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Cooling system

The cooling system of the TR6 actually works quite well…. Actually…. If you fix a few design flaws and mostly make up for lack of maintenance….


If you have fitted the “air deflector cardboard”, more than enough airflow is forced through the radiator to get rid of the heat… “Uprated special aluminum radiators” are only needed if you have tuned the engine extremely or the system is not working properly for other reasons.


This “thing” that always provides cooling at exactly the wrong time:

* When the oil/water is still cold
* At high speeds/revs\

And exactly not when you need it:

* In traffic jams/city traffic

Solution: Throw out this heavy crankshaft extension and install an electric fan…

* Consumes less energy
* Cools when it is necessary
* Doesn't cool when it would do harm (e.g. the oil doesn't get warm in winter…)

My solution: Fan from HONDA Jazz II (GD-GE) 1.4 61 kW 83 PS (03.2002-07.2008)
Water pump cover from Ford Fiesta II (good for venting and space for a thermal switch)
and an FEK (Fan Elimination Kit) to keep the pulley in place.
You just have to be careful with the space under the hood:

But that doesn't help if the system is dirty…
This happens if you use tap water and too little radiator antifreeze - which also helps against rust: Then the “frost plugs” in the head and engine block rust and the radiator+head become clogged with limescale… This has happened to many US models because it doesn't freeze much in California, Texas etc. ….

Then the only thing that helps


I used citric acid (Ebay 5Kg/15€) (100g/litre) and plenty of distilled/deionized water, as Mercedes also has in the maintenance plan for its vehicles after 200tKm…

* Drive the car onto the ramps so that you can reach the radiator at the bottom… Run the engine briefly at a higher speed…this will stir up the dirt…Don't wait for the thermostat to open! Then you'll only burn your fingers…

* Drain the cooling water from the radiator (I disconnected the large return hose at the bottom) and the engine (screw at the rear right under the manifold of cylinder six SW 3/4“)… The drain plug on the engine probably needs a lot of persuasion…and then the channel behind it will be completely blocked….

* Dispose of the old fluid properly, rinse with fresh (tap) water…You can disconnect the hoses that go to the heater from the bulkhead and hold a garden hose to it…

* Fill in citric acid solution (6 liters of distilled water + approx. 600gr citric acid powder)…close all holes beforehand8-) and drive a lap with the heater open until the thermostat opens and the radiator is also flushed…


Do not remove the thermostat for the work! Otherwise the cooling water pump will only pump the water in the radiator in a circle and the engine will not get enough cooling power! I drove for 20 minutes at high revs on the country road…

* Let everything cool down a bit and then drain and dispose of it….After that, rinse properly!

DO NOT LEAVE IT ON FOR MORE THAN A FEW HOURS, OTHERWISE SOME OLD PART WILL GIVE UP UNDER THE PRESSURE OF CITRIC ACID! * Fill up the system with 3 liters of Glysanthin G48 and distilled water… * Translated with (free version) ***


Since my engine no longer runs as rich as it did with the mechanical injection and I sometimes accelerate, I wanted to install an oil cooler to prevent the oil temperature from getting too high and to relieve the water cooler….You can buy overpriced stuff from specialized dealers….or a “Universal oil cooler with thermostat for BMW AUDI Opel VW” for 105€ including shipping.

To be able to lay the hoses properly, a few (I took 3 pieces) “Dash 10/AN10 double hose holder, clamp 19-19.5mm” for 6€ / piece

Then I made 2 more holders from square tubing

and installed everything at the next oil change: I only had to shorten the hoses a little, but that's no problem with the dash fitting…you can find videos on Youtube…

Now I have an oil temperature of less than 100° and water temperature of 85° even at a constant 180 km/h.

en/start/2_tr6/kuehlung.txt · Last modified: 18:43 11 /11/2023 by peter