Both very heavy stuff Jeff and will certainly get the job done but here are the precautionary actions to be taken with each. Both make Vinegar tame. You can drink vinegar (in small quantities) but not these two products.
https://www.apartmenttherapy.com/clr...avoid-36860665
https://www.bobvila.com/articles/muriatic-acid/

 

Quite often you will also find a lot of sand left in the block from the casting process (even after 50 odd years) which can be washed out into the radiator or heater matrix blocking the waterways. A good pressure hose blast is fine as long as you do not over pressurise the water system causing the gaskets to blow. The water system is only under 7 PSI whilst running and the radiator cap is the pressure release valve.

I used a pressure washer on my block but the engine was completely stripped ready for a rebuild at the time.

 

If a part of the system is weak and fails during flushing, it's way better than suffering a major loss of coolant when you're far from home in the worst possible location.

No one's mentioned good old/rotten old Bar's Leaks.

 

Citric Acid is an approved Mercedes part for Service Products in their all Aluminium engines & aluminium steel engines. Benz is one of the last Auto companies left that make it easy for owners by putting ALL Service Products through an arduous testing regime before approval and listing ~ many fail ~ They have done this since the 1950's. They also do random testing around the world to ensure that the Oil companies etc. are sticking to the rules & using the approved formulations. Use an approved product & you are safe & all warranties will be honoured.

 

If you are having any problems with overheating, replace with an aluminum radiator. They are easy to install and your overheating issues should disappear.

Gary

 

Nice idea Gary but if the radiator is blocked with detritus and rust then all the water ways in the block are also going to be blocked. It is a bit like giving someone with a broken leg a walking stick. They might be able to walk but it does not fix the leg. As you said "your overheating issues SHOULD disappear." No guarantees implied or accepted.
Besides and it is only a personal view Alloy Rads in a Mk2 Jaguar look awful.

 

Much is spoken about efficiency & the thermal conductivity of copper/brass vs aluminium. Copper/brass wins hands down but there are caveats regarding the interface of materials/components, manufacturing/construction methodology, core/tube spacing etc. The major benefit of aluminium is weight, cost & a level of heat transfer to air in some construction/configurations to be fair. Copper/brass will outlast aluminium in radiators by a large factor/margin. Fins have not been soldered to copper/brass radiator core tubes since Noah's Ark. (Their old loss of efficiency). So copper/brass radiators are just plain better & keep your car looking original. At coast all the fins corrode off of aluminium radiators in salt air at an unacceptable rate .

This is actually a fair minded article on the subject in layman's terms. There are far better articles but beyond the general understanding of the man in the street.

https://www.hotrodhotline.com/md/htm..._vs_copper.php

 

Thanks for that, I've been using muriatic acid for many years, hydrochloric acid too, on many different things, it works better then sand blasting for removing rust.
It gets right into the pores of steel, cast iron and leaves the good steel and cast iron behind, sand blasting does not accomplish this.
When I did my Jag Brakes, I let the bodies soak in it over night, they come out nice and grey, ready for primer and paint.
It's important to thoroughly rinse and neutralize the acid.

I use it to clean badly oxidized wiring, getting ready to solder.
It eats the aluminum oxide that plugs up brass and copper radiators, leaving the brass and copper in tact, it doesn't attack the solder.

And CLR is pretty lame stuff, I've left it in the car for a couple of day and it does work, but it sure doesn't eat the aluminum like people think it does.
What you read about both products, especially CLR, I think is more for liability purposes.

The adverts for CLR are BS, it doesn't work instantaneously like that, the person who used to clean our washrooms found it quite useless on taking the rust stains out of the toilet bowl.
Even with the water removed from the bowl, it did very little removing the rust, even full strength.
She used the whole gallon container trying to get the rust off.

And vinegar; there isn't enough vinegar on the planet to remove severs scale in an engine block, it's good for light maintenance, and that's about it.

 

Talking cast iron & steel. NOT ALUMINIUM.

It's not so much the strength of acid as much as it's chemical operation/reaction. Most strong acids will promote further rusting unless absolutely neutralised right into the pore structure of the metal. Muriatic acid is just watered down Hydrochloric acid

Phosphoric acid aqueous solution has long been used to pickle & convert rust leaving an ideal surface for painting without priming. Removes scale perfectly & is not a strong acid.

Most acids will etch metal whether they cause rust or remove it. Phosphoric acid (H3PO4) is one type of acid which removes rust by converting it (iron III oxide) to a form which can be dissolved in water. Most other strong acids cause rust.

 

A number of years ago I had a 3.8 E Type and once the outside temperature got above about 22C the temperature of the coolant started climbing and nothing I could do would bring it down. We have reasonably hard water, so I hypothesised that it was a mineral build-up inside the block, as I had already had the radiator recored and it was clean.

My Mum worked at the university and her boss happened to be a chemist, so I asked him what to use, given that materials in the cooling system. He recommended vinegar, with the caveat that all of the ethylene glycol mush be flushed first, as the reaction between acetic acid and glycol is very exothermic.

So I drained and flushed the system, then filled it wit a mix of water and Kodak Stop Bath, which is acetic acid. It has the advantage of having an indicator in it, so I can tell when it has changed from acid to base. It was also cheaper than vinegar at the time, and I had bottles of it in my darkroom. I ran the engine to bring it up to temperature and get the thermostat open, then let the engine sit for about an hour to let the reaction happen. I started the engine again to circulate everything, then drained the acid. It came out looking like milk it was so full of minerals. I let it sit in a plastic drain pan that was bigger than the footprint of the engine and in the morning I had a layer settled out about 1/2" thick. I flushed with water several times, then refilled with fresh coolant. After than the temperature gauge came up to thermostat temperature and stayed there no matter what the outside temperature was.

