Please help! Water leak from Thermostat

Hi, following on from my last thread. The Supra has developed quite a bad coolant leak from around the thermostat housing area. Just filling the rad causes it to dribble out pretty quickly. I have a new thermostat ready.

Is this a common place for leaks?

Is there any other leak prone areas around here that i should look at?

From what i can tell it seems a bit of a fiddly job to change it with all the gubbins in the way, does anyone have any tips?

Thanks in advance, Iky.

What an arse of a job, I haven't attempted it yet but from crawling around on my back it looks like the alternators gotta come off. I got coolant in my eyes

OK. Shit news, its not the thermostat housing, its something behind it. The bit at the back, does this come with a new waterpump or is it a separate item? Anyone else heard of leaks occuring in this location?

sounds like it might be the water pump. I've heard of the failing before.

Could it be the No 1 Water bypass pipe which fits into the back of the waterpump and seals with 2 o rings ?

have a look on http://www.turbosupras.com/pages/en/pages/technical/a80tsrm.htm then go to the cooling system and you'll see a diagram showing the water pump etc, on page 6

The pump is bolted to the block and only seals with an O ring, the water by pass tube is a push fit with an O ring at either end and the pump can leak thru a small hole in the body if the seals fail. IMO if you are removing the pump to change an O ring then replace it, you need to take the cam belt off so may as well do that as well.

The pump is bolted to the block and only seals with an O ring, the water by pass tube is a push fit with an O ring at either end and the pump can leak thru a small hole in the body if the seals fail. IMO if you are removing the pump to change an O ring then replace it, you need to take the cam belt off so may as well do that as well.

I've not had reason yet to take the pump off my TT yet so dont really know how it goes together, but had the pump off loads of time with the old NA and on the NA engine there is a 20mm core plug in the rear housing housing assy. Is there something like this on the TT? If so that could be where his leak is. For some reason, that plug failed twice on my na, first about 4 years ago and then again recently.

There is a core plug behind the by pass tube, it could be that, never seen one go personaly though.

There is a core plug behind the by pass tube, it could be that, never seen one go personaly though.

Hi mate, do you mean the core plug in the block? because i noticed one nearby and it seemed to be fine-dry with no wetness.

From a search, i see that there is one on the actual water pump somwhere that is a common problem, where exactly is this? If somebody has photos that would be great.

,,there is a 20mm core plug in the rear housing housing assy. Is there something like this on the TT? If so that could be where his leak is.". In my supra bought yesterday I'v got same problem is leaking from that place. 20mm hole with plug is not hold the pressure

So it looks like it's a belt off jobby, thats exactly what i was afraid of.

Ah well, at least when its done its done for the next 60k.

Quinton Hazell Waterpumps, are they any good? this is the only one that seems to come with the rear part of the thermostat housing and it seems to be for a good price from Rock Auto. I assume that the USDM Supra engine is the same as the UKDM and JDM one, if someone can please confirm.

QUINTON HAZELL Part # QCP3428

http://www.rockauto.com/catalog/moreinfo.php?pk=1324706

O.K, an update-

I have found that the leak is due to a tiny hole in the core plug at back of the thermostat housing.

Its unbelievable that so much water came out of a little tiny hole but i suppose it was under pressure when the engines running.

I noticed other guys say its 20mm so i guess N/A's have a different housing as mine is 25mm.

Hopefully i can get one soon and get it all built back together again and drive it. (if i can remember where all the nuts and bolts go!)

I managed to make my own tools to remove the crank pulley- I'm quite proud of myself.

Funny this... I've just had to change my crank pulley and then my core plug went. Called up Toyota and said they don't do the piece. So we had to make our own plug.

Funny this... I've just had to change my crank pulley and then my core plug went. Called up Toyota and said they don't do the piece. So we had to make our own plug.

How did you make your own plug may i ask?

I may have to do this if i can't get hold of one.

You need a 25mm core plug?

You need a 25mm core plug?

Yes! do you have one?

I got a garage to do it - I think they just moulded some metal into it.

Ive just had a chance to check on ebay and it seems they are pretty cheap.

Does it matter if i get a metric 25mm or an imperial 1" ?

Ive just had a chance to check on ebay and it seems they are pretty cheap.

 

Does it matter if i get a metric 25mm or an imperial 1" ?

1" = 25.4 mm, i'd have thought the Japs would have made everything in metric and not used imperial dimensions !! worth checking with one of the traders that builds engines

Just checked - closest I have is a 23mm.

I'll check the other workshop tomorrow.

Just checked - closest I have is a 23mm.

 

I'll check the other workshop tomorrow.

Cheers bud

Update - Got a plug from a local engine builders cost £1.50 It was a 1" and seemed to be a nice & tight fit. I put a thin smear of intant gasket around it and tapped it in with a socket behind it. I just need to get it all back together now.

One question, Should i put gasket sealant around the o-rings ?

I'm assuming you're using new ones?

If so, I wouldn't. A new O ring should give a good enough seal without smearing stuff all over it.

Sorry I couldn't help with the core plug but pleased you're sorted!

I'm assuming you're using new ones?

If so, I wouldn't. A new O ring should give a good enough seal without smearing stuff all over it.

 

 

Sorry I couldn't help with the core plug but pleased you're sorted!

Yes, I used new ones but ive actually already put a thin smear on because the pipes had a bit of roughness inside where the rings seal.

No worries dude, only cost a quid or so. Probably would have cost you more on P&P anyway