Radiator cowl why ?

[trchris]

Does anyone know why the radiator cowl on a 250/5 is different to the 4a and 6s ? I’m at a loss to see a reason why the top part isn’t fitted

Chris

[stuart]

27 minutes ago, trchris said:

Does anyone know why the radiator cowl on a 250/5 is different to the 4a and 6s ? I’m at a loss to see a reason why the top part isn’t fitted

Chris

Originally to allow more air to circulate around the PI installation (early days of PI).

Stuart.

[Dave McDonald]

I thought the 5/250s didn’t have any radiator ducting at all?

Dave McD 

[trchris]

Hi Dave I’ve seen some without the whole cowl ,but most without the top section mine has the whole lot so l was wondering what the reason was with all the options and which is correct 

if you’re on the drive Sunday it’ll be good to see you and have a chat 

Chris

[rcreweread]

10 hours ago, trchris said:

Hi Dave I’ve seen some without the whole cowl ,but most without the top section mine has the whole lot so l was wondering what the reason was with all the options and which is correct 

if you’re on the drive Sunday it’ll be good to see you and have a chat 

Chris

 Chris

My understanding is that the early cars had a smallish vertical wind deflector either side of the radiator, but nothing over the top, probably as Stuart surmises, to aid cooling of the fuel pump which in those early days was fitted to the bulkhead before moving to the boot later ( not sure about 250s as they wouldn't have had a PI pump).

To my mind, the end result never looked finished and all the mounting holes in the front panel were still there for fitting the TR4/4a cardboard type cowling which fell to bits fairly quickly once it got repeatedly wet.

At the time, I was supplying radiator cowls for the other models manufactured by an aftermarket supplier - we had a surprising number of TR5s in our group and one TR5 member was keen to fit one to his car so we approached the manufacturer and he agreed to send us a 4A one to alter/modify as a prototype. This wasn't difficult as the basic shape remained the same , the basic alterations being the removal of most of the O/S side panel , in order to clear the air filter housing , and the overall shortening of the front to back length as the 6 cylinder engine and rad sit further forward thane the earlier 4 pot cars.

Having returned the prototype, a production model was made and forwarded for us to fit to the members car - this fitted nicely and we were given that unit in return for the work. We were asked to provide photos of the installation which we were happy to provide and these photos are what you see in the listing below. these are now manufactured in both powder coated black ally or polished stainless steel and can be had with or without  a laser cut "TR5" logo in the top.

Ebay link here:

   https://www.ebay.co.uk/itm/257303554678?_skw=TR5+Radiator+Cowl&itmmeta=01KPY33NPMZ212R115ZPVVG9CZ&hash=item3be87caa76:g:iWIAAeSwgydpY8RI&itmprp=enc%3AA

I can provide direct contact details for the manufacturer if anyone wants them - just PM me accordingly

Cheers Rich C-R

Edited April 24 by rcreweread

[stuart]

13 hours ago, Dave McDonald said:

I thought the 5/250s didn’t have any radiator ducting at all?

Dave McD 

They originally had just a rectangular shaped section fitted flat to the left hand side of the rad only, item 96 here https://www.moss-europe.co.uk/en-gb/cooling-system-tr5-6-1967-76-tr56--15--03--01

Stuart.

Edited April 24 by stuart

[trchris]

Thanks for the replies so l can deduce that on a 250 running carburettor’s a fully enclosed cowl , which is fitted , wouldn’t benefit from changing to how the original would be ?

Chris

[rcreweread]

Just now, trchris said:

Thanks for the replies so l can deduce that on a 250 running carburettor’s a fully enclosed cowl , which is fitted , wouldn’t benefit from changing to how the original would be ?

Chris

Chris - I would happily leave as is - without a cowl, the engine bay looks unfinished in my view. FWIW, the TR6s all had a fully enveloping cowl as standard

Cheers Rich

[trchris]

Hi Rich yes I’m going to leave as is as l like you feel there’s something missing when you look at one that’s factory condition and doesn’t have it all fitted l wasn’t sure if there was any benefit leaving the top off 

Chris

Edited April 24 by trchris

[stuart]

3 minutes ago, trchris said:

Hi Rich yes I’m going to leave as is as l like you feel there’s something missing when you look at one that’s factory condition and doesn’t have it all fitted l wasn’t sure if there was any benefit leaving the top off 

Chris

One thing though on a 250 as your running carbs I would fit an elephants dick type of inlet pipe to bring air to the carbs through the side of the rad cowl if your fitting a full one.

Stuart.

[trchris]

Hi Stuart yes that is on the list of things to do in the next week or two 

Chris

[Kenrow]

13 hours ago, stuart said:

They originally had just a rectangular shaped section fitted flat to the left hand side of the rad only, item 96 here https://www.moss-europe.co.uk/en-gb/cooling-system-tr5-6-1967-76-tr56--15--03--01

Stuart.

The 250's had 2 deflectors, one on each side of the radiator... 

[trchris]

Hi Kenro

That’s interesting so the 250 had side shields instead of a radiator cowling ? I suppose that deflects more air through the radiator 

Chris

[stuart]

10 hours ago, Kenrow said:

The 250's had 2 deflectors, one on each side of the radiator... 

Yes thats correct for a 250, mine had the same 

Stuart.

 

[trchris]

As always thanks Stuart l will now investigate getting the correct shields and removing what has been fitted by the previous owner 

Chris

[stuart]

47 minutes ago, trchris said:

As always thanks Stuart l will now investigate getting the correct shields and removing what has been fitted by the previous owner 

Chris

TBH if you already have a full shield then just a duct to the carbs would be ideal.

