View Full Version : TR6 flushing your cooling system, TR6 car specific

08-09-2009, 03:10 PM
I decided to flush the cooling system on my TR6, but its really not specific to a TR6 any british car could be of benifit. purchased the radiator flush at the autoparts store, followed the directions on the product. The active chemical is sodium citrate. I didnt have a temp problem but just decided to flush the system and put in new antifreez and water wetter.

my question is does this sodium citrate really do anything, disolve anything, or help in cleaning the cooling passages? or just remove dollars from your bank account?

doing a google search seems like its a mild acid solution.

has anyone one used their on solution like muratic acid, Potassium hydroxide, something that disolves rust?
I usually am an experimenter but now thanks to the internet I ask questions first and do some research before I mess up something

Just curious


08-09-2009, 06:55 PM
The sodium citrate based cleaners do seem to help a little, but not very much. If you are not having problems and just want to clean it out a bit; that's just what you want.

Don't forget that there are copper, lead and aluminum alloys all exposed to coolant (plus whatever your water pump seals are made of). Using a stronger chemical on an otherwise running engine might not be such a good idea.

OTOH, if it already looks like this, maybe it doesn't matter <<GRAEMLIN_URL>>/grin.gif


08-09-2009, 07:02 PM
That picture just made me loose my appetite...

02-06-2010, 10:57 AM
If you are flushing the block, I think it is worth removing the plug in the block around the 4th or 5th cylinder on the manifold side. Spray the hose in there and reverse flush it as well. To do a good job you need to have the thermostat out and the radiator hoses disconnected so you don't flush any rust back into the radiator. It is surprising how much rust can build in the back portion of the block.

02-06-2010, 12:59 PM
Not unusual to have to chip away the crud, if it hasn't been cleaned in awhile. Took me several hours to get the equivalent drain hole opened up on my Stag, and I usually have to poke something through the hole to drain the block on the TR3.

Andrew Mace
02-06-2010, 01:02 PM
Not unusual to have to chip away the crud, if it hasn't been cleaned in awhile. Took me several hours to get the equivalent drain hole opened up on my Stag, and I usually have to poke something through the hole to drain the block on the TR3. :iagree: Having done no more than clearing the obstructions and using lots of water to flush, and then the usual refill with antifreeze mix, I've had cars then run 20-30 degrees cooler as shown on the dashboard gauge!

02-06-2010, 05:56 PM
Here's a pic of my TR6 car-specific backflush device..... works like a charm!


02-06-2010, 09:35 PM
That ought to work pretty well Kevin.

02-08-2010, 10:55 PM
make sure to open the heater valve &amp; keep changing the direction of the water in &amp; out of the heater. Mine took about 1.5 hours to get water that did not look like mud.

My TR-6 had been in storage. I drove it about a week before sediments clogged &amp; ruined the radiator.

Gerry M
06-27-2015, 05:04 PM
Is that the lower rad hose?

06-28-2015, 12:15 AM
I sent my block out for a commercial hot tank soak. After almost three days in the tank, I found that the drain hole was plugged. To make a long story short, this is what I pulled out of the block: https://bullfire.net/TR6/TR6-4/SDC12613a.JPG I believe it is probably casting sand.

I now do my own block and head soaks: https://bullfire.net/TR6/TR6-17/TR6-17.html

I think the phosphoric acid would also work as a flush, but I'd be careful about how long I left it in the engine. As others have mentioned, there are some metals in the system that may be affected.


06-28-2015, 12:34 AM
I miss Paul!

06-28-2015, 03:09 AM
Not too much to add to this, except I remember the first time I tried to use the block drain hole on my TR4a and nothing came out. I tried poking a stiff wire in there, still nothing, ended up turning a drill bit by had, did the trick, definitely a good idea to try to drain and flush the block. Also I when I get a car that is old and has been sitting a while I will usually just pull the radiator and reverse flush it with a garden hose, and also kind of shake it, tap it gently on something hard to encourage loose bits of rust and scale to come off. Very easy to remove the radiator on a TR4-6, as I recall you guys with sidescreen TRs don't have quite that easy of a time with it.

Also Hey Ed_h, practically your neighbor.

06-28-2015, 08:48 AM
My engine was rebuilt 15 years ago - engine and rad were hot tanked at the time. I run a completely stock cooling set up and never had any cooling issues. I run pretty much a 50/50 Coolant/H2O mix. However, as preventive maintenance I do a cooling flush (with the OTC Radiator Flush products) every other year for preventive maintenance. I do not back flush it for fear of stirring up too much crud and getting it jammed in heater or radiator cores. And, I will say the color of the coolant when I initially drain it every 2 years is pretty good. Then, I follow the instructions on the bottle and keep draining/refilling until nothing but clear water comes out. BTW, I only use distilled water.


06-28-2015, 10:36 AM
Also Hey Ed_h, practically your neighbor.

Good to know there is a fellow Cornhusker here. What part of the State?