Herald 1200 Still pushing 1 pint of coolant out every journey of more than 5 miles

[Jem 1of3]

Yes it's me again, I changed the head gasket but it still pushes coolant out of the radiator every journey there is no outward signs of it. There appears no coolant in the oil. The starts easily car runs like a dream, but is becoming a nightmare of worry as at least a pint of fluid is ejected every journey. The radiator and engine block have been flushed and refilled. The radiator cap is 13lb as described I am at a loss to know what to do. I don't even know if it's overheating it doesn't appear to be too hot. The 3 workshop manuals all say top up weekly or monthly but not every time you use the car. One says fill the radiator completely one says leave an inch gap. It's such a shame. Can anyone help?? 

[johny]

I take it yours doesnt have an bottle to collect the coolant pushed out of the system via the overflow pipe? If this is the case then the radiator is designed to have an air pocket above the level of coolant in it to absorb the expansion of the coolant as its heated and theres no point trying to fill it more.

So I would fill the system and get it to maximum temperature and then let it cool. The level you now see (the rad tubes must still be covered of course) is your correct level so measure it with a dip stick and this is now the point you need to top up to, if required, in routine maintenance....

[Pete Lewis]

the 1200 rad cap is GRC112  at 7lbs    13 is far too high and will expand hoses excessively .

and does the seal actually load against the rad filler neck there are deep and shallow caps a short one in a deep filler wont seal .

thats right never brim the rad thats always going to spill  expanded coolant a 1" gap is about the normal .

Radiator, Exhaust System and Petrol System : Canley Classics

try releasing the highest heater hose and release a bit of coolant to expel any trapped air 

does the heater work well  it may be blocked and giving you a continual air lock , the air expands when heated and this displaces the coolant 

check some of these out and let us know what you find 

Pete

 

[Colin Lindsay]

Most points already covered; it should be 7lbs cap pressure for the 1200. It's a total-loss system so once it expands, it goes off down the tube and is lost so no refilling as it cools like the 6-cylinder systems. I just fill mine to the top, the excess is lost but as Johny says long as the tops of the radiator tubes are covered it should be ok. (Look in through the neck to see what level it's really at)

It might still be a slight drip or loss under pressure from a hose?

[Jem 1of3]

Hi All, Thanks for your replies,

I have 3 workshop manuals which state a 13lb cap is correct. After a short journey it has pushed out the coolant below the radiator tubes when I remove the cap. There is no sign of a drip or any external leaks at all. Someone has suggested mounting the radiator higher to remove the air lock issue. Another suggested a bigger radiator that goes right across the front, rather than the one with wings that I have. 

Mr Pete Lewis however has hit the nail so to speak, I measured the radiator cap depth at 18-19mm the neck is 20-21mm EUREKA. I am ordering a cap now from Rimmer Brothers.

[johny]

Great yes as you put the cap on you should feel the slight resistance of the spring in it as thats compressed by the seat making contact before rotating the cap to lock it in place. If you dont feel that the cap isnt sealing....

[Josef]

2 hours ago, Jem 1of3 said:

I have 3 workshop manuals which state a 13lb cap is correct.

The 13lb cap may be right for the very last 1200s, it was switched late 1969 for the 1300 engined cars. I have a 69 built Spitfire and 69 built Herald 13/60, the Herald is slightly later and has a 13lb cap, the Spitfire a 7lb. Given a cooling system in good condition I can’t see why you wouldn’t be able to use either pressure though, as they all use the same hoses etc.

[Colin Lindsay]

2 hours ago, Jem 1of3 said:

Another suggested a bigger radiator that goes right across the front, rather than the one with wings that I have. 

Mr Pete Lewis however has hit the nail so to speak, I measured the radiator cap depth at 18-19mm the neck is 20-21mm EUREKA. I am ordering a cap now from Rimmer Brothers.

