Cooling system / thermostat

andyf · Postby **andyf** » 16 Jun 2009 08:24

Following on from my dodgy garage post a few weeks ago ref my front fog lamp wiring, the main reason I took it into the garage was to drill out and re-tap my thermostat housing (the bolts snapped off when replacing the thermostat).

When I received the invoice, they had charged for a new thermostat which I did not ask them for. After grilling them, they insist that the new stat they put in was the correct one, but I now have my doubts.

The car runs at the correct temperature for a few days, then the gauge will rise quickly to about 3/4, then fluctuate, dropping back to below 1/2, then rising again. Upon checking, the water level has dropped and I top up, and away we go. I wrote off the first few times as an air lock, but it has now done it about half a dozen times in about 5-6 weeks. Could this be caused by the incorrect thermostat without the "foot" or could it be something else?

I can also see no evidence of coolant leaks, although as it happens when driving it could of course be coming out of the overflow.

1980 persian aqua DHC

Beans · Postby **Beans** » 16 Jun 2009 11:06

Could be the thermostat being incorrect.
Just take it out and check it has the foot plate, air bleed valve and has the correct opening temperature (should be 88ÂºC).

<center>

1981 TR7 FHC Sprint (better known as 't Kreng)
1981 TR7 DHC (now completely dismantled)
Also a 1980 TR7 DHC, 1980 TR7 DHC FI, 1981 TR7 FHC
http://tr7beans.blogspot.com/</center>

bmcecosse · Postby **bmcecosse** » 16 Jun 2009 15:19

And feed the overflow pipe from the tank into a catch bottle - to see if any fluid escapes. But it would only do so if the pressure rose high enough to lift the cap release valve.

stevie_a · Postby **stevie_a** » 16 Jun 2009 17:41

I have been told that my problem with my temperature dropping

could be to do with getting an air lock in the system

and as good way to get rid of this is to drill a hole in the thermostat housing

and tap it then insert a grub screw as it is the highest point in the engine

the air would escape and eliminate air locks

do you think this would work?

after all most modern cars have somthing like this fitted

you could also rig up some way to take a good temperature reading from this point 

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If it's not broke don't fix it.

Beans · Postby **Beans** » 16 Jun 2009 21:56

Air shouldn't be a problem if the system is filled correctly AND the thermostat has a (small) air valve.

<center>

1981 TR7 FHC Sprint (better known as 't Kreng)
1980 TR7 DHC (my first car currently being restored)
In parts a 1980 TR7 PI DHC, 1981 TR7 DHC, 1981 TR7 FHC
http://tr7beans.blogspot.com/</center>

stevie_a · Postby **stevie_a** » 16 Jun 2009 22:01

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Beans

AND the thermostat has a (small) air valve.<hr height="1" noshade id="quote"></blockquote id="quote">

can you explain this one ...

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If it's not broke don't fix it.

bmcecosse · Postby **bmcecosse** » 16 Jun 2009 22:13

It should have a little 'jiggle pin' in the top. My car clears air into the expansion tank ok - without that extra tapping. But if in doubt - warm it up, switch off - then squeeze the top hose to push water (and any air) into the expansion tank.

stevie_a · Postby **stevie_a** » 22 Jun 2009 14:49

New thermostat fitted 

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by bmcecosse

then squeeze the top hose to push water (and any air) into the expansion tank.<hr height="1" noshade id="quote"></blockquote id="quote">

With expansion tank cap on or off???

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If it's not broke don't fix it.

Beans · Postby **Beans** » 22 Jun 2009 16:26

You'll have to take the cap of to check if and how much the coolant level has dropped (with cool engine of course).

As for the "jiggle pin" as BMC calls it, you should be able to hear it if it's there. If you squeeze the top hose you will hear a light ticking sound coming from inside the thermostat housing.

<center>

1981 TR7 FHC Sprint (better known as 't Kreng)
1980 TR7 DHC (my first car currently being restored)
In parts a 1980 TR7 PI DHC, 1981 TR7 DHC, 1981 TR7 FHC
http://tr7beans.blogspot.com/</center>

jbsjim · Postby **jbsjim** » 22 Jun 2009 17:14

Hi,
I'm looking for a source for the correct thermostat for the 80 FI engine - preferably a US source. I bought one from Victoria British and it does not have the relief valve and has been giving me trouble with trapped air. Can anyone help?
Thanks! Jim

FI Spyder · Postby **FI Spyder** » 22 Jun 2009 20:24

Rockauto.com has them in the States. I got mine from Robsport I believe but only after getting the wrong one and requesting one with the Triumph "foot". Thermostats are the same for all only the housing is different.

Here is what your looking for (rockauto picture):

TR7 Spider - 1978 Spifire - 1976 Spitfire - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra

Beans · Postby **Beans** » 22 Jun 2009 21:11

Air vent visible on the right hand side ...

1981 TR7 FHC Sprint (better known as 't Kreng)
1980 TR7 DHC (my first car currently being restored)
In parts a 1980 TR7 PI DHC, 1981 TR7 DHC, 1981 TR7 FHC
http://tr7beans.blogspot.com/</center>

stevie_a · Postby **stevie_a** » 22 Jun 2009 22:02

The one i took out had that air vent but the new one did not

is this an issue??

--------------------------------------------------------------

If it's not broke don't fix it.

FI Spyder · Postby **FI Spyder** » 22 Jun 2009 22:09

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by stevie_a

[maroon][b]The one i took out had that air vent but the new one did not
<hr height="1" noshade id="quote"></blockquote id="quote">

The air vent or "jiggle valve" allows air to get past the themostat so it is not trapped in the system. It could be an issue.

TR7 Spider - 1978 Spifire - 1976 Spitfire - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra

busheytrader · Postby **busheytrader** » 23 Jun 2009 08:50

Some people swear by drilling a 3mm (1/8") hole to replicate the jiggle pin bleed hole.

Whatever engine this applies to, refit the stat with the hole at the highest point.

Adam

TR7 V8 DHC Jaguar Solent Blue. 9.35cr Range Rover V8, Holley 390cfm, JWR Dual Port, 214 Cam, Lumention, Tubular Manifolds, Single Pipe Exh, 3.08 Rear, 200lb Spax & PolyBushes, Anti- Dive, Granada Vented Discs & Calipers, Braided Hoses, 4 Speed Rear Cylinders, Uprated Master Cylinder & Servo, AT 5 Spokes and Cruise Lights. No Door Stickers. Mine since July 1986, V8 from 1991

Anonymous

Cooling system / thermostat

Cooling system / thermostat

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