved. So like you I eased off the revs and it settled down again.

I will be going to Mr T tomorrow and ordering some silicon oil along with the 76 thermostat and start the repairs and testing ASAP using the links above will do some. My only other thought though Bob is that we both have milner rads fitted.

John I guess that the sun was out and was nice and warm down there that would have made my life very tough. On the Massif we had thunder storms most nights and it was jumper temps all week which for me was a good thing

Steve

 

[sae70]

Perhaps this Viscous fan oil & 76 degree thermostats are another couple of items that our m8 Mr Rubie may consider stocking

 

[BlackWidow]

Perhaps this Viscous fan oil & 76 degree thermostats are another couple of items that our m8 Mr Rubie may consider stocking

I shall PM him now and see what he can do.

Steve

 

[BlackWidow]

Went to Mr .T Today and the oil is not available in the UK from main dealer will see what Ian can do.

Steve

 

[Jon Wildsmith]

According to this thread Andy didn't go OEM

 

[AndyCook]

I got the silicone fluid from an online RC model shop - might have been ebay, I did look but cannot find the seller/invoice anywhere...

I got two bottles, I am sure it came to under £10

infact
quick google: here is a reseller
http://www.cmldistribution.co.uk/cml_pr ... 0000002851

£3.89 per bottle and £1.90 postage

took a while to find a) bottles of right quantity for reasonable price
b) correct weight of the fluid - different units are used, so take care to get correct weight

Another point, dont put too much in, you will know you have done this if fan is kicking in all the time - you will hear it roaring on acceleration, and engine power is robbed slightly and mpg suffers too, but cooling excellent..

I put too much in fan clutch on a 3.0TD 4runner, i took fan off and drained some out.,

On LC90 I topped it up last year, but not enough.
A few weeks ago, I topped up again, now i can hear the fan kicking in on hot & steep offroading

also last night I towed about 2.5-2.8 tons of load (logs plus trailer) and when i was reversing into drive after towing 10miles, I could hear the fan kickin when reving engine, i didnt notice it doing that last time I towed a load - so I am happy its working properly now

I used the 7000cst fluid and about 2/3 of a 2oz bottle

 

[BobMurphy]

I got the silicone fluid from an online RC model shop - http://www.cmldistribution.co.uk/cml_pr ... 0000002851

I used the 7000cst fluid and about 2/3 of a 2oz bottle

Thanks Andy,

Two bottles ordered

Bob.

 

[BlackWidow]

Found some at Fastrax they do from 100 cst up to 100000 cst, I have ordered 8000 and 10000 and will do some experimenting to see what are the best results. According to the links I posted above the Toyota stuff is 10000cst and that is like treacle.

Steve

 

[BlackWidow]

OK forget what I said about Fastrax which it turns out is CML distrabution............I just got an e-mail it will take 5 - 8 weeks to get my order....think I will tell them to stick it and try somewhere else.

Steve

 

[BlackWidow]

Well I found some oil so today I overhauled the viscous fan.

So I thought that I would share my day with you. Firstly I removed the fan from the car and took it to the workshop. Removing the outer bolts was easy enough but they are cross head so make sure the correct size cross head driver is used as they round of nice and easily.

Then with a rubber mallet I gently tapped arround the outside until it came apart, it took around 5 - 10 mins to do but it gave up in the end. It is worth while being very genttle as there are no replacement parts for the innards.

When I got it apart here was my first thing that did not look right. The oil was very brown and had obviously had a hard life though it still had a good viscosity. Also there was some jelly like substance in there as well especially in the friction groves. At this point you need to get yourself somthing to sit on as it took me 2 and 1/2 hours to clean these out.

As the oil is very thick it takes forever to drain the old out, but eventually I got there. Once all the oil was out I decided to test the Bi metal coil for its opporating temp range. So it was out with the frying pan and jam making thermometer and start some testing. I placed the spring half of the coupling into the frying pan and filled with water and turned on the gas. I sat there watching and thermometer slowly climbed ....80c......85c...90cccc.....95c....100c and nothing had moved everything stayed closed....URIKA I was right my fan is not working that could be why I am overheating. I was delighted I have finally found a hard fault.........it then dawned on me how am I going to fix this?

I took the coupling back to the work shop and gently teased the spring spindle and thankfully after a little gentle persusion I managed to free it off...so it was back to the kitchen and do some testing. I will now post y findingsthe readings were taken from the thermometer on the risie and the first temp is when the arm first started to move.

Upto 50c stayed closed
74c first hole open
84c 1/2 of second hole open
94c Open Fully


The next set of measurements were taken on the fall.

Down to 75c stayed fully open
At 64c 1/2 second hole closed
At 58c second hole closed
At 44c fully closed

In an ideal world the temp range is adjustable undoing the two little screws and you shoukld be able to adjust it....Warning these screws are very soft and easally damaged. I loosened the screws but no matter what I htried I was unable to get the base to turn so I have had to leave it at the Factory settings thow I would loved to set it lower but hey hoe at least I got it working.

The refill I found to be very hit and miss, I filled the non bio metal half and filled it up to the underside off the holes. Now I have read that it will take around 50mil to fill to that point but I only managed to get 30 in hope its enough. I used 10000cst which is thick oil and it took ages to flow through.

Now all that was left was to rebuild it, I cleane dthe 'o' ringand put it back and joined the two halves together. The 'O' ring may appear that it has grown since it was taken out but it will go back from where it came from but it needed all ten fingures to do it. Anyway it is all back togeether now and I am now waiting for a nice hot day to test it.

If I am honest my only concerne is that was not able to renew the spindle and spring and will not beable to tell when it sticks again until it is to late.

Steve

 

[TonyP]

Very interesting, thanks Steve. Out of interest what was the cost of a replacement unit?