What's going on here?

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rich112
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What's going on here?

Post by rich112 »

OK, so I decided that as my radiator was a bit clogged, I'd check the thermostat.

I eventually get into the housing, and WTF there is no thermostat...

Also the 'bleed' pipe that's been added to the housing was blocked solid. I got a 3.5mm drill up there and cleared it out, but I am guessing this is not standard!

The bleed is a bit of bolt with a hole drilled up it, which has of course corroded shut.

The pipe goes to the top of the rad, so I guess this should work, if it wasn't such a tiny orifice.

Any reason why its such a small bleed off?

What thermostat should be in here? (4.6 V8 with carb)
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ChrisJC
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Re: What's going on here?

Post by ChrisJC »

Bleeds don't need to be large - they are just to let any air bubbles get to the top of the system.

Maybe a previous owner had trouble with overheating, (blocked rad!!) so they removed the thermostat to 'fix' it...

Chris.
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Series IIA 4.6 V8
R/R P38 4.6 V8
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Re: What's going on here?

Post by SuperV8 »

The 4.6 had a remote thermostat - in the bottom hose. Plastic cows udder thing!

does yours have anything like that?
Dax Rush 4.6 supercharged V8 MSII

garrycol
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Re: What's going on here?

Post by garrycol »

On the earlier engines that thermostat bypass is piped into the back of the water pump. I also have a 4.6 (no dizzy) and have the pipe blocked up as there is no where to go on a 4.6 as there is no inlet on the back of its water pump.

The pipe on the earlier standard engines is to allow hot coolant to circulate past the back of the thermostat to assist it to open. Because I had it blocked in my engine there is no way coolant can pass from the engine to the radiator while the thermostat is closed and for it to open, the coolant needs to be hot. Unfortunately with the thermostat closed there is no flow and the coolant in the actual engine gets hot but as the thermostat housing is outside of the main engine and there is no hot coolant going past the area behind the thermostat, it remains closed while the engine overheats.

To get around this I drilled some small holes in the thermostat that allows the coolant to flow and heat the thermostat so it opens. This is a temporary measure and later I will put in a new undrilled thermostat and run a pipe from the bypass pipe in the thermostat housing to the lower radiator hose so there is always a flow of coolant even when the thermostat is closed.

My engine got very very hot and now I have a smoke issue with my engine that I have raised in another thread. So make sure you have a way of ensuring coolant can get through the thermostat housing to heat it up to open the thermostat.

Hence the reason have no thermostat - to protect the engine from cooking.

Garry

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Re: What's going on here?

Post by SuperV8 »

garrycol wrote:
Thu Jul 29, 2021 10:47 am
On the earlier engines that thermostat bypass is piped into the back of the water pump. I also have a 4.6 (no dizzy) and have the pipe blocked up as there is no where to go on a 4.6 as there is no inlet on the back of its water pump.

The pipe on the earlier standard engines is to allow hot coolant to circulate past the back of the thermostat to assist it to open. Because I had it blocked in my engine there is no way coolant can pass from the engine to the radiator while the thermostat is closed and for it to open, the coolant needs to be hot. Unfortunately with the thermostat closed there is no flow and the coolant in the actual engine gets hot but as the thermostat housing is outside of the main engine and there is no hot coolant going past the area behind the thermostat, it remains closed while the engine overheats.

To get around this I drilled some small holes in the thermostat that allows the coolant to flow and heat the thermostat so it opens. This is a temporary measure and later I will put in a new undrilled thermostat and run a pipe from the bypass pipe in the thermostat housing to the lower radiator hose so there is always a flow of coolant even when the thermostat is closed.

My engine got very very hot and now I have a smoke issue with my engine that I have raised in another thread. So make sure you have a way of ensuring coolant can get through the thermostat housing to heat it up to open the thermostat.

Hence the reason have no thermostat - to protect the engine from cooking.

Garry
The thermostat bypass on the 4.0/4.6 goes into the remote thermostat housing (cows udder) in the bottom hose!
Dax Rush 4.6 supercharged V8 MSII

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Re: What's going on here?

Post by garrycol »

Yes but if you have a 3.5 and inlets and thermostat you do not have the cows udder. The OPs 4.6 termostat housing is not the udder type and is near the same as the system I have on my 4.6, and not a 4.6 inlet system as he has an aftermarket system and carb - hence my comments on the bypass pipe which is blocked as mine is.

He needs to ensure coolant can heat the thermostat which should have been in the housing as the engine warms.

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Re: What's going on here?

Post by SuperV8 »

garrycol wrote:
Thu Jul 29, 2021 12:54 pm
Yes but if you have a 3.5 and inlets and thermostat you do not have the cows udder. The OPs 4.6 termostat housing is not the udder type and is near the same as the system I have on my 4.6, and not a 4.6 inlet system as he has an aftermarket system and carb - hence my comments on the bypass pipe which is blocked as mine is.

He needs to ensure coolant can heat the thermostat which should have been in the housing as the engine warms.
I was replying to your quoted comments Garry:
"I also have a 4.6 (no dizzy) and have the pipe blocked up as there is no where to go on a 4.6 as there is no inlet on the back of its water pump."

I would recommend the remote thermostat for both the OP and your engine Garry, you can get them with 82deg stat, they are pressure relieving, and also when they open they block off the bypass flow meaning ALL your coolant goes through the rad.
Dax Rush 4.6 supercharged V8 MSII

rich112
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Re: What's going on here?

Post by rich112 »

Interesting info. Thanks.

I have a temp gauge (capilary) thats fitted (sort of) into a small tee off on the waterpump inlet, from the rad lower hose.

That seems a bit dumb as it measures the cold side.

It's also in the perfect position to collect air and crud and not measure very well.... It was not reading anything when I got the car.


There is an electric temp sensor on the hot side of the thermostat, in the inlet manifold. This has a wire on that goes somewhere but not to a gauge or the fan controller... So I think this one needs a gauge putting on it, pronto!

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