Stuart.

Edited April 25 by stuart

[Tom Fremont]

I had a TR250 for decades before I knew any kind of shroud or deflector was originally fitted.

These have another air inlet in the lower valance for additional flow onto the radiator vs. the 4 cylinder cars and the deflectors slightly increase the pressure upstream of the radiator, inducing somewhat more cooling at speed though probably less than the cowls do. The open top allows a considerable amount of cool air to pass over the engine, carburetors and manifolds relative to the comparatively blocked off setup of the 4-cylinder cars and the TR6, a boon I guess for open air filters.  

[harlequin]

On 4/25/2026 at 12:48 PM, stuart said:

TBH if you already have a full shield then just a duct to the carbs would be ideal.

Stuart.

This is what I have on my TR6 which has a TR250 air box

George 

[trchris]

Hi George yes l still need to fit hoses as you have ( hoses on shelve ) l have seen that the side shields are extremely cheap so may get and try and maybe use as template for a pair of stainless ones l will still fit the air box hoses.

HI Tom nice under bonnet ( hood to you guys ) are your shields metal ?
Chris

[harlequin]

10 minutes ago, trchris said:

Hi George yes l still need to fit hoses as you have ( hoses on shelve ) l have seen that the side shields are extremely cheap so may get and try and maybe use as template for a pair of stainless ones l will still fit the air box hoses.

HI Tom nice under bonnet ( hood to you guys ) are your shields metal ?
Chris

I was told that Triumph used fibreboard for the shields to prevent the radiator being damaged in a low speed front end shunt. Ofcourse also being cheap helped with the decision.

George 

[trchris]

1 hour ago, harlequin said:

I was told that Triumph used fibreboard for the shields to prevent the radiator being damaged in a low speed front end shunt. Ofcourse also being cheap helped with the decision.

George 

Good point George 

Chris

[dave bailey]

On 4/24/2026 at 8:15 AM, rcreweread said:

 Chris

My understanding is that the early cars had a smallish vertical wind deflector either side of the radiator, but nothing over the top, probably as Stuart surmises, to aid cooling of the fuel pump which in those early days was fitted to the bulkhead before moving to the boot later ( not sure about 250s as they wouldn't have had a PI pump).

To my mind, the end result never looked finished and all the mounting holes in the front panel were still there for fitting the TR4/4a cardboard type cowling which fell to bits fairly quickly once it got repeatedly wet.

At the time, I was supplying radiator cowls for the other models manufactured by an aftermarket supplier - we had a surprising number of TR5s in our group and one TR5 member was keen to fit one to his car so we approached the manufacturer and he agreed to send us a 4A one to alter/modify as a prototype. This wasn't difficult as the basic shape remained the same , the basic alterations being the removal of most of the O/S side panel , in order to clear the air filter housing , and the overall shortening of the front to back length as the 6 cylinder engine and rad sit further forward thane the earlier 4 pot cars.

Having returned the prototype, a production model was made and forwarded for us to fit to the members car - this fitted nicely and we were given that unit in return for the work. We were asked to provide photos of the installation which we were happy to provide and these photos are what you see in the listing below. these are now manufactured in both powder coated black ally or polished stainless steel and can be had with or without  a laser cut "TR5" logo in the top.

Ebay link here:

   https://www.ebay.co.uk/itm/257303554678?_skw=TR5+Radiator+Cowl&itmmeta=01KPY33NPMZ212R115ZPVVG9CZ&hash=item3be87caa76:g:iWIAAeSwgydpY8RI&itmprp=enc%3AA

I can provide direct contact details for the manufacturer if anyone wants them - just PM me accordingly

Cheers Rich C-R

Hi Rich.

The TR5 aluminium cowl looks good. I'm tempted to get one, although I will be fitting Webers so wouldn't need the cut-away section where the air filter would be. So I guess I could fill it in with a suitable piece of aluminium, unless you think that the supplier can provide one with no cut-away?

Dave.

[rcreweread]

17 minutes ago, dave bailey said:

Hi Rich.

The TR5 aluminium cowl looks good. I'm tempted to get one, although I will be fitting Webers so wouldn't need the cut-away section where the air filter would be. So I guess I could fill it in with a suitable piece of aluminium, unless you think that the supplier can provide one with no cut-away?

Dave.

Dave - without the side cutout for the existing air filter, the shape would be the same as a 4A, albeit, it would be shorter front to back - I'll PM you the suppliers contact details

Cheers Rich

[stuart]

51 minutes ago, dave bailey said:

Hi Rich.

The TR5 aluminium cowl looks good. I'm tempted to get one, although I will be fitting Webers so wouldn't need the cut-away section where the air filter would be. So I guess I could fill it in with a suitable piece of aluminium, unless you think that the supplier can provide one with no cut-away?

Dave.

You would be better having one with a cutout and fitting a cold air /elephants dick type pipe to the carbs.

Stuart.

[Tom Fremont]

21 hours ago, trchris said:

 

HI Tom nice under bonnet ( hood to you guys ) are your shields metal ?
Chris

Hi Chris,

No, they're fibreboard as per original supposedly. Truth be told neither this one nor my driver see much rain which would likely distort these deflectors in short order - probably why I never saw an original set! They sit comfortably albeit loosely against the wheel arches while clipped to the radiator. I suppose TRIUMPH wanted something soft against the painted arches; otherwise a stiffer phenolic or other plastic might have been used.