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Hi Folks,

I have just changed the thermostat on the cylinder head of my 4A.

I noticed that the coolant was level with the top of the Cy head. The radiator is full.

So should the radiator be raised in order to raise the coolant level

Or

leave alone as it is about right.

 

Roger

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You cant raise the rad as it will hit the underside of the bonnet frame. The level in the thermostat section is often empty

Stuart.

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+1 for Stuart’s comments .

My rad overflow pipe had been rubbing the paint off the edge of the bonnet reinforcing cross member for years. In the process of recently tidying up the whole of the front under bonnet area and moving the overflow bottle to the LH side to allow a cold air inlet on the right I checked the rad height and found that the rubber spacers under the bottom mounts (fitted by me many years ago) were nearly 8mm thick. I replaced these with 1.5mm rubber washers and the hose now just clears by less than 3mm checked with 2 bits of masking tape and a dab of paint. Note the hose outlet on my rad has always pionted to the left.

Chris

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1 hour ago, RogerH said:

Hi Folks,

I noticed that the coolant was level with the top of the Cy head. The radiator is full.

Or

leave alone as it is about right. .? 

 

Roger

Not when the water is hot it isn't, it raises it, your last sentence is correct.

Mick Richards

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To get water up to the top of the thermo housing you need to fit a bleed screw to the thermostat housing and vent the air out of the engine when the engine has warmed up and the water has expanded.  You will have to re bleed after each time you open the rad cap though to maintain the full engine experience....

....or leave it all alone

Peter W

PS Simple 1/8 bsp taper plug in back top of thermo housing, also fitted a winged type rad drain tap on brother's TR2.

Thermostat Bleedscrew.jpg

Edited by BlueTR3A-5EKT
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Hi Roger,

everythink is OK with your coolant level.

I know you (and me) never fill more in than as told by the manual. Well done!

There is no need to bleed the housing, indeed you need the air in the system to be comperessed by the expanding coolant.

Als soon as the water pump runs all air is out of the housing and always as fine bubbles "in the flow".

Shure you know about my bleeding system with the inline Peugeot bottle?

With this I can decide to drive with bubbles or without within a minute - with no benefit at all.

Ciao, Marco

 

Edited by Z320
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Why not convert to a sealed system - see my article in Section B18 of the Technicalities CD.   It's what one finds on every modern vehicle.

Cheap to do, and the radiator will ALWAYS be completely full to the very top - though you won't see it because the pressure filler cap on the radiator is moved to the expansion  tank and replaced with a sealing cap.

The only parts required are: expansion tank (scrapyard), sealing cap for radiator, length of rubber hose and a couple of hose clips.

I have had a sealed system in place for some 25 years.

Ian Cornish

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6 minutes ago, ianc said:

Why not convert to a sealed system - see my article in Section B18 of the Technicalities CD.   It's what one finds on every modern vehicle.

Cheap to do, and the radiator will ALWAYS be completely full to the very top - though you won't see it because the pressure filler cap on the radiator is moved to the expansion  tank and replaced with a sealing cap.

The only parts required are: expansion tank (scrapyard), sealing cap for radiator, length of rubber hose and a couple of hose clips.

I have had a sealed system in place for some 25 years.

Ian Cornish

I do the same on my 3a using a period brass expansion tank. Like this. 

 

MG MIDGET / AUSTIN HEALEY SPRITE BRASS  RADIATOR EXPANSION TANK ARH250 https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F372742584573

 

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25 minutes ago, ianc said:

Why not convert to a sealed system - see my article in Section B18 of the Technicalities CD.   It's what one finds on every modern vehicle.

Cheap to do, and the radiator will ALWAYS be completely full to the very top - though you won't see it because the pressure filler cap on the radiator is moved to the expansion  tank and replaced with a sealing cap.

The only parts required are: expansion tank (scrapyard), sealing cap for radiator, length of rubber hose and a couple of hose clips.

I have had a sealed system in place for some 25 years.