Interesting points from both Josef and Jem; the last 1200s lasted to 1970 and may have gone to 13lbs but did they have the narrow radiator, or retain the wide version? It's probable that when the Herald engine was boosted to 49bhp in 1965 they went up to 13, but my 1967 1200s all have the wide radiator so I've no idea what radiator was used for the very late models. In any case that shouldn't affect the coolant loss.

[Pete Lewis]

having the rad cap  of correct depth is a basic must have, what pressure is pretty immaterial as this just raises the boiling point of the coolant and has no effect on usage might induce loss from leaks  

but if there is no sealing then the coolant will just escape and  a trial with the new cap before

any wild ideas of replacement radiators ,a check on the thermostat may be worthwhile 

 

pete

Edited October 7, 2023 by Pete Lewis

[Ian Foster]

Jem

You might like to review this earlier thread, which although it relates to a GT6, may be relevant to you particularly in respect of radiator neck and cap dimensions.

Ian

 

 

[Josef]

18 hours ago, Colin Lindsay said:

Interesting points from both Josef and Jem; the last 1200s lasted to 1970 and may have gone to 13lbs but did they have the narrow radiator, or retain the wide version? It's probable that when the Herald engine was boosted to 49bhp in 1965 they went up to 13, but my 1967 1200s all have the wide radiator so I've no idea what radiator was used for the very late models. In any case that shouldn't affect the coolant loss.

I happened across the answer to the question of which width rad was originally fitted to the Herald 1200s this morning. Wide rad up to GA80000, narrow from GA80001 / GB1.

[johny]

Interesting as later rad is obviously deeper so maybe there was a problem with getting good airflow to all of the wide one.... 

[Casper]

Wide radiator more copper more cost ?

[Colin Lindsay]

2 hours ago, Josef said:

I happened across the answer to the question of which width rad was originally fitted to the Herald 1200s this morning. Wide rad up to GA80000, narrow from GA80001 / GB1.

It's strange that the changeover is recorded as being so early, but I've seen it in other manuals too; GA80000 was around the changeover from the MK1 chassis to the MK2 in 1961 where the mounting changed from directly to the chassis to the suspension turrets. It's a very early engine number. My 1200 Heralds from 1962 / 63 / 64 and 67 all have the wide radiator, at least two of which are the original, and out of nearly a dozen Heralds I've owned I've never had the narrow radiator at all until I bought the 1969 13/60. I can't believe they were all replaced with the wide radiator due to a fault in all of the narrow versions somewhere through the years. Just another of the strange vagaries of Heralds!

[johny]

2 hours ago, Casper said:

Wide radiator more copper more cost ?

Cant be much as same number of tubes and case deeper...

[Pete Lewis]

and you willl likely find 13 psi will have bucket core plugs   and 7 will have dished welch plugs 

which with too much pressure will get popped out .

there is more to all this myth busting than the radiator and wild overheating statements

the whole basics need a careful approach not guesswork 

Pete

 

[DanMi]

40 minutes ago, Pete Lewis said:

and you willl likely find 13 psi will have bucket core plugs   and 7 will have dished welch plugs 

They changed to bucket plugs in about 1965 at least on the spit though retained the 7Lb radiator cap until the mk3 in 1967 (my 1966 has bucket core plugs ). Apparently they also improved the water pump seal and used different hoses to cope with the pressure (John Thomason Guide to Originality)

[Pete Lewis]

Dan thats good that puts a date into core plug changes thanks 

Pete

[Colin Lindsay]

On the Herald it's engine number GA206641HE from 1965, change to bucket-type core plugs amongst other changes such as proper rear crank seal and improved head cooling. I could see the radiator changing around this point, but the earlier date still baffles me given the vast majority of wide radiators that I've both owned or seen over the years. 