So Vinegar can definitely clean out the block, but it may not take out rust. Also the strong acids are a definite no with the combination of metals in a Jaguar engine.

 

After running the CLR through, I rigged up the garden hose with with the thermostat removed with a constant flow of clean water running through with the engine running.
Then added just water, drove around for a week, and repeated the process twice, finally adding a 50/50 mix of coolant and water.

This is what I did, it may not be for everyone, I just thought I should mention it.
I had to replace the water pump later on after all of that as it was very worn and leaking, when I took things apart, there was no indication of corrosion or damage from the CLR or the Muriatic acid, it was just nice and clean.

Note the water pump did not fail from what I did, it had been in there for 20 years, and who knows how long before I had it.

 

A lot of space is occupied on the internet discussing the relative properties of copper, brass and aluminium for effective heat transfer in car radiators. My feeling is that it’s pretty irrelevant.

The radiator serves to move thermal energy from hot water to less hot air. Assuming the hot water reaches the wet side of the metal, aluminium or copper will rapidly approach the temperature of the water. The major barrier to heat transfer is the small heat capacity of the air on the dry side. That’s why a radiator is basically a mass of fins and has a fan: to bring a sufficient mass air per second in contact with the metal to take the heat away.

To avoid over heating:

- the water (or liquid coolant) has to reach all the metal surfaces; that is the system must not be blocked

- there has to be an adequate flow of air through the radiator (that should have been designed to have a sufficient surface area)

The choice between copper/brass and aluminium should be made on cost, convenience, aesthetics. If the radiator gets blocked every few years, chose one that’s cheap and easy to swap. If you want the original look, go for that.

V12s take a lot of cooling in traffic and are incredibly good at filling their radiators with gunge. My DD6 has had three radiators over thirty years. The most recent is aluminium made by Alicool. It comes with two big electric fans and cowling. I’m hoping that it will function better than the original with the viscous clutch fan when crawling slowly uphill in very hot weather. We preferred the convenience and overall cost of the ready made arrangement over fabricating a cowl and arranging mountings etc for a system with parts all bought separately.

 

My sister only drives Toyotas & like me lives close to the sea with a nice sea view. Toyota transverse/crossflow radiators lose all their fins in 6 to 8 years in this environment & require replacement. Like most Toyota spares they are not cheap. I recommend that every time you wash your car in a sea air location that you wash the external fins on an Al radiator with fresh water to remove the salt. We will agree to disagree with the copper vs aluminium radiators within the restrictions/confines of our compact Jaguar engine compartments & grill area. Awful cosmetics aside.

Fit a nice uprated brass "tropical" radiator.

 

Glyn, I'll let the group know how my Daimler gets on. The salt hazard in the English Midlands is mainly that generously provided on our roads to remove ice and snow in the worst days of winter. However, my Daimler is not likely to be out in that sort of weather. I have always washed around the radiator to remove dirt and leaves that it's very good at collecting.

 

Yes ~ that would be interesting. Benz crossflow Al radiators seem to tolerate sea air far better. I'm sure they must be using some plating or anodising process on their radiators.

Of course you folk have the salt applied to roads to contend with.

 

What thermostats are you using? There has been quite a bit of discussion on the XJS forum about that. The main finding is that the OEM thermostats do not extend the "foot" far enough to block off the bypass passage, so the coolant is not forced to go through the radiator. At best, they only move about half the required distance.

You need a different thermostat to fully block off the passage, and when I put them in my 6.0 XJS it made quite a difference to the runnign temperatures. You're looking for a hot distance from the flange to the foot of at least 42mm. I tested some OEM Waxstat's supplied by the dealer and they only extended to 38mm. Some information here: https://www.jaguarforums.com/forum/x...6/#post2089256

 

Thank you for the suggestion and link. Grant's ideas are consistent with my own experience. However, I've never tested the dimensions of the thermostat when hot, but the thermostats have always been from the local Jaguar distributor or more recently SNG Barrett, so they 'should' be correct, but as you noted the dealers can't be trusted any more for our old cars.

At speed, even in hot weather, everything is OK. The problem has generally developed slowly as the radiator has aged and has always been worse at low speed. I think the radiator aerodynamics are much better in the XJS than the saloons and the viscous fan arrangement in my car wasn't working as well as it mght at low speed.

I've still got a few jobs before the car is back on the road. Once it is, I'll see how it goes and make the stats the next point to investigate.

Thanks again,

Peter

 

Even on our XK engines the size and position of our bypass slot varies and requires thermostats with different shrouds. Some can be difficult to locate. Fortunately the C3731/1 works a treat on the S type B Type head with narrow slot. Manufactured by Barratts.






C3731/1

 

I did look at the thermostat Barrants offers, but there is still a fair sized gap between the bore of the intake manifold and the sliding sleeve. I ended up making my own, adapting a "Series" Land Rover thermostat and adding an extra piece of brass such that the gap is less than a millimetre. It seems to work well.

 

I measured mine before installation & followed the SA crew with the C3731/1 & it works well & creates enough blanking of the slit, But I do have a tropical radiator with far greater capacity so it's not critical that I get every ounce of coolant to go via the radiator. It is one of the few mistakes in the parts manual ~ picture is correct (90). Thermostat part number is wrong. (conventional thermostat without sleeve). If the slight gap worries you a brass sleeve is available. No idea of the P/N.

For racing they either block the bypass port or fit a plug in the tube with a hole drilled in the centre.

Thermostat is 90 in PM. Sorry I cut off the 90 here.




Sleeve.