LJ78 thermostat

[Tractionman]

Hi All, tapping in to the mine of information again. heater started blowing lukewarm, so I am thinking t/stat? if so Mr T? Milners? Also read somewhere about people changing for different rating? Had the 78 for 10 years+ with no overheating probs, (2L TE) just a rad change (oem) 3/4 years ago, due to original springing several leaks, fortunately noticed on my drive overnight, any help with sourcing or rating required greatly appreciated.

Many thanks, John

 

[Yorkshire Devil]

Remove the thermostat tie a piece of string on and test operation in a cup of boiling water. Thermostat on the 2L-TE can be removed in 2 minutes. Think there is 3 bolts from memory.

I replaced with a quality Blue Print thermostat but the genuine Toyota thermostat is not that overly expensive.

 

[wobbly]

As YD says.

If you use a pattern part make sure it has a little bypass hole like the original.

The Mr T one was £18!

 

[Tractionman]

Yorkshire Devil - thanks for info I forgot about that important little hole, thought I would just replace while out rather than b*gger about testing, never replaced on the 78 in all these years, so guessing that`s it anyway - replacing never an issue, that`s easy for a change!

Wobbly - Pete, nice to catch up with you again, had to re-read toyota price!! Blue print it will be, used their filters in the past with no problems.
Did your written off 78 get moved on when you replaced with the 90?

Regards, John

 

[Tractionman]

Oops, sorry Pete, didn`t credit you with the little hole

John

 

[wobbly]

No worries.

Yep, I sold the LJ78 on ebay.

Overall did ok, am really pleased with the Prado. I do miss the 78, I would really like to try a KZJ78 for comparison with mine though.

Ive always been happy with blueprint as well.

Cheers

Pete

 

[Tractionman]

Well, here again., changed t/stat, topped up with toyo coolant and off I went. temp gauge came up to usual position, turn fan on full - just the same, luke warm.
Used to be really hot on full blast. One thing, when fan initially activated, blows warmer for about 5 seconds then luke warm. turn fan off for about 5 minutes and back on again - repeat performance !! so I am thinking blockage, any ideas?? thanks.

John

 

[wobbly]

Am thinking........I had to replace the heater matrix on my LJ, the garage did a bypass on the pipes in the engine bay.

This meant I had no heater (or leak), the hot water was recirculated in the bay, on one of the pipes was a control valve - must be connected to the levers on the dash - worth checking to make sure it's opening fully?

Also, could be that you still have air in the cooling system, they were a pig to bleed as I recall.

You could always check the temp of the pipe going to the matrix, and the temp of the return, see if there is a noticeable difference, may indicate a blockage.

Did you check the operation of the new stat in hot water first, and.....does it have a bypass hole as discussed?

Cheers

Pete

 

[Tractionman]

Pete, had you in mind when I posted and remember what a saga (and mess) when yours sprung a leak and subsequent discussions with Redd ( on that other site). As I recall he had similar probs and what a b*s*a*d to remove matrix. hoping this is not that!! Not sure how air would have entered, as only expansion tank removed recently (and replaced). but playing with water on these as you say, makes them a pig to bleed. Will check temps on pipes, maybe this will give a pointer if or where blocked. Did not check new stat first (has got hole) but as this or old make no difference, ie the same, unlikely faulty. As you say checking that valve in engine bay is a possibility thanks. I read somewhere there is a route to go when bleeding but not sure how, perhaps someone on here can shed light? many thanks, Pete.

John

 

[Tractionman]

As weather and time have been against me, had another play with this today. initially I was going to undo heater hoses that go through bulkhead and use hosepipe to flush through heater matrix. Original clips on hoses, the type that appear to need a tool for (looks like a split pin that unwinds, a bit like a corned beef tin), although I could prob. get off, wasn`t sure about refitting tight, and right size jubily clips not to hand, went another way.
With rad cap off and engine running, I squeezed every water hose visible lots of times at random (desperation - lol) careful not to pump lots of coolant out,refitted rad cap and let her idle for anther 15 mins keeping an eye on temp. the fan was then pushing out hottish air - repeated above and everything hunkydory Apparently this is `burping` It`s still a mystery how the air got in. One more thing, the little hole was at 12 o clock on stat. when removed so replaced same, now someone has said should be 9 o clock, i.e. in line with top hose, pointing towards rad. Any input on this ?? Hope this helps others with air locks and thanks for replies.

John

 

[wobbly]

Good one, well done.

Don't know about position of the hole, can't see it can be vital.

Cheers

Pete

 

[Yorkshire Devil]

I have heard of caustic soda helping in unblocking rads/matrix's this is ok on genuine oem rads that have metal tanks but avoid using it on cheapo radiators as it can melt the plastic!

 

[Tractionman]

Pete, I thought same, seems to work ok in this position. When I had the lid off , just inside the housing is a `cut out` at 12 0 clock, and this along with position of old stat seemed to confirm. Hope I don`t have to reposition as rubber seal around edge of stat will be goosed and I don`t think this is available separately.

YD, I have oem metal rad in anyway as straight replacement for leaky original, but good point about plastic if using chemicals as unblocker. Thanks, both of you.

John

 

[Yorkshire Devil]

When I had a airlock I tried everything cap off over night burping etc. the only thing that cleared it was a good old drive till the engine was red hot. I think the bleed valves you can fit on the matrix in let's are a great idea though.

 

[Tractionman]

Y.D. drove mine for around a week with next to no heat, and no change. I have done trucks, vans and cars of all types over the years and bleeding has not been necessary,must have been lucky and air worked it`s own way out!! Yeah you are right, bleed valve would be great idea. I may be talking sh/t here but I think some LC models have one on side of block, or is that a drain? apparently a nightmare to get at anyway. Cheers

John