Ian Cornish

Hi Ian,

I've been meaning to do this for a couple of years now. I bought a TR7 expansion tank and bracket but have just not got round to it..

Another winter project.

 

Roger

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30 minutes ago, ianc said:

Why not convert to a sealed system - see my article in Section B18 of the Technicalities CD.   It's what one finds on every modern vehicle.

Cheap to do, and the radiator will ALWAYS be completely full to the very top - though you won't see it because the pressure filler cap on the radiator is moved to the expansion  tank and replaced with a sealing cap.

The only parts required are: expansion tank (scrapyard), sealing cap for radiator, length of rubber hose and a couple of hose clips.

I have had a sealed system in place for some 25 years.

Ian Cornish

My 4a has been the same for the last 26 yrs too, works a treat.

Stuart.

 

photo1754.jpg

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5 minutes ago, RogerH said:

Hi Stuart,

it was one of your posts that inspired me to buy the tank. 

Sadly you never turned up to fit it:P

 

Does the pipe to the expansion tank come from the existing radiator  overflow outlet pipe stubby.

 

Roger

Yes it does, just be careful with placement of the hose clip for it as the bonnet clearance is very minimal there, in fact my pipe does just rub. If you had bothered to come and see us whenever youve been down I would have gladly fitted it for you! ;)

Stuart.

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Stuart, is your rad cap just a plain cap with no spring and is the one on the expansion tank the one that was on the rad, 7 psi ?

Chris

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1 hour ago, ChrisR-4A said:

Stuart, is your rad cap just a plain cap with no spring and is the one on the expansion tank the one that was on the rad, 7 psi ?

Chris

Yes  it is

Stuart.

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TR3 I know, but - my rad is always full to the brim. I use a simple plastic expansion bottle, open at the top, with a submerged pipe connecting to the rad overflow spigot.

The rad cap is modified to have a good seal around the top. When the water gets hot it flows into the bottle, & it flows back again when cooling down.

Bob.

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On 11/1/2019 at 1:21 PM, BlueTR3A-5EKT said:

To get water up to the top of the thermo housing you need to fit a bleed screw to the thermostat housing and vent the air out of the engine when the engine has warmed up and the water has expanded.  You will have to re bleed after each time you open the rad cap though to maintain the full engine experience....

....or leave it all alone

Peter W

PS Simple 1/8 bsp taper plug in back top of thermo housing, also fitted a winged type rad drain tap on brother's TR2.

Thermostat Bleedscrew.jpg

Forgot to add that the cooling system on my car as pictured above is sealed. Plain cap on radiator 4 psi on expansion tank.   It uses the Dolomite Sprint bottom entry expansion tank mounted on the LH inner wing.  The bleed screw in the thermo hsg, allows me to rid the system of almost all the air, and fill the system fully, I think.  I also bleed the back of my engine feed to the heater by having a tall adaptor (ex TR5/6) for the water valve. 

All works fine for me, and since going to a Tridon thermostat, plus the calibrated blank plug in the bypass, the temp sits constantly at 185 F when driving, although it does creep up when parked in traffic, then the fan comes on pulling it back down to 185.

Tridon say they will not export, so you need someone with an inside track.  (thanks Nigel) https://tridon.com.au/products/Tridon/35/479/thermostats-and-gaskets/528046/thermostat-high-flow

As we all know failure to fill the system fully on say a MGRV8 will cook the engine quite quickly, due to the top hose rising above the radiator top tank and engine.  That is why the engine is provided with a special fill valve next to the air intake plenum.


Cheers

Peter W

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27 minutes ago, Tr4aJim said:

Stuart, I notice that your coil is upside down. Doesn’t the electricity leak out?? :rolleyes:

Jim

Been like that for years without a problem. Its an early Lucas sports coil from when they were actually Lucas.

Stuart.

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18 hours ago, peejay4A said:

Handy if the DR3A fails. Oh, wait...

If you really want to know its from when I was trying out an EFI set up, it was a bit of a hybrid Webcon system but it turned out the ECU wasnt the full shilling so it was removed.

Stuart.

 

photo1.JPG

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