[DanMi]

1 hour ago, Pete Lewis said:

Dan thats good that puts a date into core plug changes thanks 

Pete

To confuse matters a bit more it wasn't a complete change. The plugs on mine to the water jacket are bucket type but the 3 on the distributer side and the big one on the back of the cam drilling (which are not to the water jacket) are still the welch type, can't really understand why they would machine the block in 2 ways but they did

[Josef]

5 hours ago, Colin Lindsay said:

On the Herald it's engine number GA206641HE from 1965, change to bucket-type core plugs amongst other changes such as proper rear crank seal and improved head cooling. I could see the radiator changing around this point, but the earlier date still baffles me given the vast majority of wide radiators that I've both owned or seen over the years. 

I’ve seen somewhere today that GA80001 (engine, not commission, number) was the first Courier van. So that matches your thought on the chassis changeover (I think?) but still, 1962 ish does seem very early. 

[Casper]

First Courier was comm no. GA444561 Dec '61/Jan '62.  Bit early for a 80000 engine no. I would have thought.

Star chasis GA80001 was July '62

Herald 1200 Hot Cam engine GA178101E Nov '64.  I have always thought that bucket core plugs = hot cam

Brass tube head from GA44651E  May '65, 'proper' rear crank seal from GA206771E Jan '66.

Most change points variable due to suppy/shortages and using up old stocks. 

They changed the fan at GA161460E ?Aug '64 to square ended metal, then again at GA225581E ?Feb '67 for the pressed type (of which there were steel and aluminium versions and a 2 blade aluminium version[? for Spit?])

All for what it is worth - probably not a lot !

C.

 

 

 

Edited October 9, 2023 by Casper

[Colin Lindsay]

GA80001 is the change of chassis and so the difference in engine mountings. There were additional changes at GA 137545 (pistons etc) and then the biggest change at GA206641 with revised head, core plugs, crank seal etc. You've also got the 1200 Coupe and 12/50 variants and the twin-carb variants - same block as the general model but uprated cam etc. I've been reading old reports and adverts and in shots of the engine bay there are both types of radiator, the 12/50 in one has a narrow version but a later 1200 ad has the wide. There seems to be a lot of cross-over, and probably using what was available in stock. 

The important thing is as Pete has posted, the cap must be correct. According to the Service Notes there are two types of 13lb cap regardless of depth; RC6 and RS6. RC6 has a sealing washer and is used for the 'open' system, where the fluid is lost down the pipe; the other RS6 has no washer and is used where there is an expansion bottle so the fluid can be drawn back in again. How those numbers transfer to modern stocks is another thing, particularly where suppliers use a 'one-size-fits-all Spitfire and Herald' approach.

[Chris A]

4 hours ago, Colin Lindsay said:

According to the Service Notes there are two types of 13lb cap regardless of depth; RC6 and RS6. RC6 has a sealing washer and is used for the 'open' system, where the fluid is lost down the pipe; the other RS6 has no washer and is used where there is an expansion bottle so the fluid can be drawn back in again. How those numbers transfer to modern stocks is another thing, particularly where suppliers use a 'one-size-fits-all Spitfire and Herald' approach.

I've been following this thread just out of idle curiosity and as a result of Colin's one size fits all comments I looked at my normal French supplier's site for the cap that is listed for a 13/60. They have 2 references - GRC114 & GRC180 so I mailed them asking what were the differences, particulary in depth. Reply : non

[johny]

5 hours ago, Colin Lindsay said:

The important thing is as Pete has posted, the cap must be correct. According to the Service Notes there are two types of 13lb cap regardless of depth; RC6 and RS6. RC6 has a sealing washer and is used for the 'open' system, where the fluid is lost down the pipe; the other RS6 has no washer and is used where there is an expansion bottle so the fluid can be drawn back in again. How those numbers transfer to modern stocks is another thing, particularly where suppliers use a 'one-size-fits-all Spitfire and Herald' approach.

When you say washer Colin its a reverse valve in the centre with its own spring which is pulled open by vacuum in the radiator. Im not sure any caps are produced now without it as of course its perfectly ok for use in a non reservoir